OpenSSH 8.2

#1

Post by beefhash » Fri, Feb 14, 2020, 5:00 AM UTC

OpenSSH 8.2
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Re: OpenSSH 8.2

#2

Post by beefhash » Fri, Feb 14, 2020, 5:14 AM UTC

Notably from the changelog:

It is now possible[1] to perform chosen-prefix attacks against the SHA-1 algorithm for less than USD$50K. For this reason, we will be disabling the "ssh-rsa" public key signature algorithm by default in a near-future release.

Re: OpenSSH 8.2

#3

Post by _-___________-_ » Fri, Feb 14, 2020, 6:16 AM UTC

Notable in this release is support for generating and using keys backed by FIDO/U2F tokens (and, with supported tokens, keys fully resident in FIDO/U2F tokens that you can transport between computers).

Re: OpenSSH 8.2

#4

Post by RL_Quine » Fri, Feb 14, 2020, 6:34 AM UTC

beefhash wrote: post #2

Notably from the changelog: It is now possible[1] to perform chosen-prefix attacks against the SHA-1 algorithm for less than USD$50K. For this reason, we will be disabling the "ssh-rsa" public key signature algorithm by default in a near-future release.

Just for fun, most users on Github have RSA keys exclusively.

Did you know that your SSH keys are public on Github?

https://github.com/taylorotwell.keys

https://github.com/alexcrichton.keys

https://github.com/andrew.keys

https://github.com/egoist.keys

https://github.com/fabpot.keys

Some of the most popular users even have DSS keys.

Re: OpenSSH 8.2

#5

Post by mongol » Fri, Feb 14, 2020, 6:44 AM UTC

beefhash wrote: post #2

Notably from the changelog: It is now possible[1] to perform chosen-prefix attacks against the SHA-1 algorithm for less than USD$50K. For this reason, we will be disabling the "ssh-rsa" public key signature algorithm by default in a near-future release.

What does chosen-prefix mean?

Re: OpenSSH 8.2

#6

Post by egyiedfyfrtjjf » Fri, Feb 14, 2020, 6:47 AM UTC

RL_Quine wrote: post #4

beefhash wrote: post #2

Notably from the changelog: It is now possible[1] to perform chosen-prefix attacks against the SHA-1 algorithm for less than USD$50K. For this reason, we will be disabling the "ssh-rsa" public key signature algorithm by default in a near-future release.

Just for fun, most users on Github have RSA keys exclusively. Did you know that your SSH keys are public on Github? https://github.com/taylorotwell.keys https://github.com/alexcrichton.keys https://github.com/andrew.keys https://github.com/egoist.keys https://github.com/fabpot.keys Some of the most popular users even have DSS keys.

As a RSA-user myself, because I learnt about ssh through the github setup guides: Will ssh-keygen generate a secure key if I don’t pass it any parameters?

Re: OpenSSH 8.2

#7

Post by microtonal » Fri, Feb 14, 2020, 6:47 AM UTC

The FIDO/U2F support is really nice! Though I had a question about this: is it only necessary for the client to use an OpenSSH version (>= 8.2) that supports this, or should the server also have support?

Re: OpenSSH 8.2

#8

Post by RL_Quine » Fri, Feb 14, 2020, 6:49 AM UTC

egyiedfyfrtjjf wrote: post #6

RL_Quine wrote: post #4

Earlier quoted context omitted.

Just for fun, most users on Github have RSA keys exclusively. Did you know that your SSH keys are public on Github? https://github.com/taylorotwell.keys https://github.com/alexcrichton.keys https://github.com/andrew.keys https://github.com/egoist.keys https://github.com/fabpot.keys Some of the most popular users even have DSS keys.

As a RSA-user myself, because I learnt about ssh through the github setup guides: Will ssh-keygen generate a secure key if I don’t pass it any parameters?

I haven't built the new version, but I assume it defaults to ed25519 now. You can otherwise make one with ssh-keygen -t ed25519.

Re: OpenSSH 8.2

#9

Post by zimmerfrei » Fri, Feb 14, 2020, 6:50 AM UTC

RL_Quine wrote: post #4

beefhash wrote: post #2

Notably from the changelog: It is now possible[1] to perform chosen-prefix attacks against the SHA-1 algorithm for less than USD$50K. For this reason, we will be disabling the "ssh-rsa" public key signature algorithm by default in a near-future release.

Just for fun, most users on Github have RSA keys exclusively. Did you know that your SSH keys are public on Github? https://github.com/taylorotwell.keys https://github.com/alexcrichton.keys https://github.com/andrew.keys https://github.com/egoist.keys https://github.com/fabpot.keys Some of the most popular users even have DSS keys.

You are conflating RSA (the algorithm) with "ssh-rsa" (the option of the SSH suite indicating authentication with RSA in combination with SHA-1). They deprecate the latter.

Other options also based on RSA such as "rsa-sha2-256/512" are fine and will remain supported. In other words, the security problem is not with RSA per se.

Having said that, I have not checked whether the people you list have RSA keys bound to SHA-1...

Re: OpenSSH 8.2

#10

Post by [deleted] » Fri, Feb 14, 2020, 6:59 AM UTC

zimmerfrei wrote: post #9

RL_Quine wrote: post #4

Earlier quoted context omitted.

Just for fun, most users on Github have RSA keys exclusively. Did you know that your SSH keys are public on Github? https://github.com/taylorotwell.keys https://github.com/alexcrichton.keys https://github.com/andrew.keys https://github.com/egoist.keys https://github.com/fabpot.keys Some of the most popular users even have DSS keys.

You are conflating RSA (the algorithm) with "ssh-rsa" (the option of the SSH suite indicating authentication with RSA in combination with SHA-1). They deprecate the latter. Other options also based on RSA such as "rsa-sha2-256/512" are fine and will remain supported. In other words, the security problem is not with RSA per se. Having said that, I have not checked whether the people you list have RSA keys bound to SHA…

[deleted]