Network Working Group T. Enghardt
Internet-Draft TU Berlin
Intended status: Informational T. Pauly
Expires: 6 September 2020 Apple Inc.
C. Perkins
University of Glasgow
K. Rose
Akamai Technologies, Inc.
C.A. Wood, Ed.
Apple Inc.
5 March 2020
A Survey of the Interaction Between Security Protocols and Transport
Services
draft-ietf-taps-transport-security-11
Abstract
This document provides a survey of commonly used or notable network
security protocols, with a focus on how they interact and integrate
with applications and transport protocols. Its goal is to supplement
efforts to define and catalog transport services by describing the
interfaces required to add security protocols. This survey is not
limited to protocols developed within the scope or context of the
IETF, and those included represent a superset of features a Transport
Services system may need to support.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 6 September 2020.
Enghardt, et al. Expires 6 September 2020 [Page 1]
Internet-Draft Transport Security Survey March 2020
Copyright Notice
Copyright (c) 2020 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
and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Non-Goals . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Transport Security Protocol Descriptions . . . . . . . . . . 6
3.1. Application Payload Security Protocols . . . . . . . . . 6
3.1.1. TLS . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1.2. DTLS . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2. Application-Specific Security Protocols . . . . . . . . . 7
3.2.1. Secure RTP . . . . . . . . . . . . . . . . . . . . . 7
3.3. Transport-Layer Security Protocols . . . . . . . . . . . 7
3.3.1. IETF QUIC . . . . . . . . . . . . . . . . . . . . . . 8
3.3.2. Google QUIC . . . . . . . . . . . . . . . . . . . . . 8
3.3.3. tcpcrypt . . . . . . . . . . . . . . . . . . . . . . 8
3.3.4. MinimalT . . . . . . . . . . . . . . . . . . . . . . 8
3.3.5. CurveCP . . . . . . . . . . . . . . . . . . . . . . . 8
3.4. Packet Security Protocols . . . . . . . . . . . . . . . . 9
3.4.1. IKEv2 with ESP . . . . . . . . . . . . . . . . . . . 9
3.4.2. WireGuard . . . . . . . . . . . . . . . . . . . . . . 9
3.4.3. OpenVPN . . . . . . . . . . . . . . . . . . . . . . . 9
4. Transport Dependencies . . . . . . . . . . . . . . . . . . . 9
4.1. Reliable Byte-Stream Transports . . . . . . . . . . . . . 10
4.2. Unreliable Datagram Transports . . . . . . . . . . . . . 10
4.2.1. Datagram Protocols with Defined Byte-Stream
Mappings . . . . . . . . . . . . . . . . . . . . . . 11
4.3. Transport-Specific Dependencies . . . . . . . . . . . . . 11
5. Application Interface . . . . . . . . . . . . . . . . . . . . 11
5.1. Pre-Connection Interfaces . . . . . . . . . . . . . . . . 12
5.2. Connection Interfaces . . . . . . . . . . . . . . . . . . 14
5.3. Post-Connection Interfaces . . . . . . . . . . . . . . . 15
5.4. Summary of Interfaces Exposed by Protocols . . . . . . . 16
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
Enghardt, et al. Expires 6 September 2020 [Page 2]
Internet-Draft Transport Security Survey March 2020
7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 18
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
10. Informative References . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction
Services and features provided by transport protocols have been
cataloged in [RFC8095]. This document supplements that work by
surveying commonly used and notable network security protocols, and
identifying the interfaces between these protocols and both transport
protocols and applications. It examines Transport Layer Security
(TLS), Datagram Transport Layer Security (DTLS), IETF QUIC, Google
QUIC (gQUIC), tcpcrypt, Internet Key Exchange with Encapsulating
Security Protocol (IKEv2 + ESP), SRTP (with DTLS), WireGuard,
CurveCP, and MinimalT. For each protocol, this document provides a
brief description. Then, it describes the interfaces between these
protocols and transports in Section 4 and the interfaces between
these protocols and applications in Section 5.
