Static ring::agreement::X25519

pub static X25519: Algorithm = agreement::Algorithm{i:
                         ec::AgreementAlgorithmImpl{curve: &CURVE25519,
                                                    ecdh: x25519_ecdh,},}

X25519 (ECDH using Curve25519) as described in RFC 7748.

Everything is as described in RFC 7748. Key agreement will fail if the result of the X25519 operation is zero; see the notes on the "all-zero value" in RFC 7748 section 6.1.