public void JwtSignatureDecode(string base64, int length, byte first, byte fiftyOneth, byte last)
{
var decode = Base64Url.Decode(base64);
var bytes = new UTF8Encoding(false).GetBytes(decode);
bytes.Length.Should().Be(length);
bytes.First().Should().Be(first);
bytes.Skip(51).First().Should().Be(fiftyOneth);
bytes.Last().Should().Be(last);
}
