public static uint Verify(OmniHashcash hashcash, ReadOnlySequence <byte> sequence, ReadOnlyMemory <byte> key)
{
if (hashcash is null)
{
throw new ArgumentNullException(nameof(hashcash));
}
if (hashcash.AlgorithmType == OmniHashcashAlgorithmType.Simple_Sha2_256)
{
var target = Hmac_Sha2_256.ComputeHash(sequence, key.Span);
return(MinerHelper.Verify_Simple_Sha2_256(hashcash.Key.Span, target));
}
return(0);
}
public static bool TryComputeHash(ReadOnlySpan <byte> password, ReadOnlySpan <byte> salt, int iterationCount, Span <byte> destination)
{
const int hashLength = 32;
int keyLength = destination.Length / hashLength;
if (destination.Length % hashLength != 0)
{
keyLength++;
}
var extendedkeyLength = (salt.Length + 4);
Span <byte> extendedkey = extendedkeyLength <= 128 ? stackalloc byte[extendedkeyLength] : new byte[extendedkeyLength];
BytesOperations.Copy(salt, extendedkey, salt.Length);
for (int i = 0; i < keyLength; i++)
{
extendedkey[salt.Length] = (byte)(((i + 1) >> 24) & 0xFF);
extendedkey[salt.Length + 1] = (byte)(((i + 1) >> 16) & 0xFF);
extendedkey[salt.Length + 2] = (byte)(((i + 1) >> 8) & 0xFF);
extendedkey[salt.Length + 3] = (byte)(((i + 1)) & 0xFF);
Span <byte> f = stackalloc byte[hashLength];
Span <byte> u = stackalloc byte[hashLength];
Hmac_Sha2_256.TryComputeHash(extendedkey, password, u);
BytesOperations.Zero(extendedkey.Slice(salt.Length, 4));
BytesOperations.Copy(u, f, hashLength);
for (int j = 1; j < iterationCount; j++)
{
Hmac_Sha2_256.TryComputeHash(u, password, u);
BytesOperations.Xor(f, u, f);
}
int position = i * hashLength;
int remain = Math.Min(hashLength, destination.Length - position);
BytesOperations.Copy(f, destination.Slice(position), remain);
}
return(true);
}
public static async ValueTask <OmniHashcash> Create(ReadOnlySequence <byte> sequence, ReadOnlyMemory <byte> key, OmniHashcashAlgorithmType hashcashAlgorithmType, int limit, TimeSpan timeout, CancellationToken token)
{
if (!EnumHelper.IsValid(hashcashAlgorithmType))
{
throw new ArgumentException(nameof(OmniHashcashAlgorithmType));
}
return(await Task.Run(() =>
{
if (hashcashAlgorithmType == OmniHashcashAlgorithmType.Simple_Sha2_256)
{
var target = Hmac_Sha2_256.ComputeHash(sequence, key.Span);
var hashcashKey = MinerHelper.Compute_Simple_Sha2_256(target, limit, timeout, token);
return new OmniHashcash(OmniHashcashAlgorithmType.Simple_Sha2_256, hashcashKey);
}
throw new NotSupportedException(nameof(hashcashAlgorithmType));
}, token));
}