New subject: Passphrase validation

24 Jun 2005

That's all well and good for a Unix environment, but what about on Windows?
No chown or chmod on there!
I believe that it is sometimes useful for the passphrase to be requested by
Stunnel on startup (on the client side), but you all make valid points.
Paul.
--- Vasil Dimov [email protected] wrote:
...
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On Wed, Jun 22, 2005 at 04:30:56PM -0700, Joseph
Mocker wrote:
...
...
It depends on how the machine were broken.
Presumably if you
...
were that hell-bent on using passprhases on
private keys, you'd
...
likely isolate stunnel to run as an unpriviledged
user in a chrooted
That is a good idea anyway :)
...
environment, and you may very well set the
coredump size to zero
...
and remove a debugger all together. So unless the
user was able
...
to break root, the effects of the break-in might
be minimized.
Private key stealing table:

the key and the plain text file, holding the

password (if any)
should always be chown root and chmod 400

stunnel is the (unprivileged) user stunnel is

running as

we assume that stunnel is running at the time of

breakage, because
this is the worst case.
key storage \ break as root stunnel other user

unencrypted key YES YES NO

crypted key/password in text file YES YES NO

crypted key/password entered at startup YES YES NO

As we see there is no difference if the private key
will be kept
crypted or unencrypted with or without text file
holding the passphrase.
What happens if the stunnel daemon is not running
during the breakage?
Note that this is an optimistic suggestion and we
should not rely on it.
key storage \ break as root stunnel other user

unencrypted key YES NO NO

crypted key/password in text file YES NO NO

crypted key/password entered at startup NO
NO NO

So the only difference in all cases is if stunnel is
not running and the
hacker gets root on the machine and the key is
crypted and the password
is entered at startup - then it will not be possible
to steal the
private key.
As a conclusion, it is obviously - that there is
really no sense to
keep the password in a text file and it makes a
LITTLE sense if the
password is entered at startup - in just one, rare,
case this setup
will save the private key.
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Re: [stunnel-users] Passphrase validation