This is a purely informative rendering of an RFC that includes verified errata. This rendering may not be used as a reference.
The following 'Verified' errata have been incorporated in this document:
EID 8807
Internet Engineering Task Force (IETF) D. Schinazi
Request for Comments: 9729 Google LLC
Category: Standards Track D. Oliver
ISSN: 2070-1721 Guardian Project
J. Hoyland
Cloudflare Inc.
February 2025
The Concealed HTTP Authentication Scheme
Abstract
Most HTTP authentication schemes are probeable in the sense that it
is possible for an unauthenticated client to probe whether an origin
serves resources that require authentication. It is possible for an
origin to hide the fact that it requires authentication by not
generating Unauthorized status codes; however, that only works with
non-cryptographic authentication schemes: cryptographic signatures
require a fresh nonce to be signed. Prior to this document, there
was no existing way for the origin to share such a nonce without
exposing the fact that it serves resources that require
authentication. This document defines a new non-probeable
cryptographic authentication scheme.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9729.
Copyright Notice
Copyright (c) 2025 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 Revised BSD License text as described in Section 4.e of the
Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.
Table of Contents
1. Introduction
1.1. Conventions and Definitions
2. The Concealed HTTP Authentication Scheme
3. Client Handling
3.1. Key Exporter Context
3.1.1. Public Key Encoding
3.2. Key Exporter Output
3.3. Signature Computation
4. Authentication Parameters
4.1. The k Parameter
4.2. The a Parameter
4.3. The p Parameter
4.4. The s Parameter
4.5. The v Parameter
5. Example
6. Server Handling
6.1. Frontend Handling
6.2. Communication Between Frontend and Backend
6.3. Backend Handling
6.4. Non-Probeable Server Handling
7. Requirements on TLS Usage
8. Security Considerations
9. IANA Considerations
9.1. HTTP Authentication Schemes Registry
9.2. TLS Keying Material Exporter Labels
9.3. HTTP Field Name
10. References
10.1. Normative References
10.2. Informative References
Acknowledgments
Authors' Addresses
1. Introduction
HTTP authentication schemes (see Section 11 of [HTTP]) allow origins
to restrict access for some resources to only authenticated requests.
While these schemes commonly involve a challenge where the origin
asks the client to provide authentication information, it is possible
for clients to send such information unprompted. This is
particularly useful in cases where an origin wants to offer a service
or capability only to "those who know", while all others are given no
indication the service or capability exists. Such designs rely on an
externally defined mechanism by which keys are distributed. For
example, a company might offer remote employee access to company
services directly via its website using their employee credentials or
offer access to limited special capabilities for specific employees
while making discovering (or probing for) such capabilities
difficult. As another example, members of less well-defined
communities might use more ephemeral keys to acquire access to
geography- or capability-specific resources, as issued by an entity
whose user base is larger than the available resources can support
(by having that entity metering the availability of keys temporally
or geographically).
While digital-signature-based HTTP authentication schemes already
exist (e.g., [HOBA]), they rely on the origin explicitly sending a
fresh challenge to the client, to ensure that the signature input is
fresh. That makes the origin probeable as it sends the challenge to
unauthenticated clients. This document defines a new signature-based
authentication scheme that is not probeable.
1.1. 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 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document uses the notation from Section 1.3 of [QUIC].
Various examples in this document contain long lines that may be
folded, as described in [RFC8792].
2. The Concealed HTTP Authentication Scheme
This document defines the "Concealed" HTTP authentication scheme. It
uses asymmetric cryptography. Clients possess a key ID and a public/
private key pair, and origin servers maintain a mapping of authorized
key IDs to associated public keys.
The client uses a TLS keying material exporter to generate data to be
signed (see Section 3) then sends the signature using the
Authorization (or Proxy-Authorization) header field (see Section 11
of [HTTP]). The signature and additional information are exchanged
using authentication parameters (see Section 4). Once the server
receives these, it can check whether the signature validates against
an entry in its database of known keys. The server can then use the
validation result to influence its response to the client, for
example, by restricting access to certain resources.
3. Client Handling
When a client wishes to use the Concealed HTTP authentication scheme
with a request, it SHALL compute the authentication proof using a TLS
keying material exporter with the following parameters:
* The label is set to "EXPORTER-HTTP-Concealed-Authentication".
