Internet DRAFT - draft-ietf-teep-protocol
draft-ietf-teep-protocol
TEEP H. Tschofenig
Internet-Draft
Intended status: Standards Track M. Pei
Expires: 14 September 2023 Broadcom
D. Wheeler
Amazon
D. Thaler
Microsoft
A. Tsukamoto
13 March 2023
Trusted Execution Environment Provisioning (TEEP) Protocol
draft-ietf-teep-protocol-12
Abstract
This document specifies a protocol that installs, updates, and
deletes Trusted Components in a device with a Trusted Execution
Environment (TEE). This specification defines an interoperable
protocol for managing the lifecycle of Trusted Components.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 14 September 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Message Overview . . . . . . . . . . . . . . . . . . . . . . 5
4. Detailed Messages Specification . . . . . . . . . . . . . . . 6
4.1. Creating and Validating TEEP Messages . . . . . . . . . . 7
4.1.1. Creating a TEEP message . . . . . . . . . . . . . . . 7
4.1.2. Validating a TEEP Message . . . . . . . . . . . . . . 7
4.2. QueryRequest Message . . . . . . . . . . . . . . . . . . 8
4.3. QueryResponse Message . . . . . . . . . . . . . . . . . . 10
4.3.1. Evidence and Attestation Results . . . . . . . . . . 14
4.4. Update Message . . . . . . . . . . . . . . . . . . . . . 15
4.4.1. Scenario 1: Having one SUIT Manifest pointing to a URI
of a Trusted Component Binary . . . . . . . . . . . . 18
4.4.2. Scenario 2: Having a SUIT Manifest include the Trusted
Component Binary . . . . . . . . . . . . . . . . . . 21
4.4.3. Scenario 3: Supplying Personalization Data for the
Trusted Component Binary . . . . . . . . . . . . . . 22
4.4.4. Scenario 4: Unlinking a Trusted Component . . . . . . 24
4.5. Success Message . . . . . . . . . . . . . . . . . . . . . 25
4.6. Error Message . . . . . . . . . . . . . . . . . . . . . . 26
5. EAT Profile . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.1. Relationship to AR4SI . . . . . . . . . . . . . . . . . . 31
6. Mapping of TEEP Message Parameters to CBOR Labels . . . . . . 32
7. Behavior Specification . . . . . . . . . . . . . . . . . . . 33
7.1. TAM Behavior . . . . . . . . . . . . . . . . . . . . . . 33
7.1.1. Handling a QueryResponse Message . . . . . . . . . . 34
7.1.1.1. Handling an Attestation Result . . . . . . . . . 34
7.1.2. Handling a Success or Error Message . . . . . . . . . 36
7.2. TEEP Agent Behavior . . . . . . . . . . . . . . . . . . . 36
8. Cipher Suites . . . . . . . . . . . . . . . . . . . . . . . . 37
8.1. TEEP Messages . . . . . . . . . . . . . . . . . . . . . . 38
8.2. EATs and SUIT Reports . . . . . . . . . . . . . . . . . . 40
9. Freshness Mechanisms . . . . . . . . . . . . . . . . . . . . 40
10. Security Considerations . . . . . . . . . . . . . . . . . . . 41
11. Privacy Considerations . . . . . . . . . . . . . . . . . . . 43
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 44
12.1. Media Type Registration . . . . . . . . . . . . . . . . 44
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 44
13.1. Normative References . . . . . . . . . . . . . . . . . . 45
13.2. Informative References . . . . . . . . . . . . . . . . . 47
A. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 48
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B. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 48
C. Complete CDDL . . . . . . . . . . . . . . . . . . . . . . . . 48
D. Examples of Diagnostic Notation and Binary Representation . . 52
D.1. QueryRequest Message . . . . . . . . . . . . . . . . . . 53
D.1.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 53
D.1.2. CBOR Binary Representation . . . . . . . . . . . . . 53
D.2. Entity Attestation Token . . . . . . . . . . . . . . . . 54
D.2.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 54
D.3. QueryResponse Message . . . . . . . . . . . . . . . . . . 55
D.3.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 55
D.3.2. CBOR Binary Representation . . . . . . . . . . . . . 56
D.4. Update Message . . . . . . . . . . . . . . . . . . . . . 57
D.4.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 57
D.4.2. CBOR Binary Representation . . . . . . . . . . . . . 59
D.5. Success Message . . . . . . . . . . . . . . . . . . . . . 59
D.5.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 59
D.5.2. CBOR Binary Representation . . . . . . . . . . . . . 59
D.6. Error Message . . . . . . . . . . . . . . . . . . . . . . 60
D.6.1. CBOR Diagnostic Notation . . . . . . . . . . . . . . 60
D.6.2. CBOR binary Representation . . . . . . . . . . . . . 60
E. Examples of SUIT Manifests . . . . . . . . . . . . . . . . . 60
Example 1: SUIT Manifest pointing to URI of the Trusted Component
Binary . . . . . . . . . . . . . . . . . . . . . . . . . 61
CBOR Diagnostic Notation of SUIT Manifest . . . . . . . . . . 61
CBOR Binary in Hex . . . . . . . . . . . . . . . . . . . . . 62
Example 2: SUIT Manifest including the Trusted Component
Binary . . . . . . . . . . . . . . . . . . . . . . . . . 62
CBOR Diagnostic Notation of SUIT Manifest . . . . . . . . . . 62
CBOR Binary in Hex . . . . . . . . . . . . . . . . . . . . . 64
Example 3: Supplying Personalization Data for Trusted Component
Binary . . . . . . . . . . . . . . . . . . . . . . . . . 64
CBOR Diagnostic Notation of SUIT Manifest . . . . . . . . . . 64
CBOR Binary in Hex . . . . . . . . . . . . . . . . . . . . . 66
E.4. Example 4: Unlink a Trusted Component . . . . . . . . . . 66
CBOR Diagnostic Notation of SUIT Manifest . . . . . . . . . . 66
CBOR Binary in Hex . . . . . . . . . . . . . . . . . . . . . 67
F. Examples of SUIT Reports . . . . . . . . . . . . . . . . . . 68
F.1. Example 1: Success . . . . . . . . . . . . . . . . . . . 68
F.2. Example 2: Faiure . . . . . . . . . . . . . . . . . . . . 68
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 69
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1. Introduction
The Trusted Execution Environment (TEE) concept has been designed to
separate a regular operating system, also referred as a Rich
Execution Environment (REE), from security-sensitive applications.
In a TEE ecosystem, device vendors may use different operating
systems in the REE and may use different types of TEEs. When Trusted
Component Developers or Device Administrators use Trusted Application
Managers (TAMs) to install, update, and delete Trusted Applications
and their dependencies on a wide range of devices with potentially
different TEEs then an interoperability need arises.
This document specifies the protocol for communicating between a TAM
and a TEEP Agent.
The Trusted Execution Environment Provisioning (TEEP) architecture
document [I-D.ietf-teep-architecture] provides design guidance and
introduces the necessary terminology.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This specification re-uses the terminology defined in
[I-D.ietf-teep-architecture].
As explained in Section 4.4 of that document, the TEEP protocol
treats each Trusted Application (TA), any dependencies the TA has,
and personalization data as separate components that are expressed in
SUIT manifests, and a SUIT manifest might contain or reference
multiple binaries (see [I-D.ietf-suit-manifest] for more details).
As such, the term Trusted Component (TC) in this document refers to a
set of binaries expressed in a SUIT manifest, to be installed in a
TEE. Note that a Trusted Component may include one or more TAs and/
or configuration data and keys needed by a TA to operate correctly.
Each Trusted Component is uniquely identified by a SUIT Component
Identifier (see [I-D.ietf-suit-manifest] Section 8.7.2.2).
Attestation related terms, such as Evidence and Attestation Results,
are as defined in [RFC9334].
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3. Message Overview
The TEEP protocol consists of messages exchanged between a TAM and a
TEEP Agent. The messages are encoded in CBOR and designed to provide
end-to-end security. TEEP protocol messages are signed by the
endpoints, i.e., the TAM and the TEEP Agent, but Trusted Applications
may also be encrypted and signed by a Trusted Component Developer or
Device Administrator. The TEEP protocol not only uses CBOR but also
the respective security wrapper, namely COSE [RFC9052]. Furthermore,
for software updates the SUIT manifest format
[I-D.ietf-suit-manifest] is used, and for attestation the Entity
Attestation Token (EAT) [I-D.ietf-rats-eat] format is supported
although other attestation formats are also permitted.
This specification defines five messages: QueryRequest,
QueryResponse, Update, Success, and Error.
A TAM queries a device's current state with a QueryRequest message.
A TEEP Agent will, after authenticating and authorizing the request,
report attestation information, list all Trusted Components, and
provide information about supported algorithms and extensions in a
QueryResponse message. An error message is returned if the request
could not be processed. A TAM will process the QueryResponse message
and determine whether to initiate subsequent message exchanges to
install, update, or delete Trusted Applications.
+------------+ +-------------+
| TAM | |TEEP Agent |
+------------+ +-------------+
QueryRequest ------->
QueryResponse
<------- or
Error
With the Update message a TAM can instruct a TEEP Agent to install
and/or delete one or more Trusted Components. The TEEP Agent will
process the message, determine whether the TAM is authorized and
whether the Trusted Component has been signed by an authorized
Trusted Component Signer. A Success message is returned when the
operation has been completed successfully, or an Error message
otherwise.
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+------------+ +-------------+
| TAM | |TEEP Agent |
+------------+ +-------------+
Update ---->
Success
<---- or
Error
4. Detailed Messages Specification
TEEP messages are protected by the COSE_Sign1 or COSE_Sign structure
as described in Section 8.1. The TEEP protocol messages are
described in CDDL format [RFC8610] below.
teep-message = $teep-message-type .within teep-message-framework
teep-message-framework = [
type: $teep-type / $teep-type-extension,
options: { * teep-option },
* any; further elements, e.g., for data-item-requested
]
teep-option = (uint => any)
; messages defined below:
$teep-message-type /= query-request
$teep-message-type /= query-response
$teep-message-type /= update
$teep-message-type /= teep-success
$teep-message-type /= teep-error
; message type numbers, uint .size 1 which takes a number from 0 to 23
$teep-type = uint .size 1
TEEP-TYPE-query-request = 1
TEEP-TYPE-query-response = 2
TEEP-TYPE-update = 3
TEEP-TYPE-teep-success = 5
TEEP-TYPE-teep-error = 6
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4.1. Creating and Validating TEEP Messages
4.1.1. Creating a TEEP message
To create a TEEP message, the following steps are performed.
1. Create a TEEP message according to the description below and
populate it with the respective content. TEEP messages sent by
TAMs (QueryRequest and Update) can include a "token". The TAM
can decide, in any implementation-specific way, whether to
include a token in a message. The first usage of a token
generated by a TAM MUST be randomly created. Subsequent token
values MUST be different for each subsequent message created by a
TAM.
2. Create a COSE Header containing the desired set of Header
Parameters. The COSE Header MUST be valid per the [RFC9052]
specification.
3. Create a COSE_Sign1 or COSE_Sign object using the TEEP message as
the COSE_Sign1 or COSE_Sign Payload; all steps specified in
[RFC9052] for creating a COSE_Sign1 or COSE_Sign object MUST be
followed.
4.1.2. Validating a TEEP Message
When TEEP message is received (see the ProcessTeepMessage conceptual
API defined in [I-D.ietf-teep-architecture] section 6.2.1), the
following validation steps are performed. If any of the listed steps
fail, then the TEEP message MUST be rejected.
1. Verify that the received message is a valid CBOR object.
2. Verify that the message contains a COSE_Sign1 or COSE_Sign
structure.
3. Verify that the resulting COSE Header includes only parameters
and values whose syntax and semantics are both understood and
supported or that are specified as being ignored when not
understood.
4. Follow the steps specified in Section 4 of [RFC9052] ("Signing
Objects") for validating a COSE_Sign1 or COSE_Sign object. The
COSE_Sign1 or COSE_Sign payload is the content of the TEEP
message.
5. Verify that the TEEP message is a valid CBOR map and verify the
fields of the TEEP message according to this specification.
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4.2. QueryRequest Message
A QueryRequest message is used by the TAM to learn information from
the TEEP Agent, such as the features supported by the TEEP Agent,
including cipher suites and protocol versions. Additionally, the TAM
can selectively request data items from the TEEP Agent via the
request parameter. Currently, the following features are supported:
* Request for attestation information,
* Listing supported extensions,
* Querying installed Trusted Components, and
* Listing supported SUIT commands.
Like other TEEP messages, the QueryRequest message is signed, and the
relevant CDDL snippet is shown below. The complete CDDL structure is
shown in Appendix C.
query-request = [
type: TEEP-TYPE-query-request,
options: {
? token => bstr .size (8..64),
? supported-freshness-mechanisms => [ + $freshness-mechanism ],
? challenge => bstr .size (8..512),
? versions => [ + version ],
* $$query-request-extensions,
* $$teep-option-extensions
},
supported-teep-cipher-suites: [ + $teep-cipher-suite ],
supported-suit-cose-profiles: [ + $suit-cose-profile ],
data-item-requested: uint .bits data-item-requested
]
The message has the following fields:
type
The value of (1) corresponds to a QueryRequest message sent from
the TAM to the TEEP Agent.
token
The value in the token parameter is used to match responses to
requests, such as to look up any implementation-specific state it
might have saved about that request, or to ignore responses to
older QueryRequest messages before some configuration changes were
made that affected their content. This is particularly useful
when a TAM issues multiple concurrent requests to a TEEP Agent.