Selected protocols represent a superset of functionality and features
a Transport Services system may need to support, both internally and
externally (via an API) for applications [I-D.ietf-taps-arch].
Ubiquitous IETF protocols such as (D)TLS, as well as non-standard
protocols such as gQUIC, are both included despite overlapping
features. As such, this survey is not limited to protocols developed
within the scope or context of the IETF. Outside of this candidate
set, protocols that do not offer new features are omitted. For
example, newer protocols such as WireGuard make unique design choices
that have implications and limitations on application usage. In
contrast, protocols such as ALTS [ALTS] are omitted since they do not
provide interfaces deemed unique.
Authentication-only protocols such as TCP-AO [RFC5925] and IPsec AH
[RFC4302] are excluded from this survey. TCP-AO adds authenticity
protections to long-lived TCP connections, e.g., replay protection
with per-packet Message Authentication Codes. (This protocol
obsoletes TCP MD5 "signature" options specified in [RFC2385].) One
prime use case of TCP-AO is for protecting BGP connections.
Similarly, AH adds per-datagram authenticity and adds similar replay
protection. Despite these improvements, neither protocol sees
general use and both lack critical properties important for emergent
transport security protocols: confidentiality, privacy protections,
and agility. Such protocols are thus omitted from this survey.
Enghardt, et al. Expires 6 September 2020 [Page 3]
Internet-Draft Transport Security Survey March 2020
1.1. Goals
This survey is intended to help identify the most common interface
surfaces between security protocols and transport protocols, and
between security protocols and applications.
One of the goals of Transport Services is to define a common
interface for using transport protocols that allows software using
transport protocols to easily adopt new protocols that provide
similar feature-sets. The survey of the dependencies security
protocols have upon transport protocols can guide implementations in
determining which transport protocols are appropriate to be able to
use beneath a given security protocol. For example, a security
protocol that expects to run over a reliable stream of bytes, like
TLS, restrict the set of transport protocols that can be used to
those that offer a reliable stream of bytes.
Defining the common interfaces that security protocols provide to
applications also allows interfaces to be designed in a way that
common functionality can use the same APIs. For example, many
security protocols that provide authentication let the application be
involved in peer identity validation. Any interface to use a secure
transport protocol stack thus needs to allow applications to perform
this action during connection establishment.
1.2. Non-Goals
While this survey provides similar analysis to that which was
performed for transport protocols in [RFC8095], it is important to
distinguish that the use of security protocols requires more
consideration.
It is not a goal to allow software implementations to automatically
switch between different security protocols, even where their
interfaces to transport and applications are equivalent. Even
between versions, security protocols have subtly different guarantees
and vulnerabilities. Thus, any implementation needs to only use the
set of protocols and algorithms that are requested by applications or
by a system policy.
2. Terminology
The following terms are used throughout this document to describe the
roles and interactions of transport security protocols:
* Transport Feature: a specific end-to-end feature that the
transport layer provides to an application. Examples include
Enghardt, et al. Expires 6 September 2020 [Page 4]
Internet-Draft Transport Security Survey March 2020
confidentiality, reliable delivery, ordered delivery, message-
versus-stream orientation, etc.
* Transport Service: a set of Transport Features, without an
association to any given framing protocol, which provides
functionality to an application.
* Transport Protocol: an implementation that provides one or more
different transport services using a specific framing and header
format on the wire. A Transport Protocol services an application.
* Application: an entity that uses a transport protocol for end-to-
end delivery of data across the network. This may also be an
upper layer protocol or tunnel encapsulation.
* Security Protocol: a defined network protocol that implements one
or more security features, such as authentication, encryption, key
generation, session resumption, and privacy. Security protocols
may be used alongside transport protocols, and in combination with
other security protocols when appropriate.
* Handshake Protocol: a protocol that enables peers to validate each
other and to securely establish shared cryptographic context.