* The context is set to the structure described in Section 3.1.
* The exporter output length is set to 48 bytes (see Section 3.2).
Note that TLS 1.3 keying material exporters are defined in
Section 7.5 of [TLS], while TLS 1.2 keying material exporters are
defined in [KEY-EXPORT].
3.1. Key Exporter Context
The TLS key exporter context is described in Figure 1, using the
notation from Section 1.3 of [QUIC]:
Signature Algorithm (16),
Key ID Length (i),
Key ID (..),
Public Key Length (i),
Public Key (..),
Scheme Length (i),
Scheme (..),
Host Length (i),
Host (..),
Port (16),
Realm Length (i),
Realm (..),
Figure 1: Key Exporter Context Format
The key exporter context contains the following fields:
Signature Algorithm: The signature scheme sent in the s Parameter
(see Section 4.4).
Key ID: The key ID sent in the k Parameter (see Section 4.1).
Public Key: The public key used by the server to validate the
signature provided by the client. Its encoding is described in
Section 3.1.1.
Scheme: The scheme for this request, encoded using the format of the
scheme portion of a URI as defined in Section 3.1 of [URI].
Host: The host for this request, encoded using the format of the
host portion of a URI as defined in Section 3.2.2 of [URI].
Port: The port for this request, encoded in network byte order.
Note that the port is either included in the URI or is the default
port for the scheme in use; see Section 3.2.3 of [URI].
Realm: The realm of authentication that is sent in the realm
authentication parameter (see Section 11.5 of [HTTP]). If the
realm authentication parameter is not present, this SHALL be
empty. This document does not define a means for the origin to
communicate a realm to the client. If a client is not configured
to use a specific realm, it SHALL use an empty realm and SHALL NOT
send the realm authentication parameter.
The Signature Algorithm and Port fields are encoded as unsigned
16-bit integers in network byte order. The Key ID, Public Key,
Scheme, Host, and Realm fields are length-prefixed strings; they are
preceded by a Length field that represents their length in bytes.
These length fields are encoded using the variable-length integer
encoding from Section 16 of [QUIC] and MUST be encoded in the minimum
number of bytes necessary.
3.1.1. Public Key Encoding
Both the "Public Key" field of the TLS key exporter context (see
above) and the a Parameter (see Section 4.2) carry the same public
key. The encoding of the public key is determined by the signature
algorithm in use as follows:
RSASSA-PSS algorithms: The public key is an RSAPublicKey structure
[PKCS1] encoded in DER [X.690]. BER encodings that are not DER
MUST be rejected.
ECDSA algorithms: The public key is an
UncompressedPointRepresentation structure defined in
Section 4.2.8.2 of [TLS], using the curve specified by the
SignatureScheme.
EdDSA algorithms: The public key is the byte string encoding defined
in [EdDSA].
This document does not define the public key encodings for other
algorithms. In order for a SignatureScheme to be usable with the
Concealed HTTP authentication scheme, its public key encoding needs
to be defined in a corresponding document.
3.2. Key Exporter Output
The key exporter output is 48 bytes long. Of those, the first 32
bytes are part of the input to the signature and the next 16 bytes
are sent alongside the signature. This allows the recipient to
confirm that the exporter produces the right values. This is
described in Figure 2, using the notation from Section 1.3 of [QUIC]:
Signature Input (256),
Verification (128),
Figure 2: Key Exporter Output Format
The key exporter output contains the following fields:
Signature Input: This is part of the data signed using the client's
chosen asymmetric private key (see Section 3.3).
Verification: The verification is transmitted to the server using
the v Parameter (see Section 4.5).
3.3. Signature Computation
Once the Signature Input has been extracted from the key exporter
output (see Section 3.2), it is prefixed with static data before
being signed. The signature is computed over the concatenation of:
* A string that consists of octet 32 (0x20) repeated 64 times
* The context string "HTTP Concealed Authentication"
* A single 0 byte that serves as a separator
* The Signature Input extracted from the key exporter output (see
Section 3.2)
For example, if the Signature Input has all its 32 bytes set to 01,
the content covered by the signature (in hexadecimal format) would
be:
2020202020202020202020202020202020202020202020202020202020202020
2020202020202020202020202020202020202020202020202020202020202020
4854545020436F6E6365616C65642041757468656E7469636174696F6E
EID 8807 (Verified) is as follows:Section: 3.3
Original Text:
48545450205369676E61747572652041757468656E7469636174696F6E
Corrected Text:
4854545020436F6E6365616C65642041757468656E7469636174696F6E
Notes:
The original hex in Figure 3 corresponds to "HTTP Signature Authentication", which is the wrong context string. Thus, it should be updated to the correct hex to reflect "HTTP Concealed Authentication" as specified in Section 3.3.
