note 54734 modified in function.mcrypt-decrypt by nlopess
| From: | nlopess@php.net | Date: | Fri, 23 Sep 2005 08:32:39 +0000 |
| Subject: | note 54734 modified in function.mcrypt-decrypt by nlopess | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-95649@lists.php.net to get a copy of this message | ||
It appears that mcrypt_decrypt pads the *RETURN STRING* with nulls ('\0') to fill out to n
* blocksize. For old C-programmers, like myself, it is easy to believe the string ends at the first
null. In PHP it does not:
strlen("abc\0\0") returns 5 and *NOT* 3
strcmp("abc", "abc\0\0") returns -2 and *NOT* 0
I learned this lesson painfully when I passed a string returned from mycrypt_decrypt into a NuSoap
message, which happily passed the nulls along to the receiver, who couldn't figure out what I
was talking about.
My solution was:
<?
$retval = mcrypt_decrypt( ...etc ...);
$retval = rtrim($retval, "\0"); // trim ONLY the nulls at the END
?>
--was--
It appears that mcrypt_decrypt pads the *RETURN STRING* with nulls ('\0') to fill out to n
* blocksize. For old C-programmers, like myself, it is easy to believe the string ends at the first
null. In PHP it does not:
strlen("abc\0\0") returns 5 and *NOT* 3
strcmp("abc", "abc\0\0") returns -2 and *NOT* 0
I learned this lesson painfully when I passed a string returned from mycrypt_decrypt into a NuSoap
message, which happily passed the nulls along to the receiver, who couldn't figure out what I
was talking about.
My solution was:
$retval = mcrypt_decrypt( ...etc ...);
$retval = rtrim($retval, '\0'); // trim ONLY the nulls at the END
----
My comments are based on PHP 4.3.4
http://php.net/manual/en/function.mcrypt-decrypt.php