* Record: Framed protocol messages.
* Record Protocol: a security protocol that allows data to be
divided into manageable blocks and protected using shared
cryptographic context.
* Session: an ephemeral security association between applications.
* Connection: the shared state of two or more endpoints that
persists across messages that are transmitted between these
endpoints. A connection is a transient participant of a session,
and a session generally lasts between connection instances.
* Peer: an endpoint application party to a session.
* Client: the peer responsible for initiating a session.
* Server: the peer responsible for responding to a session
initiation.
Enghardt, et al. Expires 6 September 2020 [Page 5]
Internet-Draft Transport Security Survey March 2020
3. Transport Security Protocol Descriptions
This section contains brief descriptions of the various security
protocols currently used to protect data being sent over a network.
These protocols are grouped based on where in the protocol stack they
are implemented, which influences which parts of a packet they
protect: Generic application payload, application payload for
specific application-layer protocols, both application payload and
transport headers, or entire IP packets.
Note that not all security protocols can be easily categorized, e.g.,
as some protocols can be used in different ways or in combination
with other protocols. One major reason for this is that channel
security protocols often consist of two components:
* A handshake protocol, which is responsible for negotiating
parameters, authenticating the endpoints, and establishing shared
keys.
* A record protocol, which is used to encrypt traffic using keys and
parameters provided by the handshake protocol.
For some protocols, such as tcpcrypt, these two components are
tightly integrated. In contrast, for IPsec, these components are
implemented in separate protocols: AH and ESP are record protocols,
which can use keys supplied by the handshake protocol IKEv2, by other
handshake protocols, or by manual configuration. Moreover, some
protocols can be used in different ways: While the base TLS protocol
as defined in [RFC8446] has an integrated handshake and record
protocol, TLS or DTLS can also be used to negotiate keys for other
protocols, as in DTLS-SRTP, or the handshake protocol can be used
with a separate record layer, as in QUIC.
3.1. Application Payload Security Protocols
The following protocols provide security that protects application
payloads sent over a transport. They do not specifically protect any
headers used for transport-layer functionality.
3.1.1. TLS
TLS (Transport Layer Security) [RFC8446] is a common protocol used to
establish a secure session between two endpoints. Communication over
this session "prevents eavesdropping, tampering, and message
forgery." TLS consists of a tightly coupled handshake and record
protocol. The handshake protocol is used to authenticate peers,
negotiate protocol options, such as cryptographic algorithms, and
derive session-specific keying material. The record protocol is used
Enghardt, et al. Expires 6 September 2020 [Page 6]
Internet-Draft Transport Security Survey March 2020
to marshal (possibly encrypted) data from one peer to the other.
This data may contain handshake messages or raw application data.
3.1.2. DTLS
DTLS (Datagram Transport Layer Security) [RFC6347] is based on TLS,
but differs in that it is designed to run over unreliable datagram
protocols like UDP instead of TCP. DTLS modifies the protocol to
make sure it can still provide the same security guarantees as TLS
even without reliability from the transport. DTLS was designed to be
as similar to TLS as possible, so this document assumes that all
properties from TLS are carried over except where specified.
3.2. Application-Specific Security Protocols
The following protocols provide application-specific security by
protecting application payloads used for specific use-cases. Unlike
the protocols above, these are not intended for generic application
use.
3.2.1. Secure RTP
Secure RTP (SRTP) is a profile for RTP that provides confidentiality,
message authentication, and replay protection for RTP data packets
and RTP control protocol (RTCP) packets [RFC3711]. SRTP provides a
record layer only, and requires a separate handshake protocol to
provide key agreement and identity management.
The commonly used handshake protocol for SRTP is DTLS, in the form of
DTLS-SRTP [RFC5764]. This is an extension to DTLS that negotiates
the use of SRTP as the record layer, and describes how to export keys
for use with SRTP.
