Composer can't require Homestead due to security error

Hi again,

Last time I posted about the preferred version of virtualbox being incompatible with ubuntu 14.04, now I have it updated to 4.3 from saucy, which is said to be working. So moving on with the how-to-deploy-homestead tutorial, I'm getting this strange error:

root@alchemy:~# mv composer.phar /usr/local/bin/composer
root@alchemy:~# composer global require "laravel/homestead=~2.0"
Changed current directory to /root/.composer
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)



  [Composer\Repository\RepositorySecurityException]
  The contents of http://packagist.org/p/symfony/console$4974e152a3de1f4a49ba
  9840f99e4f7be7c761e187392cdecc62edc5c874795b.json do not match its signatur
  e. This should indicate a man-in-the-middle attack. Try running composer ag
  ain and report this if you think it is a mistake.



require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-update]
[--update-no-dev] [--update-with-dependencies] [--ignore-platform-reqs] [package
s1] ... [packagesN]

My first reaction was to reinstall composer from scratch, but it didn't help at all. Then I started looking into .ssh, maybe an obsolete key stuck in authorized_keys, known_hosts, whatever, but since this is a fresh ubuntu installation, I found nothing.

To be honest, I never had such error with composer, moreover, I didn't find anything on the web, now I'm here, maybe you've seen something like this.