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New 25 GPU Monster Devours Passwords In Seconds

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Re: New 25 GPU Monster Devours Passwords In Seconds

#71

Post by sspiff »

Karunamon wrote: post #68
sspiff wrote: post #43

Earlier quoted context omitted.

Sure, the simple characters make it a bit easier, but the phrases tend to be much longer. The error rate on a touchscreen keyboard is high enough to really become a problem at 20+ characters when you only see the last typed character (no password review).

Using dictionary words makes it easy for more modern predictive keyboards to keep up, though. Taking the XKCD canonical example, "correct horse battery staple", it's a reasonably secure and lengthy password and includes special characters. It could also be keyed in via something like Swype or SlideIT in almost as fast as it could be keyed in on a computer keyboard.

Perhaps, depending on the user. Doesn't work well for me though.

Re: New 25 GPU Monster Devours Passwords In Seconds

#72

Post by trebor »

sspiff wrote: post #31
_b8r0 wrote: post #22

The problem with all of this is that security specialists (of which I am one, guilty as charged) have historically campaigned for more complex passwords. This worked well for conventional (non-clustered, non-accelerated) password cracking mechanisms. Sadly, this starts to fall apart with accelerated and/or distributed cracking. On average I crack a few hundred passwords a week, and more often than not organisations h…

Since reading that xkcd, I use phrases as passwords, using a simple Ruby script to generate them: w = File.readlines('/usr/share/dict/words').map { |w| w.chomp }.reject { |w| w !~ /^[A-Za-z]+$/ }; 3.times { print w[rand * w.size] }; puts I generally get an easy to remember password after about 3 tries. The biggest issue I have with this is typing in passwords on mobile devices.

A slight refactoring for Ruby 1.9.3 users, uses Array#sample to grab 3 random words, etc.

    ruby -e 'w = File.readlines("/usr/share/dict/words").map { |w| w.chomp }.reject { |w| w !~ /^[A-Za-z]+$/ }; puts w.sample(3).join(" ").downcase'

Re: New 25 GPU Monster Devours Passwords In Seconds

#73

Post by _b8r0 »

ZoFreX wrote: post #45
_b8r0 wrote: post #22

The problem with all of this is that security specialists (of which I am one, guilty as charged) have historically campaigned for more complex passwords. This worked well for conventional (non-clustered, non-accelerated) password cracking mechanisms. Sadly, this starts to fall apart with accelerated and/or distributed cracking. On average I crack a few hundred passwords a week, and more often than not organisations h…

It's worth pointing out that length is not important, only entropy is important. If you create a really long phrase by forming a sentence from very common English words, the entropy is actually really low, and if everyone started doing this you can bet your boots the password crackers would catch up. However you create your password you should take a stab at calculating the entropy (and incidentally a 10 character tr…

> It's worth pointing out that length is not important, only entropy is important.

Theoretically yes, as long as you assume the equivalent of a spherical cow in a vacuum.

We've (the security community) become very good at enforcing password schemes that are hard for users to remember and easier for computers to crack. While you could correctly assert that a 30 character long lower case letter only phrase has less entropy than a 15 character sequence of randomly generated numbers, letters of mixed case and punctuation, it makes no odds to me - I'm getting neither of them in a reasonable timeframe.

The reason for this is that if you look at the way web site passwords and company passwords are compromised it's not a single account that's hacked. It's going to be the domain or the database of password hashes. Because you're running all of these through a cracker at once you can't (as an attacker) generally afford to waste the time going through combinations of dictionary words with permutations, especially if you know that if you crack a big enough percentage of passwords you've got the access you need and can move on.

Cracking one 10 character random password with alphanumeric and special characters is a problem of scale with the password generaton algorithm. Depending on the algorithm used you can wait for appropriate rainbow tables to appear to increase your chances, for a cryptographic flaw in the algorithm or for moore's law to catch up. Trying to exhaust the same keyspace for a 30 character password (bearing in mind that the attacker is unlikely to know whether or not your password is high or low entropy, especially if other cracked passwords imply a high entropy policy is in place) is going to be much harder, and will only likely take place if no results of value have been found earlier on.

Re: New 25 GPU Monster Devours Passwords In Seconds

#74

Post by Shorel »

bigiain wrote: post #53
raverbashing wrote: post #51

Earlier quoted context omitted.

True That´s why I use a 'throwaway' password for most unimportant accounts. Sure, may be easy to break, but it isn't logging in to my gmail. Don't forget also the risk of getting locked out of your account.

I fell victim to that once, when I hadn't "upgraded" the re-used throwaway password I'd used to register to see what some random website was. When my throwaway password got exposed (in cleartext facepalm! ) by PerlMonks, within a day or so someone had used it to send Acai Berry spam through my Twitter account (which 'd completely forgotten was still using a shared/throwaway password even though it had turned from "so…

I think twitter nowadays is far from being an unimportant account.

Re: New 25 GPU Monster Devours Passwords In Seconds

#75

Post by AnIrishDuck »

itry wrote: post #66
Keyframe wrote: post #58

Earlier quoted context omitted.

I'm kind of rusty on algorithmic information theory (I'm an artist, heh)! Is there such a thing as (formalized) upper limit of what we could do as far as computing combinations go? I know of Kolmogorov complexity (vaguely), but what are the hard limits and challenges of just prodding through (faster and faster as tech goes forward) combinations until success? I plan on developing a story around that and make a movie…

"what are the hard limits and challenges of just prodding through (faster and faster as tech goes forward) combinations until success?" According to current theory of physics, every computation needs at least a certain amount of energy. So if you want to do many computations today, you will have to use a certain amount of energy today. Now lets say, you have a machine that turns any matter into energy without any los…

> According to current theory of physics, every computation needs at least a certain amount of energy.