ZRTP [RFC6189] is an alternative key agreement and identity
management protocols for SRTP. ZRTP Key agreement is performed using
a Diffie-Hellman key exchange that runs on the media path. This
generates a shared secret that is then used to generate the master
key and salt for SRTP.
3.3. Transport-Layer Security Protocols
The following security protocols provide protection for both
application payloads and headers that are used for transport
services.
Enghardt, et al. Expires 6 September 2020 [Page 7]
Internet-Draft Transport Security Survey March 2020
3.3.1. IETF QUIC
QUIC is a new standards-track transport protocol that runs over UDP,
loosely based on Google's original proprietary gQUIC protocol
[I-D.ietf-quic-transport] (See Section 3.3.2 for more details). The
QUIC transport layer itself provides support for data confidentiality
and integrity. This requires keys to be derived with a separate
handshake protocol. A mapping for QUIC of TLS 1.3
[I-D.ietf-quic-tls] has been specified to provide this handshake.
3.3.2. Google QUIC
Google QUIC (gQUIC) is a UDP-based multiplexed streaming protocol
designed and deployed by Google following experience from deploying
SPDY, the proprietary predecessor to HTTP/2. gQUIC was originally
known as "QUIC": this document uses gQUIC to unambiguously
distinguish it from the standards-track IETF QUIC. The proprietary
technical forebear of IETF QUIC, gQUIC was originally designed with
tightly-integrated security and application data transport protocols.
3.3.3. tcpcrypt
Tcpcrypt [RFC8548] is a lightweight extension to the TCP protocol for
opportunistic encryption. Applications may use tcpcrypt's unique
session ID for further application-level authentication. Absent this
authentication, tcpcrypt is vulnerable to active attacks.
3.3.4. MinimalT
MinimalT is a UDP-based transport security protocol designed to offer
confidentiality, mutual authentication, DoS prevention, and
connection mobility [MinimalT]. One major goal of the protocol is to
leverage existing protocols to obtain server-side configuration
information used to more quickly bootstrap a connection. MinimalT
uses a variant of TCP's congestion control algorithm.
3.3.5. CurveCP
CurveCP [CurveCP] is a UDP-based transport security protocol from
Daniel J. Bernstein. Unlike many other security protocols, it is
based entirely upon public key algorithms. CurveCP provides its own
reliability for application data as part of its protocol.
Enghardt, et al. Expires 6 September 2020 [Page 8]
Internet-Draft Transport Security Survey March 2020
3.4. Packet Security Protocols
The following protocols provide protection for IP packets. These are
generally used as tunnels, such as for Virtual Private Networks
(VPNs). Often, applications will not interact directly with these
protocols. However, applications that implement tunnels will
interact directly with these protocols.
3.4.1. IKEv2 with ESP
IKEv2 [RFC7296] and ESP [RFC4303] together form the modern IPsec
protocol suite that encrypts and authenticates IP packets, either for
creating tunnels (tunnel-mode) or for direct transport connections
(transport-mode). This suite of protocols separates out the key
generation protocol (IKEv2) from the transport encryption protocol
(ESP). Each protocol can be used independently, but this document
considers them together, since that is the most common pattern.
3.4.2. WireGuard
WireGuard is an IP-layer protocol designed as an alternative to IPsec
[WireGuard] for certain use cases. It uses UDP to encapsulate IP
datagrams between peers. Unlike most transport security protocols,
which rely on Public Key Infrastructure (PKI) for peer
authentication, WireGuard authenticates peers using pre-shared public
keys delivered out-of-band, each of which is bound to one or more IP
addresses. Moreover, as a protocol suited for VPNs, WireGuard offers
no extensibility, negotiation, or cryptographic agility.
3.4.3. OpenVPN
OpenVPN [OpenVPN] is a commonly used protocol designed as an
alternative to IPsec. A major goal of this protocol is to provide a
VPN that is simple to configure and works over a variety of
transports. OpenVPN encapsulates either IP packets or Ethernet
frames within a secure tunnel and can run over either UDP or TCP.
