Announcing Bellcore's Trusted Software Integrity (Betsi) System

A N N O U N C I N G ! ! ! ! !


           Bellcore's Trusted Software Integrity (Betsi) System.


Betsi addresses a security concern of software distribution in the Internet.
Currently, there is no way to know that software obtained by anonymous ftp
has not been modified since it was posted. Also, malicious software can be
posted without the offender leaving a trace. Betsi is an experimental prototype 
that is meant to provide some degree of assurance about the integrity
of software and the identity of its author. 

The current version of Betsi is an experiment. The long-term 
goals are:
   
   -  help software venders distribute programs and patches 
   -  provide accountability by linking the author of a program
      to a real person whose identity is verified off-line 
   -  allow users to run software obtained on the Internet with
      less danger of viruses and trojan horses 
   -  use cryptographically strong techniques to preserve file
      integrity
   -  scale well in the Internet community
   -  minimize effort on the part of the users
   -  use existing infrastructure and standards

Betsi is a free, experimental service. It requires use of pgp to
verify signatures from Betsi. Betsi's public key is widely available.
It can be obtained from numerous public key servers by requesting
the key for certify or Betsi. It also appears in a paper that
was submitted for publication, in the help file (described in a moment)
and at the end of this message.

For additional information on Betsi send mail to
certify@bellcore.com with subject, help. 

A copy of the paper describing Betsi can be obtained by anonymous
ftp from thumper.bellcore.com in the directory /pub/certify.
A copy of the public key for Betsi can also be found there.
It is recommended that the key be obtained from at least two
different places and compared.


Betsi's public key:

-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: 2.6

mQCNAi5I0LwAAAEEAJZi970w+Lb7onAmrnExWKrgUFbjJku29qVRlBY6/UtUH+fW
s7MtAEUKIhktJ0cDpE+5Tbi6Lev2RXmXhT1hEjwxSwVFOMJmOuMZxlj+586IKigC
vVjF+hCFKQWRXsleM/axVbpH+pNUmWcK6QMdBDFlzS/9pxdAiBPcEwSgd4ahAAUR
tBxCZXRzaSA8Y2VydGlmeUBiZWxsY29yZS5jb20+iQB1AgUQLkjREpti/eSkC5bZ
AQFzNwL8CVk6J8jhHukKKjrkdZX5VZMwuvgs7+ZIVR8fY+vpEBs6EbWAQpmm4ekV
C4D6UOYCRxARpQN09M1aE9qSz6XKkYQjs9Ul/xRLtazDAuYOAkRxO3mnrFa2u6Tc
+qXcZame
=68fV
-----END PGP PUBLIC KEY BLOCK-----

Fingerprint:

5F 34 26 5F 2A 48 6B 07  90 C9 98 C5 32 C3 44 0C

In article <199408291628.MAA19544@faline.bellcore.com>,
Avi Rubin <rubin@faline.bellcore.com> wrote:
>-----BEGIN PGP PUBLIC KEY BLOCK-----
...
>-----END PGP PUBLIC KEY BLOCK-----
>
>Fingerprint:
>
>5F 34 26 5F 2A 48 6B 07  90 C9 98 C5 32 C3 44 0C

I've seen this sort of thing several places...

Am I totally off base in thinking that distributing the fingerprint in
 the same way as the public key is close to totally pointless?
-- 
L. Todd Masco  | "Which part of 'shall not be infringed' didn't
cactus@bb.com  |   you understand?"

-----BEGIN PGP SIGNED MESSAGE-----

> In article <199408291628.MAA19544@faline.bellcore.com>,
> Avi Rubin <rubin@faline.bellcore.com> wrote:
> >-----BEGIN PGP PUBLIC KEY BLOCK-----
> ...
> >-----END PGP PUBLIC KEY BLOCK-----
> >
> >Fingerprint:
> >
> >5F 34 26 5F 2A 48 6B 07  90 C9 98 C5 32 C3 44 0C

> I've seen this sort of thing several places...

> Am I totally off base in thinking that distributing the fingerprint in
>  the same way as the public key is close to totally pointless?

Distributing the key fingerprint allows J. Random Human to correlate a
key supplied via one method with that supplied via another. For
example, now that I have the fingerprint for the Betsi key, I can
verify whether any other alleged Betsi key I see is real or not.

It's a lot easier to read off & cross-check 32-character fingerprints
than the entire key block, especially as signatures are added and the
key block grows in size.

- -Paul

- -- 
Paul Robichaux, KD4JZG        |  Demand that your elected reps support the
perobich@ingr.com             |  Constitution, the whole Constitution, and
Not speaking for Intergraph.  |  nothing but the Constitution.

-----BEGIN PGP SIGNATURE-----
Version: 2.6

iQCVAgUBLmJSdKfb4pLe9tolAQEZkgP/W7P8Edw8sEI78V3HgtDjXDo/F09Gw7VF
4FH6pMIVT9w/jT30Adf6BxL+dhb1mcHuBhnhr7bIA31cerZpt+NiVwBbqAoSh+XW
vFfkId5k3qmUIAypFQFe5BSHKS+yF6Rf8ERXZAFv2+a/ZJrpLxnW6FgFiU+dFt86
KEK/5EFiOCw=
=qlgk
-----END PGP SIGNATURE-----

I've revised my opinion: It's not close to useless, it's worse than
 useless.

Two things people seem not to be getting:

	1. Including the fingerprint with a signed message is much less
		pointless.  This was distributing the fingerprint *with
		the public key*.  That's bogus. However, even were
		this a signed message rather than a key...

	2. Encouraging people to trust the included ASCII fingerprint is
		a Bad Thing.  Why not just include these fingerprint
		things and not bother with this confusing, patented
		RSA stuff?  Much easier that way.

Great.  Here's the Betsi key, with the fingerprint included for those
 who don't want to use PGP to do the computation.

-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: 2.7

mQA9Ai5iKZAAAAEBgMAWW4+5FhyI3A5g4BT7bX8HwC6Ql4rwD/VlCNZnWZefReA5
CMJ+ot/oLrWaACcuJQAFEbQWQmV0c2kgPGNlcnRpZnlAYmIuY29tPg==
=9juv
-----END PGP PUBLIC KEY BLOCK-----

Fingerprint:

5F 34 26 5F 2A 48 6B 07  90 C9 98 C5 32 C3 44 0C

[Security or ease of use.  Choose one.]
-- 
L. Todd Masco  | "Which part of 'shall not be infringed' didn't
cactus@bb.com  |   you understand?"

[Not all observations are mine: some belong to Andrew Boardman]

Okay, I have a strong interest in this, because we want to be able to
 distribute ICE through traditional "freeware" channels while minimizing
 the threat of spoofing.

I expect much better from Bellcore.

>Betsi addresses a security concern of software distribution in the Internet.
>Currently, there is no way to know that software obtained by anonymous ftp
>has not been modified since it was posted.

Whoever wrote the blurb clearly wasn't aware of (or chose to ignore)
 the already existing practice of individuals signing their own code.

Why channel everything through this one Betsi agent?  If Betsi's key
 is compromised, *ALL* of their customers lose.

>   -  provide accountability by linking the author of a program
>      to a real person whose identity is verified off-line 

This is unnecessary, and I would claim undesirable.  A unique anonymous
 ID is just as good as a "real" one -- since you're relying upon PGP
 anyway, the mapping from signature to a known identity is one-to-one.

The only reason I can see to require this "real human" mapping is
 to try to prosecute people for bugs in their code or some contamination
 that seeps into their release.

That's not an aspect of the world I want to live in.

>   -  minimize effort on the part of the users

This, I'd love to see.  How do you securely get a user who doesn't know
 how to use PGP to verify the signature?  I think most users out there
 are not likely to learn to use PGP on their own: this is from too
 many (3+) years of tech support at Carnegie Mellon -- hardly a
 technological backwater.  People want to use their application and not
 worry about anything else.  Make the damned computer work and let
 me finish my paper and get out of here.

I guess my overall reaction to this Betsi thing is: why?

As far as I can see, this Betsi agent only sets up a single choke point
 through which all software using Betsi can be compromised, for no
 particular gain.  The current method of individuals signing their
 code with their well-known keys is far more secure and doesn't force
 the handing over of identities to the Software Police.
-- 
L. Todd Masco  | "Which part of 'shall not be infringed' didn't
cactus@bb.com  |   you understand?"