Internet DRAFT - draft-bdc-something-something-certificate
draft-bdc-something-something-certificate
Aspirational B. Campbell
Internet-Draft Ping Identity
Intended status: Informational 23 March 2021
Expires: 24 September 2021
Client-Cert HTTP Header: Conveying Client Certificate Information from
TLS Terminating Reverse Proxies to Origin Server Applications
draft-bdc-something-something-certificate-05
Abstract
This document defines the HTTP header field "Client-Cert" that allows
a TLS terminating reverse proxy to convey the client certificate of a
mutually-authenticated TLS connection to the origin server in a
common and predictable manner.
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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This Internet-Draft will expire on 24 September 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Notation and Conventions . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. HTTP Header Field and Processing Rules . . . . . . . . . . . 4
2.1. Encoding . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Client-Cert HTTP Header Field . . . . . . . . . . . . . . 4
2.3. Processing Rules . . . . . . . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Normative References . . . . . . . . . . . . . . . . . . . . 7
6. Informative References . . . . . . . . . . . . . . . . . . . 7
Appendix A. Example . . . . . . . . . . . . . . . . . . . . . . 9
Appendix B. Considerations Considered . . . . . . . . . . . . . 10
B.1. Header Injection . . . . . . . . . . . . . . . . . . . . 10
B.2. The Forwarded HTTP Extension . . . . . . . . . . . . . . 10
B.3. The Whole Certificate and Only the Whole Certificate . . 11
Appendix C. Acknowledgements . . . . . . . . . . . . . . . . . . 12
Appendix D. Document History . . . . . . . . . . . . . . . . . . 12
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
A fairly common deployment pattern for HTTPS applications is to have
the origin HTTP application servers sit behind a reverse proxy that
terminates TLS connections from clients. The proxy is accessible to
the internet and dispatches client requests to the appropriate origin
server within a private or protected network. The origin servers are
not directly accessible by clients and are only reachable through the
reverse proxy. The backend details of this type of deployment are
typically opaque to clients who make requests to the proxy server and
see responses as though they originated from the proxy server itself.
Although HTTPS is also usually employed between the proxy and the
origin server, the TLS connection that the client establishes for
HTTPS is only between itself and the reverse proxy server.
The deployment pattern is found in a number of varieties such as
n-tier architectures, content delivery networks, application load
balancing services, and ingress controllers.
Although not exceedingly prevalent, TLS client certificate
authentication is sometimes employed and in such cases the origin
server often requires information about the client certificate for
its application logic. Such logic might include access control
decisions, audit logging, and binding issued tokens or cookies to a
certificate, and the respective validation of such bindings. The
specific details from the certificate needed also vary with the
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application requirements. In order for these types of application
deployments to work in practice, the reverse proxy needs to convey
information about the client certificate to the origin application
server. A common way this information is conveyed in practice today
is by using non-standard headers to carry the certificate (in some
encoding) or individual parts thereof in the HTTP request that is
dispatched to the origin server. This solution works but
interoperability between independently developed components can be
cumbersome or even impossible depending on the implementation choices
respectively made (like what header names are used or are
configurable, which parts of the certificate are exposed, or how the
certificate is encoded). A well-known predictable approach to this
commonly occurring functionality could improve and simplify
interoperability between independent implementations.
This document aspires to standardize an HTTP header field named
"Client-Cert" that a TLS terminating reverse proxy (TTRP) adds to
requests that it sends to the backend origin servers. The header
value contains the client certificate from the mutually-authenticated
TLS connection between the originating client and the TTRP. This
enables the backend origin server to utilize the client certificate
information in its application logic. While there may be additional
proxies or hops between the TTRP and the origin server (potentially
even with mutually-authenticated TLS connections between them), the
scope of the "Client-Cert" header is intentionally limited to
exposing to the origin server the certificate that was presented by
the originating client in its connection to the TTRP.
1.1. Requirements Notation and Conventions
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.
1.2. Terminology
Phrases like TLS client certificate authentication or mutually-
authenticated TLS are used throughout this document to refer to the
process whereby, in addition to the normal TLS server authentication
with a certificate, a client presents its X.509 certificate [RFC5280]
and proves possession of the corresponding private key to a server
when negotiating a TLS connection or the resumption of such a
connection. In contemporary versions of TLS [RFC8446] [RFC5246] this
requires that the client send the Certificate and CertificateVerify
messages during the handshake and for the server to verify the
CertificateVerify and Finished messages.
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[[ HTTP2 forbids TLS renegotiation and post-handshake authentication
but it's possible with HTTP1.1 and maybe needs to be discussed
explicitly here or somewhere in this document? Naively I'd say that
the "Client-Cert" header will be sent with the data of the most
recent client cert anytime after renegotiation or post-handshake
auth. And only for requests that are fully covered by the cert but
that in practice making the determination of where exactly in the
application data the cert messages arrived is hard to impossible so
it'll be a best effort kind of thing. ]]
2. HTTP Header Field and Processing Rules
2.1. Encoding
The field-values of the HTTP header defined herein utilize the
following encoded form.
A certificate is represented in text as an "EncodedCertificate",
which is the base64-encoded (Section 4 of [RFC4648]) DER [ITU.X690]
PKIX certificate. The encoded value MUST NOT include any line
breaks, whitespace, or other additional characters. ABNF [RFC5234]
syntax for "EncodedCertificate" is shown in the figure below.
EncodedCertificate = 1*( DIGIT / ALPHA / "+" / "/" ) 0*2"="
DIGIT = <Defined in Section B.1 of [RFC5234]> ; A-Z / a-z
ALPHA = <Defined in Section B.1 of [RFC5234]> ; 0-9
2.2. Client-Cert HTTP Header Field
In the context of a TLS terminating reverse proxy (TTRP) deployment,
the TTRP makes the TLS client certificate available to the backend
application with the following header field.
Client-Cert The end-entity client certificate as an
"EncodedCertificate" value.
The "Client-Cert" header field defined herein is only for use in HTTP
requests and MUST NOT be used in HTTP responses. It is a single HTTP
header field-value as defined in Section 3.2 of [RFC7230], which MUST
NOT have a list of values or occur multiple times in a request.
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2.3. Processing Rules
This section outlines the applicable processing rules for a TLS
terminating reverse proxy (TTRP) that has negotiated a mutually-
authenticated TLS connection to convey the client certificate from
that connection to the backend origin servers. Use of the technique
is to be a configuration or deployment option and the processing
rules described herein are for servers operating with that option
enabled.
A TTRP negotiates the use of a mutually-authenticated TLS connection
with the client, such as is described in [RFC8446] or [RFC5246], and
validates the client certificate per its policy and trusted
certificate authorities. Each HTTP request on the underlying TLS
connection are dispatched to the origin server with the following
modifications:
1. The client certificate is be placed in the "Client-Cert" header
field of the dispatched request as defined in Section 2.2.
2. Any occurrence of the "Client-Cert" header in the original
incoming request MUST be removed or overwritten before forwarding
the request. An incoming request that has a "Client-Cert" header
MAY be rejected with an HTTP 400 response.
Requests made over a TLS connection where the use of client
certificate authentication was not negotiated MUST be sanitized by
removing any and all occurrences "Client-Cert" header field prior to
dispatching the request to the backend server.
Backend origin servers may then use the "Client-Cert" header of the
request to determine if the connection from the client to the TTRP
was mutually-authenticated and, if so, the certificate thereby
presented by the client.
Forward proxies and other intermediaries MUST NOT add the "Client-
Cert" header to requests, or modify an existing "Client-Cert" header.
Similarly, clients MUST NOT employ the "Client-Cert" header in
requests.
A server that receives a request with a "Client-Cert" header value
that it considers to be too large can respond with an HTTP 431 status
code per Section 5 of [RFC6585].
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3. Security Considerations
The header described herein enable a TTRP and backend or origin
server to function together as though, from the client's perspective,
they are a single logical server side deployment of HTTPS over a
mutually-authenticated TLS connection. Use of the "Client-Cert"
header outside that intended use case, however, may undermine the
protections afforded by TLS client certificate authentication.
Therefore steps MUST be taken to prevent unintended use, both in
sending the header and in relying on its value.
Producing and consuming the "Client-Cert" header SHOULD be a
configurable option, respectively, in a TTRP and backend server (or
individual application in that server). The default configuration
for both should be to not use the "Client-Cert" header thus requiring
an "opt-in" to the functionality.
In order to prevent header injection, backend servers MUST only
accept the "Client-Cert" header from a trusted TTRP (or other proxy
in a trusted path from the TTRP). A TTRP MUST sanitize the incoming
request before forwarding it on by removing or overwriting any
existing instances of the header. Otherwise arbitrary clients can
control the header value as seen and used by the backend server. It
is important to note that neglecting to prevent header injection does
not "fail safe" in that the nominal functionality will still work as
expected even when malicious actions are possible. As such, extra
care is recommended in ensuring that proper header sanitation is in
place.
The communication between a TTRP and backend server needs to be
secured against eavesdropping and modification by unintended parties.
The configuration options and request sanitization are necessarily
functionally of the respective servers. The other requirements can
be met in a number of ways, which will vary based on specific
deployments. The communication between a TTRP and backend or origin
server, for example, might be authenticated in some way with the
insertion and consumption of the "Client-Cert" header occurring only
on that connection. Alternatively the network topology might dictate
a private network such that the backend application is only able to
accept requests from the TTRP and the proxy can only make requests to
that server. Other deployments that meet the requirements set forth
herein are also possible.
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4. IANA Considerations
[[ TBD if this draft progresses, register the "Client-Cert" HTTP
header field in the "Permanent Message Header Field Names" registry
(https://www.iana.org/assignments/message-headers/message-
headers.xhtml) defined in [RFC3864] ]]
5. Normative References
[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/info/rfc8174>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>.
[ITU.X690] International Telecommunications Union, "Information
Technology - ASN.1 encoding rules: Specification of Basic
Encoding Rules (BER), Canonical Encoding Rules (CER) and
Distinguished Encoding Rules (DER)", August 2015.
[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/info/rfc2119>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/info/rfc5280>.
6. Informative References
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status
Codes", RFC 6585, DOI 10.17487/RFC6585, April 2012,
<https://www.rfc-editor.org/info/rfc6585>.
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[RFC8705] Campbell, B., Bradley, J., Sakimura, N., and T.
Lodderstedt, "OAuth 2.0 Mutual-TLS Client Authentication
and Certificate-Bound Access Tokens", RFC 8705,
DOI 10.17487/RFC8705, February 2020,
<https://www.rfc-editor.org/info/rfc8705>.
[RFC7239] Petersson, A. and M. Nilsson, "Forwarded HTTP Extension",
RFC 7239, DOI 10.17487/RFC7239, June 2014,
<https://www.rfc-editor.org/info/rfc7239>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>.
[I-D.ietf-httpbis-header-structure]
Nottingham, M. and P. Kamp, "Structured Field Values for
HTTP", Work in Progress, Internet-Draft, draft-ietf-
httpbis-header-structure-19, 3 June 2020,
<https://tools.ietf.org/html/draft-ietf-httpbis-header-
structure-19>.
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864,
DOI 10.17487/RFC3864, September 2004,
<https://www.rfc-editor.org/info/rfc3864>.
[RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
Weiler, S., and T. Kivinen, "Using Raw Public Keys in
Transport Layer Security (TLS) and Datagram Transport
Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
June 2014, <https://www.rfc-editor.org/info/rfc7250>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
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Appendix A. Example
In a hypothetical example where a TLS client presents the client and
intermediate certificate from Figure 1 when establishing a mutually-
authenticated TLS connection with the TTRP, the proxy would send the
"Client-Cert" header shown in {#example-header} to the backend. Note
that line breaks and whitespace have been added to the value of the
header field in Figure 2 for display and formatting purposes only.
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
MIIB5jCCAYugAwIBAgIBFjAKBggqhkjOPQQDAjBWMQswCQYDVQQGEwJVUzEbMBkG
A1UECgwSTGV0J3MgQXV0aGVudGljYXRlMSowKAYDVQQDDCFMZXQncyBBdXRoZW50
aWNhdGUgUm9vdCBBdXRob3JpdHkwHhcNMjAwMTE0MjEzMjMwWhcNMzAwMTExMjEz
MjMwWjA6MRswGQYDVQQKDBJMZXQncyBBdXRoZW50aWNhdGUxGzAZBgNVBAMMEkxB
IEludGVybWVkaWF0ZSBDQTBZMBMGByqGSM49AgEGCCqGSM49AwEHA0IABJf+aA54
RC5pyLAR5yfXVYmNpgd+CGUTDp2KOGhc0gK91zxhHesEYkdXkpS2UN8Kati+yHtW
CV3kkhCngGyv7RqjZjBkMB0GA1UdDgQWBBRm3WjLa38lbEYCuiCPct0ZaSED2DAf
BgNVHSMEGDAWgBTEA2Q6eecKu9g9yb5glbkhhVINGDASBgNVHRMBAf8ECDAGAQH/
AgEAMA4GA1UdDwEB/wQEAwIBhjAKBggqhkjOPQQDAgNJADBGAiEA5pLvaFwRRkxo
mIAtDIwg9D7gC1xzxBl4r28EzmSO1pcCIQCJUShpSXO9HDIQMUgH69fNDEMHXD3R
RX5gP7kuu2KGMg==
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
Figure 1: Certificate Chain (with client certificate first)
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Client-Cert: MIIBqDCCAU6gAwIBAgIBBzAKBggqhkjOPQQDAjA6MRswGQYDVQQKDBJM
ZXQncyBBdXRoZW50aWNhdGUxGzAZBgNVBAMMEkxBIEludGVybWVkaWF0ZSBDQTAeFw0y
MDAxMTQyMjU1MzNaFw0yMTAxMjMyMjU1MzNaMA0xCzAJBgNVBAMMAkJDMFkwEwYHKoZI
zj0CAQYIKoZIzj0DAQcDQgAE8YnXXfaUgmnMtOXU/IncWalRhebrXmckC8vdgJ1p5Be5
F/3YC8OthxM4+k1M6aEAEFcGzkJiNy6J84y7uzo9M6NyMHAwCQYDVR0TBAIwADAfBgNV
HSMEGDAWgBRm3WjLa38lbEYCuiCPct0ZaSED2DAOBgNVHQ8BAf8EBAMCBsAwEwYDVR0l
BAwwCgYIKwYBBQUHAwIwHQYDVR0RAQH/BBMwEYEPYmRjQGV4YW1wbGUuY29tMAoGCCqG
SM49BAMCA0gAMEUCIBHda/r1vaL6G3VliL4/Di6YK0Q6bMjeSkC3dFCOOB8TAiEAx/kH
SB4urmiZ0NX5r5XarmPk0wmuydBVoU4hBVZ1yhk=
Figure 2: Header in HTTP Request to Origin Server
Appendix B. Considerations Considered
B.1. Header Injection
This draft requires that the TTRP sanitize the headers of the
incoming request by removing or overwriting any existing instances of
the "Client-Cert" header before dispatching that request to the
backend application. Otherwise, a client could inject its own
"Client-Cert" header that would appear to the backend to have come
from the TTRP. Although numerous other methods of detecting/
preventing header injection are possible; such as the use of a unique
secret value as part of the header name or value or the application
of a signature, HMAC, or AEAD, there is no common general
standardized mechanism. The potential problem of client header
injection is not at all unique to the functionality of this draft and
it would therefor be inappropriate for this draft to define a one-off
solution. In the absence of a generic standardized solution existing
currently, stripping/sanitizing the headers is the de facto means of
protecting against header injection in practice today. Sanitizing
the headers is sufficient when properly implemented and is normative
requirement of Section 3.
B.2. The Forwarded HTTP Extension
The "Forwarded" HTTP header field defined in [RFC7239] allows proxy
components to disclose information lost in the proxying process. The
TLS client certificate information of concern to this draft could
have been communicated with an extension parameter to the "Forwarded"
header field, however, doing so would have had some disadvantages
that this draft endeavored to avoid. The "Forwarded" header syntax
allows for information about a full chain of proxied HTTP requests,
whereas the "Client-Cert" header of this document is concerned only
with conveying information about the certificate presented by the
originating client on the TLS connection to the TTRP (which appears
as the server from that client's perspective) to backend
applications. The multi-hop syntax of the "Forwarded" header is
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expressive but also more complicated, which would make processing it
more cumbersome, and more importantly, make properly sanitizing its
content as required by Section 3 to prevent header injection
considerably more difficult and error prone. Thus, this draft opted
for the flatter and more straightforward structure of a single
"Client-Cert" header.
