Hashing Method Feedback Wanted

[zach.rattner]

I did some research on hashing, and it looks like both md5() and sha1() can be reversed, given enough time and processing power. I wrote a function that (I think) would make it considerably more difficult to unhash a value. Do you think this is overkill? Are there any problems that jump out at you? Here is the code:

 

<?php
function hyper_hash($value) {
    for ($i = 0; $i < 100; $i++) {
        if ($i %2 == 0) {
            $value = sha1($value);
        }
        else if ($i %3 == 1) {
            $value = base64_encode($value);
        }
        else {
            $value = md5($value);
        }
    }
    return $value;
}

$initial = microtime(true);
echo "\"12345\" hashed to: " . hyper_hash("12345"). "<br /><br />";
$final = microtime(true);
$delta = $final - $initial;
echo "Time taken: " . $delta . " s";

?>

Here's a page with this code running: [removed]

 

Thanks for the feedback,

Zach

[lemmin]

The only possible way to "reverse" a hash is if the original string is found in a lookup table. I think your function is pretty unnecessary. You can get by hash lookups by just adding some known characters to the end of the string you are hashing and it becomes virtually unreversable.