assertion encryption: mcrypt iv size doesnt match extracted string length

Question

I've been using simpleSAMLphp without assertion encryption, and everything was great! Now I've been asked to accept encrypted assertions, and I'm getting the following warning:

Warning: mcrypt_generic_init(): Iv size incorrect; supplied length: 23, needed: 16 in /path/to/myproject/simplesaml/vendor/simplesamlphp/xmlseclibs/xmlseclibs.php on line 454

Debugging this, I found that xmlseclibs is trying to extract the iv string using a substr($data, 0, 16), and this is returning a string(23). My first guess was a multibyte issue, but mb_substr didn't do the trick either.

I've been debugging this all afternoon, and got nowhere. Any ideas?

Thanks!!

Answer 1

I solved the same problem by setting mb_func.overload=0. By default it was 2.