The Ars article seemed totally irrelevant to me since it used MD5?
A Really Good Article on How Easy it Is to Crack Passwords
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Re: A Really Good Article on How Easy it Is to Crack Passwords
#22Why not force the user to have strong login credentials? I'm creating an online system that will store users' sensitive financial data. When setting up an account, the user will have to choose a password as normal, but will also be given a passphrase of the form "correct horse battery staple" that they must write down . To log in, the user will need to enter (a) username; (b) password; and (c) passphrase. It is effec…
That's not TFA since the piece of paper with the passphrase is not "A thing you have". It's just "another thing you know." and thus brute-foreceable. It's the same as not allowing the user to choose a password but rather generate 12-character random passwords with special chars.
Authentication devices for TFA are designed, so that you really have to have the device close to you when you do a login.
Re: A Really Good Article on How Easy it Is to Crack Passwords
#23> "This is an answer to the batteryhorsestaple thing." Steube misunderstands the xkcd comic [1]. There's a really good comment which explains it: "It could be argued that Randall's example of 4 words is too short -- and indeed, for some applications, it is. However for a typical dictionary size, and genuinely random selection, it is massively stronger than "typical" passwords and in fact easily adequte to defeat the…
What makes you think he misunderstands it? For the cracker it's not about entropy per se, it's a game to come up with algorithms that crack more passwords for less compute power. The XKCD comic got a lot of mindshare so it makes sense to target algorithms towards that type of password. I think Schneier's suggestion of reducing it to the first letter of each word is vastly preferable because it packs the majority of e…
The entropy Randall calculated for "correcthorsestaplebattery" was a lower bound, meaning that if the attacker knows that you made your password out of 4 dictionary words, it still has tons of entropy. If the attacker doesn't know how you came up with your password, it'll take them even longer.
Re: A Really Good Article on How Easy it Is to Crack Passwords
#24> "This is an answer to the batteryhorsestaple thing." Steube misunderstands the xkcd comic [1]. There's a really good comment which explains it: "It could be argued that Randall's example of 4 words is too short -- and indeed, for some applications, it is. However for a typical dictionary size, and genuinely random selection, it is massively stronger than "typical" passwords and in fact easily adequte to defeat the…
What makes you think he misunderstands it? For the cracker it's not about entropy per se, it's a game to come up with algorithms that crack more passwords for less compute power. The XKCD comic got a lot of mindshare so it makes sense to target algorithms towards that type of password. I think Schneier's suggestion of reducing it to the first letter of each word is vastly preferable because it packs the majority of e…
The algorithm is not targeted against the type of password which the XKCD comic suggests. The algorithm is designed to exploit common human behavior, which is similar to the XKCD method but not identical. The significant difference is that human behavior in picking words is not random, while the XKCD method requires the word selection process to be truly random. The "iloveyousomuch" example by Steube is unlikely to be picked randomly.
salmonellaeater is right, Steube misunderstands the comic. The idea of the comic is to pick a small random selection of the 250,000 distinct words in a oxford dictionary, rather than 8 of the 95 letters from all ASCII printable characters. A selection of 3 words has then higher entropy than 8 random characters, because 250,000^3 is a bigger number than 95^8. The question then is, will 3 random words really be easier to remember than 8 ASCII printable characters?
The downside to the Schneier scheme, is that each is a common sentence (low entropy), with a chosen transformation algorithm added. Thus the quality of the password will depend on the number of transformation algorithms, and the quality of each one. If we are to use the one first described to create "tlpWENT2m", we get a password strength like:
Using strictly the first letter, would only do 2x linear increase in entropy over just searching for common sentences. Change any occurrence of common numbers substitutes for words adds (0-2x) entropy increase. Writing one of the words in all caps means 6x increase in entropy. Combined, tlpWENT2m is slightly less secure than "This little piggy went to market" + two [random number below 10] or a single letter at the end.
Re: A Really Good Article on How Easy it Is to Crack Passwords
#25Why not force the user to have strong login credentials? I'm creating an online system that will store users' sensitive financial data. When setting up an account, the user will have to choose a password as normal, but will also be given a passphrase of the form "correct horse battery staple" that they must write down . To log in, the user will need to enter (a) username; (b) password; and (c) passphrase. It is effec…
Another issue with this is it breaks password managers, including the built-in browser password storage. While you might say that's a Good Thing for security, it's not something you could easily pull off as a startup.
Due to lock-in effects, people have to deal with all manner of usability hell from their bank, but the same logic doesn't apply to startups. Not that your idea is usability hell, but you probably don't want to make it any harder than it needs to be.
I think adding a few characters to the minimum password would be equally secure and more consistent with tooling, as well as a more familiar model for users.
Also, 2FA might be easier than you think using a service like Twilio. Or another way to do it would be to let the user connect via a service that does support 2FA (e.g. Google or Twitter;and maybe adding your own password if you want to harden that).
Re: A Really Good Article on How Easy it Is to Crack Passwords
#26I don't understand the difference between "momof3g8kids" and "tlpWENT2m". Why would the latter be more secure?
Re: A Really Good Article on How Easy it Is to Crack Passwords
#27> "This is an answer to the batteryhorsestaple thing." Steube misunderstands the xkcd comic [1]. There's a really good comment which explains it: "It could be argued that Randall's example of 4 words is too short -- and indeed, for some applications, it is. However for a typical dictionary size, and genuinely random selection, it is massively stronger than "typical" passwords and in fact easily adequte to defeat the…
What makes you think he misunderstands it? For the cracker it's not about entropy per se, it's a game to come up with algorithms that crack more passwords for less compute power. The XKCD comic got a lot of mindshare so it makes sense to target algorithms towards that type of password. I think Schneier's suggestion of reducing it to the first letter of each word is vastly preferable because it packs the majority of e…
How would something attack Diceware?
There's a list of 7776 words, everyone knows what words are on the list. I suspect that sometimes people re-roll because they don't like a word or don't think they'll remember it. But I don't that that makes much difference.
Re: A Really Good Article on How Easy it Is to Crack Passwords
#28Why not force the user to have strong login credentials? I'm creating an online system that will store users' sensitive financial data. When setting up an account, the user will have to choose a password as normal, but will also be given a passphrase of the form "correct horse battery staple" that they must write down . To log in, the user will need to enter (a) username; (b) password; and (c) passphrase. It is effec…
Another issue with this is it breaks password managers, including the built-in browser password storage. While you might say that's a Good Thing for security, it's not something you could easily pull off as a startup. Due to lock-in effects, people have to deal with all manner of usability hell from their bank, but the same logic doesn't apply to startups. Not that your idea is usability hell, but you probably don't…
I recently added 2FA (OATH/Google Authenticator) support to Persowna[1], and it only took about two hours, 1:55 of which was spent on the UI. It's really not very hard.
Re: A Really Good Article on How Easy it Is to Crack Passwords
#29Passwords are broken and I really wish we would all move away from them. Persona is a nice idea with regards to privacy and control, but it's still a password that you need to remember, which can be cracked. Also, people generally don't use strong passwords. What irks me is that every OS in use today has support for strong cryptography and browser vendors could easily integrate that. We would no longer register for a…
Persona doesn't require a password. You could authenticate with an SSL certificate, a Yubikey or whatever else you want. I wrote my own, hosted identity provider (https://www.persowna.net/) which includes 2FA now, and I plan to add more of these types of authentication in the future.
Re: A Really Good Article on How Easy it Is to Crack Passwords
#30The Ars article seemed totally irrelevant to me since it used MD5?
Microsoft Active Directory servers (used in big business and government all over the world) uses one round of MD4 (no salt). That's a 4, not a 5.