Re: How can you protect a remailer's keys?

The best solution I could come up with (and was willing to write and use)
is to specify the passphrase on the command line argument to the compiler

make solaris -DPASS="foozooblue"

                -Lance

At 11:55 PM 6/1/96, Bill Stewart wrote:
>Encryption is critical for protecting against traffic analysis,
>but it's tough to protect a remailer's keys.  Unlike regular email,
>where you can type the key in as you read it, remailers need to
>run automatically once you set them up.  Some of the choices are:
>- leave it around in plaintext with only Unix file protections
>        (Ghio2 works this way - does Mixmaster?  My ghio2 version has it
>        compiled into the binary, and I try to delete it from source.)
>- type it in to a long-running remailer process
>        (with human intervention to start)
>- SSL-based remailers, where the web server handles crypto on
>        a per-machine basis instead of per-remailer
>- use unauthenticated Diffie-Hellman (either hanging off
>        a TCP port somewhere instead of mail, or
>        3 pieces of email)
>- off-line or off-site remailer such as a POP3 winsock remailer
>        that makes it Somebody Else's Problem, and separates
>        the remailer's public interface from the working parts
>- human intervention on every message (which may not be totally
>        worthless for moderated news postings, if you want to
>        take that approach to spam prevention.)
>
>Anybody have any other approaches?  These are mostly weak,
>annoying, or both.
>
>
>#                               Thanks;  Bill
># Bill Stewart +1-415-442-2215 stewarts@ix.netcom.com
># http://www.idiom.com/~wcs
>#                               Rescind Authority!

----------------------------------------------------------
Lance Cottrell   loki@obscura.com
PGP 2.6 key available by finger or server.
Mixmaster, the next generation remailer, is now available!
http://www.obscura.com/~loki/Welcome.html or FTP to obscura.com

"Love is a snowmobile racing across the tundra.  Suddenly
it flips over, pinning you underneath.  At night the ice
weasels come."
                        --Nietzsche
----------------------------------------------------------

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> From: loki@infonex.com (Lance Cottrell)
> Date: Tue, 4 Jun 1996 22:02:11 -0700
> 
> The best solution I could come up with (and was willing to write and use)
> is to specify the passphrase on the command line argument to the compiler
> 
> make solaris -DPASS="foozooblue"
> 
>                 -Lance

A far better solution would be to have a long-running daemon hold the
secret key.  The mixmaster client could talk to the key daemon through
a unix-domain socket with the permission bits set such that only the
mixmaster user can connect.  Each time the machine is rebooted, the
operator must start the daemon and give it a passphrase.

This has two advantages.  First, it's a lot harder to back up the key
by accident.  If the key ever starts making it only your daily
backups, you are completely hosed because erasing a bunch of mag tapes
would take a lot of time--and maybe you also want to keep your
backups.

Second, if your machine is seized or someone gains unauthorized
physical access to it, the easiest way to get a root shell is by
rebooting single-user.  However, if the only cleartext copy of a key
is in memory rather than in the filesystem, once the machine is
rebooted the secret key is lost.

- - mix-admin@anon.lcs.mit.edu

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