Mcrypt not installed with Laravel Homestead

I've just moved from a WAMP installation to Homestead and I can't get my app running.

When running composer install I get this error:

Use of undefined constant MCRYPT_RIJNDAEL_128 - assumed 'MCRYPT_RIJNDAEL_128'

Many people seem to have problems with that but most of them use custom installation (they install php from scratch for example). I have just followed the steps here.

I tried to grep mcrypt from php --info and not a single line is returned so I assumed mcrypt is not install.

I've run sudo apt-get install php5-mcrypt and it says:

php5-mcrypt : Depends: phpapi-20121212

I could try to install this dependency but I'm wondering if I'm doing something wrong (the point of using Homestead was to get rid of everything but the project itself, I assume).

The php version used in the vm:

PHP 7.0.2-4+deb.sury.org~trusty+1 (cli) ( NTS )
Copyright (c) 1997-2015 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2015 Zend Technologies
    with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2015, by Zend Technologies
    with Xdebug v2.4.0RC3, Copyright (c) 2002-2015, by Derick Rethans

(Not sure why it's php 7, I've never asked for that.)

Any help would be greatly appreciated :)

via Chebli Mohamed