For key establishment, OpenVPN can use TLS as a handshake protocol or
pre-shared keys.
4. Transport Dependencies
Across the different security protocols listed above, the primary
dependency on transport protocols is the presentation of data: either
an unbounded stream of bytes, or framed messages. Within protocols
that rely on the transport for message framing, most are built to run
over transports that inherently provide framing, like UDP, but some
also define how their messages can be framed over byte-stream
transports.
Enghardt, et al. Expires 6 September 2020 [Page 9]
Internet-Draft Transport Security Survey March 2020
4.1. Reliable Byte-Stream Transports
The following protocols all depend upon running on a transport
protocol that provides a reliable, in-order stream of bytes. This is
typically TCP.
Application Payload Security Protocols:
* TLS
Transport-Layer Security Protocols:
* tcpcrypt
4.2. Unreliable Datagram Transports
The following protocols all depend on the transport protocol to
provide message framing to encapsulate their data. These protocols
are built to run using UDP, and thus do not have any requirement for
reliability. Running these protocols over a protocol that does
provide reliability will not break functionality, but may lead to
multiple layers of reliability if the security protocol is
encapsulating other transport protocol traffic.
Application Payload Security Protocols:
* DTLS
* ZRTP
* SRTP
Transport-Layer Security Protocols:
* QUIC
* MinimalT
* CurveCP
Packet Security Protocols:
* IKEv2 and ESP
* WireGuard
* OpenVPN
Enghardt, et al. Expires 6 September 2020 [Page 10]
Internet-Draft Transport Security Survey March 2020
4.2.1. Datagram Protocols with Defined Byte-Stream Mappings
Of the protocols listed above that depend on the transport for
message framing, some do have well-defined mappings for sending their
messages over byte-stream transports like TCP.
Application Payload Security Protocols:
* DTLS when used as a handshake protocol for SRTP [RFC7850]
* ZRTP [RFC4571]
* SRTP [RFC4571]
Packet Security Protocols:
* IKEv2 and ESP [RFC8229]
4.3. Transport-Specific Dependencies
One protocol surveyed, tcpcrypt, has an direct dependency on a
feature in the transport that is needed for its functionality.
Specific, tcpcrypt is designed to run on top of TCP, and uses the TCP
Encryption Negotiation Option (ENO) [RFC8547] to negotiate its
protocol support.
QUIC, CurveCP, and MinimalT provide both transport functionality and
security functionality. They have a dependencies on running over a
framed protocol like UDP, but they add their own layers of
reliability and other transport services. Thus, an application that
uses one of these protocols cannot decouple the security from
transport functionality.
5. Application Interface
This section describes the interface surface exposed by the security
protocols described above. We partition these interfaces into pre-
connection (configuration), connection, and post-connection
interfaces, following conventions in [I-D.ietf-taps-interface] and
[I-D.ietf-taps-arch].
Note that not all protocols support each interface. The table in
Section 5.4 summarizes which protocol exposes which of the
interfaces. In the following sections, we provide abbreviations of
the interface names to use in the summary table.
Enghardt, et al. Expires 6 September 2020 [Page 11]
Internet-Draft Transport Security Survey March 2020
5.1. Pre-Connection Interfaces
Configuration interfaces are used to configure the security protocols
before a handshake begins or the keys are negotiated.
* Identities and Private Keys (IPK): The application can provide its
identities (certificates) and private keys, or mechanisms to
access these, to the security protocol to use during handshakes.
- TLS
- DTLS
- ZRTP
- QUIC
- MinimalT
- CurveCP
- IKEv2
- WireGuard
- OpenVPN
* Supported Algorithms (Key Exchange, Signatures, and Ciphersuites)
(ALG): The application can choose the algorithms that are
supported for key exchange, signatures, and ciphersuites.