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The token MUST be present if and only if the attestation bit is
clear in the data-item-requested value. The size of the token is
at least 8 bytes (64 bits) and maximum of 64 bytes, which is the
same as in an EAT Nonce Claim (see [I-D.ietf-rats-eat]
Section 3.3). The first usage of a token generated by a TAM MUST
be randomly created. Subsequent token values MUST be different
for each request message to distinguish the correct response from
multiple requests. The token value MUST NOT be used for other
purposes, such as a TAM to identify the devices and/or a device to
identify TAMs or Trusted Components. The TAM SHOULD set an
expiration time for each token and MUST ignore any messages with
expired tokens. The TAM MUST expire the token value after
receiving the first response containing the token value and ignore
any subsequent messages that have the same token value.
supported-teep-cipher-suites
The supported-teep-cipher-suites parameter lists the TEEP cipher
suites supported by the TAM. Details about the cipher suite
encoding can be found in Section 8.1.
supported-suit-cose-profiles
The supported-suit-cose-profiles parameter lists the SUIT profiles
supported by the TAM. Details about the cipher suite encoding can
be found in Section 8.2.
data-item-requested
The data-item-requested parameter indicates what information the
TAM requests from the TEEP Agent in the form of a bitmap.
attestation (1) With this value the TAM requests the TEEP Agent
to return an attestation payload, whether Evidence (e.g., an
EAT) or an Attestation Result, in the response.
trusted-components (2) With this value the TAM queries the TEEP
Agent for all installed Trusted Components.
extensions (4) With this value the TAM queries the TEEP Agent for
supported capabilities and extensions, which allows a TAM to
discover the capabilities of a TEEP Agent implementation.
suit-reports (8) With this value the TAM requests the TEEP Agent
to return SUIT Reports in the response.
Further values may be added in the future.
supported-freshness-mechanisms
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The supported-freshness-mechanisms parameter lists the freshness
mechanism(s) supported by the TAM. Details about the encoding can
be found in Section 9. If this parameter is absent, it means only
the nonce mechanism is supported. It MUST be absent if the
attestation bit is clear.
challenge
The challenge field is an optional parameter used for ensuring the
freshness of the attestation payload returned with a QueryResponse
message. It MUST be absent if the attestation bit is clear (since
the token is used instead in that case). When a challenge is
provided in the QueryRequest and an EAT is returned with a
QueryResponse message then the challenge contained in this request
MUST be used to generate the EAT, such as by copying the challenge
into the eat_nonce in the EAT profile Section 5 if using the Nonce
freshness mechanism. For more details see Section 9.
If any format other than EAT is used, it is up to that format to
define the use of the challenge field.
versions
The versions parameter enumerates the TEEP protocol version(s)
supported by the TAM. A value of 0 refers to the current version
of the TEEP protocol. If this field is not present, it is to be
treated the same as if it contained only version 0.
4.3. QueryResponse Message
The QueryResponse message is the successful response by the TEEP
Agent after receiving a QueryRequest message. As discussed in
Section 7.2, it can also be sent unsolicited if the contents of the
QueryRequest are already known and do not vary per message.
Like other TEEP messages, the QueryResponse message is signed, and
the relevant CDDL snippet is shown below. The complete CDDL
structure is shown in Appendix C.
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query-response = [
type: TEEP-TYPE-query-response,
options: {
? token => bstr .size (8..64),
? selected-teep-cipher-suite => $teep-cipher-suite,
? selected-version => version,
? attestation-payload-format => text,
? attestation-payload => bstr,
? suit-reports => [ + bstr ],
? tc-list => [ + system-property-claims ],
? requested-tc-list => [ + requested-tc-info ],
? unneeded-manifest-list => [ + SUIT_Component_Identifier ],
? ext-list => [ + ext-info ],
* $$query-response-extensions,
* $$teep-option-extensions
}
]
requested-tc-info = {
component-id => SUIT_Component_Identifier,
? tc-manifest-sequence-number => uint .size 8,
? have-binary => bool
}
The QueryResponse message has the following fields:
type
The value of (2) corresponds to a QueryResponse message sent from
the TEEP Agent to the TAM.
token
The value in the token parameter is used to match responses to
requests. The value MUST correspond to the value received with
the QueryRequest message if one was present, and MUST be absent if
no token was present in the QueryRequest.
selected-teep-cipher-suite
The selected-teep-cipher-suite parameter indicates the selected
TEEP cipher suite. If this parameter is not present, it is to be
treated as if the TEEP Agent accepts any TEEP cipher suites listed
in the QueryRequest, so the TAM can select one. Details about the
TEEP cipher suite encoding can be found in Section 8.1.
selected-version
The selected-version parameter indicates the TEEP protocol version
selected by the TEEP Agent. The absence of this parameter
indicates the same as if it was present with a value of 0.
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attestation-payload-format
The attestation-payload-format parameter indicates the IANA Media
Type of the attestation-payload parameter, where media type
parameters are permitted after the media type. For protocol
version 0, the absence of this parameter indicates that the format
is "application/eat+cwt;
eat_profile=https://datatracker.ietf.org/doc/html/draft-ietf-teep-
protocol-12" (see [I-D.ietf-rats-eat-media-type] for further
discussion). (RFC-editor: upon RFC publication, replace URI above
with "https://www.rfc-editor.org/info/rfcXXXX" where XXXX is the
RFC number of this document.) It MUST be present if the
attestation-payload parameter is present and the format is not an
EAT in CWT format with the profile defined below in Section 5.
attestation-payload
The attestation-payload parameter contains Evidence or an
Attestation Result. This parameter MUST be present if the
QueryResponse is sent in response to a QueryRequest with the
attestation bit set. If the attestation-payload-format parameter
is absent, the attestation payload contained in this parameter
MUST be an Entity Attestation Token following the encoding defined
in [I-D.ietf-rats-eat]. See Section 4.3.1 for further discussion.
suit-reports
If present, the suit-reports parameter contains a set of "boot"
(including starting an executable in an OS context) time SUIT
Reports as defined by SUIT_Report in Section 4 of
[I-D.ietf-suit-report], encoded using COSE as discussed in
Section 8.2. If a token parameter was present in the QueryRequest
message the QueryResponse message is in response to, the suit-
report-nonce field MUST be present in the SUIT Report with a value
matching the token parameter in the QueryRequest message. SUIT
Reports can be useful in QueryResponse messages to pass
information to the TAM without depending on a Verifier including
the relevant information in Attestation Results.
tc-list
The tc-list parameter enumerates the Trusted Components installed
on the device in the form of system-property-claims objects, as
defined in Section 4 of [I-D.ietf-suit-report]. The system-
property-claims can be used to learn device identifying
information and TEE identifying information for distinguishing
which Trusted Components to install in the TEE. This parameter
MUST be present if the QueryResponse is sent in response to a
QueryRequest with the trusted-components bit set.
requested-tc-list
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The requested-tc-list parameter enumerates the Trusted Components
that are not currently installed in the TEE, but which are
requested to be installed, for example by an installer of an
Untrusted Application that has a TA as a dependency, or by a
Trusted Application that has another Trusted Component as a
dependency. Requested Trusted Components are expressed in the
form of requested-tc-info objects. A TEEP Agent can get this
information from the RequestTA conceptual API defined in
[I-D.ietf-teep-architecture] section 6.2.1.
unneeded-manifest-list
The unneeded-manifest-list parameter enumerates the SUIT manifests
whose components are currently installed in the TEE, but which are
no longer needed by any other application. The TAM can use this
information in determining whether a SUIT manifest can be
unlinked. Each unneeded SUIT manifest is identified by its SUIT
Manifest Component ID (note that this is the Component ID for the
manifest itself, which is different from the Component ID of a
component installed by the manifest, see
[I-D.ietf-suit-trust-domains] for more discussion). A TEEP Agent
can get this information from the UnrequestTA conceptual API
defined in [I-D.ietf-teep-architecture] section 6.2.1.
ext-list
The ext-list parameter lists the supported extensions. This
document does not define any extensions. This parameter MUST be
present if the QueryResponse is sent in response to a QueryRequest
with the extensions bit set.
The requested-tc-info message has the following fields:
component-id
A SUIT Component Identifier.
tc-manifest-sequence-number
The minimum suit-manifest-sequence-number value from a SUIT
manifest for the Trusted Component. If not present, indicates
that any sequence number will do.
have-binary
If present with a value of true, indicates that the TEEP agent
already has the Trusted Component binary and only needs an Update
message with a SUIT manifest that authorizes installing it. If
have-binary is true, the tc-manifest-sequence-number field MUST be
present.
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4.3.1. Evidence and Attestation Results
Section 7 of [I-D.ietf-teep-architecture] lists information that may
appear in Evidence depending on the circumstance. However, the
Evidence is opaque to the TEEP protocol and there are no formal
requirements on the contents of Evidence.
TAMs however consume Attestation Results and do need enough
information therein to make decisions on how to remediate a TEE that
is out of compliance, or update a TEE that is requesting an
authorized change. To do so, the information in Section 7 of
[I-D.ietf-teep-architecture] is often required depending on the
policy.
Attestation Results SHOULD use Entity Attestation Tokens (EATs). Use
of any other format, such as a widely implemented format for a
specific processor vendor, is permitted but increases the complexity
of the TAM by requiring it to understand the format for each such
format rather than only the common EAT format so is not recommended.
When an EAT is used, the following claims can be used to meet those
requirements, whether these claims appear in Attestation Results, or
in Evidence for the Verifier to use when generating Attestation
Results of some form:
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+=================+===========+====================================+
| Requirement | Claim | Reference |
+=================+===========+====================================+
| Freshness proof | nonce | Section 4.1 of [I-D.ietf-rats-eat] |
+-----------------+-----------+------------------------------------+
| Device unique | ueid | Section 4.2.1 of |
| identifier | | [I-D.ietf-rats-eat] |
+-----------------+-----------+------------------------------------+
| Vendor of the | oemid | Section 4.2.3 of |
| device | | [I-D.ietf-rats-eat] |
+-----------------+-----------+------------------------------------+
| Class of the | hwmodel | Section 4.2.4 of |
| device | | [I-D.ietf-rats-eat] |
+-----------------+-----------+------------------------------------+
| TEE hardware | hwversion | Section 4.2.5 of |
| type | | [I-D.ietf-rats-eat] |
+-----------------+-----------+------------------------------------+
| TEE hardware | hwversion | Section 4.2.5 of |
| version | | [I-D.ietf-rats-eat] |
+-----------------+-----------+------------------------------------+
| TEE firmware | manifests | Section 4.2.15 of |
| type | | [I-D.ietf-rats-eat] |
+-----------------+-----------+------------------------------------+
| TEE firmware | manifests | Section 4.2.15 of |
| version | | [I-D.ietf-rats-eat] |
+-----------------+-----------+------------------------------------+
Table 1
The "manifests" claim should include information about the TEEP Agent
as well as any of its dependencies such as firmware.
4.4. Update Message
The Update message is used by the TAM to install and/or delete one or
more Trusted Components via the TEEP Agent. It can also be used to
pass a successful Attestation Report back to the TEEP Agent when the
TAM is configured as an intermediary between the TEEP Agent and a
Verifier, as shown in the figure below, where the Attestation Result
passed back to the Attester can be used as a so-called "passport"
(see section 5.1 of [RFC9334]) that can be presented to other Relying
Parties.
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+---------------+
| Verifier |
+---------------+
^ | Attestation
Evidence | v Result
+---------------+
| TAM / |
| Relying Party |
+---------------+
QueryResponse ^ | Update
(Evidence) | | (Attestation
| v Result)
+---------------+ +---------------+
| TEEP Agent |------------>| Other |
| / Attester | Attestation | Relying Party |
+---------------+ Result +---------------+
Figure 1: Example use of TEEP and attestation
Like other TEEP messages, the Update message is signed, and the
relevant CDDL snippet is shown below. The complete CDDL structure is
shown in Appendix C.
update = [
type: TEEP-TYPE-update,
options: {
? token => bstr .size (8..64),
? unneeded-manifest-list => [ + SUIT_Component_Identifier ],
? manifest-list => [ + bstr .cbor SUIT_Envelope ],
? attestation-payload-format => text,
? attestation-payload => bstr,
? err-code => uint .size 1,
? err-msg => text .size (1..128),
* $$update-extensions,
* $$teep-option-extensions
}
]
The Update message has the following fields:
type
The value of (3) corresponds to an Update message sent from the
TAM to the TEEP Agent. In case of successful processing, a
Success message is returned by the TEEP Agent. In case of an
error, an Error message is returned. Note that the Update message
is used for initial Trusted Component installation as well as for
updates and deletes.
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token
The value in the token field is used to match responses to
requests.
unneeded-manifest-list
The unneeded-manifest-list parameter enumerates the SUIT manifests
to be unlinked. Each unneeded SUIT manifest is identified by its
SUIT Manifest Component ID.
manifest-list
The manifest-list field is used to convey one or multiple SUIT
manifests to install. A manifest is a bundle of metadata about a
Trusted Component, such as where to find the code, the devices to
which it applies, and cryptographic information protecting the
manifest. The manifest may also convey personalization data.
Trusted Component binaries and personalization data can be signed
and encrypted by the same Trusted Component Signer. Other
combinations are, however, possible as well. For example, it is
also possible for the TAM to sign and encrypt the personalization
data and to let the Trusted Component Developer sign and/or
encrypt the Trusted Component binary.
attestation-payload-format
The attestation-payload-format parameter indicates the IANA Media
Type of the attestation-payload parameter, where media type
parameters are permitted after the media type. The absence of
this parameter indicates that the format is "application/eat+cwt;
eat_profile=https://datatracker.ietf.org/doc/html/draft-ietf-teep-
protocol-12" (see [I-D.ietf-rats-eat-media-type] for further
discussion). (RFC-editor: upon RFC publication, replace URI above
with "https://www.rfc-editor.org/info/rfcXXXX" where XXXX is the
RFC number of this document.) It MUST be present if the
attestation-payload parameter is present and the format is not an
EAT in CWT format with the profile defined below in Section 5.
attestation-payload
The attestation-payload parameter contains an Attestation Result.
This parameter If the attestation-payload-format parameter is
absent, the attestation payload contained in this parameter MUST
be an Entity Attestation Token following the encoding defined in
[I-D.ietf-rats-eat]. See Section 4.3.1 for further discussion.
err-code
The err-code parameter contains one of the error codes listed in
the Section 4.6, which describes the reasons for the error when
performing QueryResponse in the TAM.
err-msg
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The err-msg parameter is human-readable diagnostic text that MUST
be encoded using UTF-8 [RFC3629] in Net-Unicode format [RFC5198]
with a maximum of 128 bytes.
