GitHub - SSH Settings (ed25519)

January 10, 2026

This workflow ensures:

  • Secure key (with passphrase)
  • Convenient usage (Keychain remembers passphrase)
  • SSH-only workflow → no HTTPS credentials required

1) Check for existing keys (optional)

ls -la ~/.ssh
  • Look for id_ed25519 / id_ed25519.pub
  • If you already have a key you want to use, skip key generation

2) Generate a new ed25519 key

ed25519 refers to the Ed25519 elliptic-curve algorithm, which is the modern, faster, and more secure replacement for older RSA SSH keys. Replace the email with your GitHub email:

ssh-keygen -t ed25519 -C "nob@example.com"
  • Press Enter to accept default file (~/.ssh/id_ed25519)
  • Enter a strong passphrase

3) Ensure correct permissions

# Private key: ~/.ssh/id_ed25519
# Public key: ~/.ssh/id_ed25519.pub
chmod 700 ~/.ssh
chmod 600 ~/.ssh/id_ed25519
chmod 644 ~/.ssh/id_ed25519.pub

4) Start ssh-agent and add the key

eval "$(ssh-agent -s)"       # start agent in this session
ssh-add -K ~/.ssh/id_ed25519 # -K ensures macOS Keychain remembers the passphrase

5) Copy your public key to clipboard

Show the key and copy it manually:

cat ~/.ssh/id_ed25519.pub

# Or the command
pbcopy < ~/.ssh/id_ed25519.pub

Then select & copy the whole line (starts with ssh-ed25519 ...).

6) Add key to GitHub

  1. Open GitHub in your browser → Settings → SSH and GPG keys → New SSH key.
  2. Give it a title (e.g., “MacBook”) and paste the public key you copied.
  3. Save.

7) Test the connection

Run the command below. First time it may ask to confirm the host fingerprint → type yes.

ssh -T git@github.com

8) Clone the repo with SSH

Now clone with the SSH URL. No username or token needed.

# Clone a new repo
git clone git@github.com:metamototomo/IntelliumX.git

# Update existing repo to use SSH
git remote set-url origin git@github.com:username/repo.git

# Verify
git remote -v

# check which key is used
ssh-add -l