Expand KeyAgreement group and KDF coverage

[dancewithheart]

Address:

botan/botan-low/test/Test/Botan/Low/PubKey/KeyAgreement.hs

Line 22 in 80f148b

-- TODO: More thorough test with different KDFs and curves / groups

Adds KeyAgreement tests:

• with matrix for
  • ffdhe/ietf/3072 - FFDHE the TLS finite-field DH group family RFC 7919
  • secp384r1 - P-384 is NIST SP 800-186 recommended prime-field elliptic curve
  • secp256k1 - relevant for blockchains Bitcoin, Cardano
  • and KDF: HKDF(SHA-256), HKDF(SHA-384), KDF2(SHA-256)
• checks that different salts derive different keys
• derived key length matches keyAgreementSize

Validated with:

cabal test botan-low:test

results:

    spec_keyAgreement_matrix
      keyAgreement DH modp/ietf/2048 / HKDF(SHA-256):                                 OK (0.01s)
      keyAgreement DH modp/ietf/2048 / HKDF(SHA-384):                                 OK (0.01s)
      keyAgreement DH modp/ietf/2048 / KDF2(SHA-256):                                 OK (0.01s)
      keyAgreement DH ffdhe/ietf/3072 / HKDF(SHA-256):                                OK (0.04s)
      keyAgreement DH ffdhe/ietf/3072 / HKDF(SHA-384):                                OK (0.04s)
      keyAgreement DH ffdhe/ietf/3072 / KDF2(SHA-256):                                OK (0.04s)
      keyAgreement ECDH secp256r1 / HKDF(SHA-256):                                    OK
      keyAgreement ECDH secp256r1 / HKDF(SHA-384):                                    OK
      keyAgreement ECDH secp256r1 / KDF2(SHA-256):                                    OK
      keyAgreement ECDH secp384r1 / HKDF(SHA-256):                                    OK
      keyAgreement ECDH secp384r1 / HKDF(SHA-384):                                    OK
      keyAgreement ECDH secp384r1 / KDF2(SHA-256):                                    OK
      keyAgreement ECDH secp256k1 / HKDF(SHA-256):                                    OK
      keyAgreement ECDH secp256k1 / HKDF(SHA-384):                                    OK
      keyAgreement ECDH secp256k1 / KDF2(SHA-256):                                    OK
      keyAgreement Curve25519 / HKDF(SHA-256):                                        OK
      keyAgreement Curve25519 / HKDF(SHA-384):                                        OK
      keyAgreement Curve25519 / KDF2(SHA-256):                                        OK