将Laravel的AES 256加密器转换为C＃

Question

I need to create the same results when using Crypt::Encrypt('secret') from Laravel, in C#. I found this thread Rijndael 256 Encrypt/decrypt between c# and php? and it seemed to be what I need, but I'm having some trouble with the third argument the, initialization vector :(.

Laravel using Rijndael AES to encrypt the data. All the user has to input is a secret key, in the config folder, that is totally random and 32 characters long.

The encyrption method looks like this:

public function encrypt($value)
    {
        $iv = mcrypt_create_iv($this->getIvSize(), $this->getRandomizer());

        $value = base64_encode($this->padAndMcrypt($value, $iv));

        // Once we have the encrypted value we will go ahead base64_encode the input
        // vector and create the MAC for the encrypted value so we can verify its
        // authenticity. Then, we'll JSON encode the data in a "payload" array.
        $mac = $this->hash($iv = base64_encode($iv), $value);

        return base64_encode(json_encode(compact('iv', 'value', 'mac')));
    }

The full Encryptor.php can be found here: http://pastebin.com/yfWLPxGn

Any idea as to what I would have to input to get the same results? :)

Answer 1

Initialization vector is an input that is typically random. So, algorithm always creates a different value using the same input, key and the different IV. If you'd like to generate same result using both PHP and C# code, you need to use the same IV value.

Laravel's encrypt() does not return the encrypted value only. The value encrypt() generates a base64 encoded string which has json encoded values of iv, mac and encrypted value.

So the steps you need to apply in your C# encode() method:

1. Encode the string using the code in the link you gave.
2. base64_encode() the encrypted value. We will use this value in the further steps.
3. Create MAC (Message Authentication Code) using base64_encoded IV as the value, encrypted value as the key and sha256 as the algorithm. Take a look at this one
4. Now we have encrypted value, mac and iv.

5. Create a json string like this:

   { 
       iv: iv value (base64 encoded),
       value: encrypted value (base64 encoded), 
       mac: mac value created in 3rd step 
   }
   

6. base64 encode your this json string.

7. You're all set.