php obfuscation encrypt/decrypt

I开发者_JAVA百科s there a way to encode/decode a string using a secret key. I will use base64 to give you an example what im looking for.

<?php 

$secret = 'abc123'; 
$string = 'Hello World';
$en = base64_encode($string,$secret);//encoded output returns here

echo base64_decode($en,$secret);//output: "Hello World"

?>

so basically im asking to use a key/salt, to encode a text and then decode it back only using that same secret key. otherwise there should be a wrong output :)

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You probably want to use the mcrypt extension for PHP.

The following might be a bit overkill depending on what you want to do, but the security is pretty much guaranteed if you keep your keys safe, as AES has yet to be broken :)

function enc_aes($str, $key, $iv) {
    $aes = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, '');
    if (!$aes) die("<b>mcrypt_module_open failed!</b>");
    (mcrypt_generic_init($aes, $key, $iv) != -1) or die("<b>mcrypt_generic_init failed!</b>");

    // PHP will pad query with \0 to multiple of block size
    $ret = mcrypt_generic($aes, $str);
    mcrypt_generic_deinit($aes);
    return $ret;
}

function dec_aes($str, $key, $iv) {
    $aes = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, '');
    if (!$aes) die("<b>mcrypt_module_open failed!</b>");
    (mcrypt_generic_init($aes, $key, $iv) != -1) or die("<b>mcrypt_generic_init failed!    </b>");

    // PHP will pad query with \0 to multiple of block size
    $ret = mdecrypt_generic($aes, $str);
    mcrypt_generic_deinit($aes);
    return $ret;
}

// Specifying key & IV as hex. Obviously doing so in the source is rather unsafe...

// For example. Key is 128-bits
$key = pack("H*", "0123456789ABCDEFFEDBCA9876543210");

// For example. Initialization Vector is 64-bits
$iv = pack("H*", "0123456789ABCDEF");
$encrypted_string = enc_aes("decrypted string", $key, $iv);

// Should output "decrypted string" :]
print( dec_aes($encrypted_string, $key, $iv) );

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Mcrypt

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Tutorial on using the Mcrypt library for encryption: http://www.itnewb.com/v/PHP-Encryption-Decryption-Using-the-MCrypt-Library-libmcrypt

And a more in depth tutorial on PHP encryption in general: http://www.tuxradar.com/practicalphp/17/3/1

Warning: Encryption is very difficult to do correctly. If this is just for something simple then cool, but if you're actually trying to store sensitive information then you should really consider using software like GnuPG to handle asymmetric encryption for you. There is a PHP extension for interfacing with GnuPG.

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Mcrypt does the job!

Yet, if you want something a bit less complex you can XOR $string with your $secret to symmetrically encrypt it then encode it using base64_encode. Now if you want the real content of $string, you just have to decode it (base64_decode) and XOR it again using the same $secret.