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Entropy isn't sufficient to measure password strength

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Re: Entropy isn't sufficient to measure password strength

#31

Post by Biganon »

bigiain wrote: post #12

> Because choosing good passwords is about memorableness as well as sheer strength That's not been true ever since the development of good password managers. There are fewer than 10 passwords I remember. One of them is my password manager's master passphrase (5 misspelled-and-with-random-punctuation words). The others include stuff like my work and home laptop/disk passwords, which I can't autofill, my 3 important ba…

One could argue that you still need to remember your master password, and since it gives access to all your other passwords, it's all the more important to make it extremely strong. Therefore the randomness/memorability trade-off is still very important.

Re: Entropy isn't sufficient to measure password strength

#32

Post by Zamicol »

taeric wrote: post #26
krupan wrote: post #18

When will we stop using passwords?! They are an elementary school kid “secret club” game taken way, way too far. They are totally broken. Nobody can come up with and remember good passwords. Nobody can store passwords securely. 100% busted. Instead of continuing to debate what makes a good password, we need to put our energy into better techniques altogether! No more shared secrets! Let’s talk about one-time codes, a…

I'm curious how you think these other items work. They ultimately boil down to a shared secret that is beyond what you can remember. Which... isn't the best thing, necessarily. Consider, if I leave my hardware token at home when I go on vacation, I'm basically locked out of all of my accounts. This is fine, as I typically plan for this to be the case. But it is an attack vector. I can't even audit my protected assets…

The point of public key cryptography is that there isn't a shared secret.

Re: Entropy isn't sufficient to measure password strength

#34

Post by voiper1 »

mojuba wrote: post #23
krupan wrote: post #18

When will we stop using passwords?! They are an elementary school kid “secret club” game taken way, way too far. They are totally broken. Nobody can come up with and remember good passwords. Nobody can store passwords securely. 100% busted. Instead of continuing to debate what makes a good password, we need to put our energy into better techniques altogether! No more shared secrets! Let’s talk about one-time codes, a…

In one of my current web-based projects I decided to experiment with magic links sent via email. They are pretty convenient (and secure enough) but turns out there's a problem with mobile email clients: they tend to open links in isolated embedded browsers and then forget the cookies. For most non-technical people this is a show stopper unfortunately. I then went with one-time 6-digit sign in codes that are emailed t…

Sometimes the magic links or codes expires in X minutes. That helps them feel secure.

But like password resets, you're hosed if your email is hacked (unless you have 2FA).

Re: Entropy isn't sufficient to measure password strength

#36

Post by rvense »

c0balt wrote: post #30
nextaccountic wrote: post #27

Earlier quoted context omitted.

> 5 misspelled-and-with-random-punctuation words Why misspell and add random punctuation?

Most likely to make dictionary attacks against the password(s) ineffective.

Also makes them more resistant to people looking over your shoulder.

Re: Entropy isn't sufficient to measure password strength

#37

Post by mojuba »

voiper1 wrote: post #34
mojuba wrote: post #23

Earlier quoted context omitted.

In one of my current web-based projects I decided to experiment with magic links sent via email. They are pretty convenient (and secure enough) but turns out there's a problem with mobile email clients: they tend to open links in isolated embedded browsers and then forget the cookies. For most non-technical people this is a show stopper unfortunately. I then went with one-time 6-digit sign in codes that are emailed t…

Sometimes the magic links or codes expires in X minutes. That helps them feel secure. But like password resets, you're hosed if your email is hacked (unless you have 2FA).

Not only expiration, you also limit the number of attempts, the IP address, you verify an additional nonce token generated for the specific request, etc.

The security of your email is typically taken care of by a more sophisticated system like GMail, that will do captcha, they remember your geographic region, your habits, etc.

Given the above, I'd say alphanumeric one-time codes are better in terms of entropy and feel. They look like passwords but you don't need to remember them.

Re: Entropy isn't sufficient to measure password strength

#38

Post by spacehome »

BeefWellington wrote: post #8

There's a bit of a logical flaw here in that the argument is made against average entropy of a set of passwords, rather than individual entropy of each chosen password. This is an argument I can't find anyone making: an aggregate average entropy of the set of all passwords you use is fine for password security, rather than the entropy of each individual password. As far as I can tell this seems to be a (possibly inte…

Individual passwords don’t have entropy.

Re: Entropy isn't sufficient to measure password strength

#39

Post by yosamino »

krupan wrote: post #18

When will we stop using passwords?! They are an elementary school kid “secret club” game taken way, way too far. They are totally broken. Nobody can come up with and remember good passwords. Nobody can store passwords securely. 100% busted. Instead of continuing to debate what makes a good password, we need to put our energy into better techniques altogether! No more shared secrets! Let’s talk about one-time codes, a…

> Nobody can store passwords securely. 100% busted. [...] Let’s talk about

> one-time codes

One-time codes rely on a password: either it is stored in your 2FA App, or they rely on your email password, or they rely you storing a password somewhere else. OTP rely on stored secrets.

You can make these secrets be much larger than the humble password and call them "private keys" :

> asymmetric key cryptography, hardware tokens

If these are not protected by a passphrase they can be stolen. Which seems like a variation of "nobody can store passwords securely". To mitigate the effects of them being stolen, you need to protect them with a password.

I sympathize with your desire, but it's not that easy, although I do think that we can reduce password usage.

But fundamentally a password is a trust anchor in your brain. I have yet to find a way around this limitation.

Re: Entropy isn't sufficient to measure password strength

#40

Post by less_less »

BeefWellington wrote: post #8

There's a bit of a logical flaw here in that the argument is made against average entropy of a set of passwords, rather than individual entropy of each chosen password. This is an argument I can't find anyone making: an aggregate average entropy of the set of all passwords you use is fine for password security, rather than the entropy of each individual password. As far as I can tell this seems to be a (possibly inte…

Entropy and min-entropy are properties of distributions, not of individual samples from those distributions. So there's no meaning to "the entropy of each chosen password".
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