7. Implementation Considerations

この節では PKIX における ML-KEM の RFC 原文を保持し, algorithm identifiers, SubjectPublicKeyInfo, private key formats, ASN.1 objects, security considerations, examples を含めます.

7.  Implementation Considerations

   Though Section 7.1 of [FIPS203] mentions the potential to save seed
   values for future expansion, Algorithm 19 does not make the seed
   values available to a caller for serialization.  Similarly, the
   algorithm that expands seed values is not listed as one of the "main
   algorithms" and features "internal" in the name even though it is
   clear that it is allowed to be exposed externally for the purposes of
   expanding a key from a seed.  Below are possible ways to extend the
   APIs defined in [FIPS203] to support serialization of seed values as
   private keys.

   To support serialization of seed values as private keys, let
   Algorithm 19b denote the same procedure as Algorithm 19 in [FIPS203],
   except it returns (ek, dk, d, z) on line 7.  Additionally, Algorithm
   16 should be promoted to be a "main algorithm" for external use in
   expanding seed values.

   Note also that unlike other private key compression methods in other
   algorithms, expanding a private key from a seed is a one-way
   function, meaning that once a full key is expanded from a seed and
   the seed discarded, the seed cannot be recreated even if the full
   expanded private key is available.  For this reason, it is
   RECOMMENDED that implementations retain and export the seed, even
   when also exporting the expanded private key.