/// <summary>
/// Returns the SHA512 HMAC hash for the file
/// </summary>
/// <param name="FilePath">Path to input file</param>
/// <param name="HashKey">HMAC key</param>
/// <returns>Computed hash value [byte[]]</returns>
internal byte[] GetChecksum(string FilePath, byte[] HashKey)
{
using (SHA512HMAC hmac = new SHA512HMAC(HashKey))
{
int blockSize = hmac.BlockSize;
int bytesTotal = 0;
byte[] buffer = new byte[blockSize];
byte[] chkSum = new byte[hmac.DigestSize];
using (BinaryReader inputReader = new BinaryReader(new FileStream(FilePath, FileMode.Open, FileAccess.Read, FileShare.None)))
{
// start of file bytes
inputReader.BaseStream.Position = MessageHeader.GetHeaderSize;
int bytesRead = 0;
// read into mac
while ((bytesRead = inputReader.Read(buffer, 0, blockSize)) == blockSize)
{
hmac.BlockUpdate(buffer, 0, bytesRead);
bytesTotal += bytesRead;
if (bytesTotal > MAX_SIGNED)
break;
}
// last block
if (bytesRead > 0)
hmac.BlockUpdate(buffer, 0, bytesRead);
// get the hash
hmac.DoFinal(chkSum, 0);
}
return chkSum;
}
}
private bool MacTest3(byte[] IKm)
{
byte[] data = new CSPRng().GetBytes(33033);
byte[] hash1;
byte[] hash2;
using (StreamMac mac1 = new StreamMac(new SHA512HMAC(IKm)))
{
mac1.Initialize(new MemoryStream(data));
mac1.IsConcurrent = false;
hash1 = mac1.ComputeMac();
}
using (SHA512HMAC mac2 = new SHA512HMAC(IKm))
hash2 = mac2.ComputeMac(data);
return Compare.AreEqual(hash1, hash2);
}
private void MacTest(byte[] Key, byte[] Input, byte[] Out256, byte[] Out512)
{
byte[] hash = new byte[32];
byte[] trnHash;
// test 1: HMAC interface
HMAC hmac1 = new HMAC(new SHA256());
hmac1.Initialize(new KeyParams(Key));
hash = hmac1.ComputeMac(Input);
// truncated output, test case #5
if (Out256.Length != 32)
{
trnHash = new byte[Out256.Length];
Buffer.BlockCopy(hash, 0, trnHash, 0, Out256.Length);
if (!Compare.AreEqual(Out256, trnHash))
throw new Exception("SHA256HMAC is not equal! Expected: " + HexConverter.ToString(Out256) + " Received: " + HexConverter.ToString(trnHash));
}
else
{
if (!Compare.AreEqual(Out256, hash))
throw new Exception("SHA256HMAC is not equal! Expected: " + HexConverter.ToString(Out256) + " Received: " + HexConverter.ToString(hash));
}
// test 2: 256 hmac
using (SHA256HMAC hmac2 = new SHA256HMAC())
{
hmac2.Initialize(new KeyParams(Key));
hash = hmac2.ComputeMac(Input);
}
if (Out256.Length != 32)
{
trnHash = new byte[Out256.Length];
Buffer.BlockCopy(hash, 0, trnHash, 0, Out256.Length);
if (!Compare.AreEqual(Out256, trnHash))
throw new Exception("SHA256HMAC is not equal! Expected: " + HexConverter.ToString(Out256) + " Received: " + HexConverter.ToString(trnHash));
}
else
{
if (!Compare.AreEqual(Out256, hash))
throw new Exception("SHA256HMAC is not equal! Expected: " + HexConverter.ToString(Out256) + " Received: " + HexConverter.ToString(hash));
}
hash = new byte[32];
// test 3: HMAC interface
hmac1 = new HMAC(new SHA512());
hmac1.Initialize(new KeyParams(Key));
hash = hmac1.ComputeMac(Input);
if (Out512.Length != 64)
{
trnHash = new byte[Out512.Length];
Buffer.BlockCopy(hash, 0, trnHash, 0, Out512.Length);
if (!Compare.AreEqual(Out512, trnHash))
throw new Exception("SHA512HMAC is not equal! Expected: " + HexConverter.ToString(Out512) + " Received: " + HexConverter.ToString(trnHash));
}
else
{
if (!Compare.AreEqual(Out512, hash))
throw new Exception("SHA512HMAC is not equal! Expected: " + HexConverter.ToString(Out512) + " Received: " + HexConverter.ToString(hash));
}
// test 4: 256 hmac
using (SHA512HMAC hmac3 = new SHA512HMAC())
{
hmac3.Initialize(new KeyParams(Key));
hash = hmac3.ComputeMac(Input);
}
if (Out512.Length != 64)
{
trnHash = new byte[Out512.Length];
Buffer.BlockCopy(hash, 0, trnHash, 0, Out512.Length);
if (!Compare.AreEqual(Out512, trnHash))
throw new Exception("SHA512HMAC is not equal! Expected: " + HexConverter.ToString(Out512) + " Received: " + HexConverter.ToString(trnHash));
}
else
{
if (!Compare.AreEqual(Out512, hash))
throw new Exception("SHA512HMAC is not equal! Expected: " + HexConverter.ToString(Out512) + " Received: " + HexConverter.ToString(hash));
}
}