RFC 8448 contains multiple TLS 1.3 message traces, this commit adds two
new test cases focusing on key derivation:
- Simple 1-RTT Handshake
- Resumed 0-RTT Handshake
Additionally, the whole test suite is restructured and duplicate code is
removed and consolidated.
TLS 1.3 uses HMAC-based Extract-and-Expand Key Derivation Function (HKDF)
as defined in RFC 5869 to compute traffic secrets.
Co-authored-by: bytinbit <meline.sieber@hsr.ch>