I just wanted to post a confirmation on what DigitalNoise tried. I was having the same exact problems with Ubuntu 12.04. I ended up generating the key pair using the Linux ssh-keygen command, moving the contents of the generated public key into ~/.ssh/authorized_keys, and converting the private key into the PuTTY .ppk format.

Did the trick for me after some frustration so thanks for posting your solution!

Pendantic comment - ssh-keygen isn't a Linux command, it's a OpenSSH command developed on OpenBSD and ported to Linux.


Glad it's working though.

I'm more curious as to why Ubuntu 12.04 isn't generating the correct key or format out of the box. I made a post on the Ubuntu official forums but there were only crickets (and, considering those forums... not surprising).

>> I'm more curious as to why Ubuntu 12.04 isn't generating the correct key

It's a different product?

The Ubuntu forums have always been great for me.

Neither Ubuntu nor Putty are using keys wrong, they are just using different key formats.

SSH on Ubuntu 12.04 generates OpenSSH formated keys, it does the same as every other Linux and *BSD. If you want to use key authentication with putty you need to convert them into the .ppk format that putty uses either with puttygen or ssh-keygen.