Note that an Update message carrying one or more SUIT manifests will
inherently involve multiple signatures, one by the TAM in the TEEP
message and one from a Trusted Component Signer inside each manifest.
This is intentional as they are for different purposes.
The TAM is what authorizes apps to be installed, updated, and deleted
on a given TEE and so the TEEP signature is checked by the TEEP Agent
at protocol message processing time. (This same TEEP security
wrapper is also used on messages like QueryRequest so that Agents
only send potentially sensitive data such as Evidence to trusted
TAMs.)
The Trusted Component signer on the other hand is what authorizes the
Trusted Component to actually run, so the manifest signature could be
checked at install time or load (or run) time or both, and this
checking is done by the TEE independent of whether TEEP is used or
some other update mechanism. See section 5 of
[I-D.ietf-teep-architecture] for further discussion.
The Update Message has a SUIT_Envelope containing SUIT manifests.
Following are some example scenarios using SUIT manifests in the
Update Message.
4.4.1. Scenario 1: Having one SUIT Manifest pointing to a URI of a
Trusted Component Binary
In this scenario, a SUIT Manifest has a URI pointing to a Trusted
Component Binary.
A Trusted Component Developer creates a new Trusted Component Binary
and hosts it at a Trusted Component Developer's URI. Then the
Trusted Component Developer generates an associated SUIT manifest
with the filename "tc-uuid.suit" that contains the URI. The filename
"tc-uuid.suit" is used in Scenario 3 later.
The TAM receives the latest SUIT manifest from the Trusted Component
Developer, and the URI it contains will not be changeable by the TAM
since the SUIT manifest is signed by the Trusted Component Developer.
Pros:
* The Trusted Component Developer can ensure that the intact Trusted
Component Binary is downloaded by devices
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* The TAM does not have to send large Update messages containing the
Trusted Component Binary
Cons:
* The Trusted Component Developer must host the Trusted Component
Binary server
* The device must fetch the Trusted Component Binary in another
connection after receiving an Update message
* A device's IP address and therefore location may be revealed to
the Trusted Component Binary server
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+------------+ +-------------+
| TAM | | TEEP Agent |
+------------+ +-------------+
Update ---->
+=================== teep-protocol(TAM) ==================+
| TEEP_Message([ |
| TEEP-TYPE-update, |
| options: { |
| manifest-list: [ |
| += suit-manifest "tc-uuid.suit" (TC Developer) =+ |
| | SUIT_Envelope({ | |
| | manifest: { | |
| | install: { | |
| | override-parameters: { | |
| | uri: "https://example.org/tc-uuid.ta" | |
| | }, | |
| | fetch | |
| | } | |
| | } | |
| | }) | |
| +===============================================+ |
| ] |
| } |
| ]) |
+=========================================================+
and then,
+-------------+ +--------------+
| TEEP Agent | | TC Developer |
+-------------+ +--------------+
<----
fetch "https://example.org/tc-uuid.ta"
+======= tc-uuid.ta =======+
| 48 65 6C 6C 6F 2C 20 ... |
+==========================+
Figure 2: URI of the Trusted Component Binary
For the full SUIT Manifest example binary, see Appendix "Example 1:
SUIT Manifest pointing to URI of the Trusted Component Binary".
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4.4.2. Scenario 2: Having a SUIT Manifest include the Trusted Component
Binary
In this scenario, the SUIT manifest contains the entire Trusted
Component Binary as an integrated payload (see
[I-D.ietf-suit-manifest] Section 7.5).
A Trusted Component Developer delegates the task of delivering the
Trusted Component Binary to the TAM inside the SUIT manifest. The
Trusted Component Developer creates a SUIT manifest and embeds the
Trusted Component Binary, which is referenced in the suit-integrated-
payload element containing the fragment-only reference "#tc", in the
envelope. The Trusted Component Developer transmits the entire
bundle to the TAM.
The TAM serves the SUIT manifest containing the Trusted Component
Binary to the device in an Update message.
Pros:
* The device can obtain the Trusted Component Binary and the SUIT
manifest in one Update message.
* The Trusted Component Developer does not have to host a server to
deliver the Trusted Component Binary to devices.
Cons:
* The TAM must host the Trusted Component Binary rather than
delegating storage to the Trusted Component Developer.
* The TAM must deliver Trusted Component Binaries in Update
messages, which increases the size of the Update message.
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+------------+ +-------------+
| TAM | | TEEP Agent |
+------------+ +-------------+
Update ---->
+=========== teep-protocol(TAM) ============+
| TEEP_Message([ |
| TEEP-TYPE-update, |
| options: { |
| manifest-list: [ |
| +== suit-manifest(TC Developer) ==+ |
| | SUIT_Envelope({ | |
| | manifest: { | |
| | install: { | |
| | override-parameters: { | |
| | uri: "#tc" | |
| | }, | |
| | fetch | |
| | } | |
| | }, | |
| | "#tc": h'48 65 6C 6C ...' | |
| | }) | |
| +=================================+ |
| ] |
| } |
| ]) |
+===========================================+
Figure 3: Integrated Payload with Trusted Component Binary
For the full SUIT Manifest example binary, see Appendix "Example 2:
SUIT Manifest including the Trusted Component Binary".
4.4.3. Scenario 3: Supplying Personalization Data for the Trusted
Component Binary
In this scenario, Personalization Data is associated with the Trusted
Component Binary "tc-uuid.suit" from Scenario 1.
The Trusted Component Developer places Personalization Data in a file
named "config.json" and hosts it on an HTTPS server. The Trusted
Component Developer then creates a SUIT manifest with the URI,
specifying which Trusted Component Binary it correlates to in the
parameter 'dependency-resolution', and signs the SUIT manifest.
The TAM delivers the SUIT manifest of the Personalization Data which
depends on the Trusted Component Binary from Scenario 1.
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+------------+ +-------------+
| TAM | | TEEP Agent |
+------------+ +-------------+
Update ---->
+================= teep-protocol(TAM) ======================+
| TEEP_Message([ |
| TEEP-TYPE-update, |
| options: { |
| manifest-list: [ |
| +======== suit-manifest(TC Developer) ============+ |
| | SUIT_Envelope({ | |
| | manifest: { | |
| | common: { | |
| | dependencies: [ | |
| | {{digest-of-tc.suit}} | |
| | ] | |
| | } | |
| | dependency-resolution: { | |
| | override-parameters: { | |
| | uri: "https://example.org/tc-uuid.suit" | |
| | } | |
| | fetch | |
| | } | |
| | install: { | |
| | override-parameters: { | |
| | uri: "https://example.org/config.json" | |
| | }, | |
| | fetch | |
| | set-dependency-index | |
| | process-dependency | |
| | } | |
| | } | |
| | }) | |
| +=================================================+ |
| ] |
| } |
| ]) |
+===========================================================+
and then,
+-------------+ +--------------+
| TEEP Agent | | TC Developer |
+-------------+ +--------------+
<----
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fetch "https://example.org/config.json"
+=======config.json========+
| 7B 22 75 73 65 72 22 ... |
+==========================+
Figure 4: Personalization Data
For the full SUIT Manifest example binary, see Appendix "Example 3:
Supplying Personalization Data for Trusted Component Binary".
4.4.4. Scenario 4: Unlinking a Trusted Component
A Trusted Component Developer can also generate a SUIT Manifest that
unlinks the installed Trusted Component. The TAM delivers it when
the TAM wants to uninstall the component.
The suit-directive-unlink (see [I-D.ietf-suit-trust-domains] Section-
6.5.4) is located in the manifest to unlink the Trusted Component,
meaning that the reference count is decremented and the component is
deleted when the reference count becomes zero. (If other Trusted
Components depend on it, the reference count will not be zero.)
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+------------+ +-------------+
| TAM | | TEEP Agent |
+------------+ +-------------+
Update ---->
+=========== teep-protocol(TAM) ============+
| TEEP_Message([ |
| TEEP-TYPE-update, |
| options: { |
| manifest-list: [ |
| +== suit-manifest(TC Developer) ==+ |
| | SUIT_Envelope({ | |
| | manifest: { | |
| | install: [ | |
| | unlink | |
| | ] | |
| | } | |
| | }) | |
| +=================================+ |
| ] |
| } |
| ]) |
+===========================================+
Figure 5: Unlink Trusted Component example (summary)
For the full SUIT Manifest example binary, see Appendix E. SUIT
Example 4 (Appendix "E.4. Example 4: Unlink a Trusted Component")
4.5. Success Message
The Success message is used by the TEEP Agent to return a success in
response to an Update message.
Like other TEEP messages, the Success message is signed, and the
relevant CDDL snippet is shown below. The complete CDDL structure is
shown in Appendix C.
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teep-success = [
type: TEEP-TYPE-teep-success,
options: {
? token => bstr .size (8..64),
? msg => text .size (1..128),
? suit-reports => [ + SUIT_Report ],
* $$teep-success-extensions,
* $$teep-option-extensions
}
]
The Success message has the following fields:
type
The value of (5) corresponds to corresponds to a Success message
sent from the TEEP Agent to the TAM.
token
The value in the token parameter is used to match responses to
requests. It MUST match the value of the token parameter in the
Update message the Success is in response to, if one was present.
If none was present, the token MUST be absent in the Success
message.
msg
The msg parameter contains optional diagnostics information
encoded in UTF-8 [RFC3629] using Net-Unicode form [RFC5198] with
max 128 bytes returned by the TEEP Agent.
suit-reports
If present, the suit-reports parameter contains a set of SUIT
Reports as defined in Section 4 of [I-D.ietf-suit-report]. If a
token parameter was present in the Update message the Success
message is in response to, the suit-report-nonce field MUST be
present in the SUIT Report with a value matching the token
parameter in the Update message.
4.6. Error Message
The Error message is used by the TEEP Agent to return an error in
response to a message from the TAM.
Like other TEEP messages, the Error message is signed, and the
relevant CDDL snippet is shown below. The complete CDDL structure is
shown in Appendix C.
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teep-error = [
type: TEEP-TYPE-teep-error,
options: {
? token => bstr .size (8..64),
? err-msg => text .size (1..128),
? supported-teep-cipher-suites => [ + $teep-cipher-suite ],
? supported-freshness-mechanisms => [ + $freshness-mechanism ],
? versions => [ + version ],
? suit-reports => [ + SUIT_Report ],
* $$teep-error-extensions,
* $$teep-option-extensions
},
err-code: uint .size 1
]
The Error message has the following fields:
type
The value of (6) corresponds to an Error message sent from the
TEEP Agent to the TAM.
token
The value in the token parameter is used to match responses to
requests. It MUST match the value of the token parameter in the
message the Success is in response to, if one was present. If
none was present, the token MUST be absent in the Error message.
err-msg
The err-msg parameter is human-readable diagnostic text that MUST
be encoded using UTF-8 [RFC3629] using Net-Unicode form [RFC5198]
with max 128 bytes.
supported-teep-cipher-suites
The supported-teep-cipher-suites parameter lists the TEEP cipher
suite(s) supported by the TEEP Agent. Details about the cipher
suite encoding can be found in Section 8.1. This otherwise
optional parameter MUST be returned if err-code is
ERR_UNSUPPORTED_CIPHER_SUITES.
supported-freshness-mechanisms
The supported-freshness-mechanisms parameter lists the freshness
mechanism(s) supported by the TEEP Agent. Details about the
encoding can be found in Section 9. This otherwise optional
parameter MUST be returned if err-code is
ERR_UNSUPPORTED_FRESHNESS_MECHANISMS.
versions
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The versions parameter enumerates the TEEP protocol version(s)
supported by the TEEP Agent. This otherwise optional parameter
MUST be returned if err-code is ERR_UNSUPPORTED_MSG_VERSION.
suit-reports
If present, the suit-reports parameter contains a set of SUIT
Reports as defined in Section 4 of [I-D.ietf-suit-report]. If a
token parameter was present in the Update message the Error
message is in response to, the suit-report-nonce field MUST be
present in the SUIT Report with a value matching the token
parameter in the Update message.
err-code
The err-code parameter contains one of the error codes listed
below). Only selected values are applicable to each message.
This specification defines the following initial error messages:
ERR_PERMANENT_ERROR (1)
The TEEP request contained incorrect fields or fields that are
inconsistent with other fields. For diagnosis purposes it is
RECOMMMENDED to identify the failure reason in the error message.
A TAM receiving this error might refuse to communicate further
with the TEEP Agent for some period of time until it has reason to
believe it is worth trying again, but it should take care not to
give up on communication. In contrast, ERR_TEMPORARY_ERROR is an
indication that a more aggressive retry is warranted.
ERR_UNSUPPORTED_EXTENSION (2)
The TEEP Agent does not support an extension included in the
request message. For diagnosis purposes it is RECOMMMENDED to
identify the unsupported extension in the error message. A TAM
receiving this error might retry the request without using
extensions.
ERR_UNSUPPORTED_FRESHNESS_MECHANISMS (3)
The TEEP Agent does not support any freshness algorithm mechanisms
in the request message. A TAM receiving this error might retry
the request using a different set of supported freshness
mechanisms in the request message.
ERR_UNSUPPORTED_MSG_VERSION (4)
The TEEP Agent does not support the TEEP protocol version
indicated in the request message. A TAM receiving this error
might retry the request using a different TEEP protocol version.
ERR_UNSUPPORTED_CIPHER_SUITES (5)
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The TEEP Agent does not support any cipher suites indicated in the
request message. A TAM receiving this error might retry the
request using a different set of supported cipher suites in the
request message.
ERR_BAD_CERTIFICATE (6)
Processing of a certificate failed. For diagnosis purposes it is
RECOMMMENDED to include information about the failing certificate
in the error message. For example, the certificate was of an
unsupported type, or the certificate was revoked by its signer. A
TAM receiving this error might attempt to use an alternate
certificate.
