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              Pretty Good Privacy version 2.6.2i - READ ME FIRST
                          Notes by Stale Schumacher
                                 1995/05/07


You are looking at the README file for PGP release 2.6.2i. PGP, short for
Pretty Good Privacy, is a public key encryption package; with it, you can
secure messages you transmit against unauthorized reading and digitally sign
them so that people receiving them can be sure they come from you.


ABOUT THIS VERSION

PGP 2.6.2i is not an official PGP version. It is based on the source code for
MIT PGP 2.6.2 (the latest official version of PGP) and has been modified for
international use. PGP 2.6.2i is probably illegal to use within the USA, but
is fine in almost every other country in the world. This file only explains
what is special to version 2.6.2i. For a more thorough installation and usage
guide, refer to the file setup.doc and the documentation for PGP 2.6.2, which
is included unmodified in the doc/ subdirectory that is created when you unpack
the distribution archive.


BACKGROUND

Until about a year ago, there were only two "real" PGP versions around: PGP
2.3a which was the international freeware version, and 2.4 which was a
commercial version sold in USA by a company called ViaCrypt. However, this
situation changed dramatically in May 1994 when MIT released a special US
freeware version of PGP (2.5), in order to put an end to the legal problems
surrounding PGP. (PGP 2.3a was believed to be illegal in USA because of patent
restrictions.) The new version had a number of limitations to encourage
Americans that were using 2.3a illegally to upgrade to the legal version.
However, these limitations resulted in a well of new PGP versions, more or
less professionally put together by well-intending individuals who wanted a
more flexible PGP than that offered by MIT. Suddenly, we had ten different PGP
versions, not two.

Even though PGP 2.5 and later releases from MIT introduced many bug-fixes and
improvements over 2.3a, many non-US users of PGP have been reluctant to
upgrade to the new versions because they feel that the PGP developers have
abandoned the international PGP community by adding a number of restrictions
that are only necessary within the USA. That is why I decided to make PGP
2.6.i (and later 2.6.2i): to put an end to all the PGP "hack versions" that
flourish, and by giving the non-US users of PGP a version that is more
"digestible" than those offered by MIT, and at the same time let them benefit
from all the improvements that the new versions have introduced over PGP 2.3a.
PGP 2.6.2i is a "real" 2.6 version, as it is based on the code tree for PGP
2.6.2 and not 2.3a. This release is basically a bug-fix for PGP 2.6.i, which
was based on PGP 2.6.1.


HOW WAS IT DONE?

PGP 2.6.2i was put together by taking all the source files from PGP 2.6.2,
adding a few #ifdef's and modifying a handful of lines - and that's it. In
fact, the use of #ifdef's wherever a change has been made allows you to compile
a version that is byte-identical to MIT PGP 2.6.2. This is accomplished by
adding the -DMIT option when building the program, and by linking it with the
RSAREF library (rsaglue2) rather than MPILIB (rsaglue1). Many of the
accompanying text and documentation files for PGP 2.6.2 have also been updated
in this release, as this had not been done since PGP 2.3a. In addition, a few
minor but annoying bugs in PGP 2.6.2 have been corrected. For a detailed list
of all the changes between 2.6.2 and 2.6.2i, see the file diffs.doc.


DISTRIBUTION

PGP 2.6.2i is distributed in the following files:

- - pgp262i.zip      This is the MS-DOS executable release, which includes the
                   executable, support files, and basic documentation.

- - pgp262is.zip     This is a source code release, which includes all the
                   source code needed to compile PGP and examples of usage.
                   It also contains all the files in pgp26i.zip except the
                   pgp.exe binary.

- - pgp262is.tar.gz  This contains exactly the same files as pgp26is.zip,
                   except that they use Unix rather than MS-DOS line end
                   conventions.

If you are within the USA, you should download the files pgp262.zip,
pgp262s.zip or pgp262s.tar.gz instead.


DIFFERENCES BETWEEN PGP 2.6.2i AND 2.6.2

PGP 2.6.2i differs from MIT PGP 2.6.2 in the following ways:

  (1) It identifies itself as version 2.6.2i

      This is to clearly distinguish it from PGP 2.6.2. This is important
      because users within the USA should not use PGP 2.6.2i, and also because
      script files, shells and other PGP add-ons may need to know exactly how
      your copy of PGP will behave under different circumstances.

  (2) It uses PRZ's MPILIB instead of RSAREF

      PGP 2.3a and earlier versions use a special library for all the RSA
      encryption/decryption routines, called MPILIB, and written by Philip R.
      Zimmermann (PRZ), the original author of PGP. However, starting with
      version 2.5, all official releases of PGP have been using the RSAREF
      library from RSADSI Inc, a US company that holds the patent on the RSA
      algorithm in the USA. This change was made in order to make PGP legal
      to use within the USA.

