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99. Glossary of Cryptographic Terms: p1


This article is from the PGP FAQ, by Jeff Licquia jalicqui@prairienet.org with numerous contributions by others.

99. Glossary of Cryptographic Terms: p1

Chosen Plain Text Attack

This is the next step up from the Known Plain Text Attack. In this
version, the cryptanalyst can choose what plain text message he wishes
to encrypt and view the results, as opposed to simply taking any old
plain text that he might happen to lay his hands on. If he can recover
the key, he can use it to decode all data encrypted under this key.
This is a much stronger form of attack than known plain text. The
better encryption systems will resist this form of attack.


A chip developed by the United States Government that was to be used
as the standard chip in all encrypted communications. Aside from the
fact that all details of how the Clipper chip work remain classified,
the biggest concern was the fact that it has an acknowledged trap door
in it to allow the government to eavesdrop on anyone using Clipper
provided they first obtained a wiretap warrant. This fact, along with
the fact that it can't be exported from the United States, has led a
number of large corporations to oppose the idea. Clipper uses an 80
bit key to perform a series of nonlinear transformation on a 64 bit
data block.

EFF (Electronic Frontier Foundation)

The Electronic Frontier Foundation (EFF) was founded in July, 1990, to assure
freedom of expression in digital media, with a particular emphasis on
applying the principles embodied in the Constitution and the Bill of Rights
to computer-based communication. For further information, contact:

Electronic Frontier Foundation
1001 G St., NW
Suite 950 East
Washington, DC 20001
+1 202 347 5400
+1 202 393 5509 FAX
Internet: eff@eff.org

IDEA (International Data Encryption Algorithm)

Developed in Switzerland and licensed for non-commercial use in PGP.
IDEA uses a 128 bit user supplied key to perform a series of nonlinear
mathematical transformations on a 64 bit data block. Compare the
length of this key with the 56 bits in DES or the 80 bits in Clipper.

ITAR (International Traffic in Arms Regulations)

ITAR are the regulations covering the exporting of weapons and weapons
related technology from the United States. For some strange reason,
the government claims that data encryption is a weapon and comes under
the ITAR regulations. There is presently a move in Congress to relax
the section of ITAR dealing with cryptographic technology.

Known Plain Text Attack

A method of attack on a crypto system where the cryptanalyst has
matching copies of plain text, and its encrypted version. With weaker
encryption systems, this can improve the chances of cracking the code
and getting at the plain text of other messages where the plain text
is not known.


MPILIB (Multiple Precision Integer Library)

This is the common name for the set of RSA routines used in PGP 2.3a
and previous, as well as the international versions of PGP. It is
alleged to violate PKP's RSA patent in the USA, but is not otherwise
restricted in usage. It retains its popularity abroad because it
outperforms RSAREF and has fewer legal restrictions as well.


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