B.3. The Whole Certificate and Only the Whole Certificate
Different applications will have varying requirements about what
information from the client certificate is needed, such as the
subject and/or issuer distinguished name, subject alternative
name(s), serial number, subject public key info, fingerprint, etc..
Furthermore some applications, such as "OAuth 2.0 Mutual-TLS Client
Authentication and Certificate-Bound Access Tokens" [RFC8705], make
use of the entire certificate. In order to accommodate the latter
and ensure wide applicability by not trying to cherry-pick particular
certificate information, this draft opted to pass the full encoded
certificate as the value of the "Client-Cert" header.
The handshake and validation of the client certificate (chain) of the
mutually-authenticated TLS connection is performed by the TTRP. With
the responsibility of certificate validation falling on the TTRP,
only the end-entity certificate is passed to the backend - the root
Certificate Authority is not included nor are any intermediates.
[[ It has been suggested that more information about the certificate
chain might be needed/wanted by the backend application (to
independently evaluate the cert chain, for example, although that
seems like it would be terribly inefficient) and that any
intermediates as well as the root should also be somehow conveyed,
which is an area for further discussion should this draft progress.
One potential approach suggested by a few folks is to allow some
configurability in what is sent along with maybe a prefix token to
indicate what's being sent - something like "Client-Cert: FULL <cert>
<intermediate> <anchor>" or "Client-Cert: EE <cert>" as the strawman.
Or a perhaps a parameter or other construct of
[I-D.ietf-httpbis-header-structure] to indicate what's being sent.
It's also been suggested that the end-entity certificate by itself
might sometimes be too big (esp. e.g., with some post-quantum
signature schemes). Hard to account for it both being too much data
and not enough data at the same time. But potentially opening up
configuration options to send only specific attribute(s) from the
client certificate is a possibility for that. In the author's humble
opinion the end-entity certificate by itself strikes a good balance
for the vast majority of needs and avoids optionality. But, again,
this is an area for further discussion should this draft progress. ]]
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[[ It has also been suggested that maybe considerations for [RFC7250]
Raw Public Keys is maybe worth considering. This too is this is an
area for further discussion and consideration should this draft
progress. ]]
Appendix C. Acknowledgements
The author would like to thank the following individuals who've
contributed in various ways ranging from just being generally
supportive of bringing forth the draft to providing specific feedback
or content: Evan Anderson, Annabelle Backman, Mike Bishop, Rory
Hewitt, Fredrik Jeansson, Benjamin Kaduk, Torsten Lodderstedt,
Kathleen Moriarty, Mark Nottingham, Mike Ounsworth, Matt Peterson,
Eric Rescorla, Justin Richer, Michael Richardson, Joe Salowey, Rich
Salz, Mohit Sethi, Rifaat Shekh-Yusef, Travis Spencer, Nick Sullivan,
Peter Wu, and Hans Zandbelt.
[[ Please let me know if you've been erroneously omitted or if you
prefer not to be named ]]
Appendix D. Document History
[[ To be removed by the RFC Editor before publication as an RFC
(should that come to pass) ]]
draft-bdc-something-something-certificate-05
* Change intended status of the draft to Informational
* Editorial updates and (hopefully) clarifications
draft-bdc-something-something-certificate-04
* Update reference from draft-ietf-oauth-mtls to RFC8705
draft-bdc-something-something-certificate-03
* Expanded [[further discussion notes]] to capture some of the
feedback in and around the presentation of the draft in
SECDISPATCH at IETF 107 and add those who've provided such
feedback to the acknowledgements
draft-bdc-something-something-certificate-02
* Editorial tweaks + [[further discussion notes]]
draft-bdc-something-something-certificate-01
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* Use the RFC v3 Format or die trying
draft-bdc-something-something-certificate-00
* Initial draft after a time constrained and rushed secdispatch
presentation (https://datatracker.ietf.org/meeting/106/materials/
slides-106-secdispatch-securing-protocols-between-proxies-and-
backend-http-servers-00) at IETF 106 in Singapore with the
recommendation to write up a draft (at the end of the minutes
(https://datatracker.ietf.org/meeting/106/materials/minutes-
106-secdispatch)) and some folks expressing interest despite the
rather poor presentation
Author's Address
Brian Campbell
Ping Identity
Email: bcampbell@pingidentity.com
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