ERR_CERTIFICATE_EXPIRED (9)
A certificate has expired or is not currently valid. A TAM
receiving this error might attempt to renew its certificate before
using it again.
ERR_TEMPORARY_ERROR (10)
A miscellaneous temporary error, such as a memory allocation
failure, occurred while processing the request message. A TAM
receiving this error might retry the same request at a later point
in time.
ERR_MANIFEST_PROCESSING_FAILED (17)
The TEEP Agent encountered one or more manifest processing
failures. If the suit-reports parameter is present, it contains
the failure details. A TAM receiving this error might still
attempt to install or update other components that do not depend
on the failed manifest.
New error codes should be added sparingly, not for every
implementation error. That is the intent of the err-msg field, which
can be used to provide details meaningful to humans. New error codes
should only be added if the TAM is expected to do something
behaviorally different upon receipt of the error message, rather than
just logging the event. Hence, each error code is responsible for
saying what the behavioral difference is expected to be.
5. EAT Profile
The TEEP protocol operates between a TEEP Agent and a TAM. While the
TEEP protocol does not require use of EAT, use of EAT is encouraged
and Section 4.3 explicitly defines a way to carry an Entity
Attestation Token in a QueryResponse.
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As discussed in Section 4.3.1, the content of Evidence is opaque to
the TEEP architecture, but the content of Attestation Results is not,
where Attestation Results flow between a Verifier and a TAM (as the
Relying Party). Although Attestation Results required by a TAM are
separable from the TEEP protocol per se, this section is included as
part of the requirements for building a compliant TAM that uses EATs
for Attestation Results.
Section 7 of [I-D.ietf-rats-eat] defines the requirement for Entity
Attestation Token profiles. This section defines an EAT profile for
use with TEEP.
* profile-label: The profile-label for this specification is the URI
https://datatracker.ietf.org/doc/html/draft-ietf-teep-protocol-12
(https://datatracker.ietf.org/doc/html/draft-ietf-teep-protocol-12).
(RFC-editor: upon RFC publication, replace string with
"https://www.rfc-editor.org/info/rfcXXXX" where XXXX is the RFC
number of this document.)
* Use of JSON, CBOR, or both: CBOR only.
* CBOR Map and Array Encoding: Only definite length arrays and maps.
* CBOR String Encoding: Only definite-length strings are allowed.
* CBOR Preferred Serialization: Encoders must use preferred
serialization, and decoders need not accept non-preferred
serialization.
* CBOR Tags: CBOR Tags are not used.
* COSE/JOSE Protection: See Section 8.2.
* COSE/JOSE Algorithms: See Section 8.2.
* Detached EAT Bundle Support: DEB use is permitted.
* Key Identification: COSE Key ID (kid) is used, where the key ID is
the hash of a public key (where the public key may be used as a
raw public key, or in a certificate). See Section 7.1.1.1
discussion on the choice of hash algorithm.
* Endorsement Identification: Optional, but semantics are the same
as in Verification Key Identification.
* Freshness: See Section 9.
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* Claims Requirements:
- The following claims are required: ueid, oemid, hwmodel,
hwversion, manifests, and cnf. See Section 4.3.1 for
discussion. Other claims are optional.
- See Section 9 for discussion affecting whether the eat_nonce
claim is used.
- The sw-name claim for a Trusted Component holds the URI of the
SUIT manifest for that component.
- The manifests claim uses a SUIT manifest, where the manifest
body contains a SUIT_Reference as defined in Section 4 of
[I-D.ietf-suit-report], and the content type is as defined in
[I-D.ietf-suit-report].
A TAM implementation might simply accept a TEEP Agent as trustworthy
based on a successful Attestation Result, and if not then attempt to
update the TEEP Agent and all of its dependencies. This logic is
simple but it might result in updating some components that do not
need to be updated.
An alternate TAM implementation might use any Additional Claims to
determine whether the TEEP Agent or any of its dependencies are
trustworthy, and only update the specific components that are out of
date.
5.1. Relationship to AR4SI
[I-D.ietf-rats-ar4si] defines an EAT profile for arbitrary Relying
Parties to use with Attestation Results. However the TAM as a
Relying Party needs specific claims that are not required in the
AR4SI profile, and so needs its own more specific profile.
In some deployments, a TAM can be used as an intermediary between
Verifier and a TEEP Agent acting as an Attester in the Passport model
or acting as a Relying Party in the Background Check Model of
[RFC9334]. This is depicted in the example in Figure 1. In such a
case, both profiles need to be obtained from the Verifier: one for
use by the TAM itself, and the other to pass on to the TEEP Agent.
When the TAM and Verifier are combined into the same implementation,
obtaining both profiles can be straightforward, but when they are on
different machines, the situation is more complex, especially if
Nonces are used to ensure freshness of Evidence. There are thus
several such cases:
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1. The protocol between the TAM and the Verifier (which is outside
the scope of TEEP itself) allows requesting multiple Attestation
Results from the same Evidence. In this case, the TAM can
request both EAT profiles be returned.
2. The protocol between the TAM and the Verifier only allows
requesting one Attestation Result format, but the Evidence
freshness mechanism does not use Nonces. In this case, the TAM
can send the same Evidence in two separate requests, each
requesting a different EAT profile for the Attestation Results.
3. The protocol between the TAM and the Verifier only allows
requesting one Attestation Result format, and the Evidence
freshness mechanism uses Nonces. In this case, it is simpler to
not have the TAM be an intermediary, since the Verifier will
require a separate Nonce for each Attestation Result, but have
the Attester or Relying Party contact the Verifier directly to
get Attestation Results in the AR4SI profile.
6. Mapping of TEEP Message Parameters to CBOR Labels
In COSE, arrays and maps use strings, negative integers, and unsigned
integers as their keys. Integers are used for compactness of
encoding. Since the word "key" is mainly used in its other meaning,
as a cryptographic key, this specification uses the term "label" for
this usage as a map key.
This specification uses the following mapping:
+================================+=======+
| Name | Label |
+================================+=======+
| supported-teep-cipher-suites | 1 |
+--------------------------------+-------+
| challenge | 2 |
+--------------------------------+-------+
| versions | 3 |
+--------------------------------+-------+
| supported-suit-cose-profiles | 4 |
+--------------------------------+-------+
| selected-teep-cipher-suite | 5 |
+--------------------------------+-------+
| selected-version | 6 |
+--------------------------------+-------+
| attestation-payload | 7 |
+--------------------------------+-------+
| tc-list | 8 |
+--------------------------------+-------+
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| ext-list | 9 |
+--------------------------------+-------+
| manifest-list | 10 |
+--------------------------------+-------+
| msg | 11 |
+--------------------------------+-------+
| err-msg | 12 |
+--------------------------------+-------+
| attestation-payload-format | 13 |
+--------------------------------+-------+
| requested-tc-list | 14 |
+--------------------------------+-------+
| unneeded-manifest-list | 15 |
+--------------------------------+-------+
| component-id | 16 |
+--------------------------------+-------+
| tc-manifest-sequence-number | 17 |
+--------------------------------+-------+
| have-binary | 18 |
+--------------------------------+-------+
| suit-reports | 19 |
+--------------------------------+-------+
| token | 20 |
+--------------------------------+-------+
| supported-freshness-mechanisms | 21 |
+--------------------------------+-------+
| err-code | 23 |
+--------------------------------+-------+
Table 2
7. Behavior Specification
Behavior is specified in terms of the conceptual APIs defined in
section 6.2.1 of [I-D.ietf-teep-architecture].
7.1. TAM Behavior
When the ProcessConnect API is invoked, the TAM sends a QueryRequest
message.
When the ProcessTeepMessage API is invoked, the TAM first does
validation as specified in Section 4.1.2, and drops the message if it
is not valid. It may also do additional implementation specific
actions such as logging the results or attempting to update the TEEP
Agent to a version that does not send invalid messages. Otherwise,
it proceeds as follows.
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If the message includes a token, it can be used to match the response
to a request previously sent by the TAM. The TAM MUST expire the
token value after receiving the first response from the device that
has a valid signature and ignore any subsequent messages that have
the same token value. The token value MUST NOT be used for other
purposes, such as a TAM to identify the devices and/or a device to
identify TAMs or Trusted Components.
7.1.1. Handling a QueryResponse Message
If a QueryResponse message is received, the TAM verifies the presence
of any parameters required based on the data-items-requested in the
QueryRequest, and also validates that the nonce in any SUIT Report
matches the token sent in the QueryRequest message if a token was
present. If these requirements are not met, the TAM drops the
message. It may also do additional implementation specific actions
such as logging the results. If the requirements are met, processing
continues as follows.
If a QueryResponse message is received that contains an attestation-
payload, the TAM checks whether it contains Evidence or an
Attestation Result by inspecting the attestation-payload-format
parameter. The media type defined in Section 5 indicates an
Attestation Result, though future extensions might also indicate
other Attestation Result formats in the future. Any other
unrecognized value indicates Evidence. If it contains an Attestation
Result, processing continues as in Section 7.1.1.1.
If the QueryResponse is instead determined to contain Evidence, the
TAM passes the Evidence (via some mechanism out of scope of this
document) to an attestation Verifier (see [RFC9334]) to determine
whether the Agent is in a trustworthy state. Once the TAM receives
an Attestation Result from the Verifier, processing continues as in
Section 7.1.1.1.
7.1.1.1. Handling an Attestation Result
The Attestation Result must first be validated as follows:
1. Verify that the Attestation Result was signed by a Verifier that
the TAM trusts.
2. Verify that the Attestation Result contains a "cnf" claim (as
defined in Section 3.1 of [RFC8747]) where the key ID is the hash
of the TEEP Agent public key used to verify the signature on the
TEEP message, and the hash is computed using the Digest Algorithm
specified by one of the SUIT profiles supported by the TAM
(SHA-256 for the ones mandated in this document).
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See Sections 3.4 and 6 of [RFC8747] for more discussion.
Based on the results of attestation (if any), any SUIT Reports, and
the lists of installed, requested, and unneeded Trusted Components
reported in the QueryResponse, the TAM determines, in any
implementation specific manner, which Trusted Components need to be
installed, updated, or deleted, if any. There are in typically three
cases:
1. Attestation failed. This indicates that the rest of the
information in the QueryResponse cannot necessarily be trusted,
as the TEEP Agent may not be healthy (or at least up to date).
In this case, the TAM can attempt to use TEEP to update any
Trusted Components (e.g., firmware, the TEEP Agent itself, etc.)
needed to get the TEEP Agent back into an up-to-date state that
would allow attestation to succeed.
2. Attestation succeeded (so the QueryResponse information can be
accepted as valid), but the set of Trusted Components needs to be
updated based on TAM policy changes or requests from the TEEP
Agent.
3. Attestation succeeded, and no changes are needed.
If any Trusted Components need to be installed, updated, or deleted,
the TAM sends an Update message containing SUIT Manifests with
command sequences to do the relevant installs, updates, or deletes.
It is important to note that the TEEP Agent's Update Procedure
requires resolving and installing any dependencies indicated in the
manifest, which may take some time, and the resulting Success or
Error message is generated only after completing the Update
Procedure. Hence, depending on the freshness mechanism in use, the
TAM may need to store data (e.g., a nonce) for some time. For
example, if a mobile device needs an unmetered connection to download
a dependency, it may take hours or longer before the device has
sufficient access. A different freshness mechanism, such as
timestamps, might be more appropriate in such cases.
If no Trusted Components need to be installed, updated, or deleted,
but the QueryRequest included Evidence, the TAM MAY (e.g., based on
attestation-payload-format parameters received from the TEEP Agent in
the QueryResponse) still send an Update message with no SUIT
Manifests, to pass the Attestation Result back to the TEEP Agent.
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7.1.2. Handling a Success or Error Message
If a Success or Error message is received containing one or more SUIT
Reports, the TAM also validates that the nonce in any SUIT Report
matches the token sent in the Update message, and drops the message
if it does not match. Otherwise, the TAM handles the update in any
implementation specific way, such as updating any locally cached
information about the state of the TEEP Agent, or logging the
results.
If any other Error message is received, the TAM can handle it in any
implementation specific way, but Section 4.6 provides recommendations
for such handling.
7.2. TEEP Agent Behavior
When the RequestTA API is invoked, the TEEP Agent first checks
whether the requested TA is already installed. If it is already
installed, the TEEP Agent passes no data back to the caller.
Otherwise, if the TEEP Agent chooses to initiate the process of
requesting the indicated TA, it determines (in any implementation
specific way) the TAM URI based on any TAM URI provided by the
RequestTA caller and any local configuration, and passes back the TAM
URI to connect to. It MAY also pass back a QueryResponse message if
all of the following conditions are true:
* The last QueryRequest message received from that TAM contained no
token or challenge,
* The ProcessError API was not invoked for that TAM since the last
QueryResponse message was received from it, and
* The public key or certificate of the TAM is cached and not
expired.
When the RequestPolicyCheck API is invoked, the TEEP Agent decides
whether to initiate communication with any trusted TAMs (e.g., it
might choose to do so for a given TAM unless it detects that it has
already communicated with that TAM recently). If so, it passes back
a TAM URI to connect to. If the TEEP Agent has multiple TAMs it
needs to connect with, it just passes back one, with the expectation
that RequestPolicyCheck API will be invoked to retrieve each one
successively until there are no more and it can pass back no data at
that time. Thus, once a TAM URI is returned, the TEEP Agent can
remember that it has already initiated communication with that TAM.
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When the ProcessError API is invoked, the TEEP Agent can handle it in
any implementation specific way, such as logging the error or using
the information in future choices of TAM URI.
When the ProcessTeepMessage API is invoked, the Agent first does
validation as specified in Section 4.1.2, and if it is not valid then
the Agent responds with an Error message. Otherwise, processing
continues as follows based on the type of message.
When a QueryRequest message is received, the Agent responds with a
QueryResponse message if all fields were understood, or an Error
message if any error was encountered.
