encrypted tokens in php

Question

I'm new to encryption and utilizing this class to get tokens, Can someone help me understand what's going on these two functions with the help of references, video tutorials etc. for a deeper understanding. Purpose is to understand as well as implement in other languages using the same technique.

class Crypt {

public static function encrypt($data, $secret) {
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    $key = pack('H*', $secret);
    return base64_encode($iv . mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $data, MCRYPT_MODE_CBC, $iv));
}

public static function decrypt($data, $secret) {
    $data = base64_decode($data);
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
    $iv = substr($data, 0, $iv_size);
    $data = substr($data, $iv_size);
    $key = pack('H*', $secret);
    return trim(mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $data, MCRYPT_MODE_CBC, $iv), chr(0));
}
}

thanks

Jens A. Koch · Accepted Answer · 2014-10-18T15:12:20.727

as well as implement in other languages using the same technique

i doubt that ,)

Not an easy topic. You will have to dig into different cyphers and encryptions, especially RIJNDAEL_128 and CBC, like you posted.

If you want to learn about rinjndael, then look for AES (Advanced Encryption Standard).

SPEC You may find the offical specification at: http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf

Book This is the AES capther out of the crypto-textbook of Christof Paar and Jan Pelzl: http://wiki.crypto.rub.de/Buch/download/Understanding-Cryptography-Chapter4.pdf

Tutorial

http://www.codeplanet.eu/tutorials/cpp/51-advanced-encryption-standard.html Sorry, that this in german, but a good tutorial on the topic. I don't know if automatic translation will suffice here.

Videos

there is also a video of a cryptoanalysis of Rinjndael 48:
http://www.youtube.com/watch?v=NHuibtoL_qk - check youtube topic "AES"

Animation/Presentation

http://www.formaestudio.com/rijndaelinspector/archivos/Rijndael_Animation_v4_eng.swf

PHP Manual - Extension mCrypt

Code

curious, why it's difficult to implement in other languages, for instance I'm considering it for node.js, why I like this algorithm because it generates unique tokens each time for the same string — user2727195, Oct 18 '14 at 15:08
I think this already exists: https://github.com/chengxianga2008/node-cryptojs-aes .. check for CryptoJS AES implementation.. https://code.google.com/p/crypto-js/source/browse/tags/3.1.2/src/aes.js — Jens A. Koch, Oct 18 '14 at 15:15

encrypted tokens in php

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