$salt = $this->a1->find_salt($this->user->password);
if ($this->a1->hash_password(arr::get($_POST,'old_password'), $salt) === $this->user->password)
{
    if ($this->user->values($_POST)->check())
    {
        $this->user->save();
    }
    else
    {
        echo Kohana::Debug($this->user->validate()->errors());
    }
}