4 ms·

HashMask - Another (More Secure) Experiment in Password Masking

15 points by umbrae 17y ago

Nycto 17y ago
I was beginning to get perturbed by the inundation of password fields lately, but I actually really like this one. However, I think that it would be more effective as a browser plug-in than a site feature.
- apgwoz 17y ago
  I agree. Different implementations will undoubtably use a different visualization technique making it hard to recognize at all the different sites. Though in theory this is a non issue because everyone uses a different password per site, right?
  - slmbrhrt 17y ago
    Right, at a glance you could see if someone used the same password in more than one place. Of course, you could circumvent the whole issue by pairing the url with the password to generate the hash.
tptacek 17y ago
No, this is retarded; the "unique nonreversable visualization" is trivially attacked offline by brute forcing with a dictionary of passwords. It's just the SHA1 of your password; fundamentally no different from tacking /etc/shadow to your password field as you type. It wouldn't be retarded if it wasn't expending a lot of effort (and confusing the hell out of users) to get to that bad destination. But that's what it does. When you consider "solutions" to this "problem", model it against an adversary with a camera. The author of this post means well, but just masking the password characters, like every secure system has done for the past couple decades, remains the right answer.
- cstejerean 17y ago
  How often do you type your password next to an adversary with a camera?
  - tptacek 17y ago
    I did it about 50 times today. I'm a building full of cameras. Tell me, how often do you sweep the surrounding area for cameras before you log in somewhere? Thought so. How many times have you ever logged into something from an airport? Ever hear about the Microsoft Blue Hat talks about the pen testers who collect credentials at Sea-Tac? People just like memes. They're fun to talk about. I promise you there are 1,000 better problems for you to tackle in your app than the suboptimality of password masking. This guy managed not only to waste time, but also to promote an actively evil security extension.
    - sho 17y ago
      Why are you worried about how people with cameras could eventually brute force your password from that tiny, fuzzy smear of colour on the screen, when those same cameras can see your fingers typing the whole damn thing in, in plaintext?
      - tptacek 17y ago
        Because those cameras can see my screen easily, and not my fingers typing on the screen? Because my fingers aren't perpendicular to the floor? Because even if I was going to concede that the image of the SHA graph was going to be fuzzy, just getting the vicinity of the color reduces my search space by 1/2^(16..24)? I love "cameras could eventually brute force" in your sentence, as if we were actually talking about some crazy hard feat of image analysis and cryptography, rather than running a dictionary through SHA1 and comparing colors. Got any more arguments, sho?
        sho 17y ago
        If someone is trying to learn your password from cameras nearby, they will make sure they can see your keyboard. Of course. If you're in that kind of hostile environment, nothing is safe except biometric or card authentication. Your concern is misplaced. You should have raised the scenario of, say, spying on a screen through a window from the other side of the street. That's a much better example and in that one, you might actually have a point, although I understand it's against the rules in many organisations to allow a screen to face a window. But the "in the same building" one was ridiculous. Why bother brute forcing your squiggly coloured blotch when they can just put a tiny camera in every light, or whatever? No, no further arguments. I agree it's a bad idea, of course.
- umbrae 17y ago
  Well, as the author, I feel I better defend myself here. A: It only uses the first 20 bytes of the hash. You could narrow it down from this if you were really determined, but you'd not be able to reverse it. B: The visualization of the sparkline doesn't have the fidelity to determine between characters 6 and 7. So you'd have a range of possible characters. C: The alternative being suggested by Jakob Nielsen is no masking at all ( http://www.useit.com/alertbox/passwords.html http://www.useit.com/alertbox/passwords.html ) - which is less secure? I know this isn't the best argument, but it still is -an- argument. With that out of the way, my paranoid mind agrees with you in this context: just masking the passwords is the more secure solution. But that doesn't mean that experiments to provide a more usable approach with (arguably) equal security should be avoided.