- TLS
- DTLS
- ZRTP
- QUIC
- tcpcrypt
- MinimalT
- IKEv2
- OpenVPN
Enghardt, et al. Expires 6 September 2020 [Page 12]
Internet-Draft Transport Security Survey March 2020
* Extensions (Application-Layer Protocol Negotiation) (EXT): The
application enables or configures extensions that are to be
negotiated by the security protocol, such as ALPN [RFC7301].
- TLS
- DTLS
- QUIC
* Session Cache Management (CM): The application provides the
ability to save and retrieve session state (such as tickets,
keying material, and server parameters) that may be used to resume
the security session.
- TLS
- DTLS
- ZRTP
- QUIC
- tcpcrypt
- MinimalT
* Authentication Delegation (AD): The application provides access to
a separate module that will provide authentication, using EAP for
example.
- IKEv2
- tcpcrypt
* Pre-Shared Key Import (PSKI): Either the handshake protocol or the
application directly can supply pre-shared keys for use in
encrypting (and authenticating) communication with a peer.
- TLS
- DTLS
- ZRTP
- QUIC
- ESP
Enghardt, et al. Expires 6 September 2020 [Page 13]
Internet-Draft Transport Security Survey March 2020
- IKEv2
- OpenVPN
- tcpcrypt
- MinimalT
- WireGuard
5.2. Connection Interfaces
* Identity Validation (IV): During a handshake, the security
protocol will conduct identity validation of the peer. This can
call into the application to offload validation.
- TLS
- DTLS
- ZRTP
- QUIC
- MinimalT
- CurveCP
- IKEv2
- WireGuard
- OpenVPN
* Source Address Validation (SAV): The handshake protocol may
delegate validation of the remote peer that has sent data to the
transport protocol or application. This involves sending a cookie
exchange to avoid DoS attacks.
- DTLS
- QUIC
- IKEv2
- WireGuard
Enghardt, et al. Expires 6 September 2020 [Page 14]
Internet-Draft Transport Security Survey March 2020
5.3. Post-Connection Interfaces
* Connection Termination (CT): The security protocol may be
instructed to tear down its connection and session information.
This is needed by some protocols, e.g., to prevent application
data truncation attacks in which an attacker terminates an
underlying insecure connection-oriented protocol to terminate the
session.
- TLS
- DTLS
- ZRTP
- QUIC
- tcpcrypt
- MinimalT
- IKEv2
- OpenVPN
* Key Update (KU): The handshake protocol may be instructed to
update its keying material, either by the application directly or
by the record protocol sending a key expiration event.
- TLS
- DTLS
- QUIC
- tcpcrypt
- MinimalT
- IKEv2
* Shared Secret Export (PSKE): The handshake protocol may provide an
interface for producing shared secrets for application-specific
uses.
- TLS
- DTLS
Enghardt, et al. Expires 6 September 2020 [Page 15]
Internet-Draft Transport Security Survey March 2020
- tcpcrypt
- IKEv2
- OpenVPN
- MinimalT
* Key Expiration (KE): The record protocol can signal that its keys
are expiring due to reaching a time-based deadline, or a use-based
deadline (number of bytes that have been encrypted with the key).
This interaction is often limited to signaling between the record
layer and the handshake layer.
- ESP
* Mobility Events (ME): The record protocol can be signaled that it
is being migrated to another transport or interface due to
connection mobility, which may reset address and state validation
and induce state changes such as use of a new Connection
Identifier (CID).
- QUIC
- MinimalT
- CurveCP
- IKEv2 [RFC4555]
- WireGuard
5.4. Summary of Interfaces Exposed by Protocols
The following table summarizes which protocol exposes which
interface.
