public void SetChecksum(byte[] block, int offset, int length)
{
var byteToProcess = new byte[length];
Array.Copy(block, offset, byteToProcess, 0, length);
_checksum = ZsyncUtil.Md4Hash(byteToProcess);
}
private static bool VerifyFile(FileInfo file, string checksum)
{
using (SHA1CryptoServiceProvider crypto = new SHA1CryptoServiceProvider())
{
var buffer = File.ReadAllBytes(file.FullName);
var hash = ZsyncUtil.ByteToHex(crypto.ComputeHash(buffer));
return(hash == checksum);
}
}
public static List <BlockSum> GenerateBlocksum(byte[] input, int weakLength, int strongLength, int blockSize)
{
using (var stream = new MemoryStream(input))
{
int capacity = ((int)(input.Length / blockSize) + (input.Length % blockSize > 0 ? 1 : 0)) * (weakLength + strongLength)
+ 20;
List <BlockSum> blockSums = new List <BlockSum>();
var weakbytesMs = new MemoryStream(4);
int count = 0;
byte[] block = new byte[blockSize];
int read;
while ((read = stream.Read(block, 0, block.Length)) != 0)
{
if (read < blockSize)
{
// Pad with 0's
block = Pad(block, read, blockSize, 0);
}
//weakbytesMs.Clear();
weakbytesMs.SetLength(0);
weakbytesMs.SetLength(weakLength);
var weakCheckSum = (ushort)ZsyncUtil.ComputeRsum(block);
weakbytesMs.Position = weakbytesMs.Length - weakLength;
var strongbytesMs = new MemoryStream(ZsyncUtil.Md4Hash(block.ToArray()));
strongbytesMs.SetLength(strongLength);
byte[] strongBytesBuffer = new byte[strongLength];
strongbytesMs.Read(strongBytesBuffer, 0, strongLength);
blockSums.Add(new BlockSum(weakCheckSum, strongBytesBuffer, count));
count++;
}
return(blockSums);
}
}
public static void Make(FileInfo file)
{
//var blockSize = 2048;
var fileLength = file.Length;
var blockSize = CalculateBlocksize(file.Length);
var sequenceMatches = fileLength > blockSize ? 2 : 1;
var weakChecksumLength = CalculateWeakChecksumLength(fileLength, blockSize, sequenceMatches);
var strongCheckSumLength = CalculateStrongChecksumLength(fileLength, blockSize, sequenceMatches);
var checkSums = ComputeCheckSums(file, blockSize, fileLength, weakChecksumLength, strongCheckSumLength);
var mtime = File.GetLastWriteTimeUtc(file.FullName);
var header = new Header(ZsyncVersion, file.Name, mtime, blockSize, fileLength, sequenceMatches,
weakChecksumLength, strongCheckSumLength, null, ZsyncUtil.ByteToHex(checkSums.sha1));
var zsyncFile = new FileInfo(file.FullName + ".zsync");
WriteFile(header, new MemoryStream(checkSums.checksums), zsyncFile);
}
private static (byte[] checksums, byte[] sha1) ComputeCheckSums(FileInfo file, int blockSize, long fileLength,
int weakLength, int strongLength)
{
/*
* As per the zsync spec, a weak checksum is md4 and a strong checksum is sha1
*/
int capacity = ((int)(fileLength / blockSize) + (fileLength % blockSize > 0 ? 1 : 0)) * (weakLength + strongLength)
+ 20;
// 20 = SHA1 length
/*
* CheckSums
* WeakBytes
*
* Limit = Length
*/
var checkSumsMs = new MemoryStream(capacity);
var weakbytesMs = new MemoryStream(weakLength);
byte[] block = new byte[blockSize];
using (BufferedStream stream =
new BufferedStream(new FileStream(file.FullName, FileMode.Open, FileAccess.Read), 1000000))
{
int read;
while ((read = stream.Read(block, 0, block.Length)) != 0)
{
if (read < blockSize)
{
// Pad with 0's
block = Pad(block, read, blockSize, 0);
}
//weakbytesMs.Clear();
weakbytesMs.SetLength(0);
weakbytesMs.SetLength(weakLength);
var weakCheckSum = (ushort)ZsyncUtil.ComputeRsum(block);
//weakbytesMs.Position = weakbytesMs.Length - weakLength;
Write(checkSumsMs, MiscUtil.Conversion.EndianBitConverter.Big.GetBytes(weakCheckSum));
var strongbytesMs = new MemoryStream(ZsyncUtil.Md4Hash(block.ToArray()));
strongbytesMs.SetLength(strongLength);
byte[] strongBytesBuffer = new byte[strongLength];
strongbytesMs.Read(strongBytesBuffer, 0, strongLength);
checkSumsMs.Write(strongBytesBuffer, 0, strongLength);
}
stream.Seek(0, SeekOrigin.Begin);
var cryptoProvider = new SHA1CryptoServiceProvider();
var fileHash = cryptoProvider.ComputeHash(stream);
return(checkSumsMs.ToArray(), fileHash);
}
}
