From: remail@tamsun.tamu.edu
Date: Fri, 18 Jun 93 00:12:47 PDT
To: cypherpunks@toad.com
Subject: Shorter PGP keys
Message-ID: <9306180712.AA27809@tamsun.tamu.edu>
MIME-Version: 1.0
Content-Type: text/plain


I was thinking of trying to come up with a short form of my PGP key.
Very few people put their PGP keys into their .sig's any more because
they are so lengthy.

Here is my key, 1024 bits, as it would normally appear:

-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: 2.0

mQCNAiqsNkwAAAEEAMKWM52m5EWi0ocK4u1cC2PPyHT6tavk9PC3TB5XBYDegf3d
sldRpnjJj1r+aO08FFO+QLEI9wtBqvf1PPP5iLX7sD2uIVlJH14MPtyVtjm9ZKb8
JMtCW74045BgtHBC9yQ3V7vXNV5jM6dE2ocnH4AI/pBFrGLJPKgTA69YIUw3AAUR
tCZIYWwgRmlubmV5IDw3NDA3Ni4xMDQxQGNvbXB1c2VydmUuY29tPokAlQIFECqu
M1Tidd4O/2f3CwEByrUD/3uoV2y+Fuicrrd2oDawgOw9Ejcx6E+Ty9PVPqKvflLs
0zYyGfeFVSgBbTSDP3X91N3F68nydl9J9VA6QRCGelHM1cZRukCJ0AYbKYfpwUN0
xjEGHsDrd2gT5iWlB3vBZvi+6Ybs4rSq+gyZzVm1/+oRrMen32fz2r0CLgUtHok2
=fF6Z
-----END PGP PUBLIC KEY BLOCK-----

This has a couple of signatures on it and is pretty long.  I stripped
the signatures, figuring that people can get them from a key server,
and that helped quite a bit.  Also, the "Version: 2.x" line is not
currently used, and if you eliminate it you don't need the blank line
after it.  Also, the last line is a checksum for the key and in today's
internet environment you don't have to worry about noise that much.

Stripping all these gives:

-----BEGIN PGP PUBLIC KEY BLOCK-----
mQCNAiqsNkwAAAEEAMKWM52m5EWi0ocK4u1cC2PPyHT6tavk9PC3TB5XBYDegf3d
sldRpnjJj1r+aO08FFO+QLEI9wtBqvf1PPP5iLX7sD2uIVlJH14MPtyVtjm9ZKb8
JMtCW74045BgtHBC9yQ3V7vXNV5jM6dE2ocnH4AI/pBFrGLJPKgTA69YIUw3AAUR
tCZIYWwgRmlubmV5IDw3NDA3Ni4xMDQxQGNvbXB1c2VydmUuY29tPg==
-----END PGP PUBLIC KEY BLOCK-----

This is pretty compact and wouldn't be bad in a .sig.  We've gone from
12 to 6 lines.  I wish there were a mode in which PGP would scan a file
looking not for "-----BEGIN PGP" but rather for lines which are exactly
64 lines long and contain just the RFC1113 (or whatever it's called now)
character set.  I realize it would get fooled by PEM but maybe the user
would only run it if he knew it was a PGP file.  Then you could reduce
the key to four lines.

If you were willing to use a 512 bit key, good enough for casual use,
you could get it down to 3 lines.  This is probably an appropriate
level of privacy for people on multi-user workstations (i.e. as much
privacy as they can expect).

  Hal Finney -- 74076.1041@compuserve.com -- Stripped PGP key:
mQCNAiqsNkwAAAEEAMKWM52m5EWi0ocK4u1cC2PPyHT6tavk9PC3TB5XBYDegf3d
sldRpnjJj1r+aO08FFO+QLEI9wtBqvf1PPP5iLX7sD2uIVlJH14MPtyVtjm9ZKb8
JMtCW74045BgtHBC9yQ3V7vXNV5jM6dE2ocnH4AI/pBFrGLJPKgTA69YIUw3AAUR
tCZIYWwgRmlubmV5IDw3NDA3Ni4xMDQxQGNvbXB1c2VydmUuY29tPg==