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

NIST’s new password rules – what you need to know

nakedsecurity.sophos.com

Post reply on HN
Print view View original

201–210 of 237 posts

Re: NIST’s new password rules – what you need to know

#201

Post by sbuttgereit »

oneeyedpigeon wrote: post #165
sbuttgereit wrote: post #109

Earlier quoted context omitted.

For which they set a 4K limit on password length. I think even the commenter you replied to would find that satisfactory, being much more than 64 characters.

It's pretty arbitrary when you get to 64, IMO. If a site enforces a maximum below that, I'll feel suspicious and treat the site as if it's storing my password in plain text; that maximum or higher reassures me that they probably know what they're doing. Of course, one day, a 64-character password will be brute-forceable in milliseconds, but we hopefully won't still be having this discussion by then!

I agree, though I also think: why have some arbitrary limit at all? Mind you the 4K Django limit isn't arbitrary, they know that at some point beyond that they'll spend too much time in hashing-land and will have opened up a DoS attack vector.

I would argue 4K is effectively unlimited... maybe in the sense of an ISP/phone company "unlimited data plan" unlimited, but still... the likelihood of user knowing of the limit is very small. I use a password manager that maxes out at 100 characters in its password generator (a default I use because... why not?) However, in those small cases where I do use contrived passwords, I make use of passwords that are really pass-sentences (with a few extras thrown in). It's pretty easy for me to blow by 64 characters (and sometimes 100) in those cases; not because I think I'm gaining extra security due to length, but because I'm just throwing out the first, easiest to remember sentence that crosses my mind and that I know will be reasonably secure. A service that flummoxes that effort just makes it less likely I'll use the service (assuming that it's use is discretionary).

Re: NIST’s new password rules – what you need to know

#202

Post by euroclydon »

riskable wrote: post #70

The importance of this NIST standard cannot be understated. It has a requirement that passwords be hashed with a random salt ! Microsoft Active Directory does not use salts ! I am trying to imagine the consequences to all the businesses and agencies that must adhere to these standards suddenly coming to the realization that they must replace their Active Directory installations and what that will mean for administeri…

Can NTLM, which prevents sending the password itself across the network, work with random salts?

Re: NIST’s new password rules – what you need to know

#203

Post by binarycrusader »

danielpatrick wrote: post #184
ryanar wrote: post #87

I love this. I despise the fact that my bank restricts passwords lengths to max 16 chars, hash lengths are constant, it is ridiculous. It is a BANK, if anything they should be more secure. Instead they force me to make passwords that easily fit a password mask by restricting special characters and forcing at least one number, uppercase letter, etc. They are actually weakening the security in a vain attempt to get peo…

> there have been times my phone was dead and I didnt have a backup plan. This. Just recently this happened to me when I needed to get into my Gmail and I was shit out of luck. Didn't have my phone on me. The best Gmail would do was some sort of account reset that would take 2+ days (for good reason). I was entirely locked out, no solution short of returning home to get my phone. Anyone recommend a solid backup plan?

In the Google case you can print a set of backup codes. See the security page under your account.

Re: NIST’s new password rules – what you need to know

#204

Post by leshow »

hvidgaard wrote: post #146
whiteandnerdy wrote: post #138

Earlier quoted context omitted.

I think XKCD is correct here. If you choose four random words from a list of 2048 common words, and your attacker knows that's what you're doing, then your entropy is 4 * log_2(2048) = 44 bits. If the attacker didn't know your strategy and tried to brute force letter by letter it would be much higher - around 4 8 log_2(26)=150 bits assuming around eight letters per word - but like you said, we should assume the attac…

Can we really assume 2048 different words? 100 words make up 50% of all words written according to this https://en.wikipedia.org/wiki/Most_common_words_in_English ? I was a bit hasty of the entropy of the passphrase, my mistake. I still stand by that even if we choose from 2048 common words, generating a good passphrase (one that isn't a common sentence) is harder than we think.

BIP39 uses a wordslist of 2048 words, it selects 12 words to generate a passphrase. I believe the target is 128 bits of entropy.

Re: NIST’s new password rules – what you need to know

#205

Post by leshow »

hvidgaard wrote: post #148
jejeuhds wrote: post #141

Earlier quoted context omitted.

No, you are wrong. The number of bits of entropy in "horsestaple..." is estimated by assuming the words where chosen at random from the 2^11=2048 most common words. 4*11=44 bits in total. In practice it is even better since a hacker would also try different kinds of passwords! So no, you do not need substitute characters.

Yes, I was wrong about the entropy when writing that. But I still don't think that passphrases are as godsend as the comic make it seem. Can we really assume 2048 common words? The 100 most commonly used, make up 50% of written words. A common sentence like "I drove to the mall yesterday" is not a good passphrase, but I'm certain that people who use "rocket" as a password would do something similar.

the idea is you use a mnemonic generator to pick the words. The fact that "100 most commonly used, make up 50% of written words" (a dubious statistic, source?) is irrelevant.

Here's a mnemonic generator I wrote in Rust https://github.com/leshow/rust_mnemonic for example

Re: NIST’s new password rules – what you need to know

#206

Post by CmdrSprinkles »

OptimalRoasted wrote: post #97
koolba wrote: post #91

Earlier quoted context omitted.

