public static uint Verify_Simple_Sha2_256(ReadOnlySpan <byte> key, ReadOnlySpan <byte> value)
{
if (key == null)
{
throw new ArgumentNullException(nameof(key));
}
if (key.Length != 32)
{
throw new ArgumentOutOfRangeException(nameof(key));
}
if (value == null)
{
throw new ArgumentNullException(nameof(value));
}
if (value.Length != 32)
{
throw new ArgumentOutOfRangeException(nameof(value));
}
Span <byte> buffer = stackalloc byte[64];
byte[] hash;
{
BytesOperations.Copy(key, buffer, key.Length);
BytesOperations.Copy(value, buffer.Slice(key.Length), value.Length);
hash = Sha2_256.ComputeHash(buffer);
}
uint count = 0;
for (int i = 0; i < 32; i++)
{
for (int j = 0; j < 8; j++)
{
if (((hash[i] << j) & 0x80) == 0)
{
count++;
}
else
{
goto End;
}
}
}
End:
return(count);
}
public static bool TryComputeHash(ReadOnlySequence <byte> sequence, ReadOnlySpan <byte> key, Span <byte> destination)
{
if (destination.Length < 32)
{
throw new ArgumentOutOfRangeException(nameof(destination));
}
Span <byte> extendedKey = stackalloc byte[_blockLength];
if (key.Length > _blockLength)
{
Sha2_256.TryComputeHash(key, extendedKey);
}
else
{
BytesOperations.Copy(key, extendedKey, Math.Min(key.Length, extendedKey.Length));
}
Span <byte> ixor = stackalloc byte[_blockLength];
BytesOperations.Xor(_ipad, extendedKey, ixor);
Span <byte> oxor = stackalloc byte[_blockLength];
BytesOperations.Xor(_opad, extendedKey, oxor);
Span <byte> ihash = stackalloc byte[32];
using (var incrementalHash = IncrementalHash.CreateHash(HashAlgorithmName.SHA256))
{
incrementalHash.AppendData(ixor);
foreach (var segment in sequence)
{
incrementalHash.AppendData(segment.Span);
}
incrementalHash.TryGetHashAndReset(ihash, out _);
}
using (var incrementalHash = IncrementalHash.CreateHash(HashAlgorithmName.SHA256))
{
incrementalHash.AppendData(oxor);
incrementalHash.AppendData(ihash);
return(incrementalHash.TryGetHashAndReset(destination, out _));
}
}