When an Update message is received, the Agent attempts to unlink any
SUIT manifests listed in the unneeded-manifest-list field of the
message, and responds with an Error message if any error was
encountered. If the unneeded-manifest-list was empty, or no error
was encountered processing it, the Agent attempts to update the
Trusted Components specified in the SUIT manifests by following the
Update Procedure specified in [I-D.ietf-suit-manifest], and responds
with a Success message if all SUIT manifests were successfully
installed, or an Error message if any error was encountered. It is
important to note that the Update Procedure requires resolving and
installing any dependencies indicated in the manifest, which may take
some time, and the Success or Error message is generated only after
completing the Update Procedure.
8. Cipher Suites
TEEP requires algorithms for various purposes:
* Algorithms for signing TEEP messages exchanged between the TEEP
Agent and the TAM.
* Algorithms for signing EAT-based Evidence sent by the Attester via
the TEEP Agent and the TAM to the Verifier. (If evidence is not
encrypted by the TEEP Agent then it will be opaque to the TEEP
Agent and to the TAM.)
* Algorithms for encrypting EAT-based Evidence sent by the TEEP
Agent to the TAM. (The TAM will decrypt the encrypted Evidence
and will forward it to the Verifier.)
* Algorithms for signing and optionally encrypting SUIT reports sent
by the TEEP Agent to the TAM.
* Algorithms for signing and optionally encrypting SUIT manifests
sent by the Trusted Component Signer to the TEEP Agent.
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Further details are provided for the protection of TEEP messages,
SUIT Reports, and EATs.
8.1. TEEP Messages
The TEEP protocol uses COSE for protection of TEEP messages in both
directions. To negotiate cryptographic mechanisms and algorithms,
the TEEP protocol defines the following cipher suite structure, which
is used to specify an ordered set of operations (e.g., sign) done as
part of composing a TEEP message. Although this specification only
specifies the use of signing and relies on payload encryption to
protect sensitive information, future extensions might specify
support for encryption and/or MAC operations if needed.
; teep-cipher-suites
$teep-cipher-suite /= teep-cipher-suite-sign1-eddsa
$teep-cipher-suite /= teep-cipher-suite-sign1-es256
;The following two cipher suites have only a single operation each.
;Other cipher suites may be defined to have multiple operations.
;MANDATORY for TAM to support them, and OPTIONAL
;to support any additional ones that use COSE_Sign_Tagged, or other
;signing, encryption, or MAC algorithms.
teep-operation-sign1-eddsa = [ cose-sign1, cose-alg-eddsa ]
teep-operation-sign1-es256 = [ cose-sign1, cose-alg-es256 ]
teep-cipher-suite-sign1-eddsa = [ teep-operation-sign1-eddsa ]
teep-cipher-suite-sign1-es256 = [ teep-operation-sign1-es256 ]
;MANDATORY for TAM and TEEP Agent to support the following COSE
;operations, and OPTIONAL to support additional ones such as
;COSE_Sign_Tagged, COSE_Encrypt0_Tagged, etc.
cose-sign1 = 18 ; CoAP Content-Format value
;MANDATORY for TAM to support the following, and OPTIONAL to implement
;any additional algorithms from the IANA COSE Algorithms registry.
cose-alg-es256 = -7 ; ECDSA w/ SHA-256
cose-alg-eddsa = -8 ; EdDSA
Each operation in a given cipher suite has two elements:
* a COSE-type defined in Section 2 of [RFC9052] that identifies the
type of operation, and
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* a specific cryptographic algorithm as defined in the COSE
Algorithms registry [COSE.Algorithm] to be used to perform that
operation.
A TAM MUST support both of the cipher suites defined above. A TEEP
Agent MUST support at least one of the two but can choose which one.
For example, a TEEP Agent might choose a given cipher suite if it has
hardware support for it. A TAM or TEEP Agent MAY also support any
other algorithms in the COSE Algorithms registry in addition to the
mandatory ones listed above. It MAY also support use with COSE_Sign
or other COSE types in additional cipher suites.
Any cipher suites without confidentiality protection can only be
added if the associated specification includes a discussion of
security considerations and applicability, since manifests may carry
sensitive information. For example, Section 6 of
[I-D.ietf-teep-architecture] permits implementations that terminate
transport security inside the TEE and if the transport security
provides confidentiality then additional encryption might not be
needed in the manifest for some use cases. For most use cases,
however, manifest confidentiality will be needed to protect sensitive
fields from the TAM as discussed in Section 9.8 of
[I-D.ietf-teep-architecture].
The cipher suites defined above do not do encryption at the TEEP
layer, but permit encryption of the SUIT payload using
[I-D.ietf-suit-firmware-encryption]. See Section 10 and Section 8.2
for more discussion of specific payloads.
For the initial QueryRequest message, unless the TAM has more
specific knowledge about the TEEP Agent (e.g., if the QueryRequest is
sent in response to some underlying transport message that contains a
hint), the message does not use COSE_Sign1 with one of the above
cipher suites, but instead uses COSE_Sign with multiple signatures,
one for each algorithm used in any of the cipher suites listed in the
supported-teep-cipher-suites parameter of the QueryRequest, so that a
TEEP Agent supporting any one of them can verify a signature. If the
TAM does have specific knowledge about which cipher suite the TEEP
Agent supports, it MAY instead use that cipher suite with the
QueryRequest.
For an Error message with code ERR_UNSUPPORTED_CIPHER_SUITES, the
TEEP Agent MUST protect it with any of the cipher suites mandatory
for the TAM.
For all other TEEP messages between the TAM and TEEP Agent, the
selected TEEP cipher suite MUST be used in both directions.
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8.2. EATs and SUIT Reports
TEEP uses COSE for confidentiality of EATs and SUIT Reports sent by a
TEEP Agent. The TEEP Agent obtains a signed EAT and then SHOULD
encrypt it using the TAM as the recipient. A SUIT Report is created
by a SUIT processor, which is part of the TEEP Agent itself. The
TEEP Agent is therefore in control of signing the SUIT Report and
SHOULD encrypt it. Again, the TAM is the recipient of the encrypted
content. For content-key distribution Hybrid Public Key Encryption
(HPKE) is used in this specification. See COSE-HPKE
[I-D.ietf-cose-hpke] for more details. This specification uses the
COSE-HPKE variant for a single recipient, i.e., the TAM, which uses
COSE_Encrypt0. This variant is described in Section 3.1.1 of
[I-D.ietf-cose-hpke].
To perform encryption with HPKE the TEEP Agent needs to be in
possession of the public key of the recipient, i.e., the TAM. See
Section 5 of [I-D.ietf-teep-architecture] for more discussion of TAM
keys used by the TEEP Agent.
This specification defines cipher suites for confidentiality
protection of EATs and SUIT Reports. The TAM MUST support each
cipher suite defined below, based on definitions in
[I-D.moran-suit-mti]. A TEEP Agent MUST support at least one of the
cipher suites below but can choose which one. For example, a TEEP
Agent might choose a given cipher suite if it has hardware support
for it. A TAM or TEEP Agent MAY also support other algorithms in the
COSE Algorithms registry. It MAY also support use with COSE_Encrypt
or other COSE types in additional cipher suites.
$suit-cose-profile /= suit-sha256-es256-hpke-a128gcm
$suit-cose-profile /= suit-sha256-eddsa-hpke-a128gcm
9. Freshness Mechanisms
A freshness mechanism determines how a TAM can tell whether an
attestation payload provided in a QueryResponse is fresh. There are
multiple ways this can be done as discussed in Section 10 of
[RFC9334].
Each freshness mechanism is identified with an integer value, which
corresponds to an IANA registered freshness mechanism (see the IANA
Considerations section of
[I-D.ietf-rats-reference-interaction-models]). This document uses
the following freshness mechanisms which may be added to in the
future by TEEP extensions:
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; freshness-mechanisms
FRESHNESS_NONCE = 0
FRESHNESS_TIMESTAMP = 1
$freshness-mechanism /= FRESHNESS_NONCE
$freshness-mechanism /= FRESHNESS_TIMESTAMP
An implementation MUST support the Nonce mechanism and MAY support
additional mechanisms.
In the Nonce mechanism, the attestation payload MUST include a nonce
provided in the QueryRequest challenge. The timestamp mechanism uses
a timestamp determined via mechanisms outside the TEEP protocol, and
the challenge is only needed in the QueryRequest message if a
challenge is needed in generating the attestation payload for reasons
other than freshness.
If a TAM supports multiple freshness mechanisms that require
different challenge formats, the QueryRequest message can currently
only send one such challenge. This situation is expected to be rare,
but should it occur, the TAM can choose to prioritize one of them and
exclude the other from the supported-freshness-mechanisms in the
QueryRequest, and resend the QueryRequest with the other mechanism if
an ERR_UNSUPPORTED_FRESHNESS_MECHANISMS Error is received that
indicates the TEEP Agent supports the other mechanism.
10. Security Considerations
This section summarizes the security considerations discussed in this
specification:
Cryptographic Algorithms
TEEP protocol messages exchanged between the TAM and the TEEP
Agent are protected using COSE. This specification relies on the
cryptographic algorithms provided by COSE. Public key based
authentication is used by the TEEP Agent to authenticate the TAM
and vice versa.
Attestation
A TAM relies on signed Attestation Results provided by a Verifier,
either obtained directly using a mechanism outside the TEEP
protocol (by using some mechanism to pass Evidence obtained in the
attestation payload of a QueryResponse, and getting back the
Attestation Results), or indirectly via the TEEP Agent forwarding
the Attestation Results in the attestation payload of a
QueryResponse. See the security considerations of the specific
mechanism in use (e.g., EAT) for more discussion.
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An impersonation attack, where one TEEP Agent attempts to use the
attestation payload of another TEEP Agent, can be prevented using
a proof-of-possession approach. The "cnf" claim is mandatory in
the EAT profile for EAT for this purpose. See Section 6 of
[RFC8747] and Section 7.1.1.1 of this document for more
discussion.
Trusted Component Binaries
Each Trusted Component binary is signed by a Trusted Component
Signer. It is the responsibility of the TAM to relay only
verified Trusted Components from authorized Trusted Component
Signers. Delivery of a Trusted Component to the TEEP Agent is
then the responsibility of the TAM, using the security mechanisms
provided by the TEEP protocol. To protect the Trusted Component
binary, the SUIT manifest format is used and it offers a variety
of security features, including digital signatures and content
encryption, if a SUIT mechanism such as
[I-D.ietf-suit-firmware-encryption] is used.
Personalization Data
A Trusted Component Signer or TAM can supply personalization data
along with a Trusted Component. This data is also protected by a
SUIT manifest. Personalization data is signed and encrypted by a
Trusted Component Signer, if a SUIT mechanism such as
[I-D.ietf-suit-firmware-encryption] is used.
TEEP Broker
As discussed in section 6 of [I-D.ietf-teep-architecture], the
TEEP protocol typically relies on a TEEP Broker to relay messages
between the TAM and the TEEP Agent. When the TEEP Broker is
compromised it can drop messages, delay the delivery of messages,
and replay messages but it cannot modify those messages. (A
replay would be, however, detected by the TEEP Agent.) A
compromised TEEP Broker could reorder messages in an attempt to
install an old version of a Trusted Component. Information in the
manifest ensures that TEEP Agents are protected against such
downgrade attacks based on features offered by the manifest
itself.
Trusted Component Signer Compromise
A TAM is responsible for vetting a Trusted Component and before
distributing them to TEEP Agents.
It is RECOMMENDED to provide a way to update the trust anchor
store used by the TEE, for example using a firmware update
mechanism such as [I-D.ietf-rats-concise-ta-stores]. Thus, if a
Trusted Component Signer is later compromised, the TAM can update
the trust anchor store used by the TEE, for example using a
firmware update mechanism.
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CA Compromise
The CA issuing certificates to a TEE or a Trusted Component Signer
might get compromised. It is RECOMMENDED to provide a way to
update the trust anchor store used by the TEE, for example by
using a firmware update mechanism, Concise TA Stores
[I-D.ietf-rats-concise-ta-stores], Trust Anchor Management
Protocol (TAMP) [RFC5934] or a similar mechanism. If the CA
issuing certificates to devices gets compromised then these
devices will be rejected by a TAM, if revocation is available to
the TAM.
TAM Certificate Expiry
The integrity and the accuracy of the clock within the TEE
determines the ability to determine an expired TAM certificate, if
certificates are used.
Compromised Time Source
As discussed above, certificate validity checks rely on comparing
validity dates to the current time, which relies on having a
trusted source of time, such as [RFC8915]. A compromised time
source could thus be used to subvert such validity checks.
11. Privacy Considerations
Depending on the properties of the attestation mechanism, it is
possible to uniquely identify a device based on information in the
attestation payload or in the certificate used to sign the
attestation payload. This uniqueness may raise privacy concerns. To
lower the privacy implications the TEEP Agent MUST present its
attestation payload only to an authenticated and authorized TAM and
when using an EAT, it SHOULD use encryption as discussed in
[I-D.ietf-rats-eat], since confidentiality is not provided by the
TEEP protocol itself and the transport protocol under the TEEP
protocol might be implemented outside of any TEE. If any mechanism
other than EAT is used, it is up to that mechanism to specify how
privacy is provided.
Since SUIT Reports can also contain sensitive information, a TEEP
Agent SHOULD also encrypt SUIT Reports as discussed in Section 8.2.
In addition, in the usage scenario discussed in Section 4.4.1, a
device reveals its IP address to the Trusted Component Binary server.
This can reveal to that server at least a clue as to its location,
which might be sensitive information in some cases.
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12. IANA Considerations
12.1. Media Type Registration
IANA is requested to assign a media type for application/teep+cbor.
Type name: application
Subtype name: teep+cbor
Required parameters: none
Optional parameters: none
Encoding considerations: Same as encoding considerations of
application/cbor.
Security considerations: See Security Considerations Section of this
document.
Interoperability considerations: Same as interoperability
considerations of application/cbor as specified in [RFC8949].
Published specification: This document.