  - tptacek 17y ago
    (a) This sentence doesn't make any sense. You can't "reverse" full SHA1 any more than you can "reverse" truncated SHA1. And SHA1 hashes are only 20 bytes long. Reversing isn't the attack. (b) The goal of the attack isn't to magically conjure the password; it's to magically conjure a searchlist of several tens of passwords, which is a game-changing improvement over a searchlist of, say, 72^8 passwords, or even tens of thousands of dictionary words. (c) The alternative suggested by Jakob Nielson is manifestly and categorically asinine. Good on you for a finding an application for visualizing a SHA1 hash. You score maximum points for cleverness. But now you should retire this idea.
    - umbrae 17y ago
      (a) I wrote in haste. Obviously it's a one way hash and unreversible. Additionally, I meant the first 20 characters, which is half of the full hash. (b) Obviously. Still extraordinarily difficult given this implementation IMO. But I take your point genuinely. (c) Agreed. If you weren't so friggin inflammatory I'd think we could come to a conclusion here. I could definitely be using a more lossy visualization to be more secure. This is something I'll look into, even though I'm sure you'll still consider it 'retarded' even if it helps your grandma login to her googles more often, making you get less phone calls to fix it as a result. She's got that palsy you know.
- lhorie 17y ago
  >> model it against an adversary with a camera. Which can record your hands? :) I figure that the offline dictionary attack could be foiled if this was a Firefox extension that generated a random salt on installation. (of course, this doesn't work if you want to play WOW on an Internet Cafe) My main reaction to the experiment is that I don't know many people who touch type (at least when it comes to their password): I've had people accidentally type their password on the username field in front of me countless times because they weren't even looking at the screen. I don't see why I should worry about big brother FUD when I could embarrass myself any time by accidentally pressing caps lock instead of tab.
  - tptacek 17y ago
    Another thing I love about this discussion is the intimation ("big brother") that in order to get a picture of my screen, you have to be the NSA. And not, you know, some jackass with a camera.
    - lhorie 17y ago
      Sure, sure, it could be both. It could be my girlfriend looking over my shoulder too. But of course, I don't use an stupidly easy password and I don't let my girlfriend see me typing it (2-finger typing style, of course). I mean who does that, right? </sarcasm> :) I just find it interesting to observe the discrepancies between perception of security and actual math-backed security.
      - tptacek 17y ago
        I don't use a stupidly easy password either, but I'm not going to give you the password hash from my laptop. That's what this scheme does.
- paulgb 17y ago
  If the attacker had a video camera and the victim was a slow enough typer (I'm thinking hunt-and-pecker), brute force wouldn't even be necessary. You could incrementally build up a string that matched the password as each letter was typed using the hash generated after each letter is typed. Fidelity of the graphs wouldn't matter at this point, you would just take the closest match and backtrack if necessary.
  - tptacek 17y ago
    Oh wow, I didn't even notice that it generated graphs on a keystroke/timer (though, I mean, duh). Wow, is this bad. Number of mask dots, 2 midpoint colors, and the final color; how many passwords in any dictionary does that reduce to?
chaosmachine 17y ago
This is neat, I like it better than the last one. I would try to come up with a more lossy version. Maybe something that hashes to one of 50 animal icons. The algorithm should be good enough that any one-letter-off typo never results in the same icon. More secure, and easier to remember.
DanielStraight 17y ago
I don't understand. I thought the point was that unmasking would make typing more accurate, not that after you had already typed it, you'd be able to confirm what you had typed. I don't see the point in that at all.
TweedHeads 17y ago
Wow, besides its functionality or not, it is a really interesting approach to solving a problem. Kudos for imagination. Back to the initial problem, after successive attempts you may remember the shape and colors, problem is, most business complain new users can't remember their passwords after registering, so there won't be a second time. The only way of better remembering something is by viewing it.
TweedHeads 17y ago
Tip: instead of the himalayas try using a beachball.