      Please observe that PGP 2.6.2i does NOT use RSAREF, but rather PRZ's
      original MPILIB library, which is functionally identical to RSAREF and
      slightly faster on most platforms. Because 2.6.2i uses MPILIB rather
      than RSAREF, this PGP version is also able to verify key signatures made
      with PGP 2.2 or earlier versions. This is not true for MIT PGP, because
      the RSAREF library only understands the new PKCS signature format
      introduced in PGP 2.3.

      The use of the MPILIB library is the main reason why PGP 2.6.2i is
      probably illegal to use within the USA. If you are in the USA, you
      should compile the source code using the -DMIT option and link it with
      the RSAREF library rather than MPILIB. Note that RSAREF is NOT included
      in this distribution, so if you are a US user, it is probably easier to
      get a copy of the original MIT 2.6.2 release.

  (3) It lets you disable the "legal kludge"

      PGP 2.6.2 contains a "feature" that will cause it to generate keys and
      messages that are not readable by PGP 2.3a and earlier versions. This
      is the "legal kludge", and was introduced to encourage users in the USA
      to upgrade from PGP 2.3a.

      PGP 2.6.2i provides you with a way to disable the "legal kludge". This
      means that messages and keys generated with PGP 2.6.2i can be used and
      understood by all existing 2.x versions of PGP. To disable the legal
      kludge, uncomment the following line in your config.txt file so that it
      reads:

      legal_kludge = off

      This option may also be set on the command line: "pgp +le=off <command>".

  (4) It allows you to generate keys up to and including 2048 bits

      Because of a bug in PGP 2.6.2, this version would not let you generate
      keys bigger than 2047 bits on some platforms. This problem has been
      corrected in PGP 2.6.2i.

  (5) It contains a number of bug-fixes

      PGP 2.6.2i also fixes a number of other bugs found in PGP 2.6.2, most
      notably the signature bug for keys over 2034 bits, as reported by
      ViaCrypt.

  (6) It can be compiled on many new platforms

      PGP 2.6.2i has been modified in order to let it compile "out of the box"
      for such platforms as Amiga, Atari, FreeBSD, UnixWare and various
      flavours of VMS. It can also be compiled under MS-DOS using Borland C
      (MIT PGP 2.6.2 only supports Microsoft C).

  (7) It includes updated documentation and language files

      The language files for MIT PGP 2.6.2 had not been updated for a long
      time. This has been fixed in this version. PGP 2.6.2i comes with
      standard language files for French, Spanish and Norwegian. All the other
      text and documentation files for PGP 2.6.2i have also been brought up to
      date.


DIFFERENCES BETWEEN PGP 2.6.2i and 2.6ui

A PGP version that has been very popular among non-US users of PGP is 2.6ui.
If you have been using PGP 2.6ui up to now, you should note that PGP 2.6.2i
differs from this version in the following ways:

  (1) It is a "real" 2.6 version

      PGP 2.6.2i is based on the source code for PGP 2.6.2, whereas PGP 2.6ui
      is based on the source code for 2.3a. This means that 2.6.2i contains a
      lot of bug-fixes that are not present in 2.6ui, and it also adds a
      number of new features that are lacking in 2.6ui. These include the new
      PUBRING, SECRING, RANDSEED and COMMENT options in config.txt.

  (2) It doesn't have the version_byte option

      PGP 2.6ui has an option to allow you to choose which message format to
      use when generating keys and messages. This is the version_byte option,
      and can be set both in the config.txt file and on the command line:

      version_byte = 2    (use backwards-compatible format, default)
      version_byte = 3    (use new 2.6 format)

      In PGP 2.6.2i, the same is accomplished using the legal_kludge flag:

      legal_kludge = off  (use backwards-compatible format)
      legal_kludge = on   (use new 2.6 format, default)

  (3) It doesn't have the armor_version option

      PGP 2.6ui has an option to let you "forge" the version number in the
      ASCII armored files produced by PGP. In PGP 2.6.2i, the armor_version
      option is NOT supported, as this is a feature that is heavily misused.
      If you must change the version number of your keys and messages, you can
      do so in the language.txt file instead.


LEGAL STUFF

PGP 2.6.2i is not approved by MIT or PRZ or NSA or the Pope or anyone else.
However, it should be possible to use it legally by anyone in the free world
(i.e. all countries except USA, Iraq and a few others). There are three
reasons why people may claim (incorrectly) that PGP 2.6.2i is illegal:

   (1) It is based on source code that was illegally exported from the USA

       The ITAR regulations classifies cryptography in the same category as
       munitions, and so it is very likely that exporting PGP from the USA
       is considered illegal by US authorities. In the case of PGP 2.6.2i,
       large portions of the code were written inside the USA, and later
       exported to the rest of the world. However, this is not a problem,
       because it is the _export_ that is illegal, not the _use_ of the
       program. Once the software is (illegally) exported, anyone may use it
       legally. (I didn't export it, and I strongly recommend that you won't
       do it either.) As long as you make sure that you get your copy of PGP
       2.6.2i from somewhere outside the USA, then you should be on the safe
       side.

