Previously, lost passwords were generated via org.apache.commons.lang.RandomStringUtils, which is using java.util.Random internally. This PRNG is has a 48-bit seed, that can easily be bruteforced if an attacker is able to get the PRNG's output, for example but resetting their own account multiple times, leading to trivial privileges escalation attacks. This commit makes use of java.security.SecureRandom instead.