15 points by umbrae 17y ago

Nycto 17y ago

I was beginning to get perturbed by the inundation of password fields lately, but I actually really like this one. However, I think that it would be more effective as a browser plug-in than a site feature.

apgwoz 17y ago
I agree. Different implementations will undoubtably use a different visualization technique making it hard to recognize at all the different sites. Though in theory this is a non issue because everyone uses a different password per site, right?
- slmbrhrt 17y ago
  Right, at a glance you could see if someone used the same password in more than one place. Of course, you could circumvent the whole issue by pairing the url with the password to generate the hash.

tptacek 17y ago

No, this is retarded; the "unique nonreversable visualization" is trivially attacked offline by brute forcing with a dictionary of passwords. It's just the SHA1 of your password; fundamentally no different from tacking /etc/shadow to your password field as you type. It wouldn't be retarded if it wasn't expending a lot of effort (and confusing the hell out of users) to get to that bad destination. But that's what it does. When you consider "solutions" to this "problem", model it against an adversary with a camera. The author of this post means well, but just masking the password characters, like every secure system has done for the past couple decades, remains the right answer.

cstejerean 17y ago
How often do you type your password next to an adversary with a camera?
- tptacek 17y ago
  I did it about 50 times today. I'm a building full of cameras. Tell me, how often do you sweep the surrounding area for cameras before you log in somewhere? Thought so. How many times have you ever logged into something from an airport? Ever hear about the Microsoft Blue Hat talks about the pen testers who collect credentials at Sea-Tac? People just like memes. They're fun to talk about. I promise you there are 1,000 better problems for you to tackle in your app than the suboptimality of password masking. This guy managed not only to waste time, but also to promote an actively evil security extension.
  - sho 17y ago
    Why are you worried about how people with cameras could eventually brute force your password from that tiny, fuzzy smear of colour on the screen, when those same cameras can see your fingers typing the whole damn thing in, in plaintext?
    - tptacek 17y ago
      Because those cameras can see my screen easily, and not my fingers typing on the screen? Because my fingers aren't perpendicular to the floor? Because even if I was going to concede that the image of the SHA graph was going to be fuzzy, just getting the vicinity of the color reduces my search space by 1/2^(16..24)? I love "cameras could eventually brute force" in your sentence, as if we were actually talking about some crazy hard feat of image analysis and cryptography, rather than running a dictionary through SHA1 and comparing colors. Got any more arguments, sho?
      - sho 17y ago
        If someone is trying to learn your password from cameras nearby, they will make sure they can see your keyboard. Of course. If you're in that kind of hostile environment, nothing is safe except biometric or card authentication. Your concern is misplaced. You should have raised the scenario of, say, spying on a screen through a window from the other side of the street. That's a much better example and in that one, you might actually have a point, although I understand it's against the rules in many organisations to allow a screen to face a window. But the "in the same building" one was ridiculous. Why bother brute forcing your squiggly coloured blotch when they can just put a tiny camera in every light, or whatever? No, no further arguments. I agree it's a bad idea, of course.
umbrae 17y ago
Well, as the author, I feel I better defend myself here. A: It only uses the first 20 bytes of the hash. You could narrow it down from this if you were really determined, but you'd not be able to reverse it. B: The visualization of the sparkline doesn't have the fidelity to determine between characters 6 and 7. So you'd have a range of possible characters. C: The alternative being suggested by Jakob Nielsen is no masking at all ( http://www.useit.com/alertbox/passwords.html http://www.useit.com/alertbox/passwords.html ) - which is less secure? I know this isn't the best argument, but it still is -an- argument. With that out of the way, my paranoid mind agrees with you in this context: just masking the passwords is the more secure solution. But that doesn't mean that experiments to provide a more usable approach with (arguably) equal security should be avoided.
- tptacek 17y ago
  (a) This sentence doesn't make any sense. You can't "reverse" full SHA1 any more than you can "reverse" truncated SHA1. And SHA1 hashes are only 20 bytes long. Reversing isn't the attack. (b) The goal of the attack isn't to magically conjure the password; it's to magically conjure a searchlist of several tens of passwords, which is a game-changing improvement over a searchlist of, say, 72^8 passwords, or even tens of thousands of dictionary words. (c) The alternative suggested by Jakob Nielson is manifestly and categorically asinine. Good on you for a finding an application for visualizing a SHA1 hash. You score maximum points for cleverness. But now you should retire this idea.
  - umbrae 17y ago
    (a) I wrote in haste. Obviously it's a one way hash and unreversible. Additionally, I meant the first 20 characters, which is half of the full hash. (b) Obviously. Still extraordinarily difficult given this implementation IMO. But I take your point genuinely. (c) Agreed. If you weren't so friggin inflammatory I'd think we could come to a conclusion here. I could definitely be using a more lossy visualization to be more secure. This is something I'll look into, even though I'm sure you'll still consider it 'retarded' even if it helps your grandma login to her googles more often, making you get less phone calls to fix it as a result. She's got that palsy you know.
lhorie 17y ago
>> model it against an adversary with a camera. Which can record your hands? :) I figure that the offline dictionary attack could be foiled if this was a Firefox extension that generated a random salt on installation. (of course, this doesn't work if you want to play WOW on an Internet Cafe) My main reaction to the experiment is that I don't know many people who touch type (at least when it comes to their password): I've had people accidentally type their password on the username field in front of me countless times because they weren't even looking at the screen. I don't see why I should worry about big brother FUD when I could embarrass myself any time by accidentally pressing caps lock instead of tab.
- tptacek 17y ago
  Another thing I love about this discussion is the intimation ("big brother") that in order to get a picture of my screen, you have to be the NSA. And not, you know, some jackass with a camera.
  - lhorie 17y ago
    Sure, sure, it could be both. It could be my girlfriend looking over my shoulder too. But of course, I don't use an stupidly easy password and I don't let my girlfriend see me typing it (2-finger typing style, of course). I mean who does that, right? </sarcasm> :) I just find it interesting to observe the discrepancies between perception of security and actual math-backed security.
    - tptacek 17y ago
      I don't use a stupidly easy password either, but I'm not going to give you the password hash from my laptop. That's what this scheme does.
paulgb 17y ago
If the attacker had a video camera and the victim was a slow enough typer (I'm thinking hunt-and-pecker), brute force wouldn't even be necessary. You could incrementally build up a string that matched the password as each letter was typed using the hash generated after each letter is typed. Fidelity of the graphs wouldn't matter at this point, you would just take the closest match and backtrack if necessary.
- tptacek 17y ago
  Oh wow, I didn't even notice that it generated graphs on a keystroke/timer (though, I mean, duh). Wow, is this bad. Number of mask dots, 2 midpoint colors, and the final color; how many passwords in any dictionary does that reduce to?

chaosmachine 17y ago

This is neat, I like it better than the last one. I would try to come up with a more lossy version. Maybe something that hashes to one of 50 animal icons. The algorithm should be good enough that any one-letter-off typo never results in the same icon. More secure, and easier to remember.

DanielStraight 17y ago

I don't understand. I thought the point was that unmasking would make typing more accurate, not that after you had already typed it, you'd be able to confirm what you had typed. I don't see the point in that at all.

TweedHeads 17y ago

Wow, besides its functionality or not, it is a really interesting approach to solving a problem. Kudos for imagination. Back to the initial problem, after successive attempts you may remember the shape and colors, problem is, most business complain new users can't remember their passwords after registering, so there won't be a second time. The only way of better remembering something is by viewing it.

TweedHeads 17y ago

Tip: instead of the himalayas try using a beachball.