SSH hacked?

mouss mouss at
Tue Jan 13 22:30:56 UTC 2009

Kent Borg a écrit :
> Kent Borg wrote:
>> Private ssh keys, on the other hand, need to be in the clear to be
>> useful.
> Correction: Private keys can themselves be encrypted and protected by a
> passphrase. But what passphrase will you choose? Are you recycling those
> strings? Or, have you just shifted what your passwords pertain to, but
> not eliminated the problem of managing multiple passwords?

With password authentication, the password is stored (in a hashed form)
on the server, which is the target of attack

when you enter your key passphrase, you enter it on your local client
machine. so an attacker would need access to your client machine, but if
he does so, then he can do a lot of things (think keyloggers ... etc)

and brute forcing the passphrase for a private key is harder than brute
forcing a password. exceptionally when most passwords are few chars long.

but yes, managing multiple secrets maybe a real problem (not only our
passwords, but our credit card PIN, the PIN of the mobile phone, the
passwords on the various web sites that you registered on, ... oh and I
have to type two codes to get home!). password managers can help, but
they are not yet in wide use.

> Also, the server doesn't need the private version of the key.

which is fundamental: an attacker can't simply get a copy an /etc/shadow
(somehow) and crack it on his server.

unfortunately, this comes at a price: the server can't enforce a

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