Cryptography-Digest Digest #414, Volume #12      Fri, 11 Aug 00 05:13:00 EDT

Contents:
  Cryptography FAQ (10/10: References) ([EMAIL PROTECTED])
  Re: OTP using BBS generator? (Mok-Kong Shen)
  Re: OTP using BBS generator? (Mok-Kong Shen)
  Re: Copyright isue - SERPENT (David Blackman)

----------------------------------------------------------------------------

Crossposted-To: talk.politics.crypto,sci.answers,news.answers,talk.answers
Subject: Cryptography FAQ (10/10: References)
From: [EMAIL PROTECTED]
Reply-To: [EMAIL PROTECTED]
Date: 11 Aug 2000 08:44:23 GMT

Archive-name: cryptography-faq/part10
Last-modified: 94/06/13


This is the tenth of ten parts of the sci.crypt FAQ. The parts are
mostly independent, but you should read the first part before the rest.
We don't have the time to send out missing parts by mail, so don't ask.
Notes such as ``[KAH67]'' refer to the reference list in this part.

The sections of this FAQ are available via anonymous FTP to rtfm.mit.edu 
as /pub/usenet/news.answers/cryptography-faq/part[xx]. The Cryptography 
FAQ is posted to the newsgroups sci.crypt, talk.politics.crypto, 
sci.answers, and news.answers every 21 days.



Contents

10.1. Books on history and classical methods
10.2. Books on modern methods
10.3. Survey articles
10.4. Reference articles
10.5. Journals, conference proceedings
10.6. Other
10.7. How may one obtain copies of FIPS and ANSI standards cited herein?
10.8. Electronic sources
10.9. RFCs (available from [FTPRF])
10.10. Related newsgroups


10.1. Books on history and classical methods

  [FRIE1] Lambros D. Callimahos, William F. Friedman, Military Cryptanalytics.
          Aegean Park Press, ?.
  [DEA85] Cipher A. Deavours & Louis Kruh, Machine Cryptography and
          Modern Cryptanalysis. Artech House, 610 Washington St.,
          Dedham, MA 02026, 1985.
  [FRIE2] William F. Friedman, Solving German Codes in World War I.
          Aegean Park Press, ?.
  [GAI44] H. Gaines, Cryptanalysis, a study of ciphers and their
          solution. Dover Publications, 1944.
  [HIN00] F.H.Hinsley, et al., British Intelligence in the Second
          World War. Cambridge University Press. (vol's 1, 2, 3a, 3b
          & 4, so far). XXX Years and authors, fix XXX
  [HOD83] Andrew Hodges, Alan Turing: The Enigma. Burnett Books
          Ltd., 1983
  [KAH91] David Kahn, Seizing the Enigma. Houghton Mifflin, 1991.
  [KAH67] D. Kahn, The Codebreakers. Macmillan Publishing, 1967.
          [history] [The abridged paperback edition left out most
          technical details; the original hardcover edition is
          recommended.]
  [KOZ84] W. Kozaczuk, Enigma. University Publications of America, 1984
  [KUL76] S. Kullback, Statistical Methods in Cryptanalysis. Aegean
          Park Press, 1976.
  [SIN66] A. Sinkov, Elementary Cryptanalysis. Math. Assoc. Am. 1966.
  [WEL82] Gordon Welchman, The Hut Six Story. McGraw-Hill, 1982.
  [YARDL] Herbert O. Yardley, The American Black Chamber. Aegean Park
          Press, ?.

10.2. Books on modern methods

  [BEK82] H. Beker, F. Piper, Cipher Systems. Wiley, 1982.
  [BRA88] G. Brassard, Modern Cryptology: a tutorial.
          Spinger-Verlag, 1988.
  [DEN82] D. Denning, Cryptography and Data Security. Addison-Wesley
          Publishing Company, 1982.
  [KOB89] N. Koblitz, A course in number theory and cryptography.
          Springer-Verlag, 1987.
  [KON81] A. Konheim, Cryptography: a primer. Wiley, 1981.
  [MEY82] C. Meyer and S. Matyas, Cryptography: A new dimension in
          computer security. Wiley, 1982.
  [PAT87] Wayne Patterson, Mathematical Cryptology for Computer
          Scientists and Mathematicians. Rowman & Littlefield, 1987.
  [PFL89] C. Pfleeger, Security in Computing. Prentice-Hall, 1989.
  [PRI84] W. Price, D. Davies, Security for computer networks. Wiley, 1984. 
  [RUE86] R. Rueppel, Design and Analysis of Stream Ciphers.
          Springer-Verlag, 1986.
  [SAL90] A. Saloma, Public-key cryptography. Springer-Verlag, 1990.
  [SCH94] B. Schneier, Applied Cryptography. John Wiley & Sons, 1994.
          [errata avbl from [EMAIL PROTECTED]]
  [WEL88] D. Welsh, Codes and Cryptography. Claredon Press, 1988.

