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-
-
- Simple Cryptology
- by Dave Ferret
-
- >>> a cDc publication.......1993 <<<
- -cDc- CULT OF THE DEAD COW -cDc-
- ____ _ ____ _ ____ _ ____ _ ____
- |____digital_media____digital_culture____digital_media____digital_culture____|
-
- Handy definitions borrowed without permission from sci.crypt Frequently
- Asked Questions file:
-
- cryptology - the study of codes and ciphers
-
- cryptography - the act of inventing code or cipher systems
-
- cryptanalysis - the breaking of a code or cipher system without benefit of
- the normal deciphering mechanism(s)
- ______________________________________________________________________________
-
- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
- % What is Cryptography? (The Short Version) %
- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
- "Cryptography is the art and science of hiding data in plain sight. It is
- also the art and science of stealing data hidden in plain sight."
-
- (Both accurate definitions, by Larry Loen.)
-
- Have you ever made secret codes with your friends when you were little?
- Whether it was a number code where each letter of the alphabet had a
- substituted number, or you made a chart for each of you to translate a message,
- you were practicing a simple form of Cryptography. As far as I can back up,
- cryptology wasn't widely used until World War I, when actual machines were
- created for the sole purpose of making messages unreadable to the enemy.
-
- Cryptography is the method by which "plaintext" is encrypted into an
- unreadable form. The plaintext is the original text, before ltering to make it
- unreadable to other people. The key, or code, is the actual password (or
- whatnot) used to make it unreadable. This is a very simplistic, and not
- completely accurate view for which I apologize and again urge anyone seriously
- interested to read actual hard-copy books and papers for a more detailed
- explanation.
-
- ===============================================
- = Why are encrypted communications important? =
- ===============================================
-
- In today's electronic communication forums, encryption can be very
- mportant! Do you know for a fact that when you send a message to someone else,
- that someone hasn't read it along the way? Have you ever really sent something
- you didn't want anyone reading except the person you sent it to? As more and
- more things become online, and "paperless" communication predictions start
- coming true, it's all the more reason for encryption. Unlike the normal U.S.
- Mail where it is a crime to tamper with your mail, email-reading can commonly
- go unnoticed on electronic pathways as your message hops from system to system
- on its route towards its final destination. Just think, the average Internet
- letter makes at least two hops before it reaches its recipient, usually more.
- Even on public BBS's, your mail is usually stored in plaintext. Can you be
- sure someone else isn't reading it? The sysop? Half a dozen co-sysops and
- hangers-on? How hard would it be for system administrators to set up a process
- to "grep" (search for known text) all incoming/outgoing mail batches for
- certain catch phrases? It's not very hard, I assure you. Although most people
- probably don't do things like this, the threat is real. That's why you need to
- encrypt your messages. You have the right of privacy, as stated in the
- Constitution. That's why cryptography is so key.
-
-
- =========================================
- = Different types of encryption schemes =
- =========================================
-
- One-Way encryption algorithms: What are they?
-
- There are certain mathematical/cryptographical algorithms that will
- encrypt a string of text/numbers using a complex equation. However, you cannot
- reverse these equations again (take my word for it, it has to do with
- pieces of the equation being unknown, and purposely lost in the encryption
- process).
-
- A real-life example of one-way encryption:
-
- These types of algorithms are used when someone needs to compare text,
- such as in password validation checks. Crypt(), the Unix password validation
- routine works like this. A password is used at the key to encrypt a plaintext
- string of 0's. Then, to verify the password, the computer tries to encrypt the
- same string of plaintext with the password typed in. If a match is made to the
- original encrypted text, then the password is valid. (Note: Although you can't
- reverse this to find out what the original password/key was, you can compare
- two encryptions to see if it's the same key.)
-
-
- The "One-Time Pad"
- ==================
-
- A long string of random numbers are generated/created. Messages cannot
- be any longer than the string of random numbers, but can be shorter.
-
- The text is encrypted by XOR'ing the bits in relation to the random string
- of numbers. Bit by bit. So, anyone not knowing the original key wouldn't know
- whether the string, "123" was really "456" or "789" because in fact the
- originator and the intended receiver know it's really, "012" (wrap around
- 9->0). This is the best explanation I can come up with for this.
