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Internet-Draft The most common existing authentication mechanisms for HTTP are sent with each HTTP request, and authenticate that request instead of the underlying HTTP connection, or transport. While these mechanisms work well for existing uses of HTTP, they are not suitable for emerging applications that multiplex non-HTTP traffic inside an HTTP connection. This document describes the HTTP Transport Authentication Framework, a method of authenticating not only an HTTP request, but also its underlying transport.

Introduction The most common existing authentication mechanisms for HTTP are sent with each HTTP request, and authenticate that request instead of the underlying HTTP connection, or transport. While these mechanisms work well for existing uses of HTTP, they are not suitable for emerging applications that multiplex non-HTTP traffic inside an HTTP connection. This document describes the HTTP Transport Authentication Framework, a method of authenticating not only an HTTP request, but also its underlying transport. Traditional HTTP semantics specify that HTTP is a stateless protocol where each request can be understood in isolation . However, the emergence of QUIC as a new transport protocol that can carry HTTP and the existence of QUIC extensions such as the DATAGRAM frame enable new uses of HTTP such as and where some traffic is exchanged that is disctinct from HTTP requests and responses. In order to authenticate this traffic, it is necessary to authenticate the underlying transport (e.g., QUIC or TLS ) instead of authenticate each request individually. This mechanism aims to supplement the HTTP Authentication Framework , not replace it. Note that there is currently no mechanism for origin servers to request that user agents authenticate themselves using Transport Authentication, this is left as future work.

Conventions and Definitions 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 when, and only when, they appear in all capitals, as shown here. This document uses the Augmented BNF defined in and updated by along with the "#rule" extension defined in Section 7 of . The rules below are defined in , , , and : quoted-string = token = token68 = oid = ]]>

Computing the Authentication Proof This document only defines Transport Authentication for uses of HTTP with TLS. This includes any use of HTTP over TLS as typically used for HTTP/2, or HTTP/3 where the transport protocol uses TLS as its authentication and key exchange mechanism . The user agent leverages a TLS keying material exporter to generate a nonce which can be signed using the user-id's key. The keying material exporter uses a label that starts with the characters "EXPORTER-HTTP-Transport-Authentication-" (see for the labels and contexts used by each scheme). The TLS keying material exporter is used to generate a 32-byte key which is then used as a nonce.

Header Field Definition The "Transport-Authentication" header allows a user agent to authenticate its transport connection with an origin server.

The u Directive The OPTIONAL "u" (user-id) directive specifies the user-id that the user agent wishes to authenticate. It is encoded using Base64 (Section 4 of ).

The p Directive The OPTIONAL "p" (proof) directive specifies the proof that the user agent provides to attest to possessing the credential that matches its user-id. It is encoded using Base64 (Section 4 of ).

The a Directive The OPTIONAL "a" (algorithm) directive specifies the algorithm used to compute the proof transmitted in the "p" directive.

Transport Authentication Schemes The Transport Authentication Framework allows defining Transport Authentication Schemes, which specify how to authenticate user-ids. This documents defined the "Signature" and "HMAC" schemes.

Signature The "Signature" Transport Authentication Scheme uses asymmetric cyptography. User agents possess a user-id and a public/private key pair, and origin servers maintain a mapping of authorized user-ids to their associated public keys. When using this scheme, the "u", "p", and "a" directives are REQUIRED. The TLS keying material export label for this scheme is "EXPORTER-HTTP-Transport-Authentication-Signature" and the associated context is empty. The nonce is then signed using the selected asymmetric signature algorithm and transmitted as the proof directive. For example, the user-id "john.doe" authenticating using Ed25519 could produce the following header (lines are folded to fit):

HMAC The "HMAC" Transport Authentication Scheme uses symmetric cyptography. User agents possess a user-id and a secret key, and origin servers maintain a mapping of authorized user-ids to their associated secret key. When using this scheme, the "u", "p", and "a" directives are REQUIRED. The TLS keying material export label for this scheme is "EXPORTER-HTTP-Transport-Authentication-HMAC" and the associated context is empty. The nonce is then HMACed using the selected HMAC algorithm and transmitted as the proof directive. For example, the user-id "john.doe" authenticating using HMAC-SHA-512 could produce the following header (lines are folded to fit):

Proxy Considerations Since Transport Authentication authenticates the underlying transport by leveraging TLS keying material exporters, it cannot be transparently forwarded by proxies that terminate TLS. However it can be sent over proxied connections when TLS is performed end-to-end (e.g., when using HTTP CONNECT proxies).

Security Considerations Transport Authentication allows a user-agent to authenticate to an origin server while guaranteeing freshness and without the need for the server to transmit a nonce to the user agent. This allows the server to accept authenticated clients without revealing that it supports or expects authentication for some resources. It also allows authentication without the user agent leaking the presence of authentication to observers due to clear-text TLS Client Hello extensions.

IANA Considerations

Transport-Authentication Header Field This document, if approved, requests IANA to register the "Transport-Authentication" header in the "Permanent Message Header Field Names" registry maintained at https://www.iana.org/assignments/message-headers/.

