/// <summary>
/// Secret key operation. Decrypts biCipher with the keydata
/// in the given secret key packet.
/// </summary>
/// <param name="biInput">The ciphertext that is about to
/// be decrypted</param>
/// <param name="skpKey">The secret key packet with the key
/// material for the decryption</param>
/// <param name="strPassphrase">The passphrase for the
/// keymaterial</param>
/// <returns>The decrypted ciphertext.</returns>
/// <remarks>No remarks.</remarks>
public override BigInteger Decrypt(BigInteger[] biInput, SecretKeyPacket skpKey, string strPassphrase)
{
BigInteger[] biKeyMaterial = skpKey.GetDecryptedKeyMaterial(strPassphrase);
EG_Secret_Key eskKey = new EG_Secret_Key();
eskKey.x = biKeyMaterial[0];
eskKey.p = skpKey.PublicKey.KeyMaterial[0];
eskKey.g = skpKey.PublicKey.KeyMaterial[1];
eskKey.y = skpKey.PublicKey.KeyMaterial[2];
if (biInput.Length != 2)
throw new ArgumentException("biInput is not an ElGamal encrypted Packet");
BigInteger B = biInput[0];
BigInteger c = biInput[1];
BigInteger z = B.modPow(eskKey.x, eskKey.p).modInverse(eskKey.p);
BigInteger output = (z * c) % eskKey.p;
return output;
}
private DSA_Secret_Key ParseSecretKey(SecretKeyPacket skpKey, string strPassphrase)
{
DSA_Secret_Key dskKey = new DSA_Secret_Key();
dskKey.p = skpKey.PublicKey.KeyMaterial[0];
dskKey.q = skpKey.PublicKey.KeyMaterial[1];
dskKey.g = skpKey.PublicKey.KeyMaterial[2];
dskKey.y = skpKey.PublicKey.KeyMaterial[3];
BigInteger[] biSecretKeyMaterial = skpKey.GetDecryptedKeyMaterial(strPassphrase);
dskKey.x = biSecretKeyMaterial[0];
return dskKey;
}
private RSA_Secret_Key ParseSecretKey(SecretKeyPacket skpKey, string strPassphrase)
{
RSA_Secret_Key rskKey = new RSA_Secret_Key();
rskKey.n = skpKey.PublicKey.KeyMaterial[0];
rskKey.e = skpKey.PublicKey.KeyMaterial[1];
BigInteger[] biSecretKeyMaterial = skpKey.GetDecryptedKeyMaterial(strPassphrase);
rskKey.d = biSecretKeyMaterial[0];
rskKey.p = biSecretKeyMaterial[1];
rskKey.q = biSecretKeyMaterial[2];
rskKey.u = biSecretKeyMaterial[3];
return rskKey;
}
