8.2.3 Selecting the size (strength) of the key
The ‘Number of bits’ input box allows you to choose the strength of the key PuTTYgen will generate.
- For RSA, 2048 bits should currently be sufficient for most purposes.
- For ECDSA, only 256, 384, and 521 bits are supported. (ECDSA offers equivalent security to RSA with smaller key sizes.)
- For Ed25519, the only valid size is 256 bits.