public SymmetricSigner(ReadOnlySpan <byte> key, SignatureAlgorithm algorithm)
: base(algorithm)
{
Debug.Assert(algorithm.Category == AlgorithmCategory.Hmac);
if (key.Length << 3 < MinimumKeySizeInBits)
{
ThrowHelper.ThrowArgumentOutOfRangeException_AlgorithmRequireMinimumKeySize(key.Length << 3, algorithm.Name.ToString(), MinimumKeySizeInBits);
}
_hashSizeInBytes = Algorithm.RequiredKeySizeInBits >> 2;
_base64HashSizeInBytes = Base64Url.GetArraySizeRequiredToEncode(_hashSizeInBytes);
_hashAlgorithm = new HmacSha2(algorithm.Sha, key);
}