Hi,
Thursday, September 26, 2002, 4:45:04 AM, you wrote:
SF> How do I encrypt the data and decrypt it back using PHP? I do know that hte
SF> random number can not be used becuase it will make it impossible to decrypt
SF> it.
SF> Thanks!
Here is a simple class for encoding and decoding:
class encrypt_class{
var $secret;
function encrypt_class(){
$this->secret = 'this is a very long key, even too long for the
cipher';
}
Function encode($id){
$eid = $iv = 0;
$len = strlen($id);
$id = $len.'-'.$id;
$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;
}
}
Usage
<?
$word = 'Hello';
$e = new encrypt_class();
$encrypted = $e->encode($word);
echo "encrypted = $encrypted <br>";
$decrypted = $e->decode($encrypted);
echo "decrypted = $decrypted <br>";
if($word == $decrypted){
echo "They match <br>";
}
else{
echo "Oops they don't match <br>";
}
<?
--
regards,
Tom
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