title: Internet X.509 Public Key Infrastructure - Algorithm Identifiers for Kyber abbrev: PQC Kyber in Certificates category: std
docname: draft-ietf-lamps-kyber-certificates-latest
ipr: trust200902 keyword: Internet-Draft area: SEC workgroup: None venue: group: "Limited Additional Mechanisms for PKIX and SMIME (lamps)" type: "Working Group" mail: "[email protected]" arch: "https://mailarchive.ietf.org/arch/browse/spasm/" github: seanturner/draft-ietf-lamps-kyber-certificates
stand_alone: yes smart_quotes: no pi: [toc, sortrefs, symrefs]
name: Sean Turner
organization: sn3rd
email: [email protected]
- ins: P. Kampanakis name: Panos Kampanakis org: AWS email: [email protected]
- ins: J. Massimo name: Jake Massimo organization: AWS email: [email protected]
- ins: B. Westerbaan name: Bas Westerbaan organization: Cloudflare email: [email protected]
normative:
informative: PQCProj: target: https://csrc.nist.gov/projects/post-quantum-cryptography title: Post-Quantum Cryptography Project author: - org: National Institute of Standards and Technology date: 2016-12-20
--- abstract
This document specifies algorithm identifiers and ASN.1 encoding format for the United States National Institute of Standards and Technology's Post Quantum Cryptography Key Encapsulation Mechanism algorithms. The algorithms covered are Kyber TBD1. The encoding for public key and private key is also provided.
[EDNOTE: This draft is not expected to be finalized before the NIST PQC Project has standardized PQ algorithms. After NIST has standardized its first algorithms, this document will replace TBD, with the appropriate algorithms and parameters before proceeding to ratification. The algorithm Kyber TBD1 has been added as an example in this draft, to provide a more detailed illustration of the content - it by no means indicates its inclusion in the final version. This specification will use object identifiers for the new algorithms that are assigned by NIST, and will use placeholders until these are released.]
--- middle
The US NIST PQC Project has selected the Kyber algorithm as winner of their PQC Project {{PQCProj}}. This algorithm is a Key Encapsulation Mechanism(KEM). NIST has also defined object identifiers for these algorithms (TODO insert reference).
This document specifies the use of the Kyber algorithm in X.509 public key certifiates, see {{!RFC5280}}. It also specifies private key encoding. An ASN.1 module is included for reference purposes.
These certificates could be used as Issuers in CMS where the public key is used to encapsulate a shared secret used to derive a symmetric key used to encrypt content in CMS [EDNOTE: Add reference draft-perret-prat-lamps-cms-pq-kem]. To be used in TLS, these certificates could only be used as end-entity identity certificates and would require significant updates to the protocol [EDNOTE: Add reference draft-celi-wiggers-tls-authkem].
{::boilerplate bcp14-tagged}
Certificates conforming to {{RFC5280}} can convey a public key for any public key algorithm. The certificate indicates the algorithm through an algorithm identifier. An algorithm identifier consists of an object identifier and optional parameters.
The AlgorithmIdentifier type, which is included herein for convenience, is defined as follows:
AlgorithmIdentifier ::= SEQUENCE {
algorithm OBJECT IDENTIFIER,
parameters ANY DEFINED BY algorithm OPTIONAL
}
The fields in AlgorithmIdentifier have the following meanings:
-
algorithm identifies the cryptographic algorithm with an object identifier. XXX such OIDs are defined in Sections {{Kyber-TBD1}}.
-
parameters, which are optional, are the associated parameters for the algorithm identifier in the algorithm field.
In this document, TODO (specify number) new OIDs for identifying the different algorithm and parameter pairs. For all of the object identifiers, the parameters MUST be absent.
It is possible to find systems that require the parameters to be present. This can be due to either a defect in the original 1997 syntax or a programming error where developers never got input where this was not true. The optimal solution is to fix these systems; where this is not possible, the problem needs to be restricted to that subsystem and not propagated to the Internet.
TODO insert object-identifiers for Kyber-768, Kyber-1024 etc.
In the X.509 certificate, the subjectPublicKeyInfo field has the SubjectPublicKeyInfo type, which has the following ASN.1 syntax:
SubjectPublicKeyInfo ::= SEQUENCE {
algorithm AlgorithmIdentifier,
subjectPublicKey BIT STRING
}
The fields in SubjectPublicKeyInfo have the following meanings:
-
algorithm is the algorithm identifier and parameters for the public key (see above).
-
subjectPublicKey contains the byte stream of the public key. The algorithms defined in this document always encode the public key as TODO pick format e.g., exact multiple of 8 bits?.
The following is an example of a Kyber TBD1 public key encoded using the textual encoding defined in {{?RFC7468}}.
-----BEGIN PUBLIC KEY-----
TODO insert example public key
-----END PUBLIC KEY-------
The intended application for the key is indicated in the keyUsage certificate extension; see [RFC5280, section 4.2.1.3].
If the keyUsage extension is present in a certificate that indicates Kyber TBD1 in SubjectPublicKeyInfo, then the following MUST be present:
keyEncipherment;
"Asymmetric Key Packages" {{!RFC5958}} describes how to encode a private key in a structure that both identifies what algorithm the private key is for and allows for the public key and additional attributes about the key to be included as well. For illustration, the ASN.1 structure OneAsymmetricKey is replicated below. The algorithm-specific details of how a private key is encoded are left for the document describing the algorithm itself.
OneAsymmetricKey ::= SEQUENCE {
version Version,
privateKeyAlgorithm PrivateKeyAlgorithmIdentifier,
privateKey PrivateKey,
attributes [0] IMPLICIT Attributes OPTIONAL,
...,
[[2: publicKey [1] IMPLICIT PublicKey OPTIONAL ]],
...
}
PrivateKey ::= OCTET STRING
PublicKey ::= BIT STRING
For the keys defined in this document, the private key is always an opaque byte sequence. The ASN.1 type PqckemPrivateKey is defined in this document to hold the byte sequence. Thus, when encoding a OneAsymmetricKey object, the private key is wrapped in a PqckemPrivateKey object and wrapped by the OCTET STRING of the "privateKey" field.
PqckemPrivateKey ::= OCTET STRING
The following is an example of a Kyber TBD private key encoded using the textual encoding defined in {{RFC7468}}.
-----BEGIN PRIVATE KEY-----
TODO iser example private key
-----END PRIVATE KEY-------
The following example, in addition to encoding the Kyber TBD private key, has an attribute included as well as the public key. As with the prior example, the textual encoding defined in {{RFC7468}} is used.
-----BEGIN PRIVATE KEY-----
TODO insert example private key with attribute
-----END PRIVATE KEY-------
TODO ASN.1 Module
The Security Considerations section of {{RFC5280}} applies to this specification as well.
[EDNOTE: Discuss side-channels for Kyber TBD1.]
This document will have some IANA actions.
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{:numbered="false"}
TODO acknowledge.