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Upgrade your SSH keys

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101–110 of 159 posts

Re: Upgrade your SSH keys

#101

Post by lmm »

mastazi wrote: post #23
loeg wrote: post #10

RSA 2048 is still the openssh default, i.e., best current advice from the openssh authors. The fact that this article's author labels that as "yellow" is a red flag.

I agree. It would be nice if the line: > RSA 2048: yellow recommended to change was followed by at least some link that explains why is it unsafe. Could anyone elaborate further? UPDATE: there is now a link up in this thread, from the user fjarlq, which points to an NSA recommendation from 2015. The recommendation seems to be related to the need of having a "quantum computing resistant" key. But with quantum computin…

Many theoretical aspects of quantum computing are well-understood, just as a lot of early work on computational complexity etc. predates the existence of (nonhuman) computers.

Re: Upgrade your SSH keys

#103

Post by svenfaw »

mSparks wrote: post #80
rockdoe wrote: post #76

Earlier quoted context omitted.

You are misunderstanding. Curve25519 offers 128 bits of symmetric security, or the equivalent of a 256 bit elliptic curve key.

even if that is true. its still not enough to protect anything of value.

Absolutely incorrect. Anything above 90-100 bits of effective (symmetric) strength is currently more than enough, even against nation state actors.

Re: Upgrade your SSH keys

#105

Post by tete »

Something I don't understand is the "hate" that RSA gets. Yeah, Elliptic Curves are promising, have benefits (smaller/faster).

But RSA isn't broken, it is well understood, is "boring" (a plus on security, usually), has bigger bit sizes (according to people that know a lot more to me that's a plus point, regardless of EC requiring smaller ones, because of certain attacks), isn't hyped and sponsored by the NSA and isn't considered a bad choice by experts.

Not too many years ago Bruce Schneier was skeptical about EC, because of the NSA pushing for it. Now, I also trust djb and i an sure that ed25519 is a good cipher and there are many projects, like Tor that actually benefit from it, increasing throughput, etc., but for most use cases of SSH that might not be the issue, nor the bottleneck.

So from my naive, inexperienced point of view RSA might seem the more conservative option. And if I was worried about security I'd increase the bit size.

Am I going wrong here?

Re: Upgrade your SSH keys

#106

Post by perlgeek »

So I once read somewhere that RSA is simpler to implement than most other algorithms, and hence it's a safer choice than other algorithms, because weaknesses typically come from suboptimal implementation less than from the cryptographic algorithm. (Unless you use known-broken things like md5 or 3DES).

And I think that was in the context of some DSA or ECDSA weakness, possibly a side channel attack or something similar. I forgot the details :(

What are your thoughts on this? Should we focus more simplicity and robustness of the implementation, rather than just the strength of the algorithm itself?

Re: Upgrade your SSH keys

#107

Post by dozzie »

sillysaurus3 wrote: post #88
Godel_unicode wrote: post #87

Earlier quoted context omitted.

If you're concerned about hostname leakage in your pubkeys, you're almost certainly doing something wrong.

If you want SSH access to Github or Gitlab, you'll need to paste your pubkey there. Leaking your user@host can be a concern if you're trying to maintain anonymity, e.g. Gwern, particularly if your username is your real name. You can strip out the user@host part from the paste, but it's safer to just get rid of it. It's easy to accidentally paste the whole thing into an .ssh/authorized_keys file, for example. Admitted…

Comment section is set to what it is because this is easier way to tell where the public key comes from. It vastly simplifies key management, which is much more important than the tiny bits of anonymity you get from not setting the comment.

Re: Upgrade your SSH keys

#109

Post by acranox »

sillysaurus3 wrote: post #97
glandium wrote: post #94

Earlier quoted context omitted.

If you're trying to maintain anonymity, why is your username your real name?

Even if it's not, your default hostname when using a MacBook Pro is typically " s-MacBook-Pro.local" which reveals you're using a MacBook Pro. That info leak probably doesn't matter, but generally you want to reveal as little information as possible.

What kind of person cares enough about anonymity to change the comment in their ssh key, but not change the default hostname of their Mac? That person is very inconsistent.

Re: Upgrade your SSH keys

#110

Post by minitech »

acranox wrote: post #109
sillysaurus3 wrote: post #97

Earlier quoted context omitted.

Even if it's not, your default hostname when using a MacBook Pro is typically " s-MacBook-Pro.local" which reveals you're using a MacBook Pro. That info leak probably doesn't matter, but generally you want to reveal as little information as possible.

What kind of person cares enough about anonymity to change the comment in their ssh key, but not change the default hostname of their Mac? That person is very inconsistent.

Why does ssh-keygen include unnecessary information by default?
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