   (2) It infringes the RSA patent

       This is not a problem either, because PGP 2.6.2i is not intended for use
       in the USA (which just happens to be the only country in the world where
       the RSA patent is valid, and still the validity of this patent is
       somewhat dubious). If you are inside the USA, you should obtain a copy
       of PGP 2.6.2 instead, or compile the source using the -DMIT option and
       link it with the RSAREF library, which will in fact give you a version
       that is identical to MIT PGP 2.6.2. 

   (3) It violates the MIT license

       The second point in the MIT license for PGP 2.6.2 explicitly forbids
       anyone to remove the so-called "legal kludge". Still, this is exactly
       what PGP 2.6.2i does. However, it should be clear that this limitation
       only refers to the RSAREF versions of PGP. PGP 2.6.2i, on the other
       hand, does not use RSAREF, and so this point becomes irrelevant. If you
       still feel uncomfortable about this, take a look at the file
       przon26i.asc which is included in the distribution archive. This file
       contains a statement by Phil Zimmermann on PGP 2.6.i and the various
       "unofficial international" versions of PGP. (PGP 2.6.2i is simply a bug-
       fix for PGP 2.6.i, so everything that covers 2.6.i applies to 2.6.2i as
       well.)


COMMENTS AND BUG REPORTS

PGP 2.6.2i was put together by Stale Schumacher <staalesc@ifi.uio.no> with the
help of many individuals around the world (see the file diffs.doc for details).
All questions regarding PGP 2.6.2i should be addressed directly to him, or to
<pgp-bugs@ifi.uio.no>. Please note that PRZ, MIT and the University of Oslo
have nothing to do with this release. Comments, bug reports and suggestions for
future releases are welcome.


I WANT TO KNOW MORE!

If you want to find out more about PGP and encryption in general, there are a
number of resources available, both on paper and in electronic form. Here are a
few, to get you started:

FAQs:

    PGP Frequently Asked Questions
      http://www.prairienet.org/~jalicqui/pgpfaq.txt
      ftp://ftp.prairienet.org/pub/providers/pgp/pgpfaq.txt
    Where to Get the Latest PGP Program FAQ
      ftp://ftp.uu.net/usenet/news.answers/pgp-faq/where-is-PGP.Z
    
WWW:

    The International PGP Home Page
      http://www.ifi.uio.no/~staalesc/PGP/home.html
    Fran Litterio's PGP Page (from the Virtual Library)
      http://draco.centerline.com:8080/~franl/pgp/pgp.html
    The Official Bug List for MIT PGP 2.6.2
      http://www.mit.edu:8001/people/warlord/pgp-faq.html
    The Phil Zimmermann Legal Defense Fund Page
      http://www.netresponse.com/zldf

FTP:

    ftp://ftp.dsi.unimi.it/pub/security/crypt/PGP/
    ftp://ftp.informatik.uni-hamburg.de/pub/virus/crypt/pgp/
    ftp://ftp.csua.berkeley.edu/pub/cypherpunks/pgp/

Newsgroups:

    alt.anonymous               discussion of anonymity and anon remailers
    alt.anonymous.messages      for anonymous encrypted message transfer
    alt.privacy.clipper         Clipper, Capstone, Skipjack, Key Escrow
    alt.security                general security discussions
    alt.security.index          index to alt.security
    alt.security.pgp            discussion of PGP
    alt.security.ripem          discussion of RIPEM
    alt.security.keydist        key distribution via Usenet
    alt.society.civil-liberty   general civil liberties, including privacy
    comp.compression            discussion of compression algorithms
    comp.org.eff.news           news reports from EFF
    comp.org.eff.talk           discussion of EFF related issues
    comp.patents                discussion of S/W patents, including RSA
    comp.risks                  some mention of crypto and wiretapping
    comp.society.privacy        general privacy issues
    comp.security.announce      announcements of security holes
    misc.legal.computing        software patents, copyrights, computer laws
    sci.crypt                   methods of data encryption/decryption
    sci.math                    general math discussion
    talk.politics.crypto        general talk on crypto politics

Books:

    The Official PGP User's Guide
    by Philip R. Zimmermann
      MIT Press 1995 
      ISBN 0-262-74017-6
      216 pp. $14.95 

    PGP: Pretty Good Privacy
    by Simson Garfinkel
      O'Reilly & Associates 1994
      ISBN 1-56592-098-8
      430 pp. $24.95

    Protect Your Privacy: The PGP User's Guide
    by William Stallings
      Prentice Hall PTR 1995
      ISBN 0-13-185596-4
      302 pp. $19.95

    Applied Cryptography: Protocols, Algorithms, and Source Code in C
    by Bruce Schneier
      Wiley Publishing 1994
      ISBN 0-471-59756-2

    E-Mail Security: How to Keep Your Electronic Mail Private
    by Bruce Schneier
      Wiley Publishing
      ISBN 0-471-05318-X 


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