00
0101010101010101010101010101010101010101010101010101010101010101
Figure 3: Example Content Covered by Signature
The purpose of this static prefix is to mitigate issues that could
arise if authentication asymmetric keys were accidentally reused
across protocols (even though this is forbidden, see Section 8).
This construction mirrors that of the TLS 1.3 CertificateVerify
message defined in Section 4.4.3 of [TLS].
The resulting signature is then transmitted to the server using the p
Parameter (see Section 4.3).
4. Authentication Parameters
This specification defines the following authentication parameters.
All of the byte sequences below are encoded using base64url (see
Section 5 of [BASE64]) without quotes and without padding. In other
words, the values of these byte-sequence authentication parameters
MUST NOT include any characters other than ASCII letters, digits,
dash, and underscore.
The integer below is encoded without a minus and without leading
zeroes. In other words, the value of this integer authentication
parameter MUST NOT include any characters other than digits and MUST
NOT start with a zero unless the full value is "0".
Using the syntax from [ABNF]:
concealed-byte-sequence-param-value = *( ALPHA / DIGIT / "-" / "_" )
concealed-integer-param-value = %x31-39 1*4( DIGIT ) / "0"
Figure 4: Authentication Parameter Value ABNF
4.1. The k Parameter
The REQUIRED "k" (key ID) Parameter is a byte sequence that
identifies which key the client wishes to use to authenticate. This
is used by the backend to point to an entry in a server-side database
of known keys (see Section 6.3).
4.2. The a Parameter
The REQUIRED "a" (public key) Parameter is a byte sequence that
specifies the public key used by the server to validate the signature
provided by the client. This avoids key confusion issues (see
[SEEMS-LEGIT]). The encoding of the public key is described in
Section 3.1.1.
4.3. The p Parameter
The REQUIRED "p" (proof) Parameter is a byte sequence that specifies
the proof that the client provides to attest to possessing the
credential that matches its key ID.
4.4. The s Parameter
The REQUIRED "s" (signature scheme) Parameter is an integer that
specifies the signature scheme used to compute the proof transmitted
in the p Parameter. Its value is an integer between 0 and 65535
inclusive from the IANA "TLS SignatureScheme" registry maintained at
<https://www.iana.org/assignments/tls-parameters>.
4.5. The v Parameter
The REQUIRED "v" (verification) Parameter is a byte sequence that
specifies the verification that the client provides to attest to
possessing the key exporter output (see Section 3.2 for details).
This avoids issues with signature schemes where certain keys can
generate signatures that are valid for multiple inputs (see
[SEEMS-LEGIT]).
5. Example
For example, a client using the key ID "basement" and the signature
algorithm Ed25519 [ED25519] could produce the following header field:
NOTE: '\' line wrapping per RFC 8792
Authorization: Concealed \
k=YmFzZW1lbnQ, \
a=VGhpcyBpcyBh-HB1YmxpYyBrZXkgaW4gdXNl_GhlcmU, \
s=2055, \
v=dmVyaWZpY2F0aW9u_zE2Qg, \
p=QzpcV2luZG93c_xTeXN0ZW0zMlxkcml2ZXJz-ENyb3dkU\
3RyaWtlXEMtMDAwMDAwMDAyOTEtMD-wMC0w_DAwLnN5cw
Figure 5: Example Header Field
6. Server Handling
In this section, we subdivide the server role in two:
* The "frontend" runs in the HTTP server that terminates the TLS or
QUIC connection created by the client.
* The "backend" runs in the HTTP server that has access to the
database of accepted key identifiers and public keys.
