
Dear PGP User

Well, finally. After more than three years, we finally have the
long-awaited PGP Version 5.0 ready for release (formerly known as 3.0).
You hold in your hand one of 12 volumes (over 6000 pages!) of the
printed copy of the complete source code to PGP for Personal Privacy,
Version 5.0. In keeping with my own long-standing tradition from the
days before I started this company, our source code is being openly
published to facilitate peer review. This allows everyone to assure
themselves that there are no hidden back doors that might compromise
security.

We are pleased to be able to publish these books without having to
fight an extensive legal battle. As you may know, while a printed book
or other printed material setting forth encryption source is not itself
subject to U.S. Export Administration Regulations, (see EAR §734.3(b)(2)),
the U.S. government says it is considering whether and to what extent
scannable encryption source or object code in printed form should be
subject to regulations. We think this is rather remarkable in light of
the ruling by U.S. District Court Judge Marilyn Hall Patel who said,
"Source code ... is speach afforded by the full protection of the
First Amendment." Bernstein v. United States Dept. of State, 922 F.
Supp. 1426, 1428-30 (N.D.Cal. 1996). In any event, according to both
the export regulations and the court, the publication of this book
is perfectly legal.

It's taken longer than expected to produce this code and these books,
for a variety of reasons, not the least of which was the three-year
criminal investigation I was under from the US government. That really
slowed things down. It cut off nearly all access to my volunteer labor
force that had been so instrumental in the development of PGP versions 2.0
and above. For those of you unfamiliar with the case, the US government
was taking the position that encryption software should not be exported
without a license from the State Department. Since PGP was published for
free on the Internet in 1991 and subsequently spread all around the world,
the government assumed that the law must have been broken. That triggered
the creation of a mostly pro-bono legal defense team, a legal defense fund,
and three years of almost daily press interviews. The press was
overwhelmingly against prosecuting and the cryptographic policy issue
was drawing the wrath of the whole computer industry.

However, the investigation was closed without indictments in January 1996.
Shortly after that, I started my own company, PGP, Incorporated. We hired
a team of full-time engineers to develop products like this new product,
PGP for Personal Privacy, Version 5.0.

This new version has a lot of cool new features. The older version of PGP
(Version 2.6.2, released through MIT) was only for MS-DOS and Unix(tm).
This new version was designed from scratch to provide a graphical user
interface (GUI) environment. These volumes contain source code and tools
that can be used to build versions that run under Windows 95 and Windows NT,
as well as a version for Apple Macintosh. We also have a non-GUI version for
Unix, starting with the Linux platform. The GUI really makes the product
a breeze, with seamless integration into email packages, starting with
Qualcomm's popular Eudora, Microsoft's Exchange, and Microsoft Outlook.
Now using PGP to encrypt or decrypt your mail is just a couple of mouse
clicks away.

The new code also adds some new encryption algorthms. Probably the most
exciting is the introduction of a new public key algorithm that will
serve as an alternative to the RSA algorithm. The Diffie-Hellman and
Hellman-Merkle patents expire this year, opening the door to royalty-free
use of public key algorithms. Everyone will benefit from this, because the
whole computer industry has been forced to work with a public key patent
monopoly that stifled the use of public key algorithms for many years.
Now the field is opening up. PGP offers Diffie-Hellman (the ElGamal variant
of Diffie-Hellman) keys, and the NIST Digital Signature Standard (DSS) keys.
With these new keys comes a range of new features, including improved speed
and security. Also, there are now two separate key pairs for each user,
one pair for encrypting/decrypting (Diffie-Hellman), and one pair for
signing/veryfying (DSS). Today these are presented to the user as if they
were a single key pair. In later releases we will give the user the
capability to change his DH key without changing his DSS key.
To get the full range of benefits, it would be helpful if as much of
the PGP community as possible participates in this migration to the new
public key algorithms.

Our new code also implements new block ciphers for bulk encryption,
offering triple_DES and CAST as options, as well as continuing to support
the IDEA cipher from earlier versions of PGP. We also offer a new signature
hash algorithm, SHA-1, for computing digital signatures. The old hash
algorithm, MD5, developed by RSA Data Security Inc, has been discovered
to have serious weaknesses and is no longer recommended to make digital
signatures. To use the new SHA hash algorithm, users will have to use DSS
as their signature algorithm, because PGP's RSA signatures continue to use
the MD5 hash for backward compatability reasons.

A particularly exciting new feature is the intigration with public key
servers. Now PGP will look up public keys on a remote server on the Internet,
such as the one at MIT. When you generate a new public key, PGP will offer
to upload it to the remote key server. Anyone will be able to get anyone
else's public key whenever they need it. This will tie all PGP users
everywhere together into a global community, with a nationwide public key
infrastructure that no other encryption product can offer. This
infrastructure will grow organically, like the Internet did.


I hope that you will agree that this new release of PGP was worth the wait.


Sincerely,
Philip Zimmermann
Chief Technology Officer, Pretty Good Privacy, Inc.