10.3. Survey articles

  [ANG83] D. Angluin, D. Lichtenstein, Provable Security in Crypto-
          systems: a survey. Yale University, Department of Computer
          Science, #288, 1983.
  [BET90] T. Beth, Algorithm engineering for public key algorithms.
          IEEE Selected Areas of Communication, 1(4), 458--466,
          1990.
  [DAV83] M. Davio, J. Goethals, Elements of cryptology. in Secure
          Digital Communications, G. Longo ed., 1--57, 1983.
  [DIF79] W. Diffie, M. Hellman, Privacy and Authentication: An
          introduction to cryptography. IEEE proceedings, 67(3),
          397--427, 1979.
  [DIF88] W. Diffie, The first ten years of public key cryptography.
          IEEE proceedings, 76(5), 560--577, 1988.
  [FEI73] H. Feistel, Cryptography and Computer Privacy. Scientific 
          American, 228(5), 15--23, 1973.
  [FEI75] H. Feistel, H, W. Notz, J. Lynn Smith. Some cryptographic
          techniques for machine-to-machine data communications,
          IEEE IEEE proceedings, 63(11), 1545--1554, 1975.
  [HEL79] M. Hellman, The mathematics of public key cryptography.
          Scientific American, 130--139, 1979.
  [LAK83] S. Lakshmivarahan, Algorithms for public key
          cryptosystems. In Advances in Computers, M. Yovtis ed.,
          22, Academic Press, 45--108, 1983.
  [LEM79] A. Lempel, Cryptology in transition, Computing Surveys,
          11(4), 285--304, 1979.
  [MAS88] J. Massey, An introduction to contemporary cryptology, IEEE
          proceedings, 76(5), 533--549, 1988.
  [SIM91] G. Simmons (ed.), Contemporary Cryptology: the Science of
          Information Integrity. IEEE press, 1991.

