private static ReadOnlyMemory <byte> DK(ReadOnlyMemory <byte> key, KeyUsage usage, KeyDerivationMode kdf, int keySize, int blockSize)
{
using (var constantPool = CryptoPool.RentUnsafe <byte>(5))
{
var constant = constantPool.Memory.Slice(0, 5);
Span <byte> span = constant.Span;
span.Clear();
BinaryPrimitives.WriteInt32BigEndian(span, (int)usage);
constant.Span[4] = (byte)kdf;
return(DK(key, constant, keySize, blockSize));
}
}
private static ReadOnlyMemory <byte> DK(ReadOnlySpan <byte> key, KeyUsage usage, KeyDerivationMode kdf, int keySize, int blockSize)
{
using (var constantPool = CryptoPool.RentUnsafe <byte>(5))
{
var constant = constantPool.Memory.Slice(0, 5);
constant.Span.Fill(0);
Endian.ConvertToBigEndian((int)usage, constant.Span);
constant.Span[4] = (byte)kdf;
return(DK(key, constant, keySize, blockSize));
}
}