Subject: Re: Common misconceptions, was Re: KISS for PKIX. (Was: RE: ASN .1vs XML (used to be RE: I-D ACTION :draft-ietf-pkix-scvp- 00.txt ))

From: [email-masked]
Date: Mon, 2 Aug 1999 01:00:51 -0700

note that while software trojan horse can result in signing of incorrect data on
payment transactions .... that exploit is significantly smaller than current
situation where knowing the account number and a trivial number of other details
allows arbritrary generation of transactions from scratch. no trojans &
non-repudiation is better than trojans & repudiation ... but either one is a
great deal better than existing situation.

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From: Stephen Kent <[email-masked]>
Date: Tue, 3 Aug 1999 14:34:34 -0400

Eric,

>I believe a prompt (challenge) for a password to enable use of the private
>key for signing purposes is necessary in some instances. Automatic signing
>of a message by software always creates the potential for a repudiation
>claim by the sender, either because the software was accessed by an
>unauthorized party to effect an unauthorized transaction or because the
>authorized party is attempting to defraud by claiming the transaction was
>not authorized. In either case, the burden is on the recipient to prove
>otherwise.

A user has no direct evidence of what is being signed on his behalf,
because a lot of software and hardware is between the user and the
signature mechanism.  One may argue that some form of user prompt is
useful, but that is not a solution to the underlying problem.  Also, a user
prompt is not what we mean when we talk about "challenge-response" in this
technical environment.

Steve