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An Algorithm For Better Password Checking (technologyreview.com)

New submitter della writes: Password checkers — those things that tell you whether your password is strong or not — are good: various studies have found that they make users choose better passwords. Unfortunately, nowadays attackers use probabilistic strategies based on natural language processing to guess passwords earlier, and most checkers consist of heuristic rules that don't reflect well probabilistic attacks. To do better you could in theory simulate the attack, but if your password is not that bad, that would be very expensive or just unfeasible.

In a paper I wrote with Maurizio Filippone and presented at ACM's CCS conference, we show how you can take an attack model and a password, and through a simple formula come up quickly with a reliable estimation of how many guesses that attack would need to guess the password. You can use this to roll a better password checker, or — as we've also done in the paper — to compare different attacks.

3 of 103 comments (clear)

  1. Sick of Passwords by Anonymous Coward · · Score: 3, Informative

    I don't even care if they're secure or guessable or lexographic or written down or whatever other bullshit I'm supposed to care about.

    I am sick of these bullshit passwords and signins fucking everywhere. Every single site, every single service, every single day, input this, email that, account name, please re-enter, confirm, mandatory, change must contain a two numbers, must contain capital letters, cannot contain special characters, forgotton your password?

    I've given up. Fuck it. I'll just lurk, post anonymously while I still can. I must have over 200 accounts out there and I just don't care anymore. It's too much effort to remember all this bullshit anymore.

  2. Password1 by sims+2 · · Score: 3, Informative

    Lots of things really don't need highly secure passwords but insist on having ridiculous password requirements.

    Case in point Xbox one must login to microsoft account to setup for the first time password must have at least one capital, at least one number, at least one symbol and at least 8 characters Password1~ is an acceptable password. Pita to type on xbox controller.

    Netflix is a model for reasonable requirement's especially since it likes to log itself out at random. So less to type on wii remote is a definite plus. 4 letters minimum 0000 is an acceptable password.

    --
    Minimum threshold fixed. Thanks!
  3. Read the paper. Disagree with "symbols" by xxxJonBoyxxx · · Score: 3, Informative

    >> Symbols appear to be less predictable and placed in different locations of the password

    I disagree with the paper's conclusion based on the passwords I've seen, which FREQUENTLY just end in a "!" or other common character. Here's a different paper that goes into symbol frequency; I pulled out the relevant bit.

    In almost all cases (90%), only a single special character was used. The most popular special character sequences were all single characters: exclamation point (“!” – 29%), period (“.” – 19%), “at” symbol (“@” – 15%) and hash (“#” – 14%). These were followed by the single dash (“-“), dollar sign (“$”), space (” “), asterisk (“*”), and plus sign (“+”), each making up between 3% and 6% of the single-character special character population. Passwords containing multiple special characters mainly (68%) just repeated the same special character, such as “##” or “???.” - http://resources.infosecinstit...