Implements the proposed breaking changes to the `signature` crate from
https://github.com/RustCrypto/traits/pull/1141
Most notably the `Signature` trait has been replaced with a
`SignatureEncoding` trait which permits an internally structured
signature representation.
For consistency with the `ecdsa` crate.
This naming scheme follows the philosophy that in a digital signature
scheme, it's clearer to name keys after their roles.
DSA admittedly benefits less than other schemes where there are other
potential algorithms that can be implemented using the same core
mathematics which share the same key representations.
Adds an initial implementation of DSA (see #8)
The following things work when tested against OpenSSL:
- The generated keys are valid and can be imported and exported from/to their DER/PEM representation
- Signatures generated by this library can be successfully verified
- Signatures can be imported and exported from/into their DER representation
- Signatures generated by OpenSSL can be successfully imported and verified
Mirek Sedzinski