In most deployments, we expect both the frontend and backend roles to
be implemented in a single HTTP origin server (as defined in
Section 3.6 of [HTTP]). However, these roles can be split such that
the frontend is an HTTP gateway (as defined in Section 3.7 of [HTTP])
and the backend is an HTTP origin server.
6.1. Frontend Handling
If a frontend is configured to check the Concealed HTTP
authentication scheme, it will parse the Authorization (or Proxy-
Authorization) header field. If the authentication scheme is set to
"Concealed", the frontend MUST validate that all the required
authentication parameters are present and can be parsed correctly as
defined in Section 4. If any parameter is missing or fails to parse,
the frontend MUST ignore the entire Authorization (or Proxy-
Authorization) header field.
The frontend then uses the data from these authentication parameters
to compute the key exporter output, as defined in Section 3.2. The
frontend then shares the header field and the key exporter output
with the backend.
6.2. Communication Between Frontend and Backend
If the frontend and backend roles are implemented in the same
machine, this can be handled by a simple function call.
If the roles are split between two separate HTTP servers, then the
backend won't be able to directly access the TLS keying material
exporter from the TLS connection between the client and frontend, so
the frontend needs to explicitly send it. This document defines the
"Concealed-Auth-Export" request header field for this purpose. The
Concealed-Auth-Export header field's value is a Structured Field Byte
Sequence (see Section 3.3.5 of [STRUCTURED-FIELDS]) that contains the
48-byte key exporter output (see Section 3.2), without any
parameters. Note that Structured Field Byte Sequences are encoded
using the non-URL-safe variant of base64. For example:
NOTE: '\' line wrapping per RFC 8792
Concealed-Auth-Export: :VGhpc+BleGFtcGxlIFRMU/BleHBvcn\
Rlc+BvdXRwdXQ/aXMgNDggYnl0ZXMgI/+h:
Figure 6: Example Concealed-Auth-Export Header Field
The frontend SHALL forward the HTTP request to the backend, including
the original unmodified Authorization (or Proxy-Authorization) header
field and the newly added Concealed-Auth-Export header field.
Note that, since the security of this mechanism requires the key
exporter output to be correct, backends need to trust frontends to
send it truthfully. This trust relationship is common because the
frontend already needs access to the TLS certificate private key in
order to respond to requests. HTTP servers that parse the Concealed-
Auth-Export header field MUST ignore it unless they have already
established that they trust the sender. Similarly, frontends that
send the Concealed-Auth-Export header field MUST ensure that they do
not forward any Concealed-Auth-Export header field received from the
client.
6.3. Backend Handling
Once the backend receives the Authorization (or Proxy-Authorization)
header field and the key exporter output, it looks up the key ID in
its database of public keys. The backend SHALL then perform the
following checks:
* validate that all the required authentication parameters are
present and can be parsed correctly as defined in Section 4
* ensure the key ID is present in the backend's database and maps to
a corresponding public key
* validate that the public key from the database is equal to the one
in the Authorization (or Proxy-Authorization) header field
* validate that the verification field from the Authorization (or
Proxy-Authorization) header field matches the one extracted from
the key exporter output
* verify the cryptographic signature as defined in Section 3.3
If all of these checks succeed, the backend can consider the request
to be properly authenticated and can reply accordingly (the backend
can also forward the request to another HTTP server).
If any of the above checks fail, the backend MUST treat it as if the
Authorization (or Proxy-Authorization) header field was missing.
6.4. Non-Probeable Server Handling
Servers that wish to introduce resources whose existence cannot be
probed need to ensure that they do not reveal any information about
those resources to unauthenticated clients. In particular, such
servers MUST respond to authentication failures with the exact same
response that they would have used for nonexistent resources. For
example, this can mean using HTTP status code 404 (Not Found) instead
of 401 (Unauthorized).
The authentication checks described above can take time to compute,
and an attacker could detect use of this mechanism if that time is
observable by comparing the timing of a request for a known
nonexistent resource to the timing of a request for a potentially
authenticated resource. Servers can mitigate this observability by
slightly delaying responses to some nonexistent resources such that
the timing of the authentication verification is not observable.
This delay needs to be carefully considered to avoid having the delay
itself leak the fact that this origin uses this mechanism at all.