Enghardt, et al. Expires 6 September 2020 [Page 16]
Internet-Draft Transport Security Survey March 2020
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| Protocol |IPK|ALG | EXT |CM|AD| PSKI |IV| SAV |CT|KU| PSKE |KE|ME|
+===========+===+====+=====+==+==+======+==+=====+==+==+======+==+==+
| TLS | x | x | x |x | | x |x | |x |x | x | | |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| DTLS | x | x | x |x | | x |x | x |x |x | x | | |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| ZRTP | x | x | |x | | x |x | |x | | | | |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| QUIC | x | x | x |x | | x |x | x |x |x | | |x |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| tcpcrypt | | x | |x |x | x | | |x |x | x | | |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| MinimalT | x | x | |x | | x |x | |x |x | x | |x |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| CurveCP | x | | | | | |x | | | | | |x |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| IKEv2 | x | x | | |x | x |x | x |x |x | x | |x |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| ESP | | | | | | x | | | | | |x | |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| WireGuard | x | | | | | x |x | x | | | | |x |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
| OpenVPN | x | x | | | | x |x | |x | | x | | |
+-----------+---+----+-----+--+--+------+--+-----+--+--+------+--+--+
Table 1
x=Interface is exposed (blank)=Interface is not exposed
6. IANA Considerations
This document has no request to IANA.
7. Security Considerations
This document summarizes existing transport security protocols and
their interfaces. It does not propose changes to or recommend usage
of reference protocols. Moreover, no claims of security and privacy
properties beyond those guaranteed by the protocols discussed are
made. For example, metadata leakage via timing side channels and
traffic analysis may compromise any protocol discussed in this
survey. Applications using Security Interfaces should take such
limitations into consideration when using a particular protocol
implementation.
Enghardt, et al. Expires 6 September 2020 [Page 17]
Internet-Draft Transport Security Survey March 2020
8. Privacy Considerations
Analysis of how features improve or degrade privacy is intentionally
omitted from this survey. All security protocols surveyed generally
improve privacy by reducing information leakage via encryption.
However, varying amounts of metadata remain in the clear across each
protocol. For example, client and server certificates are sent in
cleartext in TLS 1.2 [RFC5246], whereas they are encrypted in TLS 1.3
[RFC8446]. A survey of privacy features, or lack thereof, for
various security protocols could be addressed in a separate document.
9. Acknowledgments
The authors would like to thank Bob Bradley, Frederic Jacobs, Mirja
Kuehlewind, Yannick Sierra, Brian Trammell, and Magnus Westerlund for
their input and feedback on this draft.
10. Informative References
[ALTS] Ghali, C., Stubblefield, A., Knapp, E., Li, J., Schmidt,
B., and J. Boeuf, "Application Layer Transport Security",
.
[CurveCP] Bernstein, D.J., "CurveCP -- Usable security for the
Internet", .
[I-D.ietf-quic-tls]
Thomson, M. and S. Turner, "Using TLS to Secure QUIC",
Work in Progress, Internet-Draft, draft-ietf-quic-tls-27,
21 February 2020, .
[I-D.ietf-quic-transport]
Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
and Secure Transport", Work in Progress, Internet-Draft,
draft-ietf-quic-transport-27, 21 February 2020,
.
[I-D.ietf-taps-arch]
Pauly, T., Trammell, B., Brunstrom, A., Fairhurst, G.,
Perkins, C., Tiesel, P., and C. Wood, "An Architecture for
Transport Services", Work in Progress, Internet-Draft,
draft-ietf-taps-arch-06, 23 December 2019,
.
Enghardt, et al. Expires 6 September 2020 [Page 18]
Internet-Draft Transport Security Survey March 2020
[I-D.ietf-taps-interface]
Trammell, B., Welzl, M., Enghardt, T., Fairhurst, G.,
Kuehlewind, M., Perkins, C., Tiesel, P., Wood, C., and T.
Pauly, "An Abstract Application Layer Interface to
Transport Services", Work in Progress, Internet-Draft,
draft-ietf-taps-interface-05, 4 November 2019,
.
[MinimalT] Petullo, W.M., Zhang, X., Solworth, J.A., Bernstein, D.J.,
and T. Lange, "MinimaLT -- Minimal-latency Networking
Through Better Security",
.
