SSH Key authentication fails when RFC4716 format Keys used

Issue Summary

When using SSH key authentication, a confusing error can appear in the UI or logs if the incorrect SSH key format is used.

Example Steps to Reproduce

1. Create an RSA SSH Key Pair using ssh-keygen

   ssh-keygen -t rsa
   

2. Add the Public Key to your Bitbucket Cloud account
3. Upload the Private Key to a Linked Repository configuration
4. Test the repository connection

Expected Results

The connection test is successful

Actual Results

The connection test fails, and the following exception is thrown in the UI:

Cannot decode connection params.

Notes

This occurs when the version of OpenSSH has RFC4716 as the default key format.
The SSHJ Library that Bamboo uses does not support the SSH2/RFC4716 keys.

• https://github.com/hierynomus/sshj/issues/276

Workaround

Create the key using PEM format, which RFC4716 replaced. For example:

ssh-keygen -m PEM -t rsa