Create your own hash in PHP?

Well, I need to save images with unique filenames and store t开发者_高级运维he file names in the database. I used to do MD5 hash and save the image with the filename of value obtained by hash.

However I would like to cut down the unnecessary space usage from 32 characters to 10-12 characters.

I dont want to substr() the obtained md5 hash to 12 characters.

Rather than that is there a way to create a custom hash of 10-12 characters ?

What about using the following function Tempnam

http://php.net/manual/en/function.tempnam.php

"Creates a file with a unique filename, with access permission set to 0600, in the specified directory. If the directory does not exist, tempnam() may generate a file in the system's temporary directory, and return the name of that. "

You can represent the 128 Bit MD5 hash values with just 16 characters (8 bit per character instead of just 4).

Maybe using CRC32 instead of MD5? It is 8 characters, not 32, but it is nearer to your goal.

PHP's Hash message digest framework provides tons of hash algorithms. Have fun!

To determine each hash's length, see Wikipedia.

CRC32 is 8 ASCII characters long.

I made this simple hash function to create my own hash with custom characters and size

function simple_hash($str, $size=5, $characters='0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ') {
    $hash_array = array();
    $hash = '';
    for($i=0;$i<$size;$i++){
        $hash_array[$i]=0;
    }
    for($s=0;$s<strlen($str);$s++){
        for($i=0;$i<$size;$i++){
            $hash_array[$i]=($hash_array[$i]+ord($str[$s])+$i+$s+$size)%strlen($characters);
        }
    }
    for($i=0;$i<$size;$i++){
        $hash .= $characters[$hash_array[$i]];
    }
    return $hash;
}

How to use:

<?=simple_hash('test')?>  // EIMQU
<?=simple_hash('test')?>  // EIMQU
<?=simple_hash('test',10)?> // Y26aeimquy
<?=simple_hash('test',10)?> // Y26aeimquy
<?=simple_hash('test',10,'abcdefghijkl')?> // cgkcgkcgkc
<?=simple_hash('test',10,'abcdeABCDE')?> // eDcBaeDcBa

<?=simple_hash('test2')?>  // BGLQV 
<?=simple_hash('test3')?>  // CHMRW
<?=simple_hash('a big string')?> // gsEQ2
<?=simple_hash('Ελληνικά')?> // 0gwM2
<?=simple_hash('Ελληνικα')?> // 5lBR7