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Flaws in deterministic password managers

tonyarcieri.com

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Re: Flaws in deterministic password managers

#101

Post by libeclipse »

minitech wrote: post #65
libeclipse wrote: post #2

I'm the creator of visionary[0], a deterministic password generator that the article links to. When I thought of the idea (quite a while ago), I thought it was a good idea, and I thought I was the first one there. I was wrong on both accounts. The points that the article makes are right, and people should use conventional passwords over deterministic ones. But I guess it appeals to a certain small subset of people. F…

This change seems kind of worrying: https://github.com/libeclipse/visionary/pull/40/files#r79336... The distribution of characters in “complex passwords” isn’t even?

That doesn't matter. I could just put a full stop at the end of the string and call it a complex password. The point of it was for sites that require symbols. The complex password doesn't add a meaningful amount of entropy to a sufficiently long normal password; a 32 character normal password already has log2(16^32) = 128 bits of entropy.

We rely on the seed for security, the seed being the hash that scrypt spits out

Re: Flaws in deterministic password managers

#102

Post by minitech »

libeclipse wrote: post #101
minitech wrote: post #65

Earlier quoted context omitted.

This change seems kind of worrying: https://github.com/libeclipse/visionary/pull/40/files#r79336... The distribution of characters in “complex passwords” isn’t even?

That doesn't matter. I could just put a full stop at the end of the string and call it a complex password. The point of it was for sites that require symbols. The complex password doesn't add a meaningful amount of entropy to a sufficiently long normal password; a 32 character normal password already has log2(16^32) = 128 bits of entropy. We rely on the seed for security, the seed being the hash that scrypt spits out

So it’s way too complicated for that purpose, then.

Re: Flaws in deterministic password managers

#103

Post by eikenberry »

problems wrote: post #34
eikenberry wrote: post #28

Earlier quoted context omitted.

I'd guess he doesn't mean cached, but instead means that his web browser works with this system keyring (or has its own) to save/use the passwords.

Which is bad. I've reverse engineered script kiddie malware far too many times to find them shipping "iStealer" and similar, which basically just dump browser password stores and send them to a gmail or FTP account. Often these pieces of malware include the SMTP credentials to the same gmail account or FTP access to download the results. And having seen their results, let me just say, these script kiddies can do damn…

> Do not use a browser/system keyring store under any circumstances unless you can be 100% positive that you won't accidentally run that sketchy exe you came across.

This is easy once you decide to do it. Just don't download and run random crap, don't be stupid and "curl URL | bash", etc. It really isn't that hard to be 100% if you pay attention. The main problem is that most people just don't care enough.

Re: Flaws in deterministic password managers

#104

Post by tripzilch »

shaftway wrote: post #17
ythn wrote: post #12

Earlier quoted context omitted.

I too am interested to see how long it takes assuming the attacker knows the generator ruleset (which he will have had to work out previously from two plaintext passwords of mine). Still, I don't think it's that easy to figure out the ruleset of a good password generator if you make it obscure enough. For example: Amazon: NovemberAlphaies12# Facebook: KiloFoxtrototto16& What's the ruleset? Answer: Phoenic alphabet of…

Frankly, the phonetics were trivial. So it's really... Amazon: ies12# Facebook: otto16& "Otto" made me think 8, and that led me to "sei" (I read stuff upside down when reading to my kids, so I flip letter orders easily). It didn't take long to figure out those were the length of the site. So now we're down to.... Amazon: 12# Facebook: 16& These follow a pattern (digit digit symbol), so even if I didn't notice that th…

Yup that wasn't hard at all. Also, security researchers / consultants / ___hats solve these kinds of puzzles all the time for their work and hobby. Friends I have in that business are insanely good at this sort of thing. Because apparently people always think they're so clever. One told me on multiple cases doing whitehat security consulting they studied the desk+office of the sysadmin for a bit (no post-its), pull some Sherlock Holmes magic (I don't know really) and guessed the password in 5-10 tries (no I didn't quite believe it either, but otoh this guy really doesn't like bragging nor had any reason to lie about).

Oh and if I understand the number scheme correctly:

> integer sum of the digits on either side of each digit in the Italian number

that means, when the number is "otto", meaning 8, the "digits on either side" are 7 and 9, which when you sum them, equal 7 + 9 = (8 - 1) + (8 + 1) = 8 + 8 = 16, so it's really a complicated way of saying "double that number" ... :-)

Re: Flaws in deterministic password managers

#105

Post by libeclipse »

minitech wrote: post #102
libeclipse wrote: post #101

Earlier quoted context omitted.

That doesn't matter. I could just put a full stop at the end of the string and call it a complex password. The point of it was for sites that require symbols. The complex password doesn't add a meaningful amount of entropy to a sufficiently long normal password; a 32 character normal password already has log2(16^32) = 128 bits of entropy. We rely on the seed for security, the seed being the hash that scrypt spits out

So it’s way too complicated for that purpose, then.

That's not an argument. Keep in mind that entropy is a property of password generation, not the result of the generation.

Re: Flaws in deterministic password managers

#106

Post by minitech »

libeclipse wrote: post #105
minitech wrote: post #102

Earlier quoted context omitted.

So it’s way too complicated for that purpose, then.

That's not an argument. Keep in mind that entropy is a property of password generation, not the result of the generation.

I mean, what do you want me to say? It is way too complicated. Why are you using a pre-shuffled character set and getting a permutation of it by index when the index is always extremely low compared to the number of permutations just to get some symbols in your password? Just base64-encode with a custom alphabet or something.

I never said anything about entropy, either.

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