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Xkcd Password Generator

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Re: Xkcd Password Generator

#51
post #25

Earlier quoted context omitted.

> Start with: You don't know the dictionary I used, but have to use one that seems 'good enough' (i.e. a superset of mine, if possible). People are likely to use a standard English dictionary. In my experience (which is exactly within this field) people use a fairly tight subset of the English vocabulary. So I would be quite happy to test for a dictionary of, say, 100,000 words and be hopeful of a good hit rate (note…

I actually didn't ignore the 'common' limitation (and didn't downvote you - I'm actually interested how you come up with that). Follow-up questions: - What are the first tests, before this 3rd that tests for words? I assume tests for passwords of the first/left variety in the comic? Aren't they cheaper? - 'Up to three words' is reducing the exponent of possible combinations by one. Length/number of words is relevant…

You know what; it's been so long since I played around with this stuff (it's even a separate company now, that we just consult for) that I'm way out of touch with my thought process :)

You're right; there is nothing particularly wrong with the suggestion that makes it intrinsically very weak for most uses.

I'd best stop commenting before I make a total mess :)

Sorry.

Re: Xkcd Password Generator

#52
post #25

Earlier quoted context omitted.

> he can trivially test combinations of dictionary words in very short amount of time. Explain the reasoning behind this, please. Start with: You don't know the dictionary I used, but have to use one that seems 'good enough' (i.e. a superset of mine, if possible). How many words are in there? How many combinations can you create for 'two word phrases'? (You don't know the length of my phrase) How many for three? How…

> Start with: You don't know the dictionary I used, but have to use one that seems 'good enough' (i.e. a superset of mine, if possible). People are likely to use a standard English dictionary. In my experience (which is exactly within this field) people use a fairly tight subset of the English vocabulary. So I would be quite happy to test for a dictionary of, say, 100,000 words and be hopeful of a good hit rate (note…

If the dictionary really has 100 000 words, you're looking down the barrel of 52 bits of entropy for a three word phrase

In a more likely dictionary of the 5000 most commonly used words in the English language, you still get a three word pass phrase of about 40bits of entropy. Make that a four word passphrase, and you're back up around 52 bits.

Re: Xkcd Password Generator

#53
post #33

I've been using phrases and sentences as passwords for a while, and I've found that there are 2 main problems; 1) A lot of sites, still in this day and age, have max password lengths, so I still have a lot of short passwords. Usually this is bank sites and the like. 2) Password entry fields are often very short visually, and with a long password getting lost is much easier. I find I have to type them over A LOT. The…

Especially if you are logging into multiple systems regularly using domain credentials, it rapidly becomes apparent that the faster and easier the password is to type, the better. I've found that some passwords with symbols and numbers just roll off the fingertips with a little practice, others not so much, but longer passphrases are for some reason the worst.

Re: Xkcd Password Generator

#54

A lot of comments here seem to be missing the point. The main point is to use passwords that give you the most "bang for the buck" in the sense of adding the most bits of entropy for the least difficulty of remembering. Adding an extra number, or punctuation, or certain numbers of repetitions generally adds only a little bit of entropy for a significant cost in additional challenge to your memory. Our minds are well…

171K words in the english language 4 words no spaces 171k^4 vs 255^8 for a 8 char pass

Re: Xkcd Password Generator

#55
post #14
post #12

I always thought using two password fields with simple words would be much harder to break than one field only (which can be used to really strange passwords but also for simples ones as we all know). Someone care to calculate how much it would take to break it?

Well it depends how it's stored, but assuming a fairly standard setup it wouldn't particularly help. The main issue with website security isn't people brute forcing the website login box, it's people cracking the hashes after stealing them. So if you had two easy to crack hashes stored in the database, you crack them both and off you go.

Oh, I was (like the article) assuming you would concatenate both words (add a space or something else in between if you want) and it would be all stored in just one field. What about it?

Re: Xkcd Password Generator

#56
I generally use gpw to generate long random but pronounceable passwords. Something like 'armsdaynistoppo' is fairly entropic, easy enough to remember, and when I'm used to it I can type it much faster than 4 random words.

Re: Xkcd Password Generator

#57
post #33

I've been using phrases and sentences as passwords for a while, and I've found that there are 2 main problems; 1) A lot of sites, still in this day and age, have max password lengths, so I still have a lot of short passwords. Usually this is bank sites and the like. 2) Password entry fields are often very short visually, and with a long password getting lost is much easier. I find I have to type them over A LOT. The…

Don't forget sites that require: "your password MUST contain at least one number, one uppercase letter, and one of the following characters: !, @, #, or $, but not %, ^, &, or *". I slap my forehead at how counterproductive these requirements are.

What could the reasoning behind those requirements possibly be?

Re: Xkcd Password Generator

#58
post #25

Earlier quoted context omitted.

> Start with: You don't know the dictionary I used, but have to use one that seems 'good enough' (i.e. a superset of mine, if possible). People are likely to use a standard English dictionary. In my experience (which is exactly within this field) people use a fairly tight subset of the English vocabulary. So I would be quite happy to test for a dictionary of, say, 100,000 words and be hopeful of a good hit rate (note…

I actually didn't ignore the 'common' limitation (and didn't downvote you - I'm actually interested how you come up with that). Follow-up questions: - What are the first tests, before this 3rd that tests for words? I assume tests for passwords of the first/left variety in the comic? Aren't they cheaper? - 'Up to three words' is reducing the exponent of possible combinations by one. Length/number of words is relevant…

[deleted]

Re: Xkcd Password Generator

#59
post #25

Earlier quoted context omitted.

> he can trivially test combinations of dictionary words in very short amount of time. Explain the reasoning behind this, please. Start with: You don't know the dictionary I used, but have to use one that seems 'good enough' (i.e. a superset of mine, if possible). How many words are in there? How many combinations can you create for 'two word phrases'? (You don't know the length of my phrase) How many for three? How…

> Start with: You don't know the dictionary I used, but have to use one that seems 'good enough' (i.e. a superset of mine, if possible). People are likely to use a standard English dictionary. In my experience (which is exactly within this field) people use a fairly tight subset of the English vocabulary. So I would be quite happy to test for a dictionary of, say, 100,000 words and be hopeful of a good hit rate (note…

You can't test 175000^4 = 937890625000000000000 passwords.

Re: Xkcd Password Generator

#60
post #54

A lot of comments here seem to be missing the point. The main point is to use passwords that give you the most "bang for the buck" in the sense of adding the most bits of entropy for the least difficulty of remembering. Adding an extra number, or punctuation, or certain numbers of repetitions generally adds only a little bit of entropy for a significant cost in additional challenge to your memory. Our minds are well…

171K words in the english language 4 words no spaces 171k^4 vs 255^8 for a 8 char pass

Incorrect: It's 171k^4 and 255^8.

(which works out to 8.55E20 and 1.78E19)

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