Transport Authentication Schemes Registry This document, if approved, requests IANA to create a new HTTP Transport Authentication Schemes Registry with the following entries:

TLS Keying Material Exporter Labels This document, if approved, requests IANA to register the following entries in the "TLS Exporter Labels" registry maintained at https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#exporter-labels Both of these entries are listed with the following qualifiers:

References Normative References The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document provides an overview of HTTP architecture and its associated terminology, defines the "http" and "https" Uniform Resource Identifier (URI) schemes, defines the HTTP/1.1 message syntax and parsing requirements, and describes related security concerns for implementations. This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery. This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations. The Hypertext Transfer Protocol (HTTP) is a stateless application- level protocol for distributed, collaborative, hypermedia information systems. This document defines the HTTP Authentication framework. In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Internet technical specifications often need to define a formal syntax. Over the years, a modified version of Backus-Naur Form (BNF), called Augmented BNF (ABNF), has been popular among many Internet specifications. The current specification documents ABNF. It balances compactness and simplicity with reasonable representational power. The differences between standard BNF and ABNF involve naming rules, repetition, alternatives, order-independence, and value ranges. This specification also supplies additional rule definitions and encoding for a core lexical analyzer of the type common to several Internet specifications. [STANDARDS-TRACK] This document extends the base definition of ABNF (Augmented Backus-Naur Form) to include a way to specify US-ASCII string literals that are matched in a case-sensitive manner. This document describes a Uniform Resource Name (URN) namespace that contains Object Identifiers (OIDs). This memo provides information for the Internet community. A number of protocols wish to leverage Transport Layer Security (TLS) to perform key establishment but then use some of the keying material for their own purposes. This document describes a general mechanism for allowing that. [STANDARDS-TRACK] This document describes the commonly used base 64, base 32, and base 16 encoding schemes. It also discusses the use of line-feeds in encoded data, use of padding in encoded data, use of non-alphabet characters in encoded data, use of different encoding alphabets, and canonical encodings. [STANDARDS-TRACK] Informative References This document defines the core of the QUIC transport protocol. Accompanying documents describe QUIC's loss detection and congestion control and the use of TLS for key negotiation. Note to Readers Discussion of this draft takes place on the QUIC working group mailing list (quic@ietf.org), which is archived at <https://mailarchive.ietf.org/arch/search/?email_list=quic>. Working Group information can be found at <https://github.com/ quicwg>; source code and issues list for this draft can be found at <https://github.com/quicwg/base-drafts/labels/-transport>. The QUIC transport protocol has several features that are desirable in a transport for HTTP, such as stream multiplexing, per-stream flow control, and low-latency connection establishment. This document describes a mapping of HTTP semantics over QUIC. This document also identifies HTTP/2 features that are subsumed by QUIC, and describes how HTTP/2 extensions can be ported to HTTP/3. This document defines an extension to the QUIC transport protocol to add support for sending and receiving unreliable datagrams over a QUIC connection. Discussion of this work is encouraged to happen on the QUIC IETF mailing list quic@ietf.org [1] or on the GitHub repository which contains the draft: https://github.com/tfpauly/draft-pauly-quic- datagram [2]. WebTransport [OVERVIEW] is a protocol framework that enables clients constrained by the Web security model to communicate with a remote server using a secure multiplexed transport. This document describes Http3Transport, a WebTransport protocol that is based on HTTP/3 [HTTP3] and provides support for unidirectional streams, bidirectional streams and datagrams, all multiplexed within the same HTTP/3 connection. This document describes MASQUE (Multiplexed Application Substrate over QUIC Encryption). MASQUE is a framework that allows concurrently running multiple networking applications inside an HTTP/3 connection. For example, MASQUE can allow a QUIC client to negotiate proxying capability with an HTTP/3 server, and subsequently make use of this functionality while concurrently processing HTTP/3 requests and responses. This document is a straw-man proposal. It does not contain enough details to implement the protocol, and is currently intended to spark discussions on the approach it is taking. Discussion of this work is encouraged to happen on the MASQUE IETF mailing list masque@ietf.org (mailto:masque@ietf.org) or on the GitHub repository which contains the draft: https://github.com/DavidSchinazi/masque-drafts (https://github.com/DavidSchinazi/masque-drafts). This document describes how Transport Layer Security (TLS) is used to secure QUIC. This document specifies algorithm identifiers and ASN.1 encoding formats for elliptic curve constructs using the curve25519 and curve448 curves. The signature algorithms covered are Ed25519 and Ed448. The key agreement algorithms covered are X25519 and X448. The encoding for public key, private key, and Edwards-curve Digital Signature Algorithm (EdDSA) structures is provided. Federal Information Processing Standard, FIPS The Internet Key Exchange Version 2 (IKEv2) protocol has limited support for the Elliptic Curve Digital Signature Algorithm (ECDSA). The current version only includes support for three Elliptic Curve groups, and there is a fixed hash algorithm tied to each group. This document generalizes IKEv2 signature support to allow any signature method supported by PKIX and also adds signature hash algorithm negotiation. This is a generic mechanism and is not limited to ECDSA; it can also be used with other signature algorithms.

Acknowledgments The authors would like to thank many members of the IETF community, as this document is the fruit of many hallway conversations. Using the OID for the signature and HMAC algorithms was inspired by Signature Authentication in IKEv2 .