public DiffieHellman(DiffieHellmanPublicKey publicKey, KeyAgreementKeyDerivationFunction kdFunc, KeyAgreementKeyDerivationHashAlgorithm kdHashAlgo)
: base(kdFunc, kdHashAlgo)
{
_group = DiffieHellmanGroupType.None;
_keySize = publicKey.KeySize;
_p = publicKey.P;
_g = publicKey.G;
_privateKey = GeneratePrivateKey(_p);
}
public DiffieHellman(DiffieHellmanPublicKey publicKey, KeyAgreementKeyDerivationFunction kdFunc, KeyAgreementKeyDerivationHashAlgorithm kdHashAlgo)
: base(kdFunc, kdHashAlgo)
{
_keySize = publicKey.KeySize;
_p = publicKey.P;
_g = publicKey.G;
GeneratePrivateKey();
}
protected override byte[] ComputeKey(byte[] otherPartyPublicKey)
{
DiffieHellmanPublicKey opPublicKey = new DiffieHellmanPublicKey(otherPartyPublicKey);
if (opPublicKey.Group != _group)
{
throw new CryptoException("DiffieHellman group mismatch.");
}
if (opPublicKey.KeySize != _keySize)
{
throw new CryptoException("DiffieHellman key size mismatch.");
}
if (opPublicKey.P != _p)
{
throw new CryptoException("DiffieHellman public key parameter P doesn't match.");
}
if (opPublicKey.G != _g)
{
throw new CryptoException("DiffieHellman public key parameter G doesn't match.");
}
HashAlgorithm hash;
switch (base.KeyDerivationHashAlgorithm)
{
case KeyAgreementKeyDerivationHashAlgorithm.SHA256:
hash = HashAlgorithm.Create("SHA256");
break;
case KeyAgreementKeyDerivationHashAlgorithm.SHA384:
hash = HashAlgorithm.Create("SHA384");
break;
case KeyAgreementKeyDerivationHashAlgorithm.SHA512:
hash = HashAlgorithm.Create("SHA512");
break;
default:
throw new CryptoException("Hash algorithm not supported.");
}
return(hash.ComputeHash(BigInteger.ModPow(opPublicKey.X, _privateKey, _p).ToByteArray()));
}