Here's what I use to generate answers to secret questions: This leads to things like: > "What is your first pet's name?" "q1ry9nftmxb1gmag" I haven't had it happen yet, but I wonder what a customer service rep's response will be when I spell out "yrlmduihhyju5il0" when asked what my favorite color is.

The guy on the phone laughed. I've moved to providing a few random words, easier to say over the phone than capital y lowercase r number 1.... etc.

Be careful with it. Was dealing with credit card stuff (raising limit to go on travel) and when they were verifying my identity the policy was evidently to combine my questions with a "background check"

Said background check basically being they googled my name.

Which you would think isn't a problem until you get to "What school did you graduate from?" and have to go through four levels of reps to explain that (not actually what I typed) "Omelette Du Fromage" was my way of making it harder to social engineer my account.

Re: NIST’s new password rules – what you need to know

#207

Post by marcosdumay »

hvidgaard wrote: post #182
croon wrote: post #169

Earlier quoted context omitted.

I'd go so far as to say that 2048 words aren't that many. Here's Merriam-Websters 3000 _core_ words [1]. Here's a list of 355k words [2]. [1] http://learnersdictionary.com/3000-words [2] https://github.com/dwyl/english-words

There is not 3000 _core_ words. You don't teach elementary school children 3000 words. That list is significanly smaller. In Denmark it's 120 words, then you'll be well on your way to reading and writing most basic stuff. That someone has selected 2048 words used to generate passphrases, doesn't make it easy to remember.

Eh, you may want to peek at the XKCD things explainer to see what is life under 1k words.

Everybody uses more than a few thousand words on at least one language. And selecting the least used ones will make your passprhases easier to memorize, because they have much more concrete meaning (by virtue of their rarity) than the most used words.

Re: NIST’s new password rules – what you need to know

#208

Post by marcosdumay »

hvidgaard wrote: post #148
jejeuhds wrote: post #141

Earlier quoted context omitted.

No, you are wrong. The number of bits of entropy in "horsestaple..." is estimated by assuming the words where chosen at random from the 2^11=2048 most common words. 4*11=44 bits in total. In practice it is even better since a hacker would also try different kinds of passwords! So no, you do not need substitute characters.

Yes, I was wrong about the entropy when writing that. But I still don't think that passphrases are as godsend as the comic make it seem. Can we really assume 2048 common words? The 100 most commonly used, make up 50% of written words. A common sentence like "I drove to the mall yesterday" is not a good passphrase, but I'm certain that people who use "rocket" as a password would do something similar.

Even those 44 bits are too little nowadays. Passphrases are not a godsend, but something good to use when the correct technology - a password manager - is not available.

A notable use case is choosing a master password for your password manager. And you'll want a longer phrase.

Re: NIST’s new password rules – what you need to know

#209

Post by squeaky-clean »

hvidgaard wrote: post #146
whiteandnerdy wrote: post #138

Earlier quoted context omitted.

I think XKCD is correct here. If you choose four random words from a list of 2048 common words, and your attacker knows that's what you're doing, then your entropy is 4 * log_2(2048) = 44 bits. If the attacker didn't know your strategy and tried to brute force letter by letter it would be much higher - around 4 8 log_2(26)=150 bits assuming around eight letters per word - but like you said, we should assume the attac…

Can we really assume 2048 different words? 100 words make up 50% of all words written according to this https://en.wikipedia.org/wiki/Most_common_words_in_English ? I was a bit hasty of the entropy of the passphrase, my mistake. I still stand by that even if we choose from 2048 common words, generating a good passphrase (one that isn't a common sentence) is harder than we think.

The GfyCat URL generator list is about ~1800 animals and ~8000 adjectives [0]. All fairly memorable words. Add in other types of words and 2048 quickly becomes a small number.

The words don't have to be incredibly simple, either. Grabbing a random GfyCat image from the front page gives me "OrangeLankyBasilisk" which is easy to remember, none of those words are particularly foreign. But they're not in your list of most common words, nor are any of them in XKCD's simplewriter [1], which keeps track of the 1000 most common words.

[0] https://github.com/a-type/adjective-adjective-animal/tree/ma...

[1] https://xkcd.com/simplewriter/

Edit: The words need to be randomly chosen by a computer, so it doesn't matter what the most common words are. You could generate the password from a list of 2048 spanish words or japanese words or emojis and the entropy is the same as the previous scenario (assuming the attacker knows your dictionary of symbols just like they'd know your dictionary of English words). If you let a human choose, of course the smiley-face and poop emojis are going to be picked 50% of the time, but that's not the intention of the comic or passphrases.

Re: NIST’s new password rules – what you need to know

#210

Post by CWuestefeld »

monkeywork wrote: post #145
adrr wrote: post #4

Earlier quoted context omitted.

PCI compliance requires quarterly rotation of passwords and keys.

I thought PCI compliance required you to follow A standard (they didn't dictate which one) as long as it was a recognized industry standard and you were consistent with it. NIST would qualify...

We're going through various audits for PCI right now. Our auditor insisted that we need to add checks for reuse of recent passwords.

However, I've heard that the process varies widely depending on who your auditors are. Some are apparently very permissive, but we got the other end of the spectrum.

Post reply on HN