Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

paul.reviews

Post reply on HN
Print view View original

71–80 of 87 posts

Re: Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

#71

Post by norswap »

I believe it comes from a good place, but this post is bad.

Why?

Because it doesn't apply the same comparison standard to character-based passwords than to word-based passwords.

Sure, we only use a few common dictionary words. But by the same token, our character-based passwords aren't random strings either: they are variation based on random words.

This is the basis of the xkcd advice to use 4 random words: https://xkcd.com/936/

Notice Randall gives each word 11 bits of entropy, meaning he considers each word is chosen at random amongst a pool of ~2000 words. Yet that base is still much bigger than ~64 for characters.

If you take 3 common words, you get ~8 billion possibilities. 4 common words: 17,000 billion. That's much more than than ~400 billion for a perfectly random (again: that's not the case in practice) password of 12 characters. And four words is easy to remember, 12 random characters is HARD.

If anything bad can be said about the xkcd comic, it's that it doesn't hammer the point that it has to be FOUR words. As three is much less secure (but still probably more secure than the 12 characters password people are likely to use in practice).

Re: Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

#72

Post by mcphage »

hyperpape wrote: post #61
mcphage wrote: post #53

Earlier quoted context omitted.

That's fine if your only other scheme is "exact matching words". But once you break from that, even a little bit, the number of different possible schemes balloons quickly. For instance, 3 words + a symbol at the end. A cracker can try all the words, sure. But they're probably not going to try every different "all the words plus a little twist" schemes.

Most of those schemes fall into the category of: sym,word,sym,word,sym,word,sym Where sym is 0-1 symbols or numbers, and comma indicates concatenation. If you use 5+symbols you’re probably creating enough entropy, but you’re veering into hard to type, might as well just use gibberish territory.

They are, but like—how many of these schemas is a cracker going to try between "test just words" and "brute force". There's a ton of possibilities, and I really don't think they'll bother enumerating them all. That's the point—the cracker doesn't know what schema you're going to use. Sure, maybe they'll test word lists. But not all of:

* word sym

* sym word

* word word sym

* word sym word

* sym word word

* word word word sym

* word word sym word

* word sym word word

* sym word word word

And then what about 2 symbols? Or separating words with spaces, or dashes, or underscores, or nothing? How many schemas are we up to by now? At what point is there no value to trying all of these, and just running the brute force lookup?

Re: Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

#73

Post by drbawb »

norswap wrote: post #71

I believe it comes from a good place, but this post is bad. Why? Because it doesn't apply the same comparison standard to character-based passwords than to word-based passwords. Sure, we only use a few common dictionary words. But by the same token, our character-based passwords aren't random strings either: they are variation based on random words. This is the basis of the xkcd advice to use 4 random words: https://…

This post also fails to take into account people's exposure to fiction. My vocabulary may be limited, but many of my passphrases use nouns/concepts/slang that are drawn from video games, novels, movies, etc. Some of these works (authored by family, friends, and myself) aren't even published. I reckon the chance of these "words" being included in some cracker's dictionary is quite close to zero.

Also as you point out their analysis of the entropy of random words is quite uncharitable. It fails to account for any sort of punctuation, capitalization, etc. Is my password "correct horse battery staple" or "correct Horse, battery staple!" or "CORRECT HORSE! Battery staple.", etc. There is a lot of entropy inherent in crafting a phrase.

Re: Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

#74

Post by norswap »

drbawb wrote: post #73
norswap wrote: post #71

I believe it comes from a good place, but this post is bad. Why? Because it doesn't apply the same comparison standard to character-based passwords than to word-based passwords. Sure, we only use a few common dictionary words. But by the same token, our character-based passwords aren't random strings either: they are variation based on random words. This is the basis of the xkcd advice to use 4 random words: https://…

This post also fails to take into account people's exposure to fiction. My vocabulary may be limited, but many of my passphrases use nouns/concepts/slang that are drawn from video games, novels, movies, etc. Some of these works (authored by family, friends, and myself) aren't even published. I reckon the chance of these "words" being included in some cracker's dictionary is quite close to zero. Also as you point out…

The point being that even so it's already better while simultaneously being easier to remember (because indeed, what did I capitalize again?).

Re: Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

#75

Post by hyperpape »

mcphage wrote: post #72
hyperpape wrote: post #61

Earlier quoted context omitted.

Most of those schemes fall into the category of: sym,word,sym,word,sym,word,sym Where sym is 0-1 symbols or numbers, and comma indicates concatenation. If you use 5+symbols you’re probably creating enough entropy, but you’re veering into hard to type, might as well just use gibberish territory.

