0936: "Password Strength"

[Shvabrov]

Get n bits from /dev/urandom
Base64 the bits
Try to make an incongruous (thus easily rememberable) situation describing the password

It also does wonders for your creative skills

[sunami]

I work for an unnamed organization that shall remain nameless. Their security briefing contained some computer security, a part of which was passwords on the network. The password policy is at least 3: lower case, upper case, numbers, symbols.
and cannot begin/end in numbers. And you must change your password every 90 days and it cannot "be similar to" any of your previous 25 passwords (this is enforced via software). I raised the issue of how insane it is to expect NOBODY to write down their password because after 9 months they'd have to remember some new mangled password, along with the many for other systems that we use, many of which do not have as difficult password requirements but you'd use once every month or so. So frustrating.

If my password gets compromised without my knowledge, how will 90 days between changes help? If you really cared, you'd have us change it every day! Or to be not crazy, use tokens that we do for external access, or at least dongles. Instead you're preventing me from using incredibly strong pass-phrases, or phrase-based passwords, without resorting to some mental wizardry symbol bullshit!

[zecro]

It is 2011, people.

Are you seriously still not using a string made of randomly-generated

• numbers
• symbols
• uppercase letters
• lowercase letters
• foreign script, if supported

with at least a length of 10?

Enter it enough times, and it will just become muscle memory.

[Kit.]

Hmm... was it... zebra staple... and 2 more words??? Ok, I'm using my password recovery link.

[JimmyVolatile]

All my passwords are words from the Norwegian language...which is equal to using only random letters in English (Almost kidding)

[roderik]

What I actually liked doing was thinking of a strongish password.
then changing keyboard settings to something like dvorak (basically anything that has a differing layout), typing the password, then reverting the keyboard settings to continue your work/typing/whatevers.
this has the end result of producing strings that look little like the original word (though numbers are often still the same) while being easier to remember than a random string of characters.

[Ocker3]

TRWTF (oops I forgot what site I was on) is 1000 guesses/sec

5 wrong attempts = 1 hour lockout
really, brute force attmepts shouldn't even be a problem

This!

Limits on wrong attempts which lead to a timed lockout automatically blow 'time to crack' timelines out to infinity. At 1000 guesses per second, it would take 0.6 seconds for someone brute-forcing my work password to get locked out, at which point I would have to call central office to get it unlocked. As soon as it happened a second time I'd get worried and ask them where the traffic was coming from, and they'd track down which machine was trying to crack my password and shut it down.

And I only work for a school.

I'm more worried about trojans than brute-forcing, which is why I run a lot of security on my home and work machines.

[rewolff]

What everybody who is calculating "password strength" is forgetting is that you should rank your searching order by entropy.

So while "lowercase e" is 1/26th of the lowercase letters (entropy = 4.7), it occurs some 12% in normal texts (entropy = 3.1). So instead of trying "e" once every 26 letters you should try it 1/8.

Now I'm using the frequency list of "English". In reality you should use the frequency list from passwords. Given the big lists of leaked passwords that float around, you can do a whole lot better (on average) than to test 1/2 of 26^8 combinations for an 8 character password. If you add some digram or trigram statistics you'll do even better.

[snowyowl]

While we're on the subject of paswords... if I use a new randomly generated password (41 bits) for each website, but store all but the most critical in a plaintext file in My Documents, how screwed am I should a stray Trojan find its way onto my computer?

[forest_of_leaves]

Am I really stupid and missing something, or is all this brute force discussion made moot by the fact that most websites lock you out for 5 - 60 minutes after ~5 failed password attempts?

If a hacker gets access to a database containing your password, then those time-based protections won't help you.
Normally passwords are hashed, so that they are unreadable. If the database uses a good hash, the only way to retrieve your password is via brute force. Thus the discussion of entropy.

[herbys]

And really, how secure is Tr0ub4dor&3 when you use it for every site, like many people do? (http://xkcd.com/792/)
(#792 actually made me decide to revise my passwords to all the sites I visit at least somewhat frequently. Now, I use a different password for almost every site, and they consist of interspersed letters, numbers, and punctuation. In fact, they look a lot like troubador over there. And yes, I do remember them all )

It is not necessary that people use it for every site. People can use different passwords for each site and still the owner of one of the sites will likely have the passwords for users of a few of the other sites. How? Because people often try to log in with the wrong password.
Many years ago (this was ´98, we were all young and innocent) a friend of mine managed an important internet site. He once tried (yes, it was an unethical and probably illegal experiment) to check if the usernames and passwords in his site were valid in other important sites such as eBay and Amazon. About half of them were. But what was more interesting was that if he logged passwords for failed login attempts and then tried them with the corresponding accounts, he was able to login with almost half of the ones that didn't work the first time!
Think about it: how many times you have entered your *other* password when trying to log in to some site? Do you immediately go to the important sites and change it afterwards? This is possibly not a problem if you are using different account names, but possibly not if you registered the same email.