Non-probeable resources also need to be non-discoverable for
unauthenticated users. For example, if a server operator wishes to
hide an authenticated resource by pretending it does not exist to
unauthenticated users, then the server operator needs to ensure there
are no unauthenticated pages with links to that resource and no other
out-of-band ways for unauthenticated users to discover this resource.
7. Requirements on TLS Usage
This authentication scheme is only defined for uses of HTTP with TLS
[TLS]. This includes any use of HTTP over TLS as typically used for
HTTP/2 [HTTP/2], or HTTP/3 [HTTP/3] where the transport protocol uses
TLS as its authentication and key exchange mechanism [QUIC-TLS].
Because the TLS keying material exporter is only secure for
authentication when it is uniquely bound to the TLS session
[RFC7627], the Concealed authentication scheme requires either one of
the following properties:
* The TLS version in use is greater than or equal to 1.3 [TLS].
* The TLS version in use is 1.2, and the extended master secret
extension [RFC7627] has been negotiated.
Clients MUST NOT use the Concealed HTTP authentication scheme on
connections that do not meet one of the two properties above. If a
server receives a request that uses this authentication scheme on a
connection that meets neither of the above properties, the server
MUST treat the request as if the authentication were not present.
8. Security Considerations
The Concealed HTTP authentication scheme allows a client to
authenticate to an origin server while guaranteeing freshness and
without the need for the server to transmit a nonce to the client.
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 client leaking
the presence of authentication to observers due to cleartext TLS
Client Hello extensions.
Since the freshness described above is provided by a TLS key
exporter, it can be as old as the underlying TLS connection. Servers
can require better freshness by forcing clients to create new
connections using mechanisms such as the GOAWAY frame (see
Section 5.2 of [HTTP/3]).
The authentication proofs described in this document are not bound to
individual HTTP requests; if the key is used for authentication
proofs on multiple requests on the same connection, they will all be
identical. This allows for better compression when sending over the
wire, but it implies that client implementations that multiplex
different security contexts over a single HTTP connection need to
ensure that those contexts cannot read each other's header fields.
Otherwise, one context would be able to replay the Authorization
header field of another. This constraint is met by modern web
browsers. If an attacker were to compromise the browser such that it
could access another context's memory, the attacker might also be
able to access the corresponding key, so binding authentication to
requests would not provide much benefit in practice.
Authentication asymmetric keys used for the Concealed HTTP
authentication scheme MUST NOT be reused in other protocols. Even
though we attempt to mitigate these issues by adding a static prefix
to the signed data (see Section 3.3), reusing keys could undermine
the security guarantees of the authentication.
Origins offering this scheme can link requests that use the same key.
However, requests are not linkable across origins if the keys used
are specific to the individual origins using this scheme.
9. IANA Considerations
9.1. HTTP Authentication Schemes Registry
IANA has registered the following entry in the "HTTP Authentication
Schemes" registry maintained at <https://www.iana.org/assignments/
http-authschemes>:
Authentication Scheme Name: Concealed
Reference: RFC 9729
Notes: None
9.2. TLS Keying Material Exporter Labels
IANA has registered the following entry in the "TLS Exporter Labels"
registry maintained at <https://www.iana.org/assignments/tls-
parameters>:
Value: EXPORTER-HTTP-Concealed-Authentication
DTLS-OK: N
Recommended: Y
Reference: RFC 9729
9.3. HTTP Field Name
IANA has registered the following entry in the "Hypertext Transfer
Protocol (HTTP) Field Name Registry" maintained at
<https://www.iana.org/assignments/http-fields>:
Field Name: Concealed-Auth-Export
Status: permanent
Structured Type: Item
Reference: RFC 9729
Comments: None
10. References
10.1. Normative References
[ABNF] 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>.
[BASE64] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>.
[EdDSA] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
Signature Algorithm (EdDSA)", RFC 8032,
DOI 10.17487/RFC8032, January 2017,
<https://www.rfc-editor.org/info/rfc8032>.
[HTTP] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/info/rfc9110>.
[KEY-EXPORT]
Rescorla, E., "Keying Material Exporters for Transport
Layer Security (TLS)", RFC 5705, DOI 10.17487/RFC5705,
March 2010, <https://www.rfc-editor.org/info/rfc5705>.
