protected override void SetKey(byte[] keyBytes, byte[] ivBytes)
{
base.SetKey(keyBytes, ivBytes);
if (keyBytes == null || keyBytes.Length != 32)
{
throw new ArgumentException($@"{AlgorithmName} requires a 256 bit key");
}
if (ivBytes == null || ivBytes.Length != NonceSize)
{
throw new ArgumentException($@"{AlgorithmName} requires a 192 bit nonce");
}
var nonceInt = Pack.LE_To_UInt32(ivBytes, 0, 6);
var chachaKey = HChaCha20Internal(keyBytes, nonceInt);
SetSigma(engineState);
SetKey(engineState, chachaKey);
engineState[12] = 1; // Counter
engineState[13] = 0;
engineState[14] = nonceInt[4];
engineState[15] = nonceInt[5];
}
private static uint[] HChaCha20Internal(byte[] key, uint[] nonceInt)
{
var x = new uint[16];
var intKey = Pack.LE_To_UInt32(key, 0, 8);
SetSigma(x);
SetKey(x, intKey);
SetIntNonce(x, nonceInt);
DoubleRound(x);
Array.Copy(x, 12, x, 4, 4);
return(x);
}
protected override void SetKey(byte[] keyBytes, byte[] ivBytes)
{
if (keyBytes != null)
{
if (keyBytes.Length != 16 && keyBytes.Length != 32)
{
throw new ArgumentException($@"{AlgorithmName} requires 128 bit or 256 bit key");
}
PackTauOrSigma(keyBytes.Length, engineState, 0);
// Key
Pack.LE_To_UInt32(keyBytes, 0, engineState, 4, 4);
Pack.LE_To_UInt32(keyBytes, keyBytes.Length - 16, engineState, 8, 4);
}
// IV
Pack.LE_To_UInt32(ivBytes, 0, engineState, 14, 2);
}
protected virtual void SetKey(byte[] keyBytes, byte[] ivBytes)
{
if (keyBytes != null)
{
if ((keyBytes.Length != 16) && (keyBytes.Length != 32))
{
throw new ArgumentException(AlgorithmName + " requires 128 bit or 256 bit key");
}
var tsOff = (keyBytes.Length - 16) / 4;
engineState[0] = TauSigma[tsOff];
engineState[5] = TauSigma[tsOff + 1];
engineState[10] = TauSigma[tsOff + 2];
engineState[15] = TauSigma[tsOff + 3];
// Key
Pack.LE_To_UInt32(keyBytes, 0, engineState, 1, 4);
Pack.LE_To_UInt32(keyBytes, keyBytes.Length - 16, engineState, 11, 4);
}
// IV
Pack.LE_To_UInt32(ivBytes, 0, engineState, 6, 2);
}
