Breaking PHP's mt_rand() with 2 values and no bruteforce

Posted By Charles Fol php mt_rand mt_srand predict seed bruteforce IntroductionWhile performing a pentest on an old website, we encountered a piece of code that we had not seen in a long time: <?php function resetPassword($email) { [...] $superSecretToken = md5($email . ':' . mt_rand()); [...] $this->sendEmailWithResetToken($email, $superSecretToken); } A token, deemed secret and unguessable, was

[usurausura]

タイトルExample to show that PHP's mt_rand is NOT CSPRNG (as designers said)とかの方が適切なんじゃないの

[Nyoho]

松本先生自身が「注意：Mersenne Twisterは、モンテカルロ法用疑似乱数であり、 そのままでは暗号乱数としては使えません。」と書いておられる http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/mt.html