10.4. Reference articles

  [AND83] D. Andelman, J. Reeds, On the cryptanalysis of rotor and
          substitution-permutation networks. IEEE Trans. on Inform.
          Theory, 28(4), 578--584, 1982.
  [BEN87] John Bennett, Analysis of the Encryption Algorithm Used in
          the WordPerfect Word Processing Program. Cryptologia 11(4),
          206--210, 1987.
  [BER91] H. A. Bergen and W. J. Caelli, File Security in WordPerfect
          5.0. Cryptologia 15(1), 57--66, January 1991.
  [BIH91] E. Biham and A. Shamir, Differential cryptanalysis of
          DES-like cryptosystems. Journal of Cryptology, vol. 4, #1,
          3--72, 1991.
  [BI91a] E. Biham, A. Shamir, Differential cryptanalysis of Snefru,
          Khafre, REDOC-II, LOKI and LUCIFER. In Proceedings of CRYPTO
          '91, ed. by J. Feigenbaum, 156--171, 1992.
  [BOY89] J. Boyar, Inferring Sequences Produced by Pseudo-Random
          Number Generators. Journal of the ACM, 1989.
  [BRI86] E. Brickell, J. Moore, M. Purtill, Structure in the
          S-boxes of DES. In Proceedings of CRYPTO '86, A. M. Odlyzko
          ed., 3--8, 1987.
  [BRO89] L. Brown, A proposed design for an extended DES, Computer
          Security in the Computer Age. Elsevier Science Publishers
          B.V. (North Holland), IFIP, W. J. Caelli ed., 9--22, 1989.
  [BRO90] L. Brown, J. Pieprzyk, J. Seberry, LOKI - a cryptographic
          primitive for authentication and secrecy applications.
          In Proceedings of AUSTCRYPT 90, 229--236, 1990.
  [CAE90] H. Gustafson, E. Dawson, W. Caelli, Comparison of block
          ciphers. In Proceedings of AUSCRYPT '90, J. Seberry and J.
          Piepryzk eds., 208--220, 1990.
  [CAM93] K. W. Campbell, M. J. Wiener, Proof the DES is Not a Group.
          In Proceedings of CRYPTO '92, 1993.
  [CAR86] John Carrol and Steve Martin, The Automated Cryptanalysis
          of Substitution Ciphers. Cryptologia 10(4), 193--209, 1986.
  [CAR87] John Carrol and Lynda Robbins, Automated Cryptanalysis of
          Polyalphabetic Ciphers. Cryptologia 11(4), 193--205, 1987.
  [ELL88] Carl M. Ellison, A Solution of the Hebern Messages. Cryptologia,
          vol. XII, #3, 144-158, Jul 1988.
  [EVE83] S. Even, O. Goldreich, DES-like functions can generate the
          alternating group. IEEE Trans. on Inform. Theory, vol. 29,
          #6, 863--865, 1983.
  [GAR91] G. Garon, R. Outerbridge, DES watch: an examination of the
          sufficiency of the Data Encryption Standard for financial
          institutions in the 1990's. Cryptologia, vol. XV, #3,
          177--193, 1991.
  [GIL80] Gillogly, ?. Cryptologia 4(2), 1980.
  [GM82]  Shafi Goldwasser, Silvio Micali, Probabilistic Encryption and
          How To Play Mental Poker Keeping Secret All Partial Information.
          Proceedings of the Fourteenth Annual ACM Symposium on Theory of
          Computing, 1982.
  [HUM83] D. G. N. Hunter and A. R. McKenzie, Experiments with
          Relaxation Algorithms for Breaking Simple Substitution
          Ciphers. Computer Journal 26(1), 1983.
  [KAM78] J. Kam, G. Davida, A structured design of substitution-
          permutation encryption networks. IEEE Trans. Information
          Theory, 28(10), 747--753, 1978.
  [KIN78] P. Kinnucan, Data encryption gurus: Tuchman and Meyer.
          Cryptologia, vol. II #4, 371--XXX, 1978.
  [KIN92] King and Bahler, Probabilistic Relaxation in the
          Cryptanalysis of Simple Substitution Ciphers. Cryptologia
          16(3), 215--225, 1992.
  [KIN93] King and Bahler, An Algorithmic Solution of Sequential
          Homophonic Ciphers. Cryptologia 17(2), in press.
  [KOC87] Martin Kochanski, A Survey of Data Insecurity Packages.
          Cryptologia 11(1), 1--15, 1987.
  [KOC88] Martin Kochanski, Another Data Insecurity Package.
          Cryptologia 12(3), 165--177, 1988.
  [KRU88] Kruh, ?. Cryptologia 12(4), 1988.
  [LAI90] X. Lai, J. Massey, A proposal for a new block encryption 
          standard. EUROCRYPT 90, 389--404, 1990.
  [LUB88] C. Rackoff, M. Luby, How to construct psuedorandom
          permutations from psuedorandom functions. SIAM Journal of
          Computing, vol. 17, #2, 373--386, 1988.
  [LUC88] Michael Lucks, A Constraint Satisfaction Algorithm for the
          Automated Decryption of Simple Substitution Ciphers. In
          CRYPTO '88.
  [MAS88] J. Massey, An introduction to contemporary cryptology.
          IEEE proceedings, 76(5), 533--549, 1988.
  [ME91a] R. Merkle, Fast software encryption functions. In Proceedings
          of CRYPTO '90, Menezes and Vanstone ed., 476--501, 1991.
  [MEY78] C. Meyer, Ciphertext/plaintext and ciphertext/key
          dependence vs. number of rounds for the Data Encryption
          Standard. AFIPS Conference proceedings, 47, 1119--1126,
          1978.
  [NBS77] Data Encryption Standard. National Bureau of Standards,
          FIPS PUB 46, Washington, DC, January 1977.
  [PEL79] S. Peleg and A. Rosenfeld, Breaking Substitution Ciphers
          Using a Relaxation Algorithm. CACM 22(11), 598--605, 1979.
  [REE77] J. Reeds, `Cracking' a Random Number Generator.
          Cryptologia 1(1), 20--26, 1977.
  [REE84] J. A. Reeds and P. J. Weinberger, File Security and the UNIX
          Crypt Command. AT&T Bell Laboratories Technical Journal,
          Vol. 63 #8, part 2, 1673--1684, October, 1984.
  [SHA49] C. Shannon, Communication Theory of Secrecy Systems. Bell
          System Technical Journal 28(4), 656--715, 1949.
  [SHE88] B. Kaliski, R. Rivest, A. Sherman, Is the Data Encryption
          Standard a Group. Journal of Cryptology, vol. 1, #1,
          1--36, 1988.
  [SHI88] A. Shimizu, S. Miyaguchi, Fast data encipherment algorithm
          FEAL. EUROCRYPT '87, 267--278, 1988.
  [SHI92] K. Shirriff, C. Welch, A. Kinsman, Decoding a VCR Controller
          Code. Cryptologia 16(3), 227--234, 1992.
  [SOR84] A. Sorkin, LUCIFER: a cryptographic algorithm.
          Cryptologia, 8(1), 22--35, 1984.
  [SPI93] R. Spillman et al., Use of Genetic Algorithms in
          Cryptanalysis of Simple Substitution Ciphers. Cryptologia
          17(1), 31--44, 1993.
        
