Content of KemOtherInfo in Section 5.1.3.4

[HBrock]

Decide on the content of KemOtherInfo decpending on the conclusions taken in cms-kemri The goal is to use the algorithm specification for use with CMS also for use with CMP.

KemOtherInfo ::= SEQUENCE {
  staticString      PKIFreeText,
  transactionID     OCTET STRING,
  ct                OCTET STRING
}

Questions:

• Should ct be OPTIONAL or not?
• What about the public kem key?
• Is any other content needed?
• For symmetry with cms-kemri, should we rename ct to ukm?

[HBrock]

We decided to change to

KemOtherInfo ::= SEQUENCE {
  staticString      PKIFreeText,
  transactionID     OCTET STRING,
  kemContext    [0] OCTET STRING OPTIONAL
}

and

kemContext MAY contain additional algorithm specific context information.

and further wait for cms-kemri

[HBrock]

As we cannot expect the the content of kemContext is implicit, I also added kemContect to KemCiphertextInfo.

  KemCiphertextInfo ::= SEQUENCE {
    kem              AlgorithmIdentifier{KEM-ALGORITHM, {...}},
    ct               OCTET STRING,
    kemContext   [0] OCTET STRING OPTIONAL
  }

This is in line with cms-kemri where KEMRecipientInfo also transfers ukm.

[HBrock]

Alignment meeting 26.02.24 I will move the kemContext from the KemCiphertextInfo to the KemBMParameters structure