[ijuin]

IIRC, the average person uses about 200 different words each day, 900 words in total, and knows about 2,000 - 3,000 if they're highschool educated, 8,000 - 10,000 if college educated. (Shakespeare used something like 20,000.)

You do remember correctly, but unfortunately what you remember is incorrect. The average person knows around eighty thousand words (though the number of words they often use may be much lower).

I think that the "10,000 words" estimate is supposed to exclude compound words and proper names.

[Icepick]

Just use KeePass. One don't-care password for your hardware, one high-power password for your KeePass database, and then max-length random passwords everywhere else (including your TrueCrypt volumes, of course). Doesn't even matter if they limit you to 8 characters; nobody ever tries high ASCII.

^^ That. End of story.

[rewolff]

Re: lockout:

In practice if you want to hack say the vice president of some company, you can figure out his name and his account name on several sites by just using web searches. You can then distribute the password attempts over those sites. And you need only one of those who doesn't have the lockout to go much faster. Finding one password will most likely mean you get the others "for free".

If a site locks the ACCOUNT for which multiple bad password attempts were made, you can achieve a lot of mischief (but alas not a targeted attack on a specific person) by attacking a big list of different accounts.

If a site locks the IP address from which the bad passwords were attempted, you just have to do the attack from a botnet of a few thousand hosts...

[graudrakon]

And that is why my passwords are all paragraphs from TS Eliots The Wasteland.

Or it's porno remake The Waistland.

[RAGBRAIvet]

Now *HERE'S* the way to do it:

richtig chevaux pila grapa

From left to right: correct horse battery staple

Each word in a separate language (German, French, Italian, and Spanish)

I DARE anyone to be able to guess something like this!!!

[BAReFOOt]

Again with that RETARDED “longer > complexerererer” straw man argument? *sigh*

Why do you anglophones always act like Unicode is NIH for you??

“correct horse battery staple” = [a-z ]^28 = 27^28, or realistically probably [a-zA-Z -]^28 = 54^28, or, at best, 64^28.
But in the REAL WORLD, that’s cracked in no time with a simple dictionary attack. Which for myspell/de_GB.dic is less than 46281^4!

If only ONE of those is a Unicode char, suddenly the brute force system has to be used and suddenly even 256^x doesn’t do it anymore: (remember, this is just a comparison while keeping the length)
“✔orrect horse battery staple” = realistically 109449^28 (Unicode 6.0), or even when going blindly for 16 bit, it’s still 65536^28.
I used a char that was readily available on my keyboard. But nobody has trouble adding a different one through key remapping.

So don’t spread or fall for that pseudo-smartassery.

And don’t come to me with that “but dumb people can’t do smart things…” shit. If they can’t do that, they also can’t operate cars and it’s all pearls before swine anyway since they are the biggest fucking security risk in the whole chain so that even a 4-number PIN looks like Neuromancer-level high-security magic in comparison!
There suggestions target solely the non-idiots. And those know which keys on their keyboard are not ASCII. Which the program then won’t encode in some localized table but UTF-8… and *voila*, the cracker can’t try ASCII any more.

Not that any of that, other than the dictionary attack had anything to do with real life.
Knowing social engineering, there is no point in trying to crack passwords or even exploit security holes. In a way, all you have to do, is to ask the right way. Because people, including political “leaders” (more like the lobbys’/my sock puppets), are utterly retarded cattle with no real own free will, who live in a readily manipulatable fantasy world.

[RevK]

Randall has done it again - genius.

Yes, if you know the rules someone used to make a password you have a better chance of guessing it, but it is just a numbers game. Picking 4 words from a 2,048 word dictionary of common words and you have your 44 bits which is good. You can get as strong or stronger with much shorter passwords by using random letters and digits and so on. Of course you can. Bit that 44 bits is even if the attacker knows the algorithm and the exact word list you picked, if they don't you have even more security.

The issue is, that for a given level of security, the word based algorithm is far more likely to create passwords you can remember and so make fewer mistakes and avoid having to write it on a post-it or store it on your phone...

There are issues. Password re-use is indeed a far bigger problem. Password lengths being limited breaks this algorithm too. But if you can handle the longer passwords then this is a really neat idea.

There are also cases we get where we have to quote a password to someone over the phone, and an algorithm like this makes that much simpler and less prone to mistakes.

Hence the control pages for some of our systems now have a "make password" which uses this principle to create passwords. And yes, "correct", "horse", "battery" and "staple" are in the list of words

[sotanaht]

I don't get why people bother to use strong passwords, or even variable or different passwords for unimportant sites like 90% of all web forums. I could use "Bob" for my password here and on every other webcomic forum and a number of other things, and it wouldn't matter. As long as I am not using that for my email (and then only the ones attached to the other things mentioned), bank account, any site that involves my credit card information at any time, and any site or game involving anything I would care to lose.

People who use strong passwords on frivolous things are just wasting their time. Worse are people who make requirements for strong passwords for frivolous things, as they are wasting not only MY time and energy, but possibly risking the security of whatever I would choose to use strong passwords for.

[Nyerguds]

Now I won't be able to get "correct horse battery staple" out of my head.

How about "interior crocodile alligator"?

Again with that RETARDED “longer > complexerererer” straw man argument? *sigh*

Why do you anglophones always act like Unicode is NIH for you??

“correct horse battery staple” = [a-z ]^28 = 27^28, or realistically probably [a-zA-Z -]^28 = 54^28, or, at best, 64^28.
But in the REAL WORLD, that’s cracked in no time with a simple dictionary attack. Which for myspell/de_GB.dic is less than 46281^4!

Yes, but how many people doing dictionary attacks would even think of combining words to semi-sentences?

...hm, maybe now they will. I think Randall just made his password unsafe by posting this comic :p

[Hylian]

Don't most systems only let you have a password guess every few seconds?

[Captain Chaos]

This seems like a good time to shamelessly plug my website:

http://www.passwordcard.org/

It generates colour coded, credit card sized, printable cards for you which you can use to choose strong passwords that you don't have to remember. Instead, you remember a coloured symbol, like "green dollar" or "purple square". You keep it in your wallet, which you already know how to protect well. It has its faults, but it's much safer than most people's current password practices...

[1055]

I only understood the last panel, but that was enough for me.

[Nyerguds]

This seems like a good time to shamelessly plug my website:

http://www.passwordcard.org/

It generates colour coded, credit card sized, printable cards for you which you can use to choose strong passwords that you don't have to remember. Instead, you remember a coloured symbol, like "green dollar" or "purple square". You keep it in your wallet, which you already know how to protect well. It has its faults, but it's much safer than most people's current password practices...

Eh, by remembering X (colour) and Y (symbol) coordinate, doesn't that give you only ONE letter on the chart then though?

[Azkyroth]

Also, Randall, can you please print this comic on some merchandise I can use to pull a Comic 169 on the frickin' idiots who set IT policies for the Los Rios Community College District?

[neoliminal]

The best part is that you can keep your password list in plain site because it looks like bad free form poetry, and no one wants to read that:

Ode to my passwords:

bust repairs advised problem
unseen composes allergic slag
bell detect clear steel

precedent compose lavatory smiles
closed pill vend danger
regret chalks within disregard

[smaxt]

I always joke with my friends that the best password is 12345679. Now if only I remembered which friends

Also, "correct horse battery staple" already has 64 hits on google, 4.4 million if you remove the quotes. Just a thought.

[jonadab]

I generally string my random words together with hyphens. Also, I don't limit myself to "common" words. Any word I know or can easily learn (being a glossophile, I'm constantly acquiring new vocabulary anyhow) is fair game. But this basic approach is how I generate most of my passwords.

For moderate security I use only three words:
hyacinth-gourmands-incorrectly
inking-trampolining-quintuples
speedometer-placation-coloration
irrespective-marring-ally
descriptively-fop-amusingly
competence-vegans-pluses
proven-managed-chattering
deleted-blowers-entrenchments
elisions-clobbers-retardant
(No, these are not actual passwords that I use. But you get the idea.)

For increased security (e.g., for server root passwords), I use four words and/or include one that is unlikely to be in any attacker's dictionary, either because it's an obscure nonce word from something I've read or because I just plain made it up out of whole cloth.

Four-word examples:
bonitoes-sticklers-ubiquity-biophysicist
retrieve-globing-commuters-generated
parched-clientele-snuck-inaugurates
forbidden-prefaces-crone-threateningly
distaff-midst-abnegated-telecommuters
adios-delicatessens-carbon-methods
peasants-categorizations-sextet-inevitably
trysts-galactic-uproot-edibles

Examples with one non-dictionary word:
jongleur-drafted-ordain
androgynebot-blemish-satrap
incidence-speeds-naughtification
singer-ullamari-togas
refreshers-indemnifise-precepts
stratosphere-bail-minneyar
jonasquinn-certifies-cetaceans

It is difficult to properly estimate the technical entropy in this last category of passwords, but given that no common password cracking algorithm is designed to attack it, it's probably overall more secure than the four-dictionary-words variant. A naive algorithm that just treats it as a random string of characters is looking at permutations of 20+ elements, so brute-forcing it that way would take a while even for a small botnet. (If a large botnet tried, that would be detected as a DDOS attack.)

I really don’t think it matters how secure your password is (except for more important things like online banking and PayPal).

I'm a network administrator. I have more than fifty passwords in my head. At least twenty of them are more important than your PayPal account.

Sure, for stuff that totally does not matter, like the accounts I create on every random blog and forum on the internet just so I can post some comments, where the dire consequence if someone figures out my password is that they could pretend to be me and possibly fool someone who doesn't know me at all, I just use the same password every time. I must have used that password on three hundred sites by now. It's not secure, but who cares?

For stuff that sort of kind of matters, like accounts on web services that I use for stuff that sort of matters to me, but which have no real value to anyone else, I use a different but only slightly more secure password. (Yeah, it has a non-alphabetic character in it, but it's still not very long.) If anything happens and I lose the accounts, I *can* replace them, although it would annoy me significantly.

Oh, and when I generate passwords that are going to be used by other people I follow a somewhat different pattern, but that's neither here nor there.

For server passwords and stuff, though, I treat the issue quite seriously. For network administrators, paranoia is one of our most important job skills.

If I were creating a password for a high-profile target, such as a federal government site, I'd probably take some medium-length piece of memorized text and use the first letter of each word, e.g., ItpGstofttpamtaivw,bitldhhstubhSwhahoatatwhmtu. (Since this is not a real password that I am planning to use, I'll go ahead and tell you that it's the first two verses of the epistle to the Hebrews, NIV translation. In a real scenario, I probably would have chosen a passage out of the middle of the text, rather than the beginning.) This technique only works if you have memorized a number of long passages of text, but as a former national-level Bible quizzer I'm on that like white on rice. A few more examples, just for fun:
Titmotvotrcooambnbhh,artbtitbtctsatgtp.TgGhstkwwtpitf.Tditatiit.
Piwdtglesnbcflatc,aaaehstmamdtsweasttrtbatftwtaa,bwaltoaau,pitso,eadtrtuad,iitr,iitd,ttosgatpngftfs.
Bstlc.Irtebibiytba.ItLiiwTmostattlofIwsttpbettwnltmstL.Ttaasnfbbfuphifbnfu.
Gacpp,btinp.Twiab.Tngtsftnwbtoetcora.Obaaitf.Wswhi?Wiitgw?Wwth?Ilsdopssatbpatpocas?
IatgsIkmsamskmjatFkmaIktFaIldmlfts.Ihostanotsp.Imbta.Ttwltmvatsbofaos.
Npsbhtafacooicuoapoioagj,eicaitlonf,oitm,wiasitowopd;nsapbsftsotbtpijolol.
Iwahotss.Twage.Tstblsmogh,twmtbr,atsitsftealfdfaftwsbasw.
Fiibgyhbstfatnfy,iitgoG,nbwstnocb,fwaGwciCJtdgwwGpiafutd.

Even if you know my methodology for generating these passwords, they remain strong if the passages are chosen arbitrarily. (Some of the ones above are much better in that regard than others, of course. The fifth amendment is particularly weak, as the Bill of Rights isn't a very long text and is quite commonly memorized, and on top of that several of the amendments are too short to be used.)

[espadrine]

Again with that RETARDED “longer > complexerererer” straw man argument? *sigh*

Why do you anglophones always act like Unicode is NIH for you??

“correct horse battery staple” = [a-z ]^28 = 27^28, or realistically probably [a-zA-Z -]^28 = 54^28, or, at best, 64^28.
But in the REAL WORLD, that’s cracked in no time with a simple dictionary attack. Which for myspell/de_GB.dic is less than 46281^4!

If only ONE of those is a Unicode char, suddenly the brute force system has to be used and suddenly even 256^x doesn’t do it anymore: (remember, this is just a comparison while keeping the length)
“✔orrect horse battery staple” = realistically 109449^28 (Unicode 6.0), or even when going blindly for 16 bit, it’s still 65536^28.
I used a char that was readily available on my keyboard. But nobody has trouble adding a different one through key remapping.

Unicode is a bright idea!

But your dictionary attack is void. Even at 10,000 guesses a second, 4 words in a 46281-words dictionary requires ((46281^(4))/10000)/3600/24/365, roughly 1.5 * 10^7 years to compute, or fifteen million years. Randall Munroe assumed 2048 words, and 1,000 guesses a second.

This being immensely enough for the next 10 years, we'll get to unicode in a decade; by then, websites will probably support unicode in passwords.

----

On the other hand, length restriction in passwords often means that passwords are not stored as hash (never mind salted hash, or PBKDF2), but usually, as plain values (hashs, on the other hand, have fixed sizes). That means that anyone that hacked his way into the server can read all passwords effortlessly. Even 40 years ago, Unix systems had far better protection!

This very forum restricts under 60 chars. That makes me wonder.

Password protection on the internet is a joke right now. Passwords *should*:

- be of any size,
- contain any unicode characters,
- not be truncated. Ever.

I have yet to see a website that conforms to these minima requirements.

----

Side note: http://howsecureismypassword.net/ says that Tr0ub4dor&3 would require 71 thousand years to crack. That, on the other hand, is obviously false. It is the limit of a password-checker: since it isn't a real one, it doesn't contain real-world smarter algorithms.

[sellyme]

Thank you so much for giving something to email my technologically challenged school admin. They enforce passwords with a capital, and a number. That's not the worst part, because they then tell us to write it down to remember it. I always make mine some form of expletive and/or insult.

[Diadem]

This comic leaves me horribly confused.

The English Language has, say, 10k common words (and that's being exceedingly generous with the term 'common'). So taking 4 in a random order gives 4! * 10000^4 = 2^58 combinations. If we restrict ourselves to numbers, lower case lettersn and upper case letters we have 62 different combinations. I need a length of just 10 to get more combinations. If I use Randall's estimate (which translates to a mere 1000 common words) I need only 8 characters to be more secure.

How is using a common words password more secure?

[kuuttis]

Am I the only one who knows about this site? https://www.grc.com/haystack.htm

And for the TL;DR: Use some sort of pattern of special characters in the password to increase it's size considerably.

This is harder to guess:
D0g.....................
than this:
PrXyc.N(n4k77#L!eVdAfp9

[ctbxkcd]

I've been reading this comic for about 3 years now and I just had to finally join the forum to say thank you. I've been fighting with people about this for years. I'm going to print this out and start nailing it to people's foreheads.

You may receive a few calls from some lawyers.

[PurdueSi2]

@kuuttis: Yes, thank you. Was just about to make a post with a link to Gibson's site.

[Enokh]

I just use my bank account number as my password. Problem solved!

[Jeouwemoer]

Randall is completely wrong here. How the hell is correct horse battery staple easier to remember than tr0ub4dor?

Four different random words for each account you have...

It would be far harder for most people to remember that.

[neoliminal]

For those in the know, the best way to keep your password secure is to KEEP THE QUOTE MARKS.

"password", for example, is a very strong password.

When they send you your "random-password" and tell you to use it without the quotes, simply change it and keep the quotes. This way you can keep a record in your email of your password.

For extra security, use backquotes.

\"password\" really messes with most cracking programs.

[Cz-David]

Just use this ... where ever possible... anyone can do ctrl c ctrl v ... and encrypt the file you store those in... safely

Code: Select all

https://www.grc.com/passwords.htm

[Tormuse]

That's it. I can't get that phrase out of my head.

Get out of my head, correcthorsebatteystaple!

[JudeMorrigan]

I work for an unnamed organization that shall remain nameless. Their security briefing contained some computer security, a part of which was passwords on the network. The password policy is at least 3: lower case, upper case, numbers, symbols.
and cannot begin/end in numbers. And you must change your password every 90 days and it cannot "be similar to" any of your previous 25 passwords (this is enforced via software). I raised the issue of how insane it is to expect NOBODY to write down their password because after 9 months they'd have to remember some new mangled password, along with the many for other systems that we use, many of which do not have as difficult password requirements but you'd use once every month or so. So frustrating.

I so hear you. I used to work for an organization with very similar rules, and while I was never tempted to write my password down, those rules did wind up making me build more order into my passwords than I would have had otherwise. And I'd lay long odds that I had coworkers who used keyboard patterns that were ripe for reverse-brute forcing. (Or whatever the technical term is for getting a bunch of user names and trying a smaller set of likely passwords across them.)

Actually more banks should use two-factor authentication, rather than merely increasing password strength via policy change.

Also, this. I always found it to be rather hilarious that my battle.net account was more secure than my bank account. Or the aforementioned work account.