Flaws in deterministic password managers
tonyarcieri.com
Flaws in deterministic password managers
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Re: Flaws in deterministic password managers
#2I'm the creator of visionary[0], a deterministic password generator that the article links to. When I thought of the idea (quite a while ago), I thought it was a good idea, and I thought I was the first one there. I was wrong on both accounts.
The points that the article makes are right, and people should use conventional passwords over deterministic ones.
But I guess it appeals to a certain small subset of people. For some servers and things that I own I find myself using it sometimes: it turns a relatively strong password into a monster of a password.
Another useful use is that it's good at sharing passwords for things with friends, and for that, it's surprisingly handy.
For the average person however, the disadvantages and the things that could go wrong outweigh the advantages. Keepass is what you should be using.
Re: Flaws in deterministic password managers
#3The only deterministic password manager you need is your own mind. Come up with a set of password rules that are generic enough to accommodate all these issues. For example my deterministic password manager might be:
1. random english wordx2 + first 4 letters of registered domain, all caps + remaining lowercase + number of letters in domain (integer) + symbols associated with digits of the integer digits
2. If site doesn't allow special characters, remove them
3. If site requires a shorter password than the generated one, trim the minimum number of characters from the front of the password until the criteria is met.
So, using my above rules my password for Ycombinator would be:
coppercopperYCOMbinator11!!
If the site restricts passwords to max 12 characters, it would become:
Mbinator11!!
Re: Flaws in deterministic password managers
#4The only deterministic password manager you need is your own mind. Come up with a set of password rules that are generic enough to accommodate all these issues. For example my deterministic password manager might be: 1. random english wordx2 + first 4 letters of registered domain, all caps + remaining lowercase + number of letters in domain (integer) + symbols associated with digits of the integer digits 2. If site d…
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Re: Flaws in deterministic password managers
#5The only deterministic password manager you need is your own mind. Come up with a set of password rules that are generic enough to accommodate all these issues. For example my deterministic password manager might be: 1. random english wordx2 + first 4 letters of registered domain, all caps + remaining lowercase + number of letters in domain (integer) + symbols associated with digits of the integer digits 2. If site d…
> If the site restricts passwords to max 12 characters
The problem with this is that most sites are designed by idiots and don't state their pointless password rules on the login page - only on the 'change password' page. So you can be trying your coppercopperYCOMbinator11!! password and thinking "why the hell doesn't this work?", then after 10 minutes you give up and go to change it and see "Your password must be between 8 and 12 characters and contain a symbol." So infuriating.
Re: Flaws in deterministic password managers
#6The only deterministic password manager you need is your own mind. Come up with a set of password rules that are generic enough to accommodate all these issues. For example my deterministic password manager might be: 1. random english wordx2 + first 4 letters of registered domain, all caps + remaining lowercase + number of letters in domain (integer) + symbols associated with digits of the integer digits 2. If site d…
First, your proposed scheme relies on doubling words to get complexity without imposing too much of a tax on the user. But because passwords must be reasonable to type, that rule (and any rule like it --- I get that the "key" in this scheme is in part the weird rules you come up with) limits you to smaller words, which can very quickly be searched.
Worse, an attacker who sees one of your passwords has a pretty decent shot at brute forcing the rules you use, and an attacker who sees two of them has the rules and has totally cracked your scheme.
To get real entropy from english word passwords, you have to use several different words. In each password. Which: nobody is saying that's a bad idea. They're saying: you should just have 1Password do that for you, because keeping all those passwords in your head is a chore, and normal people cheat and reuse passwords.
Re: Flaws in deterministic password managers
#7The only deterministic password manager you need is your own mind. Come up with a set of password rules that are generic enough to accommodate all these issues. For example my deterministic password manager might be: 1. random english wordx2 + first 4 letters of registered domain, all caps + remaining lowercase + number of letters in domain (integer) + symbols associated with digits of the integer digits 2. If site d…
I think a password manager (minus some of the scary bits like browser plugins) is a much better option than a mental password generation scheme. Maybe some folks can handle this but I think this is a non-ideal general recommendation.
Re: Flaws in deterministic password managers
#8The only deterministic password manager you need is your own mind. Come up with a set of password rules that are generic enough to accommodate all these issues. For example my deterministic password manager might be: 1. random english wordx2 + first 4 letters of registered domain, all caps + remaining lowercase + number of letters in domain (integer) + symbols associated with digits of the integer digits 2. If site d…
> If the site restricts passwords to max 12 characters The problem with this is that most sites are designed by idiots and don't state their pointless password rules on the login page - only on the 'change password' page. So you can be trying your coppercopperYCOMbinator11!! password and thinking "why the hell doesn't this work?", then after 10 minutes you give up and go to change it and see "Your password must be be…
That's very true. I forgot to mention that I also have a spreadsheet that has site-specific password rules so that I can do a lookup and see how I need to adapt my generated password.
Maybe what we really need instead of deterministic password generators is an authoritative database that tracks the password rules of all the different sites on the internet so we can easily look it up and/or publicly shame companies with asinine password policies.
Re: Flaws in deterministic password managers
#9The only deterministic password manager you need is your own mind. Come up with a set of password rules that are generic enough to accommodate all these issues. For example my deterministic password manager might be: 1. random english wordx2 + first 4 letters of registered domain, all caps + remaining lowercase + number of letters in domain (integer) + symbols associated with digits of the integer digits 2. If site d…
A password like that would probably be guessed by a good password cracker pretty quickly.
I've taken the liberty of following your procedure for an un-named domain. If anyone's got a password cracker running, I'd be interested how long it takes to break this SHA256 hash: dae640f98b6894d2f6eab5755b22918be46b0d219ea10d3ceea06ebe538a75d1. Post once you've guessed it.
Just use 'pwgen -s 22'; it generates 128-bit passwords, which will never be guessed.
Re: Flaws in deterministic password managers
#10The only deterministic password manager you need is your own mind. Come up with a set of password rules that are generic enough to accommodate all these issues. For example my deterministic password manager might be: 1. random english wordx2 + first 4 letters of registered domain, all caps + remaining lowercase + number of letters in domain (integer) + symbols associated with digits of the integer digits 2. If site d…
First, your proposed scheme relies on doubling words to get complexity without imposing too much of a tax on the user. But because passwords must be reasonable to type, that rule (and any rule like it --- I get that the "key" in this scheme is in part the weird rules you come up with) limits you to smaller words, which can very quickly be searched. Worse, an attacker who sees one of your passwords has a pretty decent…
> Worse, an attacker who sees one of your passwords has a pretty decent shot at brute forcing the rules you use, and an attacker who sees two of them has the rules and has totally cracked your scheme.
If an attacker is specifically targeting me and thinking about my passwords, there's not much I can do at that point. Password security in general kind of relies on attackers scanning huge quantities of credentials and going for the low hanging fruit.
Plus, I still don't get why 1Password is better than a password generator on the 4th point. I get that yes you need 2 things (both the master key and the ciphertext), but how does that protect you? The cipher text is available to anyone who logs in. If I get your 1Password credentials, what's to stop me from logging into 1Password.com as you?