USAFE: the use of the USAFE command
===================================

An archive can be protected by one or more uncrackable, unbreakable
and unforgeable UltraSeals. Checking if an archive has seals, and if
these are intact, is done with USAFE.

An archive with one or more seals cannot be changed without breaking
these seals. This prevents virus infection, cracking, etc.. Each seal
contains information about who put it on the archive. This information
always includes name and address.

This document contains the following paragraphs:

        - A. Command
        - B. How secure are these seals?
        - C. How to create seals?
        - D. Very important note!
        - E. Error levels
        - Z. Summary


1.A COMMAND.
============

Command: USAFE arch

   The archive arch.uc2 is verified.

If the archive is protected by one or more UltraSeals, USAFE verifies
if all these seals are intact. USAFE reports if seals are present, and
if they are intact. If seals are broken this is reported as well.


1.B HOW SECURE ARE THESE SEALS?
===============================

The principle of 'authenticity verification' is not new. Many archivers
are doing it already. BUT most of these are based on 'security by
obscurity'. They keep their method secret and hope nobody finds out
how it works. For most of these archivers, some or multiple ways of
cracking them are known. Sometimes even a program to automate forging
is available!

USAFE is NOT based on 'security by obscurity'. It is build on digital
signature technology. The digital signature technology, USAFE uses, is
based on Lucas Exponentiation. It uses prime factors of 300 and 400
bits, which is much more than the current industry standard safety
limits. No known technology exists for breaking these signatures in
feasible time.

USAFE is slower than weaker authenticity verification methods. But this
is the price you have to pay for real, instead of fake security. On a
386/33 machine USAFE needs about 7.5 seconds for each seal.


1.C HOW TO CREATE SEALS?
========================

Seals are created by USEAL.EXE which is only directly available from
AIP-NL. It is the only product we do not distribute via resellers. Each
USEAL.EXE is distributed on a seperate diskette. Each distributed
diskette is unique.


1.D VERY IMPORTANT NOTE!
========================

ALL software AIP-NL will ever ship, will be protected by a seal. This
includes upgrades etc.. If you discover files which claim to be from
AIP-NL, but are not protected by a seal, DO NOT USE THEM, but report
them to AIP-NL immediately.


1.E ERROR LEVELS.
=================

USAFE returns an 'errorlevel' to DOS (e.g. for detection in batch
files). The following levels are defined:

   0   the archive contains one or more seals which are all intact

   1   the archive does not contain any seals

   2   the archive contains one or more seals, which are broken

   3+  other errors


1.Z SUMMARY.
============

USAFE arch    verifies the UltraSeals (if present) in arch.uc2