The Appraiser
by Roedy Green ©1996-2009 Canadian Mind Products
This essay does not describe an existing computer program, just
one that should exist. This essay is about a suggested
student
project in Java programming. This essay gives a rough overview of how it
might work. I have
no source, object, specifications, file layouts or
anything else useful to implementing this project. Everything I have to say to
help you with this project is written below. I am
not prepared to help
you implement it; I have too many other projects of my own.
I do contract work for a living, which could include writing a program such as
this. However, I don’t do people’s homework
for them. That just robs them of an education.
You have my full permission to implement this project in any way you please and
to keep all the profits from your endeavor.
Introduction
This is a tool for appraisers of jewelry, houses, cars, horses etc. The problem with a written appraisal is there is no
way to know just by looking at it if it is genuine. To be sure, the buyer has to contact the appraiser, and check. There
is possibility for fraud in counterfeit appraisals, totally bogus appraisals, in setting up phony appraisers or people
who masquerade as known legitimate appraisers.
The idea is to use digital signing to validate appraisals.
How It Works
The signing authority issues digital certificates to appraisers, charging them a fee. The digital certificate they
receive attests to the qualifications they claim, and to the identity they claim. It is otherwise almost identical to a
Java code-signing private/public key certificate you would buy from Thawte. The appraisers digitally sign their
appraisals with their certificate’s private key. The appraisal may contain text, HTML, images, a date, and of
course a dollar figure.
People who have had their homes appraised for example, could get a yearly update purely electronically. Electronic
appraisals would have an official expiry date.
To validate an electronic appraisal, you get the seller to email it to you. You run a Java Web Start validator program
that downloads its code from the signing authority. That code then does the verification. It does not need online access
to either the signing authority or the appraiser to work. It would easily fit into a laptop, but probably not a hand-held
just yet.
The validation program verifies the electronic signature and can assure you that the appraisal was indeed made by that
appraiser, and some details about that appraiser’s qualifications.
Revocation
Let us say some years down the road somebody stole a copy of an appraiser’s private key certificate or even
figured out how to crack the system entirely. Because the client program is Java Web Start, it would soon know about the
problem, and could request more secure replacement appraisals for any it hand on file.
Fraud
The simplest fraud is to offer to validate the appraisal using phony software that looks like the real thing. Always
use your own computer to validate appraisals.
Always use your own copy of the software to validate appraisals.
Always use your own Internet connection to get software updates.