8.2.2 Selecting the type of key

Before generating a key pair using PuTTYgen, you need to select which type of key you need.

The current version of the SSH protocol, SSH-2, supports several different key types, although specific servers may not support all of them. PuTTYgen can generate:

• An RSA key for use with the SSH-2 protocol.
• A DSA key for use with the SSH-2 protocol.
• An ECDSA (elliptic curve DSA) key for use with the SSH-2 protocol.
• An EdDSA key (Edwards-curve DSA, another elliptic curve algorithm) for use with the SSH-2 protocol.

PuTTYgen can also generate an RSA key suitable for use with the old SSH-1 protocol (which only supports RSA); for this, you need to select the ‘SSH-1 (RSA)’ option. Since the SSH-1 protocol is no longer considered secure, it's rare to need this option.