4 ms·

Xkcd Password Generator

24 points by jolux 11y ago

trhway 11y ago
instead of remembering passwords i remember only one function i've been using for many years which takes the name of the site as an argument and returns the password as the result.
hliyan 11y ago
Two years ago I wrote about why this type of password is no longer safe: https://medium.com/@hnlean/imp3n3tr-ble5832-not-an-impenetrable-password-anymore-db9f4fbff1ba https://medium.com/@hnlean/imp3n3tr-ble5832-not-an-impenetra... (See step #6 in the list of steps in the article) I'm sure the situation has only got worse since then.
- archagon 11y ago
  Xkcd was advocating diceware, not "making up a passphrase". If your pool of words is sufficiently large, your rolls are random, and you have enough rolls, your password should be as secure as a random number.
- DanBC 11y ago
  The point of a passphrase is to randomly generate each word in the phrase. Even Diceware, which uses a list of 7776 words, is resistant to attacks if you have a 7 word passphrase. You use your long random passphrase to protect your password safe. The passwords in your safe are long randomly generated strings of lower case, upper case, digits, and special chars. > But you’re forgetting the massive GPU array. The hacker runs a program that generates random combinations of two, three or four dictionary words and tries it against your password hash. It’s going to take a while because the number of such combinations are very large, but it’s not impossible. If the hacker is really obsessive about it, he will just keep the program running for weeks until a match is found. No one today recommends 4 word passphrases - 7 word is the minimum. But 4 words is probably better than most passwords that people use at the moment.
- orless 11y ago
  > But you’re forgetting the massive GPU array. The hacker runs a program that generates random combinations of two, three or four dictionary words and tries it against your password hash. It’s going to take a while because the number of such combinations are very large, but it’s not impossible. The xkcd comic suggests a combination of four from a very modest 2000 (2^11) common words resulting in ca. 2^44 combinations to check. It also assumes 100 guesses/sec which result in over 500 years to break. That's precise math and a somewhat reasonable assumption. You counter this with an argument like "the number of such combinations are very large, but it’s not impossible". You give no new numbers, no counter-assumptions, you don't argue that 100 guesses per second is too slow, you just state this. So in this form your argument is ungrounded.
  - StavrosK 11y ago
    100 guesses/sec is really slow, though, when a desktop pc can do billions of SHA hashes a second.
archagon 11y ago
Ever since reading that xkcd comic and learning about diceware, I've really wanted to create a password generator that could spin out complete diceware sentences of arbitrary length. (Markov chains?) Mnemonics of various kinds could be taken into consideration: rhymes, onomatopoeia, etc. Instead of a 4-word nonsense passphrase, you'd get something like "the red rancid raccoon bit into the butter bucket biscuit" — easy to remember and secure. Unfortunately, I'm not too familiar with this subset of programming. (Limiting the word pool of each slot due to mnemonics would complicate the entropy calculation, but it should still be fairly straightforward.)
slavik81 11y ago
I kind of feel like all these passwords schemes and discussions about password strength fundamentally miss the point. Password reuse is the single greatest threat that any user faces. Nobody's going to guess your gmail password, even if its just six random lowercase letters. They're going to get it from a database dump of a compromised site where you reused that password. I have well over a hundred websites listed in my password manager. There is not a chance that I could remember a unique password for every one of them, no matter how easy they were.
- k__ 11y ago
  Wouldn't it be then enough to just simply use a unique scheme? I mean if noone will guess your password and just use possible DB dumps, this would be more than enough: G#00gl3 A#m4z0n F#4c3b00k ...
  - rakoo 11y ago
    If a human can see one of your passwords, it's extremely easy to crack the other ones, no matter H0w m4ny tricks you try to use.
    - slavik81 11y ago
      Indeed. That's not just theoretical danger either. Attackers will guess obvious patterns or simple variations on known passwords. https://www.guildwars2.com/en/news/mike-obrien-on-account-security/ https://www.guildwars2.com/en/news/mike-obrien-on-account-se...
    - k__ 11y ago
      I know, but the OP said DB dumps are the biggest problems, not the password strength or if someone sees me typing it
      - slavik81 11y ago
        Even that ridiculously weak password scheme would probably stay secure until there were a few DB dumps. Then you'd be screwed for reusing the same password scheme across multiple sites. That was sort of my point: reuse is the enemy.
qrmn 11y ago
I just use Diceware: https://qrmn.uk/dwr/ https://qrmn.uk/dwr/ (With thanks to Alyssa Rowan for the CSPRNG design. Public domain - feel free to copy it.) For really important stuff, actual dice just to make sure.
brianclements 11y ago
The most important thing I realized when it comes to passwords was the classification into 2 types: strong passwords (keys, local login, local encryption, master passwords for password managers) which is best generated using the Xkcd method, and then the less obvious disposable passwords (all non-local usage, i.e. websites and other temporary need). For the later, I use SuperGenPass[1]. It ensures that 1) my passwords are not reused across sites and 2) they are strong without the need to remember them directly. Because SGP uses hashes, it is very easy to add counters to existing passwords/secret phrases and create a brand new password without much mental effort. I've outlined such a procedure in the issues[2]. Using counters in the "secret" field, I will probably never ever need to change my master passphrase. I won't deny though that for mobile use, it's a bit cumbersome. The Android app is fine and free[3], and iOS app is a buck[4]. And overall it's a pain if you must login to sites frequently (ideally, using a native app reduces this greatly, login once until you manually logout). It's also pretty confusing for non-technical people to get behind. I actually sent out an entire email blast to friends and family giving them my best attempt at an explanation, argument, and tutorial of how to use it. I don't think anyone did it. So while the interface is kind of clumsy, the strategy is solid and I love knowing that I can use it. [1]: http://www.supergenpass.com http://www.supergenpass.com [2]: https://github.com/chriszarate/supergenpass/issues/40#issuecomment-61357038 https://github.com/chriszarate/supergenpass/issues/40#issuec... [3]: https://play.google.com/store/apps/details?id=info.staticfree.SuperGenPass&hl=en https://play.google.com/store/apps/details?id=info.staticfre... [4]: https://itunes.apple.com/us/app/supergenpass/id451606360?mt=8 https://itunes.apple.com/us/app/supergenpass/id451606360?mt=...
ninjin 11y ago
Neat, I have the following in my `.bashrc` to accomplish pretty much the same thing. It should be noted that I do not use it for passwords (I have a password safe for that), but I do use it for passphrases since I may have to read them over the phone. secret () { # '\u' for `sed` is a GNU extension. shuf /usr/share/dict/words \ | grep '^[A-Za-z]\+$' \ | head -n 3 \ | sed -e 's|$.$$.*$|\u\1\2|g' \ | tr -d '\n' \ | sed -e 's|$|\n|g' } > for _ in `seq 7`; do secret; done InterweaveMakariosEncrusting DisseminatingAgriculturalistCautioned EffectuatingCobblersEgos AccidentalKopeckRevolts RefDivansUndersigns SalesmanSubmitterFlak TempsIlluminedQuickening
- StavrosK 11y ago
  Good luck reading "makarios" over the phone, though. You need a phonetically distinct alphabet, like the NATO alphabet, and entropy is very low there.
  - ninjin 11y ago
    Your mileage may wary, but I have never had any issues reading them to the human operators. Security questions are bad policy anyway and I assume that they are less picky when hearing "SiloRepossessedTapir" compared to "SiloRepossessTapir", than for "Mary" to "Maria".
    - StavrosK 11y ago
      Wouldn't such a misheard phrase make the password you've set not match?