This is not, strictly speaking, true. You are talking, I believe, about Lanadauer's principle [1]. This states that it is the destruction of entropy that costs energy. There are computational methods that can theoretically avoid these energy losses [2]. In fact, Lanadaer theorized about reversible computing in his original paper [3].

Bremmerman's limit, mentioned below, is more applicable.

1. http://en.wikipedia.org/wiki/Landauer%27s_principle 2. http://en.wikipedia.org/wiki/Reversible_computing 3. http://www.cc.gatech.edu/computing/nano/documents/Bennett%20...

Re: New 25 GPU Monster Devours Passwords In Seconds

#76

Post by btgeekboy »

bigiain wrote: post #53
raverbashing wrote: post #51

Earlier quoted context omitted.

True That´s why I use a 'throwaway' password for most unimportant accounts. Sure, may be easy to break, but it isn't logging in to my gmail. Don't forget also the risk of getting locked out of your account.

I fell victim to that once, when I hadn't "upgraded" the re-used throwaway password I'd used to register to see what some random website was. When my throwaway password got exposed (in cleartext facepalm! ) by PerlMonks, within a day or so someone had used it to send Acai Berry spam through my Twitter account (which 'd completely forgotten was still using a shared/throwaway password even though it had turned from "so…

FYI, I've learned a little trick that 1Password doesn't seem to share widely. Go into your Dropbox, and in the 1Password.agilekeychain folder there is a file named 1Password.html. It's a read-only instance of your 1Password keychain usable in anything with a browser.

Re: New 25 GPU Monster Devours Passwords In Seconds

#77

Post by schlomie28 »

dfc wrote: post #15
xorgar831 wrote: post #10

Earlier quoted context omitted.

The problem with PBKDF2 however is that if you pick a weak password it's useless. It would be better if they included an option for a key as well like other password safes do.

"The problem with INSERT-SOMETHING however is that if you pick a weak password it's useless" When is this not the case?

When you have a key as well.

Re: New 25 GPU Monster Devours Passwords In Seconds

#78

Post by codex »

vonuebelgarten wrote: post #65
ZoFreX wrote: post #45

Earlier quoted context omitted.

It's worth pointing out that length is not important, only entropy is important. If you create a really long phrase by forming a sentence from very common English words, the entropy is actually really low, and if everyone started doing this you can bet your boots the password crackers would catch up. However you create your password you should take a stab at calculating the entropy (and incidentally a 10 character tr…

> It's worth pointing out that length is not important, only entropy is important. Entropy is important, but multi-word passwords stills being efficient since their alphabet is quite large when compared with common alpha-symbolic-numeric passwords. For example, a completely random password with 12 digits and upper/lower case letters have (26+26+10)^12 = 3.226e21 possibilities. Quite good unless you need to memorize t…

I should point out that multi-word passwords have at least one disadvantage: if you can figure out which letters were used and/or the password's length, and you know the password is multi-word, then it becomes easier to derive what the password was.

So, for example, if you used a multi-word password on your ATM machine, and someone aimed an infrared camera at the machine after you left and retrieved the set of buttons that you pressed, the game would be over if your password were short--or at least much closer to being over if it were long.

Alternatively, an attacker could eavesdrop on your keyboard sounds and capture the timing of the clicks, thereby inferring candidate sets of letters. Or they could examine how much oil is on each key of your keyboard, or how much each key is worn, and adjust for the stats on the English language, etc.

Or, as in the ATM case, an agent could interrupt you right after you've entered your password on a false pretext ("Excuse me, I need help.") and surreptitiously take an in infrared photo of your keyboard. This is plausible in many semi-public scenarios (bank teller, etc.)

I think the saving grace here is that a sufficiently long password uses most letters in the English alphabet--but it is still prone to attack if you can at least get the relative ordering of some of the letters, or you know the password's length (by listening to the number of keyboard clicks, for example).

Re: New 25 GPU Monster Devours Passwords In Seconds

#79

Post by ars »

Karunamon wrote: post #69
ars wrote: post #26

Earlier quoted context omitted.

There are 3 types: What you know. What you have. What you are. And of the 3 What you know (i.e. password) is the most secure when used properly. It's impossible to steal without your knowledge, and it's impossible to misplace. What you have (eg. physical key) can be stolen from you - or even borrowed, used, and returned without you ever knowing. It can also be copied, and it can be lost - sometimes without being awar…

What you are.. trivial to copy - even from a distance.. A retinal print?

Very easy - just use a telescope.

Re: New 25 GPU Monster Devours Passwords In Seconds

#80

Post by mrb »

lallysingh wrote: post #52

Can I rent something equivalent from Amazon by the hour? I wonder how much that would cost.

No. Amazon only has Nvidia hardware in their EC2 GPU clusters. Nvidia is not equivalent as it is significantly slower than AMD/ATI hardware for password cracking. Eg. a top-of-the line AMD GPU brute-forces MD5 hashes about 5x faster than a top-of-the-line Nvidia GPU, see: http://golubev.com/gpuest.htm

I don't know any computing provider who rent out AMD GPUs... (This would be a startup opportunity.)

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