5.6 Is DES a group? It has been frequently asked whether DES encryption is closed under composition; i.e., is encrypting a plaintext under one DES key and then encrypting the result under another key always equivalent to a single encryption under a single key? Algebraically, is DES a group? If so, then DES might be weaker than would otherwise be the case; see [39] for a more complete discussion. However, the answer is no, DES is not a group [18]; this issue was settled only recently, after many years of speculation and circumstantial evidence. This result seems to imply that techniques such as triple encryption do in fact increase the security of DES. RSA Laboratories is the research and consultation division of RSA Data Security, Inc., the company founded by the inventors of the RSA public-key cryptosystem. RSA Laboratories reviews, designs and implements secure and efficient cryptosystems of all kinds. Its clients include government agencies, telecommunications companies, computer manufacturers, software developers, cable TV broadcasters, interactive video manufacturers, and satellite broadcast companies, among others. For more information about RSA Laboratories, call or write to RSA Laboratories 100 Marine Parkway Redwood City, CA 94065 (415) 595-7703 (415) 595-4126 (fax) PKCS, RSAREF and RSA Laboratories are trademarks of RSA Data Security, Inc. All other trademarks belong to their respective companies. This document is available in ASCII, Postscript, and Latex formats via anonymous FTP to rsa.com:/pub/faq. Please send comments and corrections to faq-editor@rsa.com. === DISTRIBUTION: How to obtain this document This document has been brought to you in part by CRAM, involved in the redistribution of valuable information to a wider USENET audience (see below). The most recent version of this document can be obtained via the author's instructions above. 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For information, send mail to <tmp@netcom.com>. \ \ \ \ \ \ \ \ \ | / / / / / / / / / / _______ ________ _____ _____ _____ /// \\\ ||| \\\ /// \\\ |||\\\///||| ||| ~~ ||| /// ||| ||| ||| \\// ||| ||| __ |||~~~\\\ |||~~~||| ||| ~~ ||| \\\ /// ||| \\\ ||| ||| ||| ||| ~~~~~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ / / / / / / / / / | \ \ \ \ \ \ \ \ \ \ C y b e r s p a t i a l R e a l i t y A d v a n c e m e n t M o v e m e n t * CIVILIZING CYBERSPACE: send `info cypherwonks' to majordomo@lists.eunet.fi * From netcom.com!ix.netcom.com!howland.reston.ans.net!news.sprintlink.net!gatech!blo om-beacon.mit.edu!senator-bedfellow.mit.edu!faqserv Sun Jun 11 10:50:40 1995 Xref: netcom.com sci.crypt:37593 talk.politics.crypto:10206 alt.security.ripem:1369 sci.answers:2676 talk.answers:723 alt.answers:9579 news.answers:44828 Path: netcom.com!ix.netcom.com!howland.reston.ans.net!news.sprintlink.net!gatech!blo om-beacon.mit.edu!senator-bedfellow.mit.edu!faqserv From: faq-editor@rsa.com Newsgroups: sci.crypt,talk.politics.crypto,alt.security.ripem,sci.answers,talk.answers,alt.answers ,news.answers Subject: RSA Cryptography Today FAQ (3/3) Supersedes: <cryptography-faq/rsa/part3_799598431@rtfm.mit.edu> Followup-To: poster Date: 26 May 1995 10:39:09 GMT Organization: none Lines: 1129 Approved: news-answers-request@mit.edu Expires: 30 Jun 1995 10:38:42 GMT Message-ID: <cryptography-faq/rsa/part3_801484722@rtfm.mit.edu> References: <cryptography-faq/rsa/part1_801484722@rtfm.mit.edu> Reply-To: faq-editor@rsa.com NNTP-Posting-Host: bloom-picayune.mit.edu X-Last-Updated: 1994/06/13 Originator: faqserv@bloom-picayune.MIT.EDU Archive-name: cryptography-faq/rsa/part3 Last-modified: 93/09/20 Version: 2.0 Distribution-agent: tmp@netcom.com (This document has been brought to you in part by CRAM. See the bottom for more information, including instructions on how to obtain updates.) === Answers To FREQUENTLY ASKED QUESTIONS About Today's Cryptography Paul Fahn RSA Laboratories 100 Marine Parkway Redwood City, CA 94065 Copyright (c) 1993 RSA Laboratories, a division of RSA Data Security, Inc. All rights reserved. Version 2.0, draft 2f Last update: September 20, 1993 . Jun 1995 10:38:42 GMT Message-ID: <cryptography-faq/rsa /part3 _801484722@rtfm.mit.edu> References: <cryptography-faq/rsa /part1 _801484722@rtfm.mit.edu> Reply-To: faq-editor@rsa.com. Archive-name: cryptography-faq/rsa /part3 Last-modified: 93/09/20 Version: 2.0 Distribution-agent: tmp@netcom.com (This document has been brought to you in part by CRAM. See the bottom for. sci.crypt,talk.politics.crypto,alt.security.ripem,sci.answers,talk.answers,alt.answers ,news.answers Subject: RSA Cryptography Today FAQ (3/3) Supersedes: <cryptography-faq/rsa /part3 _799598431@rtfm.mit.edu> Followup-To: poster Date: 26 May 1995 10:39:09 GMT Organization: