PuTTYgen for Mac

Free SSH key generator

PuTTYgen is a free and open-source key generating software. It is one of the components of the networking client called PuTTy. Its basic function is to create public and private SSH key pairs to be used with WinSCP. The app generates RSA, DSA, ECDSA, and Ed25519 keys, which are public-key cryptosystems focused on secure data transmission and digital signatures. As a component of PuTTy, you can find PuTTYgen inside its window. However, you can also download it separately.

Using PuTTYgen

When you run the PuTTYgen the app, you will see two main choices. You can generate a new key pair or load an existing one. When creating a new one, you need to select which type of key you want and its corresponding strength. Then press the Generate button and wait for the app to generate the key. Once done, select a comment field and a passphrase. You can then save the private key to disk, and your key pair is ready to use.

The public key can be copied to your server by either copy-pasting it from the public key to the OpenSSH authorized_keys file box or through the Save public key button. You don't need to do it immediately. If you want, you can load the private key back into the app later. Then the public key will be available for copying and pasting. You can also load existing key pairs to the app, which can change its passphrase and comment. You can even make extra copies of the public key.

Before generating a key pair, it is important to know the type of key that PuTTYgen supports. The app currently supports key types for both SSH-2 and SSH-1 protocols. However, SSH-1 only supports one key, which is Rivest–Shamir–Adleman (RSA). Meanwhile, SSH-2 supports multiple key types, including Digital Signature Algorithm (DSA), Elliptic Curve Digital Signature Algorithm (ECDSA), and Ed25519.

Final thoughts

PuTTYgen is a useful networking tool that allows users to generate SSH keys. It simplifies the process and creates new key pairs with a few clicks. Moreover, it allows the loading of existing ones so that you can make changes to them. The app is not strictly related to PuTTy. You can even download it separately if you only need to generate public and private key pairs. However, PuTTy users will need it for the creation of the SSH keys.