The following is an exerpt from the PGP documentation by Phil
Zimmerman:

Why Do You Need PGP?
====================

It's personal.  It's private.  And it's no one's business but yours.
You may be planning a political campaign, discussing your taxes, or
having an illicit affair.  Or you may be doing something that you
feel shouldn't be illegal, but is.  Whatever it is, you don't want
your private electronic mail (E-mail) or confidential documents read
by anyone else.  There's nothing wrong with asserting your privacy. 
Privacy is as apple-pie as the Constitution.  

Perhaps you think your E-mail is legitimate enough that encryption is
unwarranted.  If you really are a law-abiding citizen with nothing to
hide, then why don't you always send your paper mail on postcards? 
Why not submit to drug testing on demand?  Why require a warrant for
police searches of your house?  Are you trying to hide something? 
You must be a subversive or a drug dealer if you hide your mail
inside envelopes.  Or maybe a paranoid nut.  Do law-abiding citizens
have any need to encrypt their E-mail?

What if everyone believed that law-abiding citizens should use
postcards for their mail?  If some brave soul tried to assert his
privacy by using an envelope for his mail, it would draw suspicion. 
Perhaps the authorities would open his mail to see what he's hiding. 
Fortunately, we don't live in that kind of world, because everyone
protects most of their mail with envelopes.  So no one draws suspicion
by asserting their privacy with an envelope.  There's safety in
numbers.  Analogously, it would be nice if everyone routinely used
encryption for all their E-mail, innocent or not, so that no one drew
suspicion by asserting their E-mail privacy with encryption.  Think
of it as a form of solidarity.

Today, if the Government wants to violate the privacy of ordinary
citizens, it has to expend a certain amount of expense and labor to
intercept and steam open and read paper mail, and listen to and
possibly transcribe spoken telephone conversation.  This kind of
labor-intensive monitoring is not practical on a large scale.  This
is only done in important cases when it seems worthwhile. 

More and more of our private communications are being routed through
electronic channels.  Electronic mail is gradually replacing
conventional paper mail.  E-mail messages are just too easy to
intercept and scan for interesting keywords.  This can be done
easily, routinely, automatically, and undetectably on a grand scale. 
International cablegrams are already scanned this way on a large
scale by the NSA. 

We are moving toward a future when the nation will be crisscrossed
with high capacity fiber optic data networks linking together all our
increasingly ubiquitous personal computers.  E-mail will be the norm
for everyone, not the novelty it is today.  The Government will
protect our E-mail with Government-designed encryption protocols. 
Probably most people will acquiesce to that.  But perhaps some people
will prefer their own protective measures.

Senate Bill 266, a 1991 omnibus anti-crime bill, had an unsettling
measure buried in it.  If this non-binding resolution had become real
law, it would have forced manufacturers of secure communications
equipment to insert special "trap doors" in their products, so that
the Government can read anyone's encrypted messages.  It reads:  "It
is the sense of Congress that providers of electronic communications
services and manufacturers of electronic communications service
equipment shall insure that communications systems permit the
Government to obtain the plain text contents of voice, data, and
other communications when appropriately authorized by law."  This
measure was defeated after rigorous protest from civil libertarians
and industry groups.  

In 1992, the FBI Digital Telephony wiretap proposal was introduced to
Congress.  It would require all manufacturers of communications
equipment to build in special remote wiretap ports that would enable
the FBI to remotely wiretap all forms of electronic communication
from FBI offices.  Although it never attracted any sponsors in
Congress in 1992 because of citizen opposition, it was reintroduced in
1994.  

Most alarming of all is the White House's bold new encryption policy
initiative, under development at NSA since the start of the Bush
administration, and unveiled April 16th, 1993.  The centerpiece of
this initiative is a Government-built encryption device, called the
"Clipper" chip, containing a new classified NSA encryption
algorithm.  The Government is encouraging private industry to design
it into all their secure communication products, like secure phones,
secure FAX, etc.  AT&T is now putting the Clipper into their secure
voice products.  The catch:  At the time of manufacture, each Clipper
chip will be loaded with its own unique key, and the Government gets
to keep a copy, placed in escrow.  Not to worry, though-- the
Government promises that they will use these keys to read your
traffic only when duly authorized by law.  Of course, to make Clipper
completely effective, the next logical step would be to outlaw other
forms of cryptography.

If privacy is outlawed, only outlaws will have privacy.  Intelligence
agencies have access to good cryptographic technology.  So do the big
arms and drug traffickers.  So do defense contractors, oil companies,
and other corporate giants.  But ordinary people and grassroots
political organizations mostly have not had access to affordable
"military grade" public-key cryptographic technology.  Until now.

PGP empowers people to take their privacy into their own hands.  
There's a growing social need for it.  That's why I wrote it.

