Browse Prior Art Database

Method for Non-Invasive Certified Mail

IP.com Disclosure Number: IPCOM000013632D
Original Publication Date: 2001-Apr-14
Included in the Prior Art Database: 2003-Jun-18
Document File: 3 page(s) / 30K

Publishing Venue

IBM

Abstract

A method to achieve certfied mail in a fair as well as non-invasive manner is described. This is the first technique to achieve non-invasiveness.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 52% of the total text.

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Method for Non-Invasive Certified Mail

  A method to achieve certfied mail in a fair as well as
non-invasive manner is described. This is the first technique to
achieve non-invasiveness.

Certified mail is a well studied problem where one player (A)
sends a message to another player (B) and expects a
non-repudiable receipt in return. This is an instance of the
general problem of "fair exchange". As usual, the requirement
from A's point of view is that if she does not get a receipt,
then B does not gain any information about the content of the
message. Similarly B's requirement is that if he does not get the
whole message, A must not get any advantage in obtaining a
receipt that is non-repudiable by B.

There have been various solutions to this problem with various
levels of practicality. The so-called "optimistic fair exchange"
solutions, which currently represent the most practical
approaches to certified mail, make use of a trusted third party
to implement certified mail. However, the third party is used
only in exceptional circumstances. All the certified mail
protocols of this type specify the format of the receipt. In this
sense, these protocols are "invasive". It is likely that the
format of receipts are decided due to other considerations (e.g.,
legal and business practice). Hence non-invasive protocols can be
very attractive.

In this article, a certified mail protocol is described which is
non-invasive. The protocol is based on the known optimistic
fair-exchange protocol (N. Asokan, M. Schunter, M. Waidner:
"Optimistic Protocols for Fair Exchange"; Proc. 4th ACM Conf. on
Computer and Communication Security, Zurich, April 1997, pp.6-17,
US patent appl. 09/181442) and uses the same building block
called verifiable encryption.

The new protocol is an improvement over a straight-forward
instantiation of the general fair exchange protocol by requiring
only one of the expensive verifiable encryptions instead of two.

Protocols

As with the optimistic fair-exchange protocol, there are four sub
protocols named "exchange", "A-resolve", "B-resolve", and
"abort". The protocol is explained at a high level. Concre...