Posted by Tom Rogers on 01/14/05 07:40

Hi,

Friday, January 14, 2005, 7:53:30 AM, you wrote:
BD> Howdy all -

BD> I have RTFM and STFW and I still can't get encryption to work. What I
BD> finally ended up with from the PHP documentation is long, unwieldy,
BD> confusing, and doesn't work. I give up. I threw my big mess away and
BD> would like to start from scratch.

BD> Could anyone point me to a web page or other documentation that shows a
BD> SIMPLE example of encryption? I need two-way encryption & decryption,
BD> not a one-way hash. I'll be using this to obfuscate get parameters.

BD> Any pointers appreciated. Thanks all,

BD> - Brian

Here is a class that uses mcrypt that might be helpful:


class encrypt_class{
var $secret;
function encrypt_class(){
$this->secret = 'put pass string here';
}
Function encode($id){
$eid = $iv = 0;
$len = strlen($id);
$id = $len.'-'.$id; //encode the string length for trimming later
$td = mcrypt_module_open(MCRYPT_TripleDES, "", MCRYPT_MODE_ECB, "");
$key = substr($this->secret, 0, mcrypt_enc_get_key_size ($td));
$iv = pack("a".mcrypt_enc_get_iv_size($td),$iv);
mcrypt_generic_init ($td, $key, $iv);
$eid = base64_encode(mcrypt_generic ($td, $id));
mcrypt_generic_deinit($td);
return $eid;
}
Function decode($eid){
$id = $iv = 0;
$td = mcrypt_module_open (MCRYPT_TripleDES, "", MCRYPT_MODE_ECB, "");
$key = substr($this->secret, 0, mcrypt_enc_get_key_size ($td));
$iv = pack("a".mcrypt_enc_get_iv_size($td),$iv);
mcrypt_generic_init ($td, $key, $iv);
$id = mdecrypt_generic ($td, base64_decode($eid));
$len = strtok($id,'-');
$id = substr($id,(strlen($len)+1),$len);
mcrypt_generic_deinit($td);
return $id;
}
}

//useage
$str = "Hello World";
$enc = new encrypt_class();
$estr = $enc->encode($str);
echo "$estr<br>";
$dstr = $enc->decode($estr);
echo "$dstr<br>";

--
regards,
Tom

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