- It's a proven technique and is considered quite secure.
-
-
- Single-Key Encryption
- =====================
-
- This is what most non-crypto-speak people would understand as an
- encryption system. You enter one string of characters (or whatnot - The KEY)
- and encrypt your plaintext with this key. Anyone with knowledge of what this
- key is can decrypt and read the plaintext.
-
-
- Public-Key Encryption
- =====================
-
- This is gaining a large following during the time of this writing with
- such programs as RIPEM, PGP, and the availability of RSAREF, a RSA Public Key
- algorithm library. RIPEM, and PGP (Pretty Good Privacy by Phil Zimmerman) are
- both examples of RSA Public Key systems. There are two distinct parts to a
- public key system, the PUBLIC key and the PRIVATE key.
-
- o The PUBLIC key is given out to everyone you know who would want to send
- you an encrypted message.
-
- o The PRIVATE key you keep secret and do not disclose to anyone.
-
- How it works: User A (Iskra) wants to send a message to User B (B00gerHed)
- so Iskra encrypts a message to B00gerHed using BH's public key that was given
- out at the last HoHoCon. No one except B00gerHed has the private key to
- decrypt the message. So he takes his private key, the counterpart to his
- public key, and decrypts the message sent to him by Iskra. Viola. He now sees
- that the new red boxes are no longer working because AT&T has cinched up the
- timing checks. However, Veggie (User C) has intercepted the encrypted message
- and is trying to figure out what they are talking about. But because he
- doesn't have B00gerHed's private key, he cannot read it. A successful use of
- public key encryption.
-
- There are a LOT of books on this, so that's all I'm going to say.
-
-
- %%%%%%%%%%%%%%%%%%%%%%%%%%%%
- % Books, journals et al... %
- %%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
- NOTE: A lot of the best and most complete sources of cryptography and some
- algorithms are classified by the United States Government. However, there are
- still a decent number I can suggest. Also, the NSA has been pushing for
- legislation to require all encryption schemes to be "breakable" in a reasonable
- matter of time with back doors or weaknesses so THEY can decrypt your messages.
- This is a violation of your rights. I hope you would oppose such things.
-
- Thanks to the following people for some info:
- Larry Loen - lwloen@rchland.vnet.ibm.com 11/92)
- cme@ellisun.sw.stratus.com (Carl Ellison) 11/92)
- Alec Chambers (jac54@cas.org)
- mrr@scss3.cl.msu.edu (Mark Riordan)
-
-
- David Kahn, The Codebreakers, Macmillan, 1967 [history; excellent]
-
- H.F. Gaines, Cryptanalysis, Dover, 1956 [originally 1939, as
- Elementary Cryptanalysis].
-
- Abraham Sinkov, Elementary Cryptanalysis, Math. Assoc. of Amer., 1966.
-
- D. Denning, Cryptography and Data Security, Addison-Wesley, 1983.
-
- [ Dorothy Denning, also wrote a paper proposing all public key ]
- [ systems be required to "register" their private keys with the ]
- [ NSA or other agency for decryption should the gov't feel it ]
- [ necessary. ]
-
- Alan G. Konheim, Cryptography: A Primer, Wiley-Interscience, 1981.
-
- Meyer and Matyas, Cryptography: A New Dimension in Computer Data Security,
- John Wiley & Sons, 1982.
-
-
- Books can be ordered from Aegan Park Press. They aren't cheap, but they
- are the only known public source for most of these and other books of
- historical and analytical interest.
-
- Write for catalog to:
-
- Aegean Park Press
- P.O. Box 2837
- Laguna Hills, CA 92654-0837
-
-
- Cryptologia: a cryptology journal, quarterly since Jan 1977.
- Cryptologia; Rose-Hulman Institute of Technology; Terre Haute,
- Indiana 47803 [general: systems, analysis, history, ...]
-
- Gordon Welchman, The Hut Six Story, McGraw-Hill, 1982.
- [excellent description of his WW-II crypto work (breaking the German
- Enigma); discussion of modern cryptological implications]
-
- --
- Various books available from Artech House, 610 Washington St., Dedham, MA
- 02026; including:
-
- Deavours & Hruh, Machine Cryptography and Modern Cryptanalysis.
