Add TLS signature (de)serialization
The supported signature schemes are:
- ECDSA, curve P-256
- RSASSA-PKCS1-V1_5
The supported hash function is:
- SHA256
(See RFC 6962, §2.1.4.)
The serialized signatures are Digitally-Signed structs, see RFC 5246 §4.7.
Edited by Rasmus Dahlberg