Upgrade your SSH keys
blog.g3rt.nl
Upgrade your SSH keys
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Re: Upgrade your SSH keys
#2For those who have just updated to macOS Sierra, the default SSH client configuration is to not allow ssh-dss keys any longer.
Follow these instructions to update your keys.
Re: Upgrade your SSH keys
#3I disagree with the author. Before you go upgrading into ed25519, beware that the NSA/NIST is moving away from elliptical curve cryptography because it's very vulnerable to cracking with quantum attacks[0].
"So let me spell this out: despite the fact that quantum computers seem to be a long ways off and reasonable quantum-resistant replacement algorithms are nowhere to be seen, NSA decided to make this announcement publicly and not quietly behind the scenes. Weirder still, if you haven’t yet upgraded to Suite B, you are now being urged not to. In practice, that means some firms will stay with algorithms like RSA rather than transitioning to ECC at all. And RSA is also vulnerable to quantum attacks."
Stick with the battle tested RSA keys, which are susceptible but not as much as ECC crypto. 4097 or even better 8192-bit lengths.
There's no perceptible user benefits to using ed25519 and it's not even supported everywhere. Also you won't have to rotate all of your keys when workable quantum computers start crackin' everything.
[0] https://blog.cryptographyengineering.com/2015/10/22/a-riddle...
Re: Upgrade your SSH keys
#4LOL! nice try obama.
more security with a private key that is only 68 characters! and they claim that is a benefit because of all the copy and pasting you do... you know... because it's so much harder to copy and paste twice as many characters. select all, ctrl-c... OH NO!
and yet it's brute force safe! you know... because making the keyspace smaller by orders of magnitude makes brute force... harder?
elliptic curves! you mean like the last try the NSA did to weaken the privacy of everyone? let me guess... the arbitrary coefficient is 777 again? JACKPOT! WE OWN ALL THE IDIOTS.
you are all idiots.
Re: Upgrade your SSH keys
#5Re: Upgrade your SSH keys
#6If you have any RHEL machines, you might wanna keep an RSA (or ECDSA) key around. RHEL doesn't support Ed25519.
I haven't checked, but I presume this also goes for CentOS, Scientific Linux, and other derivatives.
Re: Upgrade your SSH keys
#7I disagree with the author. Before you go upgrading into ed25519, beware that the NSA/NIST is moving away from elliptical curve cryptography because it's very vulnerable to cracking with quantum attacks[0]. "So let me spell this out: despite the fact that quantum computers seem to be a long ways off and reasonable quantum-resistant replacement algorithms are nowhere to be seen, NSA decided to make this announcement p…
Both RSA and Elliptic Curve will fall to practical quantum computing, so the idea that you should use (weaker, slower) RSA today instead of curves because of QC is... dubious.
If you see quantum computing as a practical threat (because: you're encrypting and storing static data that needs to resist cryptanalysis for 20-50 years), you need to use a post-quantum cryptosystem. Unfortunately: nobody knows which pq systems will truly hold up to practical quantum computing, and it's possible --- even likely --- that implementations of pq schemes have dumb errors that nobody has thought to check for yet.
That's why Google's first foray into deploying pq crypto feeds both a curve computation and a Ring-LWE PQ computation into its KDF, so that unknown bugs in the RLWE exchange can't destroy the security of TLS. That's how you would seriously account for quantum computing in SSH.
The recommendations in this post are solid.
Re: Upgrade your SSH keys
#8[deleted]
Re: Upgrade your SSH keys
#9Can someone explain to me why RSA 2048 is "recommended to change"? It's still the default for gpg keys and as far as I know is widely thought to be secure for at least few hundred years!
Re: Upgrade your SSH keys
#10RSA 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.