/// <summary>
/// Calculate the binary MD5 hash of a binary input
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static byte[] GetHash(byte[] input)
{
if (null == input)
{
throw new System.ArgumentNullException(nameof(input), "Unable to calculate hash over null input data");
}
//Intitial values defined in RFC 1321
ABCDStruct abcd = new ABCDStruct();
abcd.A = 0x67452301;
abcd.B = 0xefcdab89;
abcd.C = 0x98badcfe;
abcd.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>
/// Calculate a CRC for the provided byte array
/// </summary>
/// <param name="data"></param>
/// <param name="length"></param>
/// <returns>A 4 byte CRC value created by calculating an MD5 hash of the provided byte array</returns>
public static byte[] CalculateCRC(byte[] data, int length)
{
if (length < data.Length)
{
byte[] shortData = new byte[length];
Array.Copy(data, shortData, length);
data = shortData;
}
//to be FIPS compliant we have to not use the Crypto-API version of MD5.
byte[] crc = MD5Core.GetHash(data);
//This is a big bogus - I'm just going to take the first four bytes. We really should
//go find the true CRC32 algorithm
return(new byte[4] {
crc[0], crc[1], crc[2], crc[3]
});
}
