mcrypt_decrypt() error change key size

Question

mcrypt_decrypt(): Key of size 15 not supported by this algorithm. Only keys of sizes 16, 24 or 32 supported

How Can I fix this issue? my

Answer 1

You don't need to pad the key with "\0".

I had the same issue when migrating to a new PHP 7 server and I got the message :

mcrypt_decrypt(): Key of size 19 not supported by this algorithm. Only keys of sizes 16, 24 or 32 supported.

The key I had in the code was a string of 19 characters, I simply changed it to a string of 32 characters and everything was fine again.

So as the error message suggests, use a valid size key.