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[Resolved] Cookie Encryption

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thnn
I am trying to two-way encrypt the data in a cookie so that a user cannot change it. However I do not want to use MD5 as it is one way. I also do not want to use rot13 because it is insecure. Does anyone know if MCrypt is installed on the server?

Also does anyone know of anyway I could two-way encrypt the data in a cookie.

Last edited by thnn on Thu Dec 15, 2005 10:59 pm; edited 1 time in total
thnn
OK i worked out i need to use MCrypt. I just though it would share how I did it with everyone.

Code:
<?php

       function cookieencode($input)
       {
       $key = "yourkey";

       $td = mcrypt_module_open('blowfish', '', 'ecb', '');
       $ks = mcrypt_enc_get_key_size($td);
       $key = substr($key, 0, $ks);
       $iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
       mcrypt_generic_init($td, $key, $iv);
       
       //do the encrpyting
       $encrypted_data = mcrypt_generic($td, $input);
       //end the system
       mcrypt_generic_deinit($td);
       mcrypt_module_close($td);
       //return the results
       return $encrypted_data;
       }

       function cookiedecode($input)
       {
       $key = "yourkey";

       $td = mcrypt_module_open('blowfish', '', 'ecb', '');
       $ks = mcrypt_enc_get_key_size($td);
       $key = substr($key, 0, $ks);
       $iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
       mcrypt_generic_init($td, $key, $iv);
       
       //do the decrpyting
       $decrypt = mdecrypt_generic($td, $input);
       //end the system
       mcrypt_generic_deinit($td);
       mcrypt_module_close($td);
       //return the results
       return $decrypt;
       }
   
?>


Then you can call the different functions depending on what you want to do. Example to encode you would call cookieencode or to decode you would call cookiedecode.
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