FIX: Kyber KEM with a KDF + some nitpicks #2982
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Previously, ::algo_name() contained the algorithm parameters (e.g. -90s-512) as well. This was impractical and did not align with other algorithms in the library. Instead, Kyber_...::mode() now gives acces to the specific algorithm parameters used.
Previously, the KEM operations would simply assume "Raw" and ignore KDF as well as provider parameters.
This would have resulted in an exception before. Similar behaviour was already implemented for the key agreement public key operation.
When either kyber or kyber_90s was disabled at build time we caused a test failure.
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Turns out that the implementation of Kyber needed a bit more polishing:
KEM_XXcryption_with_KDFHence, the interface would simply ignore the KDF and provider preferences of the user and always return the "Raw" shared secret.
Kyber...::algo_name()incorporated the algorithm parametersI.e. the algo name would be reported as "Kyber-1024-90s-r3". This is not in line with the rest of the library's algorithms. Now,
algo_name()will always report "Kyber-r3" and the key classes provide an additional::mode()accessor to investigate the algorithm parameters. To integrate with Kyber's preliminary OIDs, theKyberModeenum is now a small class that can perform the translation from and to OIDs.In contrast to
PK_Ops::Key_Agreement_with_KDFthe respective KEM operations did not allow for a "Raw" KDF. This is needed though, e.g. to implement TLS 1.3 hybrid key exchange.