/// <summary>
/// When overridden in a derived class, routes data written to the object into the hash algorithm for computing the hash.
/// </summary>
/// <param name="array">The input to compute the hash code for.</param>
/// <param name="ibStart">The offset into the byte array from which to begin using data.</param>
/// <param name="cbSize">The number of bytes in the byte array to use as data.</param>
protected override void HashCore(byte[] array, int ibStart, int cbSize)
{
int startIndex = ibStart;
int totalArrayLength = _dataSize + cbSize;
if (totalArrayLength >= 64)
{
Array.Copy(array, startIndex, _data, _dataSize, 64 - _dataSize);
// Process message of 64 bytes (512 bits)
MD5Core.GetHashBlock(_data, ref _abcd, 0);
startIndex += 64 - _dataSize;
totalArrayLength -= 64;
while (totalArrayLength >= 64)
{
Array.Copy(array, startIndex, _data, 0, 64);
MD5Core.GetHashBlock(array, ref _abcd, startIndex);
totalArrayLength -= 64;
startIndex += 64;
}
_dataSize = totalArrayLength;
Array.Copy(array, startIndex, _data, 0, totalArrayLength);
}
else
{
Array.Copy(array, startIndex, _data, _dataSize, cbSize);
_dataSize = totalArrayLength;
}
_totalLength += cbSize;
}
public static byte[] GetHash(byte[] input)
{
if (null == input)
{
throw new System.ArgumentNullException("input", "Unable to calculate hash over null input data");
}
//Intitial values defined in RFC 1321
ABCDStruct abcd = new ABCDStruct {
A = 0x67452301, B = 0xefcdab89, C = 0x98badcfe, D = 0x10325476
};
//We pass in the input array by block, the final block of data must be handled specialy for padding & length embeding
int startIndex = 0;
while (startIndex <= input.Length - 64)
{
MD5Core.GetHashBlock(input, ref abcd, startIndex);
startIndex += 64;
}
// The final data block.
return(MD5Core.GetHashFinalBlock(input, startIndex, input.Length - startIndex, abcd, (Int64)input.Length * 8));
}
/// <summary>
/// When overridden in a derived class, finalizes the hash computation after the last data is processed by the cryptographic stream object.
/// </summary>
/// <returns>The computed hash code.</returns>
protected override byte[] HashFinal()
{
base.HashValue = MD5Core.GetHashFinalBlock(_data, 0, _dataSize, _abcd, _totalLength * 8);
return(base.HashValue);
}