[PKCS1] Moriarty, K., Ed., Kaliski, B., Jonsson, J., and A. Rusch,
"PKCS #1: RSA Cryptography Specifications Version 2.2",
RFC 8017, DOI 10.17487/RFC8017, November 2016,
<https://www.rfc-editor.org/info/rfc8017>.
[QUIC] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/info/rfc9000>.
[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>.
[RFC7627] Bhargavan, K., Ed., Delignat-Lavaud, A., Pironti, A.,
Langley, A., and M. Ray, "Transport Layer Security (TLS)
Session Hash and Extended Master Secret Extension",
RFC 7627, DOI 10.17487/RFC7627, September 2015,
<https://www.rfc-editor.org/info/rfc7627>.
[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>.
[RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
"Handling Long Lines in Content of Internet-Drafts and
RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
<https://www.rfc-editor.org/info/rfc8792>.
[STRUCTURED-FIELDS]
Nottingham, M. and P. Kamp, "Structured Field Values for
HTTP", RFC 9651, DOI 10.17487/RFC9651, September 2024,
<https://www.rfc-editor.org/info/rfc9651>.
[TLS] 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>.
[URI] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[X.690] ITU-T, "Information technology - ASN.1 encoding Rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER)", ITU-T Recommendation X690, ISO/IEC 8825-1:2021,
February 2021, <https://www.itu.int/rec/T-REC-X.690>.
10.2. Informative References
[ED25519] Josefsson, S. and J. Schaad, "Algorithm Identifiers for
Ed25519, Ed448, X25519, and X448 for Use in the Internet
X.509 Public Key Infrastructure", RFC 8410,
DOI 10.17487/RFC8410, August 2018,
<https://www.rfc-editor.org/info/rfc8410>.
[HOBA] Farrell, S., Hoffman, P., and M. Thomas, "HTTP Origin-
Bound Authentication (HOBA)", RFC 7486,
DOI 10.17487/RFC7486, March 2015,
<https://www.rfc-editor.org/info/rfc7486>.
[HTTP/2] Thomson, M., Ed. and C. Benfield, Ed., "HTTP/2", RFC 9113,
DOI 10.17487/RFC9113, June 2022,
<https://www.rfc-editor.org/info/rfc9113>.
[HTTP/3] Bishop, M., Ed., "HTTP/3", RFC 9114, DOI 10.17487/RFC9114,
June 2022, <https://www.rfc-editor.org/info/rfc9114>.
[MASQUE-ORIGINAL]
Schinazi, D., "The MASQUE Protocol", Work in Progress,
Internet-Draft, draft-schinazi-masque-00, 28 February
2019, <https://datatracker.ietf.org/doc/html/draft-
schinazi-masque-00>.
[QUIC-TLS] Thomson, M., Ed. and S. Turner, Ed., "Using TLS to Secure
QUIC", RFC 9001, DOI 10.17487/RFC9001, May 2021,
<https://www.rfc-editor.org/info/rfc9001>.
[SEEMS-LEGIT]
Jackson, D., Cremers, C., Cohn-Gordon, K., and R. Sasse,
"Seems Legit: Automated Analysis of Subtle Attacks on
Protocols That Use Signatures", CCS '19: Proceedings of
the 2019 ACM SIGSAC Conference on Computer and
Communications Security, pp. 2165-2180,
DOI 10.1145/3319535.3339813, November 2019,
<https://doi.org/10.1145/3319535.3339813>.
Acknowledgments
The authors would like to thank many members of the IETF community,
as this document is the fruit of many hallway conversations. In
particular, the authors would like to thank David Benjamin, Reese
Enghardt, Nick Harper, Dennis Jackson, Ilari Liusvaara, François
Michel, Lucas Pardue, Justin Richer, Ben Schwartz, Martin Thomson,
and Chris A. Wood for their reviews and contributions. The mechanism
described in this document was originally part of the first iteration
of MASQUE [MASQUE-ORIGINAL].
Authors' Addresses
David Schinazi
Google LLC
1600 Amphitheatre Parkway
Mountain View, CA 94043
United States of America
Email: dschinazi.ietf@gmail.com
David M. Oliver
Guardian Project
Email: david@guardianproject.info
URI: https://guardianproject.info
Jonathan Hoyland
Cloudflare Inc.
Email: jonathan.hoyland@gmail.com