PuTTY Key Generator

PuTTYgen is the key generator that ships with PuTTY. It creates SSH key pairs, saves the private key in PuTTY's PPK format, and imports or exports keys in other formats like PEM and OpenSSH. On Windows it's a GUI app installed alongside PuTTY; on macOS and Linux it's a command-line tool called puttygen, installed via 'brew install putty' or 'apt install putty-tools'. This page performs the same generation step in your browser, so nothing needs installing.

The cryptographic key is identical; only the file container differs. OpenSSH keys (what ssh-keygen creates) are what the ssh command on Linux and macOS reads. PPK is PuTTY's own container, which stores the public key, private key, and a tamper-check MAC in one structured text file. PuTTY only loads PPK files, and OpenSSH only loads its own formats, which is why converting between the two is such a common task.

Two steps. First, put the public key line on the server: append it to ~/.ssh/authorized_keys for the user you log in as. Second, point PuTTY at the private key: in the session settings go to Connection > SSH > Auth > Credentials and browse to the .ppk file, then save the session. Alternatively, load the .ppk into Pageant (PuTTY's key agent) and every PuTTY session will use it automatically.

There is no official PuTTYgen GUI for macOS, but the command-line version installs cleanly with Homebrew: 'brew install putty' gives you puttygen in the terminal. Run 'puttygen -t ed25519 -o key.ppk' to generate a key. That said, on a Mac you rarely need PPK at all, since the built-in ssh command uses OpenSSH keys. PPK only matters when the key will be used by PuTTY or WinSCP on Windows.

Keys generated here are saved without a passphrase, because PPK v3's passphrase protection uses Argon2 key derivation that is best done by PuTTY's own tooling. To add one: open the .ppk in PuTTYgen (or run 'puttygen key.ppk -P' on the command line), set a passphrase, and save. From then on PuTTY prompts for it when loading the key, and Pageant asks once per session.