24 points by jolux 11y ago

instead of remembering passwords i remember only one function i've been using for many years which takes the name of the site as an argument and returns the password as the result.

hliyan 11y ago

Two years ago I wrote about why this type of password is no longer safe: https://medium.com/@hnlean/imp3n3tr-ble5832-not-an-impenetrable-password-anymore-db9f4fbff1ba https://medium.com/@hnlean/imp3n3tr-ble5832-not-an-impenetra... (See step #6 in the list of steps in the article) I'm sure the situation has only got worse since then.

archagon 11y ago
Xkcd was advocating diceware, not "making up a passphrase". If your pool of words is sufficiently large, your rolls are random, and you have enough rolls, your password should be as secure as a random number.
DanBC 11y ago
The point of a passphrase is to randomly generate each word in the phrase. Even Diceware, which uses a list of 7776 words, is resistant to attacks if you have a 7 word passphrase. You use your long random passphrase to protect your password safe. The passwords in your safe are long randomly generated strings of lower case, upper case, digits, and special chars. > But you’re forgetting the massive GPU array. The hacker runs a program that generates random combinations of two, three or four dictionary words and tries it against your password hash. It’s going to take a while because the number of such combinations are very large, but it’s not impossible. If the hacker is really obsessive about it, he will just keep the program running for weeks until a match is found. No one today recommends 4 word passphrases - 7 word is the minimum. But 4 words is probably better than most passwords that people use at the moment.
orless 11y ago
> But you’re forgetting the massive GPU array. The hacker runs a program that generates random combinations of two, three or four dictionary words and tries it against your password hash. It’s going to take a while because the number of such combinations are very large, but it’s not impossible. The xkcd comic suggests a combination of four from a very modest 2000 (2^11) common words resulting in ca. 2^44 combinations to check. It also assumes 100 guesses/sec which result in over 500 years to break. That's precise math and a somewhat reasonable assumption. You counter this with an argument like "the number of such combinations are very large, but it’s not impossible". You give no new numbers, no counter-assumptions, you don't argue that 100 guesses per second is too slow, you just state this. So in this form your argument is ungrounded.
- StavrosK 11y ago
  100 guesses/sec is really slow, though, when a desktop pc can do billions of SHA hashes a second.

