Setting up ssh public key authentication on macOS using a YubiKey 4
I largely followed Florin's blog post, but have a few notes to add regarding issues I encountered:
Basic setup notes
- I used a YubiKey 4, while the blog describes using a YubiKey NEO. I'm sure a YubiKey 5 would also work. I'm also running macOS 10.13.6.
- I installed GPGTools as recommended. However, as I'll note later, it seems that
gpg-agentonly automatically starts when gpg is used; for ssh, you'll need to ensure it's running.
- Before generating your keys, decide what key size you want to use. If you run the
gpg --edit-card, look for the
Key attributesline to see what is currently selected. On my YubiKey 4, it defaulted to 2048 bits for all keys:
Key attributes ...: rsa2048 rsa2048 rsa2048