An SSH key is a pair of files. The private key stays on your computer and proves who you are. The public key is safe to share: you give it to a server, and the server lets in whoever holds the matching private key. No passwords.
1. Check whether you already have one
On Linux, macOS, or Windows PowerShell:
ls ~/.sshIf you see id_ed25519.pub (or id_rsa.pub), you already have a key. Skip to step 3.
2. Make a new key
Linux, macOS, and Windows 10 or 11 (in PowerShell) all come with OpenSSH. Run:
ssh-keygen -t ed25519 -C "you@example.com"- Press Enter to save it in the default place.
- Choose a passphrase. It protects the key if someone copies your laptop’s files. You can leave it empty, but you shouldn’t.
On Android, install Termux, then run pkg install openssh and the same ssh-keygen command.
3. Find your public key
cat ~/.ssh/id_ed25519.pubIt’s one line that starts with ssh-ed25519. That line is what you paste when you join mukto.net, or add to a git forge.
Keep the private key private
The file without .pub on the end, id_ed25519, never leaves your computer. Don’t paste it anywhere, don’t email it, don’t commit it to git. If you think someone has it, make a new key and replace the old public key everywhere you used it.
Don’t want to type the passphrase every time?
Add the key to your SSH agent once per login session:
ssh-add ~/.ssh/id_ed25519