10.5. Journals, conference proceedings

  CRYPTO
  Eurocrypt
  IEEE Transactions on Information Theory
  Cryptologia: a cryptology journal, quarterly since Jan 1977.
          Cryptologia; Rose-Hulman Institute of Technology; Terre Haute
          Indiana 47803 [general: systems, analysis, history, ...]
  Journal of Cryptology; International Association for Cryptologic
          Research; published by Springer Verlag (quarterly since
          1988).
  The Cryptogram (Journal of the American Cryptogram Association);
          18789 West Hickory Street; Mundelein, IL 60060; [primarily
          puzzle cryptograms of various sorts]
  Cryptosystems Journal, Published by Tony Patti, P.O. Box 188,
          Newtown PA, USA 18940-0188 or [EMAIL PROTECTED]
          Publisher's comment: Includes complete cryptosystems with
          source and executable programs on diskettes. Tutorial. The
          typical cryptosystems supports multi-megabit keys and Galois
          Field arithmetic. Inexpensive hardware random number
          generator details.
  Computer and Communication Security Reviews, published by Ross Anderson.
          Sample issue available from various ftp sites, including
          black.ox.ac.uk. Editorial c/o [EMAIL PROTECTED] Publisher's
          comment: We review all the conference proceedings in this field,
          including not just Crypto and Eurocrypt, but regional gatherings
          like Auscrypt and Chinacrypt. We also abstract over 50 journals,
          and cover computer security as well as cryptology, so readers can
          see the research trends in applications as well as theory.
  Infosecurity News, MIS Training Institute Press, Inc. 498 Concord Street
          Framingham MA 01701-2357. This trade journal is oriented toward 
          administrators and covers viruses, physical security, hackers, 
          and so on more than cryptology. Furthermore, most of the articles 
          are written by vendors and hence are biased.  Nevertheless, there 
          are occasionally some rather good cryptography articles.

10.6. Other

  Address of note: Aegean Park Press, P.O. Box 2837, Laguna Hills, CA
  92654-0837. Answering machine at 714-586-8811.  Toll Free at 800 736-
  3587, and FAX at 714 586-8269.

  The ``Orange Book'' is DOD 5200.28-STD, published December 1985 as
  part of the ``rainbow book'' series. Write to Department of Defense,
  National Security Agency, ATTN: S332, 9800 Savage Road, Fort Meade, MD
  20755-6000, and ask for the Trusted Computer System Evaluation
  Criteria. Or call 301-766-8729.

  The ``Orange Book'' will eventually be replaced by the U.S. Federal 
  Criteria for Information Technology Security (FC) online at the NIST
  site [FTPNS], which also contains information on other various proposed 
  and active federal standards.

  [BAMFD] Bamford, The Puzzle Palace. Penguin Books, 1982.
  [GOO83] I. J. Good, Good Thinking: the foundations of probability and
          its applications. University of Minnesota Press, 1983.
  [KNU81] D. E. Knuth, The Art of Computer Programming, volume 2:
          Seminumerical Algorithms. Addison-Wesley, 1981.
  [KUL68] Soloman Kullback, Information Theory and Statistics.
          Dover, 1968.
  [YAO88] A. Yao, Computational Information Theory. In Complexity in
          Information Theory, ed. by Abu-Mostafa, 1988.

10.7. How may one obtain copies of FIPS and ANSI standards cited herein?

  Many textbooks on cryptography contain complete reprints of the FIPS
  standards, which are not copyrighted.

  The following standards may be ordered from the
      U.S. Department of Commerce, National Technical Information Service,
      Springfield, VA 22161.