archagon 11y ago

Ever since reading that xkcd comic and learning about diceware, I've really wanted to create a password generator that could spin out complete diceware sentences of arbitrary length. (Markov chains?) Mnemonics of various kinds could be taken into consideration: rhymes, onomatopoeia, etc. Instead of a 4-word nonsense passphrase, you'd get something like "the red rancid raccoon bit into the butter bucket biscuit" — easy to remember and secure. Unfortunately, I'm not too familiar with this subset of programming. (Limiting the word pool of each slot due to mnemonics would complicate the entropy calculation, but it should still be fairly straightforward.)

slavik81 11y ago

I kind of feel like all these passwords schemes and discussions about password strength fundamentally miss the point. Password reuse is the single greatest threat that any user faces. Nobody's going to guess your gmail password, even if its just six random lowercase letters. They're going to get it from a database dump of a compromised site where you reused that password. I have well over a hundred websites listed in my password manager. There is not a chance that I could remember a unique password for every one of them, no matter how easy they were.

k__ 11y ago
Wouldn't it be then enough to just simply use a unique scheme? I mean if noone will guess your password and just use possible DB dumps, this would be more than enough: G#00gl3 A#m4z0n F#4c3b00k ...
- rakoo 11y ago
  If a human can see one of your passwords, it's extremely easy to crack the other ones, no matter H0w m4ny tricks you try to use.
  - slavik81 11y ago
    Indeed. That's not just theoretical danger either. Attackers will guess obvious patterns or simple variations on known passwords. https://www.guildwars2.com/en/news/mike-obrien-on-account-security/ https://www.guildwars2.com/en/news/mike-obrien-on-account-se...
  - k__ 11y ago
    I know, but the OP said DB dumps are the biggest problems, not the password strength or if someone sees me typing it
    - slavik81 11y ago
      Even that ridiculously weak password scheme would probably stay secure until there were a few DB dumps. Then you'd be screwed for reusing the same password scheme across multiple sites. That was sort of my point: reuse is the enemy.

qrmn 11y ago

I just use Diceware: https://qrmn.uk/dwr/ https://qrmn.uk/dwr/ (With thanks to Alyssa Rowan for the CSPRNG design. Public domain - feel free to copy it.) For really important stuff, actual dice just to make sure.

brianclements 11y ago

The most important thing I realized when it comes to passwords was the classification into 2 types: strong passwords (keys, local login, local encryption, master passwords for password managers) which is best generated using the Xkcd method, and then the less obvious disposable passwords (all non-local usage, i.e. websites and other temporary need). For the later, I use SuperGenPass[1]. It ensures that 1) my passwords are not reused across sites and 2) they are strong without the need to remember them directly. Because SGP uses hashes, it is very easy to add counters to existing passwords/secret phrases and create a brand new password without much mental effort. I've outlined such a procedure in the issues[2]. Using counters in the "secret" field, I will probably never ever need to change my master passphrase. I won't deny though that for mobile use, it's a bit cumbersome. The Android app is fine and free[3], and iOS app is a buck[4]. And overall it's a pain if you must login to sites frequently (ideally, using a native app reduces this greatly, login once until you manually logout). It's also pretty confusing for non-technical people to get behind. I actually sent out an entire email blast to friends and family giving them my best attempt at an explanation, argument, and tutorial of how to use it. I don't think anyone did it. So while the interface is kind of clumsy, the strategy is solid and I love knowing that I can use it. [1]: http://www.supergenpass.com http://www.supergenpass.com [2]: https://github.com/chriszarate/supergenpass/issues/40#issuecomment-61357038 https://github.com/chriszarate/supergenpass/issues/40#issuec... [3]: https://play.google.com/store/apps/details?id=info.staticfree.SuperGenPass&hl=en https://play.google.com/store/apps/details?id=info.staticfre... [4]: https://itunes.apple.com/us/app/supergenpass/id451606360?mt=8 https://itunes.apple.com/us/app/supergenpass/id451606360?mt=...

ninjin 11y ago

Neat, I have the following in my `.bashrc` to accomplish pretty much the same thing. It should be noted that I do not use it for passwords (I have a password safe for that), but I do use it for passphrases since I may have to read them over the phone. secret () { # '\u' for `sed` is a GNU extension. shuf /usr/share/dict/words \ | grep '^[A-Za-z]\+$' \ | head -n 3 \ | sed -e 's|$.$$.*$|\u\1\2|g' \ | tr -d '\n' \ | sed -e 's|$|\n|g' } > for _ in `seq 7`; do secret; done InterweaveMakariosEncrusting DisseminatingAgriculturalistCautioned EffectuatingCobblersEgos AccidentalKopeckRevolts RefDivansUndersigns SalesmanSubmitterFlak TempsIlluminedQuickening

StavrosK 11y ago
Good luck reading "makarios" over the phone, though. You need a phonetically distinct alphabet, like the NATO alphabet, and entropy is very low there.
- ninjin 11y ago
  Your mileage may wary, but I have never had any issues reading them to the human operators. Security questions are bad policy anyway and I assume that they are less picky when hearing "SiloRepossessedTapir" compared to "SiloRepossessTapir", than for "Mary" to "Maria".
  - StavrosK 11y ago
    Wouldn't such a misheard phrase make the password you've set not match?