/// <summary>
/// Combines a hash and domain to the input format used by Herumi (the G2 initial X value).
/// </summary>
/// <returns>true if the operation was successful; false if the destination is not large enough to hold the result</returns>
public bool TryCombineHashAndDomain(ReadOnlySpan <byte> hash, ReadOnlySpan <byte> domain, Span <byte> destination,
out int bytesWritten)
{
if (destination.Length < 2 * InitialXPartLength)
{
bytesWritten = 0;
return(false);
}
if (hash.Length != HashLength)
{
throw new ArgumentOutOfRangeException(nameof(hash), hash.Length,
$"Hash with domain must be {HashLength} bytes long.");
}
if (domain.Length != DomainLength)
{
throw new ArgumentOutOfRangeException(nameof(domain), domain.Length,
$"Domain must be {DomainLength} bytes long.");
}
var hashWithDomain = new Span <byte>(new byte[HashLength + DomainLength]);
hash.CopyTo(hashWithDomain);
domain.CopyTo(hashWithDomain.Slice(HashLength));
unsafe
{
fixed(byte *destinationPtr = destination)
fixed(byte *hashPtr = hashWithDomain)
{
Bls384Interop.HashWithDomainToFp2(destinationPtr, hashPtr);
}
}
bytesWritten = 2 * InitialXPartLength;
return(true);
}