      FIPS PUB 46-1 Data Encryption Standard  (this is DES)
      FIPS PUB 74   Guidelines for Implementing as Using the NBS DES
      FIPS PUB 81   DES Modes of Operation
      FIPS PUB 113  Computer Data Authentication (using DES)

  [Note: The address below has been reported as invalid.]
  The following standards may be ordered from the
      American National Standards Institute Sales Office,
      1430 Broadway, New York, NY 10018.
      Phone 212.642.4900

      ANSI X3.92-1981  Data Encryption Algorithm (identical to FIPS 46-1)
      ANSI X3.106-1983 DEA Modes of Operation    (identical to FIPS 113)

  Notes:  Figure 3 in FIPS PUB 46-1 is in error, but figure 3 in X3.92-1981
      is correct. The text is correct in both publications.


10.8. Electronic sources

  Anonymous ftp:

  [FTPAL] kampi.hut.fi:alo/des-dist.tar.Z
  [FTPBK] ftp.uu.net:bsd-sources/usr.bin/des/
  [FTPCB] ftp.uu.net:usenet/comp.sources.unix/volume10/cbw/
  [FTPCP] soda.berkeley.edu:/pub/cypherpunks
  [FTPDF] ftp.funet.fi:pub/unix/security/destoo.tar.Z
  [FTPDQ] rsa.com:pub/faq/
  [FTPEY] ftp.psy.uq.oz.au:pub/DES/
  [FTPMD] rsa.com:?
  [FTPMR] ripem.msu.edu:pub/crypt/newdes.tar.Z
  [FTPNS] csrc.nist.gov:/bbs/nistpubs
  [FTPOB] ftp.3com.com:Orange-Book
  [FTPPF] prep.ai.mit.edu:pub/lpf/
  [FTPPK] ucsd.edu:hamradio/packet/tcpip/crypto/des.tar.Z
  [FTPPX] ripem.msu.edu:pub/crypt/other/tran-and-prngxor.shar
  [FTPRF] nic.merit.edu:documents/rfc/
  [FTPSF] beta.xerox.com:pub/hash/
  [FTPSO] chalmers.se:pub/unix/des/des-2.2.tar.Z
  [FTPTR] ripem.msu.edu:pub/crypt/other/tran-and-prngxor.shar
  [FTPUF] ftp.uu.net:usenet/comp.sources.unix/volume28/ufc-crypt/
  [FTPWP] garbo.uwasa.fi:pc/util/wppass2.zip

  World Wide Web pages:

  [WWWQC] http://www.quadralay.com/www/Crypt/Crypt.html
          Quadralay Cryptography archive
  [WWWVC] ftp://furmint.nectar.cs.cmu.edu/security/README.html
          Vince Cate's Cypherpunk Page 

10.9. RFCs (available from [FTPRF])

  [1424]  B. Kaliski, Privacy Enhancement for Internet Electronic Mail:
          Part IV: Key Certification and Related Services. RFC 1424,
          February 1993.
  [1423]  D. Balenson, Privacy Enhancement for Internet Electronic Mail:
          Part III: Algorithms, Modes, and Identifiers. RFC 1423,
          February 1993.
  [1422]  S. Kent, Privacy Enhancement for Internet Electronic Mail:
          Part II: Certificate-Based Key Management. RFC 1422, February
          1993.
  [1421]  J. Linn, Privacy Enhancement for Internet Electronic Mail:
          Part I: Message Encryption and Authentication Procedures. RFC
          1421, February 1993.

10.10. Related newsgroups

  There are other newsgroups which a sci.crypt reader might want also to
  read. Some have their own FAQs as well.

  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.society.civil-liberty     general civil liberties, including privacy
  comp.compression              discussion of compression algorithms and code
  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.math                      general math discussion
  talk.politics.crypto          politics of cryptography

------------------------------

From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: OTP using BBS generator?
Date: Fri, 11 Aug 2000 11:13:06 +0200



Bryan Olson wrote:
> 
> Mok-Kong Shen wrote:
> [...]
> > I want on the other hand once again to stress that the
> > short (or long) cycles being very heatedly disputed up
> > till now in this thread are those of the direct output of
> > the congruence relation and NOT of the LSB. There need
> > not necessarily exist a mathematically definite and
> > practically useful relationship between these two types
> > of cycle lengths. Since the user is using LSB, ONLY the
> > cycle length of LSB is of interest to him.
> 
> The reductions from QR and factoring holds for the
> unpredictability of the least significant bit (and a few
> other bits at the low end according to more recent results).
> All that the open question means is that even if one does
> filter out short state cycles, one still has not proven a
> long output cycle.  This is only a problem for those who
> thought the state-cycle test would prove security for each
> possible key, and that would be nonsense even if we knew the
> output cycle to be long.

