

Is a passphrase-protected SSH private key susceptible to a dictionary attack? - Inversechi
https://security.stackexchange.com/questions/39676/is-a-passphrase-protected-ssh-private-key-susceptible-to-a-dictionary-attack

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2bluesc
The accepted answer is somewhat behind the times. Now the best way to secure a
private ssh key is using the the new format utilizing bcrypt's kdf[1] added to
OpenSSH 6.5[2].

The new format makes it significantly harder (read: slower) to crack private
keys, something much needed.

I've been using the new key format with ecdsa and ed25519. It's worth nothing
that and some things like GNOME Keyring's ssh-agent don't support the format
just yet, so things like ssh-add to the agent appear to fail and I haven't
looked any deeper yet.

[1] [http://www.tedunangst.com/flak/post/new-openssh-key-
format-a...](http://www.tedunangst.com/flak/post/new-openssh-key-format-and-
bcrypt-pbkdf)

[2]
[http://www.openssh.com/txt/release-6.5](http://www.openssh.com/txt/release-6.5)

