Encryption and decryption with MachineKey C #

Question

Im trying to encrypt and decrypt an identifier using MachineKey.

Here is my code that calls the encryption and decryption functions:

 var encryptedId = Encryption.Protect(profileId.ToString(), UserId);
 var decryptedId = Encryption.UnProtect(encryptedId, UserId);

Here are the functions:

public static string Protect(string text, string purpose)
{
    if(string.IsNullOrEmpty(text))
    {
        return string.Empty;
    }

    byte[] stream = Encoding.Unicode.GetBytes(text);
    byte[] encodedValues = MachineKey.Protect(stream, purpose);
    return HttpServerUtility.UrlTokenEncode(encodedValues);
}

public static string UnProtect(string text, string purpose)
{
    if(string.IsNullOrEmpty(text))
    {
        return string.Empty;
    }

    byte[] stream = HttpServerUtility.UrlTokenDecode(text);
    byte[] decodedValues = MachineKey.Unprotect(stream, purpose);
    return Encoding.UTF8.GetString(decodedValues);
}

The method input Protectis 15. This causes the encryptedId variable to contain the following line:6wOttbtJoVBV7PxhVWXGz4AQVYcuyHvTyJhAoPu4Okd2aKhhCGbKlK_T4q3GgirotfOZYZXke0pMdgwSmC5vxg2

To encrypt this, I send this string as a parameter to the method UnProtect. The result of decryption should be 15, but instead:1\05\0

I do not understand why. Who can help me?

I have a trid to use only integers in this function, but I still have the same problem. Decryption output is different.

Answer 1

, , UTF-16 (Encoding.Unicode) ( \0, , , 2 ), UTF-8 (Encoding.UTF8). .