How to change key size in OpenSSH?

Question

How to change key size in OpenSSH? I would like to change it from 1024 key size length to 512.

Answer 1

I am pretty sure this is what you are after. You need to use ssh-keygen.

ssh-keygen -t rsa -b 512

this should create a 512 rsa crypto key

Answer 2

There's also a ServerKeyBits option in sshd_config, can set that to a minimum of 512.