security/libomemo-c: new port -- for of libsignal-protocol-c with OMEMO support
This is a fork of libsignal-protocol-c, an implementation of Signal's
ratcheting forward secrecy protocol that works in synchronous and asynchronous
messaging. The fork adds support for OMEMO as defined in XEP-0384 versions
0.3.0 and later.
- OMEMO version 0.3.0 uses the original libsignal-protocol-c implementation
with its protocol versions 2 and 3.
- OMEMO version 0.4.0+ is implemented using a new protocol version 4
internally. In comparison with protocol version 3, it changes:
- HKDF info strings
- Protocol buffer encoding
- Signature scheme (uses XEd25519 instead of custom "Curve25519 signatures")
- Specification-compliant double ratchet
- Support for Ed25519 public keys
- Various serializations
- Removes unused functionality