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Horcrux: A Password Manager for Paranoids

arxiv.org

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Re: Horcrux: A Password Manager for Paranoids

#41

Post by patrickmn »

w8rbt wrote: post #34
patrickmn wrote: post #18

Earlier quoted context omitted.

All such deterministic algorithms are seeded by something. This is their basic flaw. Guess the seed and you get all the passwords. With a password manager that randomly generates unique passwords, you don't have that problem, but you do have to synchronize the data.

The master password of the password manager has the same issue plus the burden of storage.

It's not the same issue. With your approach, a compromise of the seed is catastrophic and reveals everything. With a regular password manager, you also need access to the vault encrypted using that master password. That's not a given -- most password managers either store their vaults locally or offer 2FA when synced.

(Nevermind that you can't change individual passwords or the master password at will with a deterministic scheme.)

Re: Horcrux: A Password Manager for Paranoids

#42

Post by JohnStrange »

thinkMOAR wrote: post #10

If you are paranoid, then there is only one option, you are the password manager. Certainly not a piece of software you didn't author yourself. Else you are not truly paranoid.

I'm paranoid enough to only use my own password manager, but if you must use a password manager written by someone else then don't use one that runs in a web browser. Moreover, although this doesn't apply in this case, don't use a password manager that stores anything on a server not totally controlled by you.

Re: Horcrux: A Password Manager for Paranoids

#43

Post by admax88q »

thinkMOAR wrote: post #28
_jal wrote: post #16

Earlier quoted context omitted.

Are you trying to tell me what my threat model should be? That makes me suspicious...

No, actually only stating truly paranoid people would not use a 3rd party password manager. Else you still have somewhat trust in third parties, making you not paranoid. Your reply however... stamps paranoid label on it :)

If you were that paranoid you wouldn't be using a web browser in the first place. After all, its some 3rd party software that has access to your passwords.

There seems to be a growing chatter on HN and elsewhere about how you can't trust free software because you didn't audit/write it yourself.

I'm not sure if people actually believe that or use it as a way to point out how they're smarter than other people.

Sure its possible that the free software contains something malicious, but such an attitude is not constructive. If you only used software you wrote yourself you might as well not use a computer. There are degrees of trust, balancing of risks, and free software has a much better reputation of not containing malicious code.

Re: Horcrux: A Password Manager for Paranoids

#44

Post by simias »

arianvanp wrote: post #29
simias wrote: post #27

Earlier quoted context omitted.

I tried doing that a few years ago, random password constraints made it highly impractical. And if you end up using a database for storing your nonces and hashing schemes you'll end up with the same limitations and attack vectors the parent was complaining about.

nonces and hashing schemes are not very sensitive information though. The nonce does not make the HMAC more predictible in any way

A well encrypted password store isn't more sensitive though. That's the whole concept behind services like lastpass that host an encrypted blob in the "cloud".

You could argue that it makes offline attacks easier because many encrypted storage formats have a way to check if the decryption was successful or not but you could remove this feature if that was a problem for you. And at any rate using a strong enough passphrase would make this attack impractical in the first place. And being notified when you used a wrong passphrase is pretty useful IMO.

Re: Horcrux: A Password Manager for Paranoids

#45

Post by danjoc »

Sticking with zx2c4 pass. It is an assembly of gnupg, git, and pwgen. Trusted open source components. Works with a Yubikey (opensc and gpg-agent) to prevent private key theft via software. PassFF extension provides excellent browser integration. Android Password Store and OpenKeychain allow pass and yubikey to work on my mobile. Strong 2 factor password storage everywhere I need it.

My biggest problem these days is dealing with sites that don't allow 30+ char passwords with full range of special characters. Almost exclusively, banks.

Re: Horcrux: A Password Manager for Paranoids

#46

Post by kodablah »

baby wrote: post #9
Nyubis wrote: post #4

The trick of entering a dummy username and password, which is then modified in the post request sounds a whole lot better than playing clipboard roulette or messing with the DOM.

This sounds pretty cool! What I'm wondering, is how they are intercepting the POST request and at what level?

I have not read yet, but my guess is they are taking all HTTP requests from the page and looking for their dummy username/password and replacing that. Not every login form (though we would like it) is in a form tag w/ an explicit action. Some SPA's will do an AJAX post of JSON w/ the credentials embedded (which is bad practice, but happens).

Actually, the more I think about it, I don't think I want this extension to do that...how does it know how long between when the fake fields are entered and when I press submit? Now I am going to read the paper...

Edit: Yup, the extension intercepts all network traffic even before you click submit. If you, e.g., hash on the client side this password manager will break. If you never click submit, this extension will continue to read all HTTP bytes from the page going back to the server it seems, looking for some strings...not sure the perf implications of this.

Re: Horcrux: A Password Manager for Paranoids

#47

Post by 0xfeba »

fictioncircle wrote: post #12
thinkMOAR wrote: post #10

If you are paranoid, then there is only one option, you are the password manager. Certainly not a piece of software you didn't author yourself. Else you are not truly paranoid.

If you can audit the code yourself, you can treat it as code you authored. (assuming you are competent to perform the audit)

Relevant: https://en.wikipedia.org/wiki/Underhanded_C_Contest

Re: Horcrux: A Password Manager for Paranoids

#48

Post by pitaa »

danjoc wrote: post #45

Sticking with zx2c4 pass. It is an assembly of gnupg, git, and pwgen. Trusted open source components. Works with a Yubikey (opensc and gpg-agent) to prevent private key theft via software. PassFF extension provides excellent browser integration. Android Password Store and OpenKeychain allow pass and yubikey to work on my mobile. Strong 2 factor password storage everywhere I need it. My biggest problem these days is d…

What is it with banks and their annoyingly terrible "security" requirements? My old bank once sent me an email saying I had to reset my password. The email seemed legit, but upon following the link therein something didn't seem quite right. So I use another device to visit my bank's site directly. Upon trying to login, I get redirected to the same form I reached from the email link and had a sinking realization that my bank did indeed expect me to fill in my name, address, SSN, DOB, debit card number, and PIN just to reset my password.

I sent a strongly worded email to a handful of people at the bank asking them if they really thought it was a good idea to teach their customers that its okay to click a link in an email claiming to be from their bank and provide that much personal information. I never got more than a canned response back, but several months later they did overhaul their password reset procedure to a more typical one.

Re: Horcrux: A Password Manager for Paranoids

#49

Post by madamelic »

phinnaeus wrote: post #20
thinkMOAR wrote: post #15

Earlier quoted context omitted.

True, in theory, though in practice, i know plenty of capable people but almost none of them bothers to read the openssh source (or even a subset, like recent changes) before updating or recompiling.

Make sure you read the code of the compiler you're using as well, and bootstrap/compile it from that source instead of trusting an existing compiler binary.

I wish I could find the story where someone actually had this issue.

Basically, the story was that a program for grad research was inserting all kinds of nasty, anti-semetic things into text and it turned out the previous grad student had poisoned the compiler which was modifying the strings and was able to re-poison it every time through something else.

I forgot the exact details but it is an amazing read.

Re: Horcrux: A Password Manager for Paranoids

#50

Post by abalone »

w8rbt wrote: post #14

I think all password managers that store passwords are flawed. Storage is a burden. The store must be synced between devices, secured, backed-up, etc. and it can be stolen. I believe that passwords should be deterministically generated when needed, not retrieved from a store. I'm not sure why this approach is not seen more often. Edit: It seems people don't understand what I mean... I just put some code here to bette…

I looked at your code. All it does is generate a password based on user-supplied input. This does not lessen the need for password managers. People still have to remember the input.
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