The RC5(R) Encryption Algorithm
General Information
RSA Laboratories
Revised April 7, 1995
This document copyright (C) 1995 RSA Laboratories, a division of RSA
Data Security, Inc. License is granted to reproduce, copy, post, or
distribute in any manner, provided this document is kept intact and
no modifications, deletions, or additions are made.
RC5 is a registered trademark of RSA Data Security, Inc. Patent
pending.
WHAT IS IT?
The RC5 encryption algorithm is a new fast symmetric block cipher
developed by Ron Rivest for RSA Laboratories. Intended as a possible
successor to the Data Encryption Standard, RC5 has a variable word
size, a variable number of rounds, and a variable-length secret key,
so the user can explicitly manipulate the trade-off between higher
speed and higher security. RC5 is suitable for hardware or software
implementations; the encryption and decryption algorithms are
exceptionally simple. A novel feature of RC5 is the heavy use of
data-dependent rotations.
HOW TO GET IT
To get a copy of Ron Rivest's paper describing the algorithm, send
electronic mail to <rc5-paper@rsa.com>; a Postscript version will be
returned. A LaTeX version is available via anonymous ftp to ftp.rsa.com
in the pub/rc5 directory.
You can also get a copy of our reference implementation of RC5, but
to do so you must be a U.S. or Canadian person, and you must return
the following paragraph to <rc5-administrator@rsa.com>:
I am hereby requesting a copy of the reference implementation of
the RC5 encryption algorithm for personal use and evaluation. I
acknowledge that no rights to copy, distribute, or sell the
Program are granted, and that such use of the Program is
prohibited. The electronic mail address to which I am requesting
that the reference implementation be transmitted is located in
the United States of America or Canada and I am a United States
citizen, a Canadian citizen, or a permanent resident of the
United States.
EVALUATION CONTEST
Through Summer 1995, we are encouraging people to evaluate the RC5
algorithm, both for security and performance. In fact, we are
offering prizes for the best papers on the security and performance
of RC5. You don't have to break RC5 to win, just provide the most
thorough and accurate analysis. For more information on the contest,
send electronic mail to <rc5-prizes@rsa.com>.
LICENSES
After the evaluation period---and assuming RC5 holds up to
scrutiny---RSA Laboratories will begin encouraging development of
applications based on RC5, and granting license to the algorithm as
well as the reference* implementation. At the present time, license
is granted *only* for personal use and evaluation.
Our intent is that non-commercial use would be free, and commercial
use would incur a fixed, one-time licensing fee to support continued
research at RSA Laboratories.
USERS' GROUP
Developments on RC5 analysis and licensing will be posted to the
<rc5-users@rsa.com> mailing list. To join, send electronic mail to
<rc5-users-request@rsa.com>.
QUESTIONS?
If you have questions or comments about RC5, send electronic mail to
<rc5-administrator@rsa.com>.
ABOUT RSA LABORATORIES
RSA Laboratories is the research and development 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.
RSA Laboratories also offers Seminar Series covering technical
background as well as the latest developments in cryptography, and
Technical Reports exploring cryptography in depth.
RSA Laboratories draws upon the talents of the following people:
Len Adleman, distinguished associate - Ph.D., University of
California, Berkeley; Henry Salvatori professor of computer
science at University of Southern California; co-inventor of
RSA public-key cryptosystem; co-founder of RSA Data Security, Inc.
Taher Elgamal, senior associate - Ph.D., Stanford University;
inventor of Elgamal public-key cryptosystem based on discrete
logarithms; holder of three patents for data compression algorithms
and implementations
Martin Hellman, distinguished associate - Ph.D., Stanford University;
professor of electrical engineering at Stanford University;
co-inventor of public-key cryptography, exponential key exchange;
IEEE fellow; IEEE Centennial Medal recipient
Burt Kaliski, chief scientist - Ph.D., MIT; former visiting assistant
professor at Rochester Institute of Technology; editor of Public-Key
Cryptography Standards; general chair of CRYPTO '91; member, Internet
Privacy and Security Research Group; chair, IEEE P1363 working group
Cetin Koc, associate - Ph.D., University of California, Santa
Barbara; assistant professor at Oregon State University
Ron Rivest, distinguished associate - Ph.D., Stanford University;
professor of computer science at MIT; co-inventor of RSA public-key
cryptosystem; co-founder of RSA Data Security, Inc.; member of
National Academy of Engineering; director of International
Association for Cryptologic Research; program co-chair of ASIACRYPT
'91
Matt Robshaw, research scientist - Ph.D., University of London; member
of EUROCRYPT '91 organizing committee
Yiqun Lisa Yin, research scientist - Ph.D., MIT
RSA Laboratories seeks the talents of other people as well. If you're
interested, please write or call us.
ADDRESSES
RSA Laboratories
100 Marine Parkway, Suite 500
Redwood City, CA 94065 USA
(415) 595-7703
(415) 595-4126 (fax)
e-mail: rsa-labs@rsa.com