They are, but like—how many of these schemas is a cracker going to try between "test just words" and "brute force". There's a ton of possibilities, and I really don't think they'll bother enumerating them all. That's the point—the cracker doesn't know what schema you're going to use. Sure, maybe they'll test word lists. But not all of: * word sym * sym word * word word sym * word sym word * sym word word * word word…

Most of those are covered by what I wrote. I said they’re ranges of 0-1 symbols.

Re: Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

#76

Post by mcphage »

hyperpape wrote: post #75
mcphage wrote: post #72

Earlier quoted context omitted.

They are, but like—how many of these schemas is a cracker going to try between "test just words" and "brute force". There's a ton of possibilities, and I really don't think they'll bother enumerating them all. That's the point—the cracker doesn't know what schema you're going to use. Sure, maybe they'll test word lists. But not all of: * word sym * sym word * word word sym * word sym word * sym word word * word word…

Most of those are covered by what I wrote. I said they’re ranges of 0-1 symbols.

Right, but my point is that since the cracker doesn't know which you're going to use, they'll need to stick to broad schemas that will take a long time. It doesn't matter if you only use 1 symbol, if the cracker needs to try every combination of up to 5 symbols. And even a broad schema like you suggest—which would take a long time to complete—will have holes that would be easy to squeak through, which means even those broad schemas have minimal value.

Ultimately, even a schema like "sym? word sym? word sym? word sym? word sym?" is useless. They'll have to use brute force, and that means the difficulty of cracking your password is back to being based on the length.

Re: Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

#77

Post by pa7ch »

gravy wrote: post #5

The ONE thing stopping me from using a password manager is fear that I'll lose the master password. How do I get over this fear? Another thing is for example Chrome's built in password manager. If I make a bunch of accounts with these passwords, do I NEED Chrome to ever be able to log in to these accounts?

I just remember two strong passwords. My master password for my manager and my gmail password. My gmail can recover pretty much all my other passwords. Also I keep backup secrets for my gmail as well. This feels robust enough, but backing up my password manager might be wise too.

Re: Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

#78

Post by mkesper »

pa7ch wrote: post #77
gravy wrote: post #5

The ONE thing stopping me from using a password manager is fear that I'll lose the master password. How do I get over this fear? Another thing is for example Chrome's built in password manager. If I make a bunch of accounts with these passwords, do I NEED Chrome to ever be able to log in to these accounts?

I just remember two strong passwords. My master password for my manager and my gmail password. My gmail can recover pretty much all my other passwords. Also I keep backup secrets for my gmail as well. This feels robust enough, but backing up my password manager might be wise too.

What if your gmail account gets locked due to reasons you're not even aware of? Oh wait, that couldn't possibly happen...

Re: Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

#79

Post by PaulMoore »

evrydayhustling wrote: post #20

I guess this is a good primer for some folks, but there are two really spurious arguments: (1) Your working vocabulary of 20k words is irrelevant. If you pick the words yourself, they aren't random and your random-word-vocabulary (the ones you'd actually pick) is waaaay less. If you use a randomizer, which you should, just give it the full dictionary (or say, top 100k for memorability). (2) Faced with the suggestion…

Hi evrydayhustling

"If you use a randomizer, which you should"

That's a big IF. People should use a password manager, or create unique random passwords for every site... but they don't. Of course, if someone other than you chooses the words, you'd need to include the entire dictionary.

"But go to 5, and you're solid for 400y. This is so clearly relevant that excluding it seems suspect."

I haven't excluded this; I make reference to DiceWare at the bottom of the page. This covers both using more words chosen at random, which is the entire point.

Thanks

Re: Passwords: Using 3 Random Words Is a Really Bad Idea (2017)

#80

Post by PaulMoore »

strictnein wrote: post #31

No, using 3 random words isn't "a really bad idea". That's complete nonsense. The only "really bad idea" for passwords is password reuse. A unique 14 character three word password for each site you use will protect you from the threats you face online. The fact that someone can relatively quickly crack your password if you used 3 random words is meaningless. That only works if they knew that you did that in the first…

Hi strictnein

Erm, haven't you proven my point for me?

You can't say "The fact that someone can relatively quickly crack your password if you used 3 random words is meaningless" and "isn't a really bad idea" in the same sentence.

"Capitalize one random letter in all of that, throw a number between the second or third letter, add dashes, whatever and they're totally screwed"

So.... ignore the "just use 3 words" advice completely and add random letters, numbers and dashes to make it secure? You'll find that's the advice we've given for years... and it too is ignored.

Post reply on HN