Serialization mismatches break DSA_PrivateToPublic and KDF_SRTP/SRTCP structured inputs

[Kr0emer]

DSA_PrivateToPublic::Serialize only writes priv, but the generator emits p/g/priv and the wolfCrypt module expects p/g. Structured mutator also parses p/g/priv, so the fields get lost and the module receives empty/invalid p/g.
KDF_SRTP/KDF_SRTCP::Serialize do not write index, yet the generator fills it and the wolfCrypt implementations consume it. Structured mutator previously read the field, but it’s missing in the payload, causing misalignment and fallback to byte-level mutation.
Impact:

Structured mutations for these operations mostly fail or degrade to byte-level mutation.
Backends cannot use full parameters; coverage drops and OutOfData may occur.
Suggested fixes:

In DSA_PrivateToPublic::Serialize, serialize g, p, and priv in the same order as the generator/mutator.
In KDF_SRTP and KDF_SRTCP::Serialize, serialize index along with key/salt/kdr/key1-3Size.

[Kr0emer]

In modules/openssl/module.cpp, OpDSA_PrivateToPublic only sets priv; p/q/g remain null and DSA_generate_key typically returns no result, so the operation is effectively unusable on OpenSSL.
Fix suggestion: parse op.p, op.g, and op.priv into BIGNUMs and compute pub = g^priv mod p (e.g., via BN_mod_exp), returning the decimal string. This leverages the serialized p/g/priv and makes the OpenSSL backend able to produce a public key.