Yosemite OpenSSH is too old to read ECDSA SSH keys

Posted by Orville Bennett on December 15, 2015
Read time: about 1 minute

Yosemite SSH is too old to read ecdsa SSH keys?

As you may, or may not know, I am a Front-end user interface engineer.1 I got a new Macbook Pro from work recently, to better facilitate my developer duties.2 Prior to this I was working on my personal machine with Arch Linux installed.3 Since linux and the BSDs (on which OS X is based) are so similar, I was able to transfer large portions of my linux environment to OS X with minimal downtime.

Or would have, had I not run into problems with SSH. After copying my ~/.ssh directory from my linux box to OS X, I tried to log in to some remote machines. Much to my chagrin, I recieved the following prompt from our gitolite server indicating problems with SSH pubkey:

ssh -T git@gitserver
git@10.44.91.15's password:

After some searching on the internet I re-ran the command with the -vvv switch as ssh -T git@gitserver:

debug1: Next authentication method: publickey
debug1: Trying private key: /Users/obennett/.ssh/id_ecdsa
debug1: key_parse_private_pem: PEM_read_PrivateKey failed
debug1: read PEM private key done: type <unknown>
Saving password to keychain failed
debug1: key_parse_private_pem: PEM_read_PrivateKey failed
debug1: read PEM private key done: type <unknown>
debug1: Next authentication method: password

My interpretation of this debug output was that OS X Yosemite didn’t support ECDSA SSH keys. Not intending to debug this any further I generated some RSA keys and went along my merry way. The RSA keys worked fine. We call that kind of thing a workaround.

  1. This is the official job title bestowed upon me, but simple Front-end developer will suffice. Although, I do perform a fair bit of server backend (dev ops) duties as well – e.g. setting up and maintaining our gitolite server. 

  2. Well, that and I didn’t like the Dell machine I had. It was a nice machine, but it wasn’t a mac. As I mentioned previously I’d put Ubuntu linux on my macbook pro to work around some very nasty hardware issues in the dedicated video car–issues which rendered my display useless. 

  3. Going with Arch Linux and and there rolling release allows me to have to most up to date packages available.