- [operation and breaking of cipher machines through about 1955]
-
- Deavours, et al., CRYPTOLOGY Yesterday, Today, and Tomorrow.
- [Cryptologia reprints - 1st volume]
-
- Deavours, et al., CRYPTOLOGY: Machines, History & Methods.
- [Cryptologia reprints - 2nd volume]
- --
-
- Cryptologia
- Rose-Hulman Institute of Technology
- Terre Haute, Indiana 47803
- Cryptologia: a cryptology journal, quarterly since Jan 1977.
-
- Journal of the International Association for Cryptologic Research.
- [quarterly since 1988]
-
- The RSA paper: The Comm. of the ACM, Feb 1978, p. 120.
-
- Claude Shannon's 2 1940's papers in the Bell System Tech Journal.
-
- Herbert O. Yardley, The American Black Chamber, Bobbs-Merrill, 1931.
- [First hand history - WW-I era]
-
- Edwin Layton, "And I Was There", William Morrow & Co., 1985.
- [First hand history - WW-II]
-
- W. Kozaczuk, Enigma, University Publications of America, 1984.
- [First hand history (Rejewski's) - pre-WW-II]
-
- Journal of Cryptology
- Springer-Verlag New York, Inc.
- Service Center Secaucus
- 44 Hartz Way
- Secaucus, NJ 07094
- (201)348-4033
- $87/year + $8 postage & handling. Published three times a year.
-
- Cryptosystems Journal
- Tony Patti, Editor and Publisher
- P.O. Box 188
- Newtown, PA 18940-0188
- (215)579-9888
- tony_s_patti@cup.portal.com
- $45/year. Published three times a year. Journal dedicated to the
- implementation of cryptographic systems on IBM PC's. Emphasis on
- tutorial/pragmatic aspects. Evidently all articles are written by the
- publisher.
-
- Forbidden Knowledge
- P.O. Box 770813
- Lakewood, OH 44107
- $18 a year - make check or m/o to Darren Smith (editor). Jack Jeffries
- (cj137@cleveland.Freenet.Edu) says that this is a local publication which has
- articles on cryptology. That's all I know about it.
-
- The Cryptogram
- Journal of the American Cryptogram Association
- P.O. Box 6454
- Silver Spring, MD 20906
- This is the Journal of the American Cryptogram Assocation, available by
- joining the ACA. Dues are probably about $20/year by now. Published six times
- a year. Contains mostly puzzles for you to solve. No techniques invented after
- 1920 are used, with simple substitution being the most common. Also contains
- articles on classical cryptosystems, and book reviews.
-
- The Cryptogram Computer Supplement
- Dan Veeneman
- P.O. Box 7
- Burlington, IL 60109 USA
- $2.50/issue. Published three times a year for ACA members. Newsletter
- for computer hobbyist members of the ACA.
-
- The Public Key
- George H. Foot, Editor
- Waterfall, Uvedale Road
- Oxted, Surry RH8 0EW
- United Kingdom
- Cost unknown. Magazine devoted to public key cryptography, especially
- amongst personal computer owners. Note that RSA's patents do not apply in
- Europe, hence the existence of this magazine.
-
- Surveillant,
- Lock Box Mail Unit 18757
- Washington, DC 20036-8757
- 6 issues/year, $48.00. Announces new acquisitions and has some news from
- the intelligence field. Each issue comes with a check-off order form for books
- announced in that issue.
- ______________________________________________________________________________
-
- I suggest if you have the time and access to follow the Usenet groups, as
- they have heaps of info. Also, reading the sci.crypt FAQ and the few online
- publications including Dorothy Denning's work will help you gain a better
- understanding. In fact, probably better than this hack job.
-
- Exeunt.
- _______ __________________________________________________________________
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- (' ') |ftp - zero.cypher.com in pub/cdc |ftp - ftp.eff.org in pub/cud/cdc|
- (U) |==================================================================|
- .ooM |Copr. 1993 cDc communications by Dave Ferret 04/01/93-#226|
- \_______/|All Rights Drooled Away. [cDc/K-rAd people are we]|
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