help with mcrypt

tutorialstuff

This seems to work fine in IE8, but whenever I view it in FF3, There is some weird trailing characters after the decrypted text.

$decryption_key = "Yru8S09edICE";
$cipher_alg=MCRYPT_RIJNDAEL_256;

function hex2bin($data) {
    $len = strlen($data);
    return pack("H" . $len, $data);
} 

$iv = bin2hex(mcrypt_create_iv(mcrypt_get_iv_size($cipher_alg, MCRYPT_MODE_CBC), MCRYPT_RAND));

$encryppted_text = mcrypt_encrypt($cipher_alg, $decryption_key, 'this is text', MCRYPT_MODE_CBC, hex2bin($iv));

print $encryppted_text."<br />";

$decrypted_text = mcrypt_decrypt($cipher_alg, $decryption_key, $encryppted_text, MCRYPT_MODE_CBC, hex2bin($iv));

print $decrypted_text;

NogDog

Just guessing that it might be padding the string with nulls. Try:

$decrypted_text = rtrim($decrypted_text, "\0\4");

tutorialstuff

That seems to do the trick, but can you tell me why it would be doing that?

halojoy

When mcrypt encrypts
it handles, processes blocks. They can often be 8 chars length.
But the last block of the text might not be 8 chars.
So mcrypt fills in the number of chars missing until 8 in last block.
A sort of padding. Often is this done with ASCII(0) = null

Sometimes these blocks are 16 chars in length.

Therte are other ways to remove, avoid such 'extra chars'.
But the solution you got here is the easiest way.