public BitString MixKeys(TDESKeys keys, List <BitString> lastThreeOpResults)
{
if (keys == null)
{
throw new ArgumentNullException(nameof(keys));
}
if (lastThreeOpResults == null || lastThreeOpResults.Count < 3)
{
throw new ArgumentException("Need three cipherText entries to mix keys", nameof(lastThreeOpResults));
}
var newKey1 = keys.KeysAsBitStrings[0].XOR(lastThreeOpResults[0]);
var newKey2 = keys.KeysAsBitStrings[1].XOR(lastThreeOpResults[0]);
var newKey3 = keys.KeysAsBitStrings[2].XOR(lastThreeOpResults[0]);
if (keys.KeyOption == KeyOptionValues.ThreeKey)
{
newKey2 = keys.KeysAsBitStrings[1].XOR(lastThreeOpResults[1]);
newKey3 = keys.KeysAsBitStrings[2].XOR(lastThreeOpResults[2]);
}
if (keys.KeyOption == KeyOptionValues.TwoKey)
{
newKey2 = keys.KeysAsBitStrings[1].XOR(lastThreeOpResults[1]);
}
byte[] outputArray = new byte[24];
Array.Copy(newKey1.ToBytes(), outputArray, 8);
Array.Copy(newKey2.ToBytes(), 0, outputArray, 8, 8);
Array.Copy(newKey3.ToBytes(), 0, outputArray, 16, 8);
return(new BitString(outputArray));
}
public TDESContext(TDESKeys keys, BlockCipherDirections function)
{
Schedule = new List <KeySchedule>();
Function = function;
for (int keyIdx = 0; keyIdx < keys.Keys.Count; keyIdx++)
{
var workingFunction = GetWorkingFunction(keyIdx);
var keySched = new KeySchedule(keys.Keys[keyIdx], workingFunction, true);
Schedule.Add(keySched);
}
}
public BitString MixKeys(TDESKeys keys, List <BitString> previousOutputs)
{
if (keys == null)
{
throw new ArgumentNullException(nameof(keys));
}
if (previousOutputs == null ||
(previousOutputs.Count * previousOutputs[0].BitLength) < 192)
{
throw new ArgumentException("Need 192 bits of previous outputs", nameof(previousOutputs));
}
var outputBitString = new BitString(192);
previousOutputs.Reverse();
foreach (var previousOutput in previousOutputs)
{
outputBitString = outputBitString.ConcatenateBits(previousOutput);
}
var newKey1 = keys.KeysAsBitStrings[0].XOR(outputBitString.Substring(0, 64));
var newKey2 = keys.KeysAsBitStrings[1].XOR(outputBitString.Substring(0, 64));
var newKey3 = keys.KeysAsBitStrings[2].XOR(outputBitString.Substring(0, 64));
if (keys.KeyOption == KeyOptionValues.ThreeKey)
{
newKey2 = keys.KeysAsBitStrings[1].XOR(outputBitString.Substring(64, 64));
newKey3 = keys.KeysAsBitStrings[2].XOR(outputBitString.Substring(128, 64));
}
if (keys.KeyOption == KeyOptionValues.TwoKey)
{
newKey2 = keys.KeysAsBitStrings[1].XOR(outputBitString.Substring(64, 64));
}
byte[] outputArray = new byte[24];
Array.Copy(newKey1.ToBytes(), outputArray, 8);
Array.Copy(newKey2.ToBytes(), 0, outputArray, 8, 8);
Array.Copy(newKey3.ToBytes(), 0, outputArray, 16, 8);
return(new BitString(outputArray));
}
private void PopulateKeySchedule()
{
var contextDirection = BlockCipherDirections.Encrypt;
switch (_direction)
{
case BlockCipherDirections.Encrypt:
contextDirection = !_useInverseCipher ? BlockCipherDirections.Encrypt : BlockCipherDirections.Decrypt;
break;
case BlockCipherDirections.Decrypt:
contextDirection = !_useInverseCipher ? BlockCipherDirections.Decrypt : BlockCipherDirections.Encrypt;
break;
default:
throw new ArgumentException(nameof(_direction));
}
var keys = new TDESKeys(new BitString(_key));
_context = new TDESContext(keys, contextDirection);
}
