public static byte[] DeriveX3DhSecretReceiver(Curve25519KeyPair selfIdentityKeyPair,
Curve25519KeyPair selfSignedPreKeyPair, Curve25519KeyPair otherIdentityKey, Curve25519KeyPair ephemeralKey,
Curve25519KeyPair selfOneTimePreKeyPair = null)
{
byte[] dh1 = selfSignedPreKeyPair.CalculateSharedSecret(otherIdentityKey);
byte[] dh2 = selfIdentityKeyPair.CalculateSharedSecret(ephemeralKey);
byte[] dh3 = selfSignedPreKeyPair.CalculateSharedSecret(ephemeralKey);
IEnumerable <byte> dhConcat = dh1.Concat(dh2).Concat(dh3);
if (!(selfOneTimePreKeyPair is null))
{
byte[] dh4 = selfOneTimePreKeyPair.CalculateSharedSecret(ephemeralKey);
dhConcat = dhConcat.Concat(dh4);
}
return(X3DhKdf(dhConcat.ToArray(), X3DhProtocolInfo));
}
public byte[] CalculateSharedSecret(Curve25519KeyPair otherKey)
{
return(CalculateSharedSecret(otherKey.XPublicKey));
}
public static byte[] CalculateInitialAssociatedData(Curve25519KeyPair identityKeyA,
Curve25519KeyPair identityKeyB)
{
return(identityKeyA.XPublicKey.Concat(identityKeyB.XPublicKey).ToArray());
}