Exactly. If we KNEW the output cycle of LSB to be long!
But it is unfortunate that we don't yet know. It is 
important to realize this point, independent of what 
the reality (which we don't yet know) is. (Before FLT 
was proved, there were speculations that it were wrong. 
Now we know that FLT is right. It could have come out 
the other way, though.) This is why I pleaded to do
some extensive experiments, if a theoretical study of
the issue is difficult.

M. K. Shen

------------------------------

From: Mok-Kong Shen <[EMAIL PROTECTED]>
Subject: Re: OTP using BBS generator?
Date: Fri, 11 Aug 2000 11:13:31 +0200



David Hopwood wrote:
> 

> In any case, a phrase of the length suggested above is far too much of a
> mouthful to expect anyone to use it in practice. Personally, I would prefer
> something like "security supported by proof".

Well, 'security proved under certain assumptions' is better
in my view.

> The nature
> of Usenet tends to amplify this kind of reporting bias - we don't know
> how many people tested BBS (or more generally looked for unusual output
> characteristics for any cryptosystem), and found nothing at all to suggest
> non-randomness.

I should be very grateful, if my post, however inappropriate
or wrong it may later turn out to be, serves the purpose to 
cause a lot of people to test BBS and verify its quality,
so that the users can more easily have confidence on it.
(I mean readers that have difficulties to fully understand
BBS' paper.) Sofar, there is yet no follow-up containing 
any result of actual tests, however.
 
> [...]

> > Further, as David Hopgood
> 
> Hopwood
> 
> > pointed out and probably
> > ignored by most experts till present, the BBS paper
> > left open the issue of the relationship between the
> > cycle length of the numbers from the congruence
> > relation and the cycle length of the LSBs.
> 
> I'm sure that anyone who read the paper in full was aware of this.
> However, it doesn't really matter to the security of BBS; the
> proof that the LSBs (not the x_i values) are indistinguishable from
> random except with negligable probability and under the assumption that
> factoring is intractable, does not depend on any unproven conjectures
> about cycle length.

If there is a gap (in the theory presented) between the 
two types of cycle lengths but the security of LSB can 
nonetheless be established, I wonder why (as far as I 
learned here) BBS did the trouble at all to investigate 
cases where the cycle length of the direct output of the 
congruence (not that of the LSB) could somehow be avoided 
to have short cycles. (This cycle length is the point 
that has lead to long discussions here till now.)

Note, however, what Terry Ritter pointed out. If the 
cycle of LSB is extremely short, then the bit sequence 
is evidently not useful in crypto anyway, isn't it? 
(We need only consider an example of say, a period
length of 10, to see the point.) That is, in that case 
we wouldn't NEED to care if there is or is not any 
connection with the hardness of factoring or what 
not. The exclusion of use of BBS would then simply be 
a purely 'practical' issue quite independent of the
high math. Now, apparently we don't at the current
moment know much about the probability of occurrence
of very short cycles of LSB (but only some, I suppose,
about the cycles of the direct output of the congruence 
relation). That's why we need to investigate that 
through performing extensive tests in my humble view, 
unless we have a clear-cut theory on the cycle length 
of LSB.

M. K. Shen

------------------------------

From: David Blackman <[EMAIL PROTECTED]>
Subject: Re: Copyright isue - SERPENT
Date: Fri, 11 Aug 2000 19:08:58 +1000

kihdip wrote:
> 
> A candidate for AES has to be free for everybody to use, but is it correct
> that SERPENT has some limitations in implementations because of a copyright
> ??

The implementation of SERPENT that i have seen is copyrighted, but is
available for free under the Gnu Public Licence. However the algorithm
itself is not covered by that copyright, only that particular
implementation is.

Several other implementations of SERPENT exist (there are links on the
SERPENT homepage) but i don't know what copyright or licence rules they
have.

If you don't like the GPL, you are free to write your own implementation
of SERPENT and put whatever copyright and licence you like on it
(including none). Detailed description and test vectors are provided in
case anyone wants to do this. This rule will apply for the winner of AES
because that's one of the contest rules. But it applies to SERPENT (and
TWOFISH and RIJNDAEL, and i think now even MARS?) even if they don't
win.

> Kim

------------------------------


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