[OpenVPN] "OpenVPN cryptographic layer", .
[RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5
Signature Option", RFC 2385, DOI 10.17487/RFC2385, August
1998, .
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, DOI 10.17487/RFC3711, March 2004,
.
[RFC4302] Kent, S., "IP Authentication Header", RFC 4302,
DOI 10.17487/RFC4302, December 2005,
.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, DOI 10.17487/RFC4303, December 2005,
.
[RFC4555] Eronen, P., "IKEv2 Mobility and Multihoming Protocol
(MOBIKE)", RFC 4555, DOI 10.17487/RFC4555, June 2006,
.
[RFC4571] Lazzaro, J., "Framing Real-time Transport Protocol (RTP)
and RTP Control Protocol (RTCP) Packets over Connection-
Oriented Transport", RFC 4571, DOI 10.17487/RFC4571, July
2006, .
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
.
Enghardt, et al. Expires 6 September 2020 [Page 19]
Internet-Draft Transport Security Survey March 2020
[RFC5764] McGrew, D. and E. Rescorla, "Datagram Transport Layer
Security (DTLS) Extension to Establish Keys for the Secure
Real-time Transport Protocol (SRTP)", RFC 5764,
DOI 10.17487/RFC5764, May 2010,
.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, .
[RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP:
Media Path Key Agreement for Unicast Secure RTP",
RFC 6189, DOI 10.17487/RFC6189, April 2011,
.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, .
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, .
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, .
[RFC7850] Nandakumar, S., "Registering Values of the SDP 'proto'
Field for Transporting RTP Media over TCP under Various
RTP Profiles", RFC 7850, DOI 10.17487/RFC7850, April 2016,
.
[RFC8095] Fairhurst, G., Ed., Trammell, B., Ed., and M. Kuehlewind,
Ed., "Services Provided by IETF Transport Protocols and
Congestion Control Mechanisms", RFC 8095,
DOI 10.17487/RFC8095, March 2017,
.
[RFC8229] Pauly, T., Touati, S., and R. Mantha, "TCP Encapsulation
of IKE and IPsec Packets", RFC 8229, DOI 10.17487/RFC8229,
August 2017, .
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
.
Enghardt, et al. Expires 6 September 2020 [Page 20]
Internet-Draft Transport Security Survey March 2020
[RFC8547] Bittau, A., Giffin, D., Handley, M., Mazieres, D., and E.
Smith, "TCP-ENO: Encryption Negotiation Option", RFC 8547,
DOI 10.17487/RFC8547, May 2019,
.
[RFC8548] Bittau, A., Giffin, D., Handley, M., Mazieres, D., Slack,
Q., and E. Smith, "Cryptographic Protection of TCP Streams
(tcpcrypt)", RFC 8548, DOI 10.17487/RFC8548, May 2019,
.
[WireGuard]
Donenfeld, J.A., "WireGuard -- Next Generation Kernel
Network Tunnel",
.
Authors' Addresses
Theresa Enghardt
TU Berlin
Marchstr. 23
10587 Berlin
Germany
Email: ietf@tenghardt.net
Tommy Pauly
Apple Inc.
One Apple Park Way
Cupertino, California 95014,
United States of America
Email: tpauly@apple.com
Colin Perkins
University of Glasgow
School of Computing Science
Glasgow G12 8QQ
United Kingdom
Email: csp@csperkins.org
Kyle Rose
Akamai Technologies, Inc.
150 Broadway
Cambridge, MA 02144,
Enghardt, et al. Expires 6 September 2020 [Page 21]
Internet-Draft Transport Security Survey March 2020
United States of America
Email: krose@krose.org
Christopher A. Wood (editor)
Apple Inc.
One Apple Park Way
Cupertino, California 95014,
United States of America
Email: cawood@apple.com
Enghardt, et al. Expires 6 September 2020 [Page 22]