/**
* @return <c>true</c> if the keyDigest is compatible with the specified saltData and saltHash
*/
public bool Validate(byte[] saltData, byte[] saltHash)
{
Check16Bytes(saltData, "saltData");
Check16Bytes(saltHash, "saltHash");
// validation uses the RC4 for block zero
RC4 rc4 = CreateRC4(0);
byte[] saltDataPrime = new byte[saltData.Length];
Array.Copy(saltData, saltDataPrime, saltData.Length);
rc4.Encrypt(saltDataPrime);
byte[] saltHashPrime = new byte[saltHash.Length];
Array.Copy(saltHash, saltHashPrime, saltHash.Length);
rc4.Encrypt(saltHashPrime);
using (MD5 md5 = new MD5CryptoServiceProvider())
{
byte[] finalSaltResult = md5.ComputeHash(saltDataPrime);
//if (false)
//{ // set true to see a valid saltHash value
// byte[] saltHashThatWouldWork = xor(saltHash, xor(saltHashPrime, finalSaltResult));
// Console.WriteLine(HexDump.ToHex(saltHashThatWouldWork));
//}
return(Arrays.Equals(saltHashPrime, finalSaltResult));
}
}
public void Xor(byte[] buf, int pOffSet, int pLen)
{
int nLeftInBlock;
nLeftInBlock = _nextRC4BlockStart - _streamPos;
if (pLen <= nLeftInBlock)
{
// simple case - this read does not cross key blocks
_rc4.Encrypt(buf, pOffSet, pLen);
_streamPos += pLen;
return;
}
int offset = pOffSet;
int len = pLen;
// start by using the rest of the current block
if (len > nLeftInBlock)
{
if (nLeftInBlock > 0)
{
_rc4.Encrypt(buf, offset, nLeftInBlock);
_streamPos += nLeftInBlock;
offset += nLeftInBlock;
len -= nLeftInBlock;
}
RekeyForNextBlock();
}
// all full blocks following
while (len > RC4_REKEYING_INTERVAL)
{
_rc4.Encrypt(buf, offset, RC4_REKEYING_INTERVAL);
_streamPos += RC4_REKEYING_INTERVAL;
offset += RC4_REKEYING_INTERVAL;
len -= RC4_REKEYING_INTERVAL;
RekeyForNextBlock();
}
// finish with incomplete block
_rc4.Encrypt(buf, offset, len);
_streamPos += len;
}