private static bool VerifyChecksum(byte[] raw, XISFChecksumTypeEnum cksumType, string providedCksum)
{
string computedCksum;
SHA3Managed sha3;
using (MyStopWatch.Measure($"XISF Checksum = {cksumType}")) {
switch (cksumType)
{
case XISFChecksumTypeEnum.SHA1:
SHA1 sha1 = new SHA1CryptoServiceProvider();
computedCksum = GetStringFromHash(sha1.ComputeHash(raw));
sha1.Dispose();
break;
case XISFChecksumTypeEnum.SHA256:
SHA256 sha256 = new SHA256CryptoServiceProvider();
computedCksum = GetStringFromHash(sha256.ComputeHash(raw));
sha256.Dispose();
break;
case XISFChecksumTypeEnum.SHA512:
SHA512 sha512 = new SHA512CryptoServiceProvider();
computedCksum = GetStringFromHash(sha512.ComputeHash(raw));
sha512.Dispose();
break;
case XISFChecksumTypeEnum.SHA3_256:
sha3 = new SHA3Managed(256);
computedCksum = GetStringFromHash(sha3.ComputeHash(raw));
sha3.Dispose();
break;
case XISFChecksumTypeEnum.SHA3_512:
sha3 = new SHA3Managed(512);
computedCksum = GetStringFromHash(sha3.ComputeHash(raw));
sha3.Dispose();
break;
default:
return(false);
}
}
if (computedCksum.Equals(providedCksum))
{
return(true);
}
else
{
Logger.Error($"XISF: Invalid data block checksum! Expected: {providedCksum} Got: {computedCksum}");
return(false);
}
}
/// <summary>
/// Convert the ushort array to a byte arraay, compressing with the requested algorithm if required
/// </summary>
/// <param name="data"></param>
/// <returns>Uncompressed or compressed byte array</returns>
private byte[] PrepareArray(ushort[] data)
{
byte[] outArray;
/*
* Convert the ushort[] into a byte[]
* From here onwards we deal in byte arrays only
*/
byte[] byteArray = new byte[data.Length * ShuffleItemSize];
Buffer.BlockCopy(data, 0, byteArray, 0, data.Length * ShuffleItemSize);
/*
* Compress the data block as configured.
*/
using (MyStopWatch.Measure($"XISF Compression = {CompressionType}")) {
if (CompressionType == XISFCompressionTypeEnum.LZ4)
{
if (ByteShuffling)
{
CompressionName = "lz4+sh";
byteArray = Shuffle(byteArray, ShuffleItemSize);
}
else
{
CompressionName = "lz4";
}
byte[] tmpArray = new byte[LZ4Codec.MaximumOutputSize(byteArray.Length)];
int compressedSize = LZ4Codec.Encode(byteArray, 0, byteArray.Length, tmpArray, 0, tmpArray.Length, LZ4Level.L00_FAST);
outArray = new byte[compressedSize];
Array.Copy(tmpArray, outArray, outArray.Length);
tmpArray = null;
}
else if (CompressionType == XISFCompressionTypeEnum.LZ4HC)
{
if (ByteShuffling)
{
CompressionName = "lz4hc+sh";
byteArray = Shuffle(byteArray, ShuffleItemSize);
}
else
{
CompressionName = "lz4hc";
}
byte[] tmpArray = new byte[LZ4Codec.MaximumOutputSize(byteArray.Length)];
int compressedSize = LZ4Codec.Encode(byteArray, 0, byteArray.Length, tmpArray, 0, tmpArray.Length, LZ4Level.L06_HC);
outArray = new byte[compressedSize];
Array.Copy(tmpArray, outArray, outArray.Length);
tmpArray = null;
}
else if (CompressionType == XISFCompressionTypeEnum.ZLIB)
{
if (ByteShuffling)
{
CompressionName = "zlib+sh";
byteArray = Shuffle(byteArray, ShuffleItemSize);
}
else
{
CompressionName = "zlib";
}
outArray = ZlibStream.CompressBuffer(byteArray);
}
else
{
outArray = new byte[byteArray.Length];
Array.Copy(byteArray, outArray, outArray.Length);
CompressionName = null;
}
}
// Revert to the original data array in case the compression is bigger than uncompressed
if (outArray.Length > byteArray.Length)
{
if (ByteShuffling)
{
//As the original array is shuffled it needs to be unshuffled again - this scenario should be highly unlikely anyways
outArray = Unshuffle(byteArray, ShuffleItemSize);
}
else
{
outArray = byteArray;
}
CompressionType = XISFCompressionTypeEnum.NONE;
Logger.Debug("XISF output array is larger after compression. Image will be prepared uncompressed instead.");
}
if (CompressionType != XISFCompressionTypeEnum.NONE)
{
double percentChanged = (1 - ((double)outArray.Length / (double)byteArray.Length)) * 100;
Logger.Debug($"XISF: {CompressionType} compressed {byteArray.Length} bytes to {outArray.Length} bytes ({percentChanged.ToString("#.##")}%)");
}
/*
* Checksum the data block as configured.
* If the data block is compressed, we always checksum the compressed form, not the uncompressed form.
*/
using (MyStopWatch.Measure($"XISF Checksum = {ChecksumType}")) {
SHA3Managed sha3;
switch (ChecksumType)
{
case XISFChecksumTypeEnum.SHA1:
SHA1 sha1 = new SHA1CryptoServiceProvider();
Checksum = GetStringFromHash(sha1.ComputeHash(outArray));
ChecksumName = "sha-1";
sha1.Dispose();
break;
case XISFChecksumTypeEnum.SHA256:
SHA256 sha256 = new SHA256CryptoServiceProvider();
Checksum = GetStringFromHash(sha256.ComputeHash(outArray));
ChecksumName = "sha-256";
sha256.Dispose();
break;
case XISFChecksumTypeEnum.SHA512:
SHA512 sha512 = new SHA512CryptoServiceProvider();
Checksum = GetStringFromHash(sha512.ComputeHash(outArray));
ChecksumName = "sha-512";
sha512.Dispose();
break;
case XISFChecksumTypeEnum.SHA3_256:
sha3 = new SHA3Managed(256);
Checksum = GetStringFromHash(sha3.ComputeHash(outArray));
ChecksumName = "sha3-256";
sha3.Dispose();
break;
case XISFChecksumTypeEnum.SHA3_512:
sha3 = new SHA3Managed(512);
Checksum = GetStringFromHash(sha3.ComputeHash(outArray));
ChecksumName = "sha3-512";
sha3.Dispose();
break;
case XISFChecksumTypeEnum.NONE:
default:
Checksum = null;
ChecksumName = null;
break;
}
}
return(outArray);
}
