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SFTP (SSH2) doesn't support ed25519?

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  • SFTP (SSH2) doesn't support ed25519?

    I have been using an ecdsa key pair to authenticate my SSH connections from my desktop to my local servers. I was able to SSH into a local server as root via a terminal without any password challenge.

    I set up SFTP(SSH2) 'root' user profiles for each of my servers in Beyond Compare (specifying the SSH private key file and a blank password), and that worked great.

    Recently I upgraded to a ed25519 key pair, and while I can still SSH via terminal into those same accounts, Beyond Compare no longer connects.

    Even though the password field is blank and the correct SSH private key file is specified in the profile, I still get an 'Invalid Login' dialog, and the following in the log window:

    01/29/2017 12:28:33 PM Connecting to matrix
    01/29/2017 12:28:33 PM Server key [DSS 1024 xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx]
    01/29/2017 12:28:33 PM No more authentication methods available
    01/29/2017 12:28:33 PM Connection closed.
    01/29/2017 12:28:33 PM Connection failed: Connection lost (error code is 115)
    01/29/2017 12:28:36 PM Unable to load sftp://root@matrix/: Connection lost (error code is 115)

    Is this due to a lack of support for ed25519, and if so, is there an update coming that will address this?


    --- ADDITIONAL INFO: ---

    Beyond Compare 4 64-bit Edition v4.1.9 build 21719 on Debian Jessie

    I have OpenSSH 7.4 installed, and I'm running ssh-agent with my X-session. I was using a passphrase along with the ed25519 key initially, but I eventually removed it from the key, thinking that was what was causing the issue with BeyondCompare. I still have no ability to connect with the ed25519 key, even without a passphrase, so ssh-agent is probably not relevant here.

  • #2

    Thanks. We can confirm that ed25519 keys aren't supported by our current library. If there are any other keys set up in ssh-agent or the Profile settings, BC4 will attempt to use them (and prompt for Passphrase if needed), and if none of them work we'll then prompt for Password if that authentication method is available.

    Enhancing our key support is something on our radar, but would require the library to update its support or finding another solution.
    Aaron P Scooter Software


    • #3
      Are there any plans to make ed25519 keys supported, by upgrading the library sooner, rather than later? (Curious: what library is BC dependant on?)
      Every couple of months or so, this article, , resurfaces on HN and other sites. I would definitely use Beyond Compare more if I could use my ed25519 key pair. Having to use another client or a different key pair is annoying.


      • #4
        Thanks for the feedback. This isn't a feature we've been able to tackle yet, but this is a great resource link and I'll add it to our wishlist entry on the subject.
        Aaron P Scooter Software


        • #5


          • #6
            Thanks, ed25519 support is still on the todo list for a future version of Beyond Compare. Releasing a 64-bit Mac version (BC 4.3) and the first few rounds of bug fixes has dominated our development schedule. Once 64-bit Mac settles down we plan to get back to other items on our todo list.
            Chris K Scooter Software