Applications that use this media type: TEEP protocol implementations
Fragment identifier considerations: N/A
Additional information: Deprecated alias names for this type: N/A
Magic number(s): N/A
File extension(s): N/A
Macintosh file type code(s): N/A
Person to contact for further information: teep@ietf.org
Intended usage: COMMON
Restrictions on usage: none
Author: See the "Authors' Addresses" section of this document
Change controller: IETF
13. References
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13.1. Normative References
[COSE.Algorithm]
IANA, "COSE Algorithms", n.d.,
<https://www.iana.org/assignments/cose/
cose.xhtml#algorithms>.
[I-D.ietf-cose-hpke]
Tschofenig, H. and B. Moran, "Use of Hybrid Public-Key
Encryption (HPKE) with CBOR Object Signing and Encryption
(COSE)", Work in Progress, Internet-Draft, draft-ietf-
cose-hpke-03, 27 February 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-cose-
hpke-03>.
[I-D.ietf-rats-eat]
Lundblade, L., Mandyam, G., O'Donoghue, J., and C.
Wallace, "The Entity Attestation Token (EAT)", Work in
Progress, Internet-Draft, draft-ietf-rats-eat-19, 19
December 2022, <https://datatracker.ietf.org/doc/html/
draft-ietf-rats-eat-19>.
[I-D.ietf-rats-reference-interaction-models]
Birkholz, H., Eckel, M., Pan, W., and E. Voit, "Reference
Interaction Models for Remote Attestation Procedures",
Work in Progress, Internet-Draft, draft-ietf-rats-
reference-interaction-models-07, 10 March 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-rats-
reference-interaction-models-07>.
[I-D.ietf-suit-firmware-encryption]
Tschofenig, H., Housley, R., Moran, B., Brown, D., and K.
Takayama, "Encrypted Payloads in SUIT Manifests", Work in
Progress, Internet-Draft, draft-ietf-suit-firmware-
encryption-09, 24 October 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-suit-
firmware-encryption-09>.
[I-D.ietf-suit-manifest]
Moran, B., Tschofenig, H., Birkholz, H., Zandberg, K., and
O. Rønningstad, "A Concise Binary Object Representation
(CBOR)-based Serialization Format for the Software Updates
for Internet of Things (SUIT) Manifest", Work in Progress,
Internet-Draft, draft-ietf-suit-manifest-22, 27 February
2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
suit-manifest-22>.
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[I-D.ietf-suit-report]
Moran, B. and H. Birkholz, "Secure Reporting of Update
Status", Work in Progress, Internet-Draft, draft-ietf-
suit-report-04, 24 October 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-suit-
report-04>.
[I-D.ietf-suit-trust-domains]
Moran, B. and K. Takayama, "SUIT Manifest Extensions for
Multiple Trust Domains", Work in Progress, Internet-Draft,
draft-ietf-suit-trust-domains-01, 24 October 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-suit-
trust-domains-01>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/rfc/rfc3629>.
[RFC5198] Klensin, J. and M. Padlipsky, "Unicode Format for Network
Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008,
<https://www.rfc-editor.org/rfc/rfc5198>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8747] Jones, M., Seitz, L., Selander, G., Erdtman, S., and H.
Tschofenig, "Proof-of-Possession Key Semantics for CBOR
Web Tokens (CWTs)", RFC 8747, DOI 10.17487/RFC8747, March
2020, <https://www.rfc-editor.org/rfc/rfc8747>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/rfc/rfc8949>.
[RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Structures and Process", STD 96, RFC 9052,
DOI 10.17487/RFC9052, August 2022,
<https://www.rfc-editor.org/rfc/rfc9052>.
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[RFC9334] Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
W. Pan, "Remote ATtestation procedureS (RATS)
Architecture", RFC 9334, DOI 10.17487/RFC9334, January
2023, <https://www.rfc-editor.org/rfc/rfc9334>.
13.2. Informative References
[I-D.ietf-rats-ar4si]
Voit, E., Birkholz, H., Hardjono, T., Fossati, T., and V.
Scarlata, "Attestation Results for Secure Interactions",
Work in Progress, Internet-Draft, draft-ietf-rats-ar4si-
04, 2 March 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-rats-ar4si-04>.
[I-D.ietf-rats-concise-ta-stores]
Wallace, C., Housley, R., Fossati, T., and Y. Deshpande,
"Concise TA Stores (CoTS)", Work in Progress, Internet-
Draft, draft-ietf-rats-concise-ta-stores-00, 6 December
2022, <https://datatracker.ietf.org/doc/html/draft-ietf-
rats-concise-ta-stores-00>.
[I-D.ietf-rats-eat-media-type]
Lundblade, L., Birkholz, H., and T. Fossati, "EAT Media
Types", Work in Progress, Internet-Draft, draft-ietf-rats-
eat-media-type-02, 10 March 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-rats-
eat-media-type-02>.
[I-D.ietf-teep-architecture]
Pei, M., Tschofenig, H., Thaler, D., and D. M. Wheeler,
"Trusted Execution Environment Provisioning (TEEP)
Architecture", Work in Progress, Internet-Draft, draft-
ietf-teep-architecture-19, 24 October 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-teep-
architecture-19>.
[I-D.moran-suit-mti]
Moran, B., "Mandatory-to-Implement Algorithms for Creators
and Consumers of Software Update for the Internet of
Things manifests", Work in Progress, Internet-Draft,
draft-moran-suit-mti-02, 24 October 2022,
<https://datatracker.ietf.org/doc/html/draft-moran-suit-
mti-02>.
[RFC5934] Housley, R., Ashmore, S., and C. Wallace, "Trust Anchor
Management Protocol (TAMP)", RFC 5934,
DOI 10.17487/RFC5934, August 2010,
<https://www.rfc-editor.org/rfc/rfc5934>.
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[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/rfc/rfc8610>.
[RFC8915] Franke, D., Sibold, D., Teichel, K., Dansarie, M., and R.
Sundblad, "Network Time Security for the Network Time
Protocol", RFC 8915, DOI 10.17487/RFC8915, September 2020,
<https://www.rfc-editor.org/rfc/rfc8915>.
A. Contributors
We would like to thank Brian Witten (Symantec), Tyler Kim (Solacia),
Nick Cook (Arm), and Minho Yoo (IoTrust) for their contributions to
the Open Trust Protocol (OTrP), which influenced the design of this
specification.
B. Acknowledgements
We would like to thank Eve Schooler for the suggestion of the
protocol name.
We would like to thank Kohei Isobe (TRASIO/SECOM), Ken Takayama
(SECOM) Kuniyasu Suzaki (TRASIO/AIST), Tsukasa Oi (TRASIO), and
Yuichi Takita (SECOM) for their valuable implementation feedback.
We would also like to thank Carsten Bormann and Henk Birkholz for
their help with the CDDL.
C. Complete CDDL
Valid TEEP messages adhere to the following CDDL data definitions,
except that SUIT_Envelope and SUIT_Component_Identifier are specified
in [I-D.ietf-suit-manifest].
This section is informative and merely summarizes the normative CDDL
snippets in the body of this document.
teep-message = $teep-message-type .within teep-message-framework
teep-message-framework = [
type: $teep-type / $teep-type-extension,
options: { * teep-option },
* any; further elements, e.g., for data-item-requested
]
teep-option = (uint => any)
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; messages defined below:
$teep-message-type /= query-request
$teep-message-type /= query-response
$teep-message-type /= update
$teep-message-type /= teep-success
$teep-message-type /= teep-error
; message type numbers, uint .size 1 which takes a number from 0 to 23
$teep-type = uint .size 1
TEEP-TYPE-query-request = 1
TEEP-TYPE-query-response = 2
TEEP-TYPE-update = 3
TEEP-TYPE-teep-success = 5
TEEP-TYPE-teep-error = 6
version = uint .size 4
ext-info = uint .size 4
; data items as bitmaps
data-item-requested = &(
attestation: 0,
trusted-components: 1,
extensions: 2,
suit-reports: 3,
)
query-request = [
type: TEEP-TYPE-query-request,
options: {
? token => bstr .size (8..64),
? supported-freshness-mechanisms => [ + $freshness-mechanism ],
? challenge => bstr .size (8..512),
? versions => [ + version ],
* $$query-request-extensions,
* $$teep-option-extensions
},
supported-teep-cipher-suites: [ + $teep-cipher-suite ],
supported-eat-suit-cipher-suites: [ + $eat-suit-cipher-suite ],
data-item-requested: uint .bits data-item-requested
]
; teep-cipher-suites
$teep-cipher-suite /= teep-cipher-suite-sign1-eddsa
$teep-cipher-suite /= teep-cipher-suite-sign1-es256
;The following two cipher suites have only a single operation each.
;Other cipher suites may be defined to have multiple operations.
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;MANDATORY for TAM to support them, and OPTIONAL
;to support any additional ones that use COSE_Sign_Tagged, or other
;signing, encryption, or MAC algorithms.
teep-operation-sign1-eddsa = [ cose-sign1, cose-alg-eddsa ]
teep-operation-sign1-es256 = [ cose-sign1, cose-alg-es256 ]
teep-cipher-suite-sign1-eddsa = [ teep-operation-sign1-eddsa ]
teep-cipher-suite-sign1-es256 = [ teep-operation-sign1-es256 ]
;MANDATORY for TAM and TEEP Agent to support the following COSE
;operations, and OPTIONAL to support additional ones such as
;COSE_Sign_Tagged, COSE_Encrypt0_Tagged, etc.
cose-sign1 = 18 ; CoAP Content-Format value
;MANDATORY for TAM to support the following, and OPTIONAL to implement
;any additional algorithms from the IANA COSE Algorithms registry.
cose-alg-es256 = -7 ; ECDSA w/ SHA-256
cose-alg-eddsa = -8 ; EdDSA
; eat-suit-cipher-suites
$eat-suit-cipher-suite /= eat-suit-cipher-suite-hpke-v1-base
eat-suit-cipher-suite-hpke-v1-base = [ teep-operation-hpke-v1-base ]
eat-suit-operation-hpke-v1-base = [ cose-encrypt0, HPKE-v1-BASE ]
cose-encrypt0 = 16 ; CoAP Content-Format value
HPKE-v1-BASE = -1 ; TBD
; freshness-mechanisms
FRESHNESS_NONCE = 0
FRESHNESS_TIMESTAMP = 1
$freshness-mechanism /= FRESHNESS_NONCE
$freshness-mechanism /= FRESHNESS_TIMESTAMP
query-response = [
type: TEEP-TYPE-query-response,
options: {
? token => bstr .size (8..64),
? selected-teep-cipher-suite => $teep-cipher-suite,
? selected-version => version,
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? attestation-payload-format => text,
? attestation-payload => bstr,
? suit-reports => [ + bstr ],
? tc-list => [ + system-property-claims ],
? requested-tc-list => [ + requested-tc-info ],
? unneeded-manifest-list => [ + SUIT_Component_Identifier ],
? ext-list => [ + ext-info ],
* $$query-response-extensions,
* $$teep-option-extensions
}
]
requested-tc-info = {
component-id => SUIT_Component_Identifier,
? tc-manifest-sequence-number => uint .size 8,
? have-binary => bool
}
update = [
type: TEEP-TYPE-update,
options: {
? token => bstr .size (8..64),
? unneeded-manifest-list => [ + SUIT_Component_Identifier ],
? manifest-list => [ + bstr .cbor SUIT_Envelope ],
? attestation-payload-format => text,
? attestation-payload => bstr,
* $$update-extensions,
* $$teep-option-extensions
}
]
teep-success = [
type: TEEP-TYPE-teep-success,
options: {
? token => bstr .size (8..64),
? msg => text .size (1..128),
? suit-reports => [ + SUIT_Report ],
* $$teep-success-extensions,
* $$teep-option-extensions
}
]
teep-error = [
type: TEEP-TYPE-teep-error,
options: {
? token => bstr .size (8..64),
? err-msg => text .size (1..128),
? supported-teep-cipher-suites => [ + $teep-cipher-suite ],
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? supported-freshness-mechanisms => [ + $freshness-mechanism ],
? versions => [ + version ],
? suit-reports => [ + SUIT_Report ],
* $$teep-error-extensions,
* $$teep-option-extensions
},
err-code: uint .size 1
]
; The err-code parameter, uint .size 1 which takes a number from 0 to 23
ERR_PERMANENT_ERROR = 1
ERR_UNSUPPORTED_EXTENSION = 2
ERR_UNSUPPORTED_FRESHNESS_MECHANISMS = 3
ERR_UNSUPPORTED_MSG_VERSION = 4
ERR_UNSUPPORTED_CIPHER_SUITES = 5
ERR_BAD_CERTIFICATE = 6
ERR_CERTIFICATE_EXPIRED = 9
ERR_TEMPORARY_ERROR = 10
ERR_MANIFEST_PROCESSING_FAILED = 17
; labels of mapkey for teep message parameters in
; uint .size 1 which takes a number from 0 to 23
supported-teep-cipher-suites = 1
challenge = 2
versions = 3
supported-eat-suit-cipher-suites = 4
selected-teep-cipher-suite = 5
selected-version = 6
attestation-payload = 7
tc-list = 8
ext-list = 9
manifest-list = 10
msg = 11
err-msg = 12
attestation-payload-format = 13
requested-tc-list = 14
unneeded-manifest-list = 15
component-id = 16
tc-manifest-sequence-number = 17
have-binary = 18
suit-reports = 19
token = 20
supported-freshness-mechanisms = 21
D. Examples of Diagnostic Notation and Binary Representation
This section includes some examples with the following assumptions:
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* The device will have two TCs with the following SUIT Component
Identifiers:
- [ 0x000102030405060708090a0b0c0d0e0f ]
- [ 0x100102030405060708090a0b0c0d0e0f ]
* SUIT manifest-list is set empty only for example purposes (see
Appendix E for actual manifest examples)
D.1. QueryRequest Message
D.1.1. CBOR Diagnostic Notation
/ query-request = /
[
/ type: / 1 / TEEP-TYPE-query-request /,
/ options: /
{
/ token / 20 : h'A0A1A2A3A4A5A6A7A8A9AAABACADAEAF',
/ versions / 3 : [ 0 ] / 0 is current TEEP Protocol /
},
/ supported-teep-cipher-suites: / [ [ [ 18, -7 ] ], / Sign1 using ES256 /
[ [ 18, -8 ] ] / Sign1 using EdDSA /
],
/ data-item-requested: / 3 / attestation | trusted-components /
]
D.1.2. CBOR Binary Representation
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85 # array(5)
01 # unsigned(1) / TEEP-TYPE-query-request /
A2 # map(2)
14 # unsigned(20) / token: /
50 # bytes(16)
A0A1A2A3A4A5A6A7A8A9AAABACADAEAF
03 # unsigned(3) / versions: /
81 # array(1) / [ 0 ] /
00 # unsigned(0)
82 # array(2) / supported-teep-cipher-suites /
81 # array(1)
82 # array(2)
12 # unsigned(18) / cose-sign1 /
26 # negative(6) / -7 = cose-alg-es256 /
81 # array(1)
82 # array(2)
12 # unsigned(18) / cose-sign1 /
27 # negative(7) / -8 = cose-alg-eddsa /
82 # array(2) / supported-suit-cose-profiles /
82 # array(2) / suit-sha256-es256-hpke-a128gcm /
26 # negative(6) / -7 = cose-alg-es256 /
01 # unsigned(1) / 1 = A128GCM */
82 # array(2) / suit-sha256-eddsa-hpke-a128gcm /
27 # negative(7) / -8 = cose-alg-eddsa /
01 # unsigned(1) / 1 = A128GCM */
03 # unsigned(3) / attestation | trusted-components /
D.2. Entity Attestation Token
This is shown below in CBOR diagnostic form. Only the payload signed
by COSE is shown.
