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sm-discuss - Re: [SM-Discuss] STRONGER POLICY for gpg signatures to replace MD5[*] and ALSO new SOURCE_HASH support

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  • From: "Sergey A. Lipnevich" <sergey AT optimaltec.com>
  • To: sm-discuss AT lists.ibiblio.org
  • Subject: Re: [SM-Discuss] STRONGER POLICY for gpg signatures to replace MD5[*] and ALSO new SOURCE_HASH support
  • Date: Mon, 29 Aug 2005 16:39:20 -0400

Quoting "Jeremy Blosser (emrys)" <jblosser-smgl AT firinn.org>:

What you're saying is that signing something doesn't mean anything except that
it was signed by <person>. Why then your signature on a blank piece of paper
different from a signature on a contract?

Because of the legally agreed context of the contract. Contracts and other
legal documents usually make this explicit, with language like "we, the
undersigned parties...", and also an explicit list in the terms of the
contact of who is involved. That list combined with the non-repudiation of

Very nice. So you *are* implying that a contract must be read, right? What
happens if it's too long to read or written in a dialect you are not familiar
with?

the signature is what binds the signee to the terms of the contact, not the
signature by itself. I can go out and sign my name on whatever contracts I
want but if I'm not a listed party to the contact it doesn't really mean
anything beyond that I wrote my name on a piece of paper.

My point exactly! So why do that? Why sign your name on a piece of paper if it
*doesn't mean anything*? That's what you do when you sign a tarball having no
idea what's inside.

Even things like mailing invoices usually contain language to make it clear
if you're signing that you just received a box vs. have inspected and
agreed that the contents match the invoice. And even that doesn't say you

That's why I said that doing this is akin to signing a contract simply because
it has no grammar or spelling errors, without understanding the meaning. If I
have a reasonable way to make sure the contract says the right thing, I'd sign
it. But what if I don't? I can's sign such a contract.

But my original statement there has nothing to do with what is easiest. I
said that the primary use and meaning of a cryptographic signature is
transmission integrity verification. That has nothing to do with if there
are other methods to accomplish the same thing.

We're in complete disagreement about this one. I was countering your statement,
not making provisions for what's easier. My point is that there are adequate
ways to ensure integrity without involving non-repudiation and authenticity.

Well if it's a shared key than "framing" means nothing anyway, because
there's no longer non-repudiation at the individual level. And all of
these things already assume our own developers are trusted; if someone
wants to be malicious there are much easier things to attack. I believe
those with the access already share keys for the tarballs we distribute.

Let me give you an example. A spell contains a line:
$EDITOR $SCRIPT
What happens when EDITOR is not set? Right, the script runs. If this script does
rm -fr * (no leading slash) but is run from root, chaos begins. If I wrote this
piece of code and you signed it, who's responsible? My point is, "framing" can
be unintentional.

So, am I getting my freedom back or I have to sign everything in sight with my
name and hope it doesn't destroy your PC? As I said, I'm not asking for
agreement, I'm asking to leave my options open.

Sergey.






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