Just for kicks, I wanted to try using an ECDSA key for ssh authentication. Unfortunately, the OpenSSH bundled with Mountain Lion (10.8) does not support ECDSA keys (nor can one even be generated with ssh-keygen.) The man pages for ssh-keygen and ssh-agent say they support ECDSA, but this is due to a naive man page generation assuming that since the OpenSSL library supports it, OpenSSH will too. Also, a PCI compliant OpenSSH isn’t bundled with OS X Lion (10.7) or older so this will also be useful for those users as well. Thankfully, Homebrew already has a recipe for installing an up-to-date OpenSSH so most of the work of upgrading is already done.