D.2.1. CBOR Diagnostic Notation
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/ eat-claim-set = /
{
/ cnf / 8: {
/ kid / 3 : h'ba7816bf8f01cfea414140de5dae2223'
h'b00361a396177a9cb410ff61f20015ad'
},
/ eat_nonce / 10: h'948f8860d13a463e8e',
/ ueid / 256: h'0198f50a4ff6c05861c8860d13a638ea',
/ oemid / 258: h'894823', / IEEE OUI format OEM ID /
/ hwmodel / 259: h'549dcecc8b987c737b44e40f7c635ce8'
/ Hash of chip model name /,
/ hwversion / 260: ["1.3.4", 1], / Multipartnumeric /
/ manifests / 273: [
[ 60, / application/cbor, TO BE REPLACED /
/ with the format value for a /
/ SUIT_Reference once one is allocated /
{ / SUIT_Reference /
/ suit-report-manifest-uri / 1: "https://example.com/manifest.cbor",
/ suit-report-manifest-digest / 0:[
/ algorithm-id / -16 / "sha256" /,
/ digest-bytes / h'a7fd6593eac32eb4be578278e6540c5c'
h'09cfd7d4d234973054833b2b93030609'
]
}
]
]
}
D.3. QueryResponse Message
D.3.1. CBOR Diagnostic Notation
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/ query-response = /
[
/ type: / 2 / TEEP-TYPE-query-response /,
/ options: /
{
/ token / 20 : h'A0A1A2A3A4A5A6A7A8A9AAABACADAEAF',
/ selected-teep-cipher-suite / 5 : [ [ 18, -7 ] ] / only use ES256 /,
/ selected-version / 6 : 0,
/ attestation-payload / 7 : h'' / empty only for example purpose /,
/ tc-list / 8 : [
{
/ system-component-id / 0 : [ h'0102030405060708090A0B0C0D0E0F' ],
/ suit-parameter-image-digest / 3: << [
/ suit-digest-algorithm-id / -16 / SHA256 /,
/ suit-digest-bytes / h'a7fd6593eac32eb4be578278e6540c5c09cfd7d4d234973054833b2b93030609'
/ SHA256 digest of tc binary /
] >>
},
{
/ system-component-id / 0 : [ h'1102030405060708090A0B0C0D0E0F' ],
/ suit-parameter-version / 28 : [1, 0, 0] / ver 1.0.0 /
}
]
}
]
D.3.2. CBOR Binary Representation
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82 # array(2)
02 # unsigned(2) / TEEP-TYPE-query-response /
A5 # map(5)
14 # unsigned(20) / token: /
50 # bytes(16)
A0A1A2A3A4A5A6A7A8A9AAABACADAEAF
05 # unsigned(5) / selected-teep-cipher-suite: /
81 # array(1)
82 # array(2)
12 # unsigned(18) / cose-sign1 /
26 # negative(6) / -7 = cose-alg-es256 /
06 # unsigned(6) / selected-version: /
00 # unsigned(0)
07 # unsigned(7) / attestation-payload: /
40 # bytes(0)
# ""
08 # unsigned(8) / tc-list: /
82 # array(2)
A2 # map(2)
00 # unsigned(0) / system-component-id: /
81 # array(1)
4F # bytes(15)
0102030405060708090A0B0C0D0E0F
03 # unsigned(3) / suit-parameter-image-digest: /
58 24 # bytes(36)
822F5820A7FD6593EAC32EB4BE578278E6540C5C09CFD7D4D234973054833B2B93030609
A2 # map(2)
00 # unsigned(0) / system-component-id: /
81 # array(1)
4F # bytes(15)
1102030405060708090A0B0C0D0E0F
18 1C # unsigned(28) / suit-parameter-version: /
83 # array(3)
01 # unsigned(1)
00 # unsigned(0)
00 # unsigned(0)
D.4. Update Message
D.4.1. CBOR Diagnostic Notation
/ update = /
[
/ type: / 3 / TEEP-TYPE-update /,
/ options: /
{
/ token / 20 : h'A0A1A2A3A4A5A6A7A8A9AAABACADAEAF',
/ manifest-list / 10 : [
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<<
/ SUIT_Envelope / {
/ suit-authentication-wrapper / 2: << [
<< [
/ suit-digest-algorithm-id: / -16 / suit-cose-alg-sha256 /,
/ suit-digest-bytes: / h'DB601ADE73092B58532CA03FBB663DE49532435336F1558B49BB622726A2FEDD'
] >>,
<< / COSE_Sign1_Tagged / 18( [
/ protected: / << {
/ algorithm-id / 1: -7 / ES256 /
} >>,
/ unprotected: / {},
/ payload: / null,
/ signature: / h'5B2D535A2B6D5E3C585C1074F414DA9E10BD285C99A33916DADE3ED38812504817AC48B62B8E984EC622785BD1C411888BE531B1B594507816B201F6F28579A4'
] ) >>
] >>,
/ suit-manifest / 3: << {
/ suit-manifest-version / 1: 1,
/ suit-manifest-sequence-number / 2: 3,
/ suit-common / 3: << {
/ suit-components / 2: [
[
h'544545502D446576696365', / "TEEP-Device" /
h'5365637572654653', / "SecureFS" /
h'8D82573A926D4754935332DC29997F74', / tc-uuid /
h'7461' / "ta" /
]
],
/ suit-common-sequence / 4: << [
/ suit-directive-override-parameters / 20, {
/ suit-parameter-vendor-identifier / 1: h'C0DDD5F15243566087DB4F5B0AA26C2F',
/ suit-parameter-class-identifier / 2: h'DB42F7093D8C55BAA8C5265FC5820F4E',
/ suit-parameter-image-digest / 3: << [
/ suit-digest-algorithm-id: / -16 / suit-cose-alg-sha256 /,
/ suit-digest-bytes: / h'8CF71AC86AF31BE184EC7A05A411A8C3A14FD9B77A30D046397481469468ECE8'
] >>,
/ suit-parameter-image-size / 14: 20
},
/ suit-condition-vendor-identifier / 1, 15,
/ suit-condition-class-identifier / 2, 15
] >>
} >>,
/ suit-install / 9: << [
/ suit-directive-override-parameters / 20, {
/ suit-parameter-uri / 21: "https://example.org/8d82573a-926d-4754-9353-32dc29997f74.ta"
},
/ suit-directive-fetch / 21, 15,
/ suit-condition-image-match / 3, 15
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] >>
} >>
}
>>
] / array of bstr wrapped SUIT_Envelope /
}
]
D.4.2. CBOR Binary Representation
82 # array(2)
03 # unsigned(3) / TEEP-TYPE-update /
A2 # map(2)
14 # unsigned(20) / token: /
50 # bytes(16)
A0A1A2A3A4A5A6A7A8A9AAABACADAEAF
0A # unsigned(10) / manifest-list: /
81 # array(1)
59 014E # bytes(336)
A2025873825824822F5820DB601ADE73092B58532CA03FBB663DE495
32435336F1558B49BB622726A2FEDD584AD28443A10126A0F658405B2D53
5A2B6D5E3C585C1074F414DA9E10BD285C99A33916DADE3ED38812504817
AC48B62B8E984EC622785BD1C411888BE531B1B594507816B201F6F28579
A40358D4A401010203035884A20281844B544545502D4465766963654853
65637572654653508D82573A926D4754935332DC29997F74427461045854
8614A40150C0DDD5F15243566087DB4F5B0AA26C2F0250DB42F7093D8C55
BAA8C5265FC5820F4E035824822F58208CF71AC86AF31BE184EC7A05A411
A8C3A14FD9B77A30D046397481469468ECE80E14010F020F0958458614A1
15783B68747470733A2F2F6578616D706C652E6F72672F38643832353733
612D393236642D343735342D393335332D3332646332393939376637342E
7461150F030F
D.5. Success Message
D.5.1. CBOR Diagnostic Notation
/ teep-success = /
[
/ type: / 5 / TEEP-TYPE-teep-success /,
/ options: /
{
/ token / 20 : h'A0A1A2A3A4A5A6A7A8A9AAABACADAEAF'
}
]
D.5.2. CBOR Binary Representation
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82 # array(2)
05 # unsigned(5) / TEEP-TYPE-teep-success /
A1 # map(1)
14 # unsigned(20) / token: /
50 # bytes(16)
A0A1A2A3A4A5A6A7A8A9AAABACADAEAF
D.6. Error Message
D.6.1. CBOR Diagnostic Notation
/ teep-error = /
[
/ type: / 6 / TEEP-TYPE-teep-error /,
/ options: /
{
/ token / 20 : h'A0A1A2A3A4A5A6A7A8A9AAABACADAEAF',
/ err-msg / 12 : "disk-full"
},
/ err-code: / 17 / ERR_MANIFEST_PROCESSING_FAILED /
]
D.6.2. CBOR binary Representation
83 # array(3)
06 # unsigned(6) / TEEP-TYPE-teep-error /
A2 # map(2)
14 # unsigned(20) / token: /
50 # bytes(16)
A0A1A2A3A4A5A6A7A8A9AAABACADAEAF
0C # unsigned(12) / err-msg: /
69 # text(9)
6469736B2D66756C6C # "disk-full"
11 # unsigned(17) / ERR_MANIFEST_PROCESSING_FAILED /
E. Examples of SUIT Manifests
This section shows some examples of SUIT manifests described in
Section 4.4.
The examples are signed using the following ECDSA secp256r1 key with
SHA256 as the digest function.
