mcrypt_encrypt(): Key of size [closed]

Question

mcrypt_encrypt(): Key of size 10 not supported by this algorithm. Only keys of sizes 16, 24 or 32 supported!

http://i.stack.imgur.com/qE1ZD.png

How can I fix this??

Answer 1

Used to be if your key was too short that PHP would pad it with \0. This is no longer the case since PHP version 5.6.0. You should check how big required key is for the cipher being used: http://php.net/manual/en/function.mcrypt-get-key-size.php Note there are other ways to check key size, check the documentation. Simple way I understand key size: a string like 'fubar' in ASCII is 5 * 8 = 40 bytes (8 bytes per char). But that's making assumptions about character set in use. Some comments at php.net better explain how to roll a key of correct size:

$key = pack('H*', "bcb04b7e103a0cd8b54763051cef08bc55abe029fdebae5e1d417e2ffb2a00a3");

Here the 64 char string will be converted into 32 byte key because bc is a byte, b0 is another, etc. From http://php.net/manual/en/function.mcrypt-encrypt.php

You can double check number of bytes with strlen(). From above example strlen($key) will print out 32.