An implementation of XEdDSA, based on ref10 by Daniel J. Bernstein.
XEdDSA is a signature scheme that utilizes the birational maps between
Curve25519 and Ed25519 (defined in RFC 7748 on page 5) to create and
verify digital signatures with Curve25519 keys.
XEdDSA is also specified for Curve448/Ed448, which is not covered by
this library.
This library has a set of functions surrounding Curve25519 and Ed25519
key pairs, to make this library a toolset around both curves instead
of just an implementation of XEdDSA.