COSE_Sign1 Cryptographic Key:
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-----BEGIN PRIVATE KEY-----
MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgApZYjZCUGLM50VBC
CjYStX+09jGmnyJPrpDLTz/hiXOhRANCAASEloEarguqq9JhVxie7NomvqqL8Rtv
P+bitWWchdvArTsfKktsCYExwKNtrNHXi9OB3N+wnAUtszmR23M4tKiW
-----END PRIVATE KEY-----
The corresponding public key can be used to verify these examples:
-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEhJaBGq4LqqvSYVcYnuzaJr6qi/Eb
bz/m4rVlnIXbwK07HypLbAmBMcCjbazR14vTgdzfsJwFLbM5kdtzOLSolg==
-----END PUBLIC KEY-----
Example 1: SUIT Manifest pointing to URI of the Trusted Component Binary
CBOR Diagnostic Notation of SUIT Manifest
/ SUIT_Envelope / {
/ authentication-wrapper / 2: << [
<< [
/ digest-algorithm-id: / -16 / cose-alg-sha256 /,
/ digest-bytes: / h'B892B75B262B728EC2C16C2774A730DC804BC87252DAFC57A0098284C3E73587'
] >>,
<< / COSE_Sign1_Tagged / 18([
/ protected: / << {
/ algorithm-id / 1: -7 / ES256 /
} >>,
/ unprotected: / {},
/ payload: / null,
/ signature: / h'B888EE88553CF894A4921F5FF8B3289C354AFAC504E2526D0DB0EE576069D9599BDF68C7EE6E41B8C1BE78524F082FF62E760F3814F57B18BDB96249CBD8B3E1'
]) >>
] >>,
/ manifest / 3: << {
/ manifest-version / 1: 1,
/ manifest-sequence-number / 2: 3,
/ common / 3: << {
/ components / 2: [
[
h'544545502D446576696365', / "TEEP-Device" /
h'5365637572654653', / "SecureFS" /
h'8D82573A926D4754935332DC29997F74', / tc-uuid /
h'7461' / "ta" /
]
],
/ shared-sequence / 4: << [
/ directive-override-parameters / 20, {
/ parameter-vendor-identifier / 1: h'C0DDD5F15243566087DB4F5B0AA26C2F',
/ parameter-class-identifier / 2: h'DB42F7093D8C55BAA8C5265FC5820F4E',
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/ parameter-image-digest / 3: << [
/ digest-algorithm-id: / -16 / cose-alg-sha256 /,
/ digest-bytes: / h'8CF71AC86AF31BE184EC7A05A411A8C3A14FD9B77A30D046397481469468ECE8'
] >>,
/ parameter-image-size / 14: 20
},
/ condition-vendor-identifier / 1, 15,
/ condition-class-identifier / 2, 15
] >>
} >>,
/ manifest-component-id / 5: [
h'544545502D446576696365', / "TEEP-Device" /
h'5365637572654653', / "SecureFS" /
h'8D82573A926D4754935332DC29997F74', / tc-uuid /
h'73756974' / "suit" /
],
/ install / 17: << [
/ directive-override-parameters / 20, {
/ parameter-uri / 21: "https://example.org/8d82573a-926d-4754-9353-32dc29997f74.ta"
},
/ directive-fetch / 21, 15,
/ condition-image-match / 3, 15
] >>
} >>
}
CBOR Binary in Hex
A2025873825824822F5820B892B75B262B728EC2C16C2774A730DC804BC8
7252DAFC57A0098284C3E73587584AD28443A10126A0F65840B888EE8855
3CF894A4921F5FF8B3289C354AFAC504E2526D0DB0EE576069D9599BDF68
C7EE6E41B8C1BE78524F082FF62E760F3814F57B18BDB96249CBD8B3E103
590101A501010203035884A20281844B544545502D446576696365485365
637572654653508D82573A926D4754935332DC29997F7442746104585486
14A40150C0DDD5F15243566087DB4F5B0AA26C2F0250DB42F7093D8C55BA
A8C5265FC5820F4E035824822F58208CF71AC86AF31BE184EC7A05A411A8
C3A14FD9B77A30D046397481469468ECE80E14010F020F05844B54454550
2D446576696365485365637572654653508D82573A926D4754935332DC29
997F7444737569741158458614A115783B68747470733A2F2F6578616D70
6C652E6F72672F38643832353733612D393236642D343735342D39333533
2D3332646332393939376637342E7461150F030F
Example 2: SUIT Manifest including the Trusted Component Binary
CBOR Diagnostic Notation of SUIT Manifest
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/ SUIT_Envelope / {
/ authentication-wrapper / 2: << [
<< [
/ digest-algorithm-id: / -16 / cose-alg-sha256 /,
/ digest-bytes: / h'C20DE9B1378EC787D9A9F7C3B0F196E4C51FB519E3FFD45A6B985CE3E9222993'
] >>,
<< / COSE_Sign1_Tagged / 18([
/ protected: / << {
/ algorithm-id / 1: -7 / ES256 /
} >>,
/ unprotected: / {},
/ payload: / null,
/ signature: / h'3A95608085653743E582395417CC381DCD77370D353D938A71B72411289EF406D5A7783AB6DE6901FAD0D4EF85B777A3C3F46C5631D24EADE7A4AD2E76D2AF4A'
]) >>
] >>,
/ manifest / 3: << {
/ manifest-version / 1: 1,
/ manifest-sequence-number / 2: 3,
/ common / 3: << {
/ components / 2: [
[
h'544545502D446576696365', / "TEEP-Device" /
h'5365637572654653', / "SecureFS" /
h'8D82573A926D4754935332DC29997F74', / tc-uuid /
h'7461' / "ta" /
]
],
/ shared-sequence / 4: << [
/ directive-override-parameters / 20, {
/ vendor-id / 1: h'C0DDD5F15243566087DB4F5B0AA26C2F' / c0ddd5f1-5243-5660-87db-4f5b0aa26c2f /,
/ class-id / 2: h'DB42F7093D8C55BAA8C5265FC5820F4E' / db42f709-3d8c-55ba-a8c5-265fc5820f4e /,
/ image-digest / 3: << [
/ algorithm-id: / -16 / SHA-256 /,
/ digest-bytes: / h'8CF71AC86AF31BE184EC7A05A411A8C3A14FD9B77A30D046397481469468ECE8'
] >>,
/ image-size / 14: 20
},
/ condition-vendor-identifier / 1, 15,
/ condition-class-identifier / 2, 15
] >>
} >>,
/ manifest-component-id / 5: [
h'544545502D446576696365', / "TEEP-Device" /
h'5365637572654653', / "SecureFS" /
h'8D82573A926D4754935332DC29997F74', / tc-uuid /
h'73756974' / "suit" /
],
/ install / 17: << [
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/ directive-override-parameters / 20, {
/ uri / 21: "#tc"
},
/ directive-fetch / 21, 15,
/ condition-image-match / 3, 15
] >>
} >>,
"#tc" : h'48656C6C6F2C2053656375726520576F726C6421' / "Hello, Secure World!" /
}
CBOR Binary in Hex
A3025873825824822F5820C20DE9B1378EC787D9A9F7C3B0F196E4C51FB5
19E3FFD45A6B985CE3E9222993584AD28443A10126A0F658403A95608085
653743E582395417CC381DCD77370D353D938A71B72411289EF406D5A778
3AB6DE6901FAD0D4EF85B777A3C3F46C5631D24EADE7A4AD2E76D2AF4A03
58C7A501010203035884A20281844B544545502D44657669636548536563
7572654653508D82573A926D4754935332DC29997F744274610458548614
A40150C0DDD5F15243566087DB4F5B0AA26C2F0250DB42F7093D8C55BAA8
C5265FC5820F4E035824822F58208CF71AC86AF31BE184EC7A05A411A8C3
A14FD9B77A30D046397481469468ECE80E14010F020F05844B544545502D
446576696365485365637572654653508D82573A926D4754935332DC2999
7F744473756974114C8614A11563237463150F030F632374635448656C6C
6F2C2053656375726520576F726C6421
Example 3: Supplying Personalization Data for Trusted Component Binary
CBOR Diagnostic Notation of SUIT Manifest
/ SUIT_Envelope / {
/ authentication-wrapper / 2: << [
<< [
/ digest-algorithm-id: / -16 / cose-alg-sha256 /,
/ digest-bytes: / h'99D1AD5D2C44320B247BB37B8CDB418CADA53590DF4EF928E30240F5717088FA'
] >>,
<< / COSE_Sign1_Tagged / 18([
/ protected: / << {
/ algorithm-id / 1: -7 / ES256 /
} >>,
/ unprotected: / {},
/ payload: / null,
/ signature: / h'447D94B8249CB15AA544EF2315BCBBC8DC1F8A790DC863D6CC83F799DF3576AFAEDC2E63512E5C0699F62B20A555CF4176E1D7018FE748D9BFEF47A4E1C8889E'
]) >>
] >>,
/ manifest / 3: << {
/ manifest-version / 1: 1,
/ manifest-sequence-number / 2: 3,
/ common / 3: << {
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/ dependencies / 1: {
/ component-index / 1: {
/ dependency-prefix / 1: [
h'544545502D446576696365', / "TEEP-Device" /
h'5365637572654653', / "SecureFS" /
h'8D82573A926D4754935332DC29997F74', / tc-uuid /
h'73756974' / "suit" /
]
}
},
/ components / 2: [
[
h'544545502D446576696365', / "TEEP-Device" /
h'5365637572654653', / "SecureFS" /
h'636F6E6669672E6A736F6E' / "config.json" /
]
],
/ shared-sequence / 4: << [
/ directive-set-component-index / 12, 0,
/ directive-override-parameters / 20, {
/ vendor-id / 1: h'C0DDD5F15243566087DB4F5B0AA26C2F' / c0ddd5f1-5243-5660-87db-4f5b0aa26c2f /,
/ class-id / 2: h'DB42F7093D8C55BAA8C5265FC5820F4E' / db42f709-3d8c-55ba-a8c5-265fc5820f4e /,
/ image-digest / 3: << [
/ algorithm-id: / -16 / SHA-256 /,
/ digest-bytes: / h'AAABCCCDEEEF00012223444566678889ABBBCDDDEFFF01112333455567778999'
] >>,
/ image-size / 14: 64
},
/ condition-vendor-identifier / 1, 15,
/ condition-class-identifier / 2, 15
] >>
} >>,
/ manifest-component-id / 5: [
h'544545502D446576696365', / "TEEP-Device" /
h'5365637572654653', / "SecureFS" /
h'636F6E6669672E73756974' / "config.suit" /
],
/ validate / 7: << [
/ directive-set-component-index / 12, 0,
/ condition-image-match / 3, 15
] >>,
/ dependency-resolution / 15: << [
/ directive-set-component-index / 12, 1,
/ directive-override-parameters / 20, {
/ uri / 21: "https://example.org/8d82573a-926d-4754-9353-32dc29997f74.suit"
},
/ directive-fetch / 21, 2,
/ condition-image-match / 3, 15
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] >>,
/ install / 17: << [
/ directive-set-component-index / 12, 1,
/ directive-process-dependency / 11, 0,
/ directive-set-component-index / 12, 0,
/ directive-override-parameters / 20, {
/ uri / 21: "https://example.org/config.json"
},
/ directive-fetch / 21, 2,
/ condition-image-match / 3, 15
] >>
} >>
}
CBOR Binary in Hex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E.4. Example 4: Unlink a Trusted Component
CBOR Diagnostic Notation of SUIT Manifest
/ SUIT_Envelope / {
/ authentication-wrapper / 2: << [
<< [
/ digest-algorithm-id: / -16 / cose-alg-sha256 /,
/ digest-bytes: / h'F9D837B7118A8972360022D51AC5319023D245A76F7504079B9ED01C0B4934F2'
] >>,
<< / COSE_Sign1_Tagged / 18([
/ protected: / << {
/ algorithm-id / 1: -7 / ES256 /
} >>,
/ unprotected: / {},
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/ payload: / null,
/ signature: / h'332BE0CC2D109F23ADF1D220CECA17EA38047814A6CE0389AC370A32AB2008B44C67789CEFEEEC9208FEBC55EA60AC2E88365498D70689C190BBDAD2E60072B9'
]) >>
] >>,
/ manifest / 3: << {
/ manifest-version / 1: 1,
/ manifest-sequence-number / 2: 18446744073709551615 / UINT64_MAX /,
/ common / 3: << {
/ components / 2: [
[
h'544545502D446576696365', / "TEEP-Device" /
h'5365637572654653', / "SecureFS" /
h'8D82573A926D4754935332DC29997F74', / tc-uuid /
h'7461' / "ta" /
]
],
/ common-sequence / 4: << [
/ directive-override-parameters / 20, {
/ vendor-id / 1: h'C0DDD5F15243566087DB4F5B0AA26C2F' / c0ddd5f1-5243-5660-87db-4f5b0aa26c2f /,
/ class-id / 2: h'DB42F7093D8C55BAA8C5265FC5820F4E' / db42f709-3d8c-55ba-a8c5-265fc5820f4e /
},
/ condition-vendor-identifier / 1, 15,
/ condition-class-identifier / 2, 15
] >>
} >>,
/ manifest-component-id / 5: [
h'544545502D446576696365', / "TEEP-Device" /
h'5365637572654653', / "SecureFS" /
h'8D82573A926D4754935332DC29997F74', / tc-uuid /
h'73756974' / "suit" /
],
/ install / 17: << [
/ directive-set-component-index / 12, 0,
/ directive-unlink / 33, 0
] >>
} >>
}
CBOR Binary in Hex
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A2025873825824822F5820F9D837B7118A8972360022D51AC5319023D245
A76F7504079B9ED01C0B4934F2584AD28443A10126A0F65840332BE0CC2D
109F23ADF1D220CECA17EA38047814A6CE0389AC370A32AB2008B44C6778
9CEFEEEC9208FEBC55EA60AC2E88365498D70689C190BBDAD2E60072B903
58A0A50101021BFFFFFFFFFFFFFFFF03585BA20281844B544545502D4465
76696365485365637572654653508D82573A926D4754935332DC29997F74
42746104582B8614A20150C0DDD5F15243566087DB4F5B0AA26C2F0250DB
42F7093D8C55BAA8C5265FC5820F4E010F020F05844B544545502D446576
696365485365637572654653508D82573A926D4754935332DC29997F7444
737569741146840C00182100
F. Examples of SUIT Reports
This section shows some examples of SUIT reports.
F.1. Example 1: Success
SUIT Reports have no records if no conditions have failed. The URI
in this example is the reference URI provided in the SUIT manifest.
{
/ suit-report-manifest-digest / 1:<<[
/ algorithm-id / -16 / "sha256" /,
/ digest-bytes / h'a7fd6593eac32eb4be578278e6540c5c'
h'09cfd7d4d234973054833b2b93030609'
]>>,
/ suit-report-manifest-uri / 2: "tam.teep.example/personalisation.suit",
/ suit-report-records / 4: []
}
F.2. Example 2: Faiure
{
/ suit-report-manifest-digest / 1:<<[
/ algorithm-id / -16 / "sha256" /,
/ digest-bytes / h'a7fd6593eac32eb4be578278e6540c5c09cfd7d4d234973054833b2b93030609'
]>>,
/ suit-report-manifest-uri / 2: "tam.teep.example/personalisation.suit",
/ suit-report-records / 4: [
{
/ suit-record-manifest-id / 1:[],
/ suit-record-manifest-section / 2: 7 / dependency-resolution /,
/ suit-record-section-offset / 3: 66,
/ suit-record-dependency-index / 5: 0,
/ suit-record-failure-reason / 6: 404
}
]
}
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where the dependency-resolution refers to:
{
authentication-wrapper,
/ manifest / 3:<<{
/ manifest-version / 1:1,
/ manifest-sequence-number / 2:3,
common,
dependency-resolution,
install,
validate,
run,
text
}>>,
}
and the suit-record-section-offset refers to:
<<[
/ directive-set-dependency-index / 13,0 ,
/ directive-set-parameters / 19,{
/ uri / 21:'tam.teep.example/'
'edd94cd8-9d9c-4cc8-9216-b3ad5a2d5b8a.suit',
} ,
/ directive-fetch / 21,2 ,
/ condition-image-match / 3,15
]>>,
Authors' Addresses
Hannes Tschofenig
Austria
Email: hannes.tschofenig@gmx.net
Mingliang Pei
Broadcom
United States of America
Email: mingliang.pei@broadcom.com
David Wheeler
Amazon
United States of America
Email: davewhee@amazon.com
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Dave Thaler
Microsoft
United States of America
Email: dthaler@microsoft.com
Akira Tsukamoto
Japan
Email: akira.tsukamoto@gmail.com
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