private static byte[] ComputeX(DSASigner dsa_signer, byte[] dsa_public_key_bytes_encoded, byte[] key_id_byte_array, byte[] hashed_m_byte_array_data)
{
if (key_id_byte_array == null || key_id_byte_array.Length < 1)
{
throw new ArgumentException("ComputeX: The key id byte array should not be null/empty");
}
if (hashed_m_byte_array_data == null || hashed_m_byte_array_data.Length < 1)
{
throw new ArgumentException("ComputeX: The hashed m byte array should not be null/empty");
}
if (dsa_signer == null)
{
throw new ArgumentException("ComputeX: DSA signer object cannot be null");
}
byte[] _signature_r_byte_array = null;
byte[] _signature_s_byte_array = null;
dsa_signer.GenerateSignature(hashed_m_byte_array_data, ref _signature_r_byte_array, ref _signature_s_byte_array);
if (_signature_r_byte_array == null || _signature_r_byte_array.Length < 1)
{
throw new InvalidDataException("ComputeX: The computed DSA signature parameter 'r' byte array cannot be null/empty");
}
if (_signature_s_byte_array == null || _signature_s_byte_array.Length < 1)
{
throw new InvalidDataException("ComputeX: The computed DSA signature parameter 's' byte array cannot be null/empty");
}
byte[] _hashed_m_data_signature = null;
byte[] _encoded_key_id_byte_array = null;
try
{
byte[] _encoded_signature_r_byte_array = null;
byte[] _encoded_signature_s_byte_array = null;
/* This is unnecessary. It's just here to complement DecodeMacfromBytes used in IsEncryptedSignatureVerified().
* It should be removed if performance becomes an issue. */
Utility.EncodeOTRMacBE(_signature_r_byte_array, ref _encoded_signature_r_byte_array);
Utility.EncodeOTRMacBE(_signature_s_byte_array, ref _encoded_signature_s_byte_array);
if (_encoded_signature_r_byte_array == null || _encoded_signature_r_byte_array.Length < 1)
{
throw new InvalidDataException("ComputeX: The encoded DSA signature parameter 'r' byte array cannot be null/empty");
}
if (_encoded_signature_s_byte_array == null || _encoded_signature_s_byte_array.Length < 1)
{
throw new InvalidDataException("ComputeX: The encoded DSA signature parameter 's' byte array cannot be null/empty");
}
_hashed_m_data_signature = new byte[_encoded_signature_r_byte_array.Length + _encoded_signature_s_byte_array.Length];
Buffer.BlockCopy(_encoded_signature_r_byte_array, 0, _hashed_m_data_signature, 0, _encoded_signature_r_byte_array.Length);
Buffer.BlockCopy(_encoded_signature_s_byte_array, 0, _hashed_m_data_signature, _encoded_signature_r_byte_array.Length, _encoded_signature_s_byte_array.Length);
Utility.EncodeOTRInt(key_id_byte_array, ref _encoded_key_id_byte_array);
}
catch (Exception ex)
{
throw new InvalidDataException("ComputeX:" + ex.ToString());
}
if (_encoded_key_id_byte_array == null || _encoded_key_id_byte_array.Length < 1)
{
throw new InvalidDataException("ComputeX: The encoded key id byte array should not be null/empty");
}
int _x_data_array_length = _encoded_key_id_byte_array.Length + dsa_public_key_bytes_encoded.Length + _hashed_m_data_signature.Length;
byte[] _x_data_array = new byte[_x_data_array_length];
Buffer.BlockCopy(dsa_public_key_bytes_encoded, 0, _x_data_array, 0, dsa_public_key_bytes_encoded.Length);
Buffer.BlockCopy(_encoded_key_id_byte_array, 0, _x_data_array, dsa_public_key_bytes_encoded.Length, _encoded_key_id_byte_array.Length);
Buffer.BlockCopy(_hashed_m_data_signature, 0, _x_data_array, dsa_public_key_bytes_encoded.Length + _encoded_key_id_byte_array.Length, _hashed_m_data_signature.Length);
return(_x_data_array);
}