Possible regression: YubiKey PKCS#11 ECDSA signing on Linux

Hello Stanislav,

Thank you for the detailed report and for testing with OpenSSH. Since the same YubiKey and libykcs11.so work with the native client, the token and the library themselves look fine. I need a few details to narrow down what RDM is doing differently.

1. Which RDM Linux version was the last one where this setup worked, and how did you install RDM (DEB package, Flatpak or something else)?

2. In RDM, open the settings under Application > Paths. Which value is set in "Smart card PKCS library"? Is it /usr/lib/x86_64-linux-gnu/libykcs11.so, or still the default (opensc-pkcs11)?

3. Which type of key does the YubiKey provide? This command lists the public keys exposed by the library, with their type (for example ssh-rsa or ecdsa-sha2-nistp256):
  ssh-keygen -D /usr/lib/x86_64-linux-gnu/libykcs11.so
  Please send me the output. It contains public keys only, so it is safe to share. If the command asks for your PIN, please just tell me, and do not include the PIN in your reply.

4. How is the SSH entry configured? Please tell me:
  - whether "Use smart card" is enabled and whether a PIN is saved in the entry
  - whether a private key or certificate is also set in the entry
  - whether "Use SSH authentication agent" is enabled in the Advanced tab

5. Please send the session log with the highest detail:
  - In the SSH entry, open the Logs tab, enable logging, set "Log path type" to Custom, enter a full path in your home folder such as /home/<your user>/rdm-ssh.log, and set Verbose to 4.
  - Connect once so that the error appears.
  - Send me the log file. Please make sure your PIN does not appear in it.

6. If you can, also send the output of your working command with the extra detail, so we can compare what OpenSSH offers and signs with what RDM does:
  ssh -vvv -I /usr/lib/x86_64-linux-gnu/libykcs11.so user@host

I will review everything as soon as I receive it. I cannot confirm yet whether this is a defect in RDM, so I do not want to promise a fix before we understand the cause.

Best regards,