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); }