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Ken Thompson's Unix Password

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Re: Ken Thompson's Unix Password

#151

Post by dekhn »

Gunax wrote: post #51
dekhn wrote: post #40

i deduced my dad's password when I was a middle-schooler. The uni micro had a teletype and although it did not echo password characters, if you mistyped your password, it would print the mistyped password, and knowing a bit about my dad, I could figure out what the correct password was. I logged in and sent himself an email reminding him to use a better password.

That's just a bad system design, not your dad's fault really: "You're password 'huntet2' is invalid" unless the password is just random characters, anyone can guess how it was mistyped. Hell, even if it was just random characters, one could just assume that it's one character-off from the real password, and try shifting each character around.

My dad's fault was to bring the printout home and leave it in a public location.

Re: Ken Thompson's Unix Password

#152

Post by kissgyorgy »

jedberg wrote: post #143

Back when I worked in IT many years ago, one of the things I did each week was run JohnTheRipper on our password file. If it cracked your password, it sent you an email saying your password was weak and you had to change it. If you were in the next week's batch, it emailed you and told you "your password is foobar, which we discovered by cracking the password file, and it is weak. You must change it". Yes, I emailed…

Even if the guy was creepy, you are an asshole revealing something he thought nobody could ever know. That's the same thing like reading his personal letters or similar.

Re: Ken Thompson's Unix Password

#153

Post by colejohnson66 »

hangonhn wrote: post #117
yjftsjthsd-h wrote: post #5

I'm shocked at how well the old hashing stood up; sure, it's totally crackable today, but a well-picked password still took 4+ days to crack on modern hardware, which is remarkable. (Granted, it doesn't sound like they did anything fancy like throwing a hundred cloud instances at it or something; I'm not saying you should use DES today:) )

Would this suggest that 3DES with a sufficiently long password is still safe for now?

Doubt it. It took 4 days for just one top of the line GPU. Any dedicated attacker will have farms to parallelize it even further. It’s not exactly linear, but with just 4 GPUs (~$4000; well within the reach of any dedicated attacker), that’s one day. Not to mention the fact that GPUs have still been roughly following Moore’s Law in terms of performance.

It’s probably safe from the casual attacker who just downloads a password list and runs a one word dictionary attack, but for a dedicated attacker, let alone a nation state, it’s not secure.

TL;DR: Just use AES. Even an ASIC isn’t powerful enough for that. Searching the entire key space would take more energy than the universe has. Compare that to DES that can have its entire key space searched in a few days.[0]

Edit: you said triple DES, not single. My point still stands. DES, even 3DES, is not secure. If I can crack a DES password in 4 days, I can crack a 3DES password in 12. AES with a strong password is virtually uncrackable.

[0]: https://en.wikipedia.org/wiki/EFF_DES_cracker

Re: Ken Thompson's Unix Password

#154

Post by tom_mellior »

TallGuyShort wrote: post #144
jedberg wrote: post #143

Back when I worked in IT many years ago, one of the things I did each week was run JohnTheRipper on our password file. If it cracked your password, it sent you an email saying your password was weak and you had to change it. If you were in the next week's batch, it emailed you and told you "your password is foobar, which we discovered by cracking the password file, and it is weak. You must change it". Yes, I emailed…

I'm all for the effective strength enforcement and ejecting the creepy guy, but some people do have strong passwords that, a bad idea though it may be, embed something deeply personal to them. Just something to keep in mind before automating the sharing of cracked passwords for otherwise legitimate purposes. I consider my passwords my private information, even if they are no longer secure from a technical standpoint…

Agreed. I would hope that the first email was automated and nobody actually looked at the results of cracking the passwords. In the second week, you arguably had less expectation of privacy.

Re: Ken Thompson's Unix Password

#156

Post by mongol »

jedberg wrote: post #143

Back when I worked in IT many years ago, one of the things I did each week was run JohnTheRipper on our password file. If it cracked your password, it sent you an email saying your password was weak and you had to change it. If you were in the next week's batch, it emailed you and told you "your password is foobar, which we discovered by cracking the password file, and it is weak. You must change it". Yes, I emailed…

I don't know what to think about this. A password is supposed to be secret so I don't know what a naughty phrase in secret is a violation of? It is not very different from writing something naughty in a private diary, or even thinking a naughty thing.

Re: Ken Thompson's Unix Password

#157

Post by travisjungroth »

kissgyorgy wrote: post #152
jedberg wrote: post #143

Back when I worked in IT many years ago, one of the things I did each week was run JohnTheRipper on our password file. If it cracked your password, it sent you an email saying your password was weak and you had to change it. If you were in the next week's batch, it emailed you and told you "your password is foobar, which we discovered by cracking the password file, and it is weak. You must change it". Yes, I emailed…

Even if the guy was creepy, you are an asshole revealing something he thought nobody could ever know. That's the same thing like reading his personal letters or similar.

Eh, he was typing that phrase at a work keyboard everyday.

Re: Ken Thompson's Unix Password

#159

Post by SettembreNero »

colejohnson66 wrote: post #153
hangonhn wrote: post #117

Earlier quoted context omitted.

Would this suggest that 3DES with a sufficiently long password is still safe for now?

Doubt it. It took 4 days for just one top of the line GPU. Any dedicated attacker will have farms to parallelize it even further. It’s not exactly linear, but with just 4 GPUs (~$4000; well within the reach of any dedicated attacker), that’s one day. Not to mention the fact that GPUs have still been roughly following Moore’s Law in terms of performance. It’s probably safe from the casual attacker who just downloads a…

3DES is a little more secure than plain DES (but still worse than AES)
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