330 lines
15 KiB
Plaintext
330 lines
15 KiB
Plaintext
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__________ __ __
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/ _______/ /_/ / /
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/ /______ __ __ ___ _____ / / _____
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/______ / / / / \/ / / _ / / / / __/
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_______/ / / / / /\_/ / / // / / / / /-_
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/_________/ /_/ /_/ /_/ / ___/ /_/ /----/
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/ /
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/_/
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________ __ __
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/ ______/ / / / /
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/ / ______ __ __ _____ =/ /=____ / / ____ ____ __ __
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/ / / __ _/ / / / / / _ / / / /__ / / / /__ / /__ / / / / /
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/ /_____ / /-// / /_/ / / // / / / //_// / / //_// //_// / /_/ /
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/_______/ /_/ /_/ /___ / / ___/ /_/ /___/ /_/ /___/ /_ / /___ /
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___/ / / / ___/ / ___/ /
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/____/ /_/ /____/ /____/
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Simple Cryptology
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by Dave Ferret
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>>> a cDc publication.......1993 <<<
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-cDc- CULT OF THE DEAD COW -cDc-
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____ _ ____ _ ____ _ ____ _ ____
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|____digital_media____digital_culture____digital_media____digital_culture____|
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Handy definitions borrowed without permission from sci.crypt Frequently
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Asked Questions file:
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cryptology - the study of codes and ciphers
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cryptography - the act of inventing code or cipher systems
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cryptanalysis - the breaking of a code or cipher system without benefit of
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the normal deciphering mechanism(s)
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______________________________________________________________________________
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% What is Cryptography? (The Short Version) %
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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"Cryptography is the art and science of hiding data in plain sight. It is
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also the art and science of stealing data hidden in plain sight."
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(Both accurate definitions, by Larry Loen.)
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Have you ever made secret codes with your friends when you were little?
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Whether it was a number code where each letter of the alphabet had a
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substituted number, or you made a chart for each of you to translate a message,
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you were practicing a simple form of Cryptography. As far as I can back up,
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cryptology wasn't widely used until World War I, when actual machines were
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created for the sole purpose of making messages unreadable to the enemy.
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Cryptography is the method by which "plaintext" is encrypted into an
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unreadable form. The plaintext is the original text, before ltering to make it
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unreadable to other people. The key, or code, is the actual password (or
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whatnot) used to make it unreadable. This is a very simplistic, and not
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completely accurate view for which I apologize and again urge anyone seriously
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interested to read actual hard-copy books and papers for a more detailed
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explanation.
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===============================================
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= Why are encrypted communications important? =
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===============================================
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In today's electronic communication forums, encryption can be very
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mportant! Do you know for a fact that when you send a message to someone else,
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that someone hasn't read it along the way? Have you ever really sent something
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you didn't want anyone reading except the person you sent it to? As more and
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more things become online, and "paperless" communication predictions start
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coming true, it's all the more reason for encryption. Unlike the normal U.S.
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Mail where it is a crime to tamper with your mail, email-reading can commonly
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go unnoticed on electronic pathways as your message hops from system to system
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on its route towards its final destination. Just think, the average Internet
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letter makes at least two hops before it reaches its recipient, usually more.
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Even on public BBS's, your mail is usually stored in plaintext. Can you be
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sure someone else isn't reading it? The sysop? Half a dozen co-sysops and
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hangers-on? How hard would it be for system administrators to set up a process
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to "grep" (search for known text) all incoming/outgoing mail batches for
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certain catch phrases? It's not very hard, I assure you. Although most people
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probably don't do things like this, the threat is real. That's why you need to
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encrypt your messages. You have the right of privacy, as stated in the
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Constitution. That's why cryptography is so key.
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=========================================
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= Different types of encryption schemes =
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=========================================
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One-Way encryption algorithms: What are they?
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There are certain mathematical/cryptographical algorithms that will
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encrypt a string of text/numbers using a complex equation. However, you cannot
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reverse these equations again (take my word for it, it has to do with
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pieces of the equation being unknown, and purposely lost in the encryption
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process).
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A real-life example of one-way encryption:
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These types of algorithms are used when someone needs to compare text,
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such as in password validation checks. Crypt(), the Unix password validation
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routine works like this. A password is used at the key to encrypt a plaintext
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string of 0's. Then, to verify the password, the computer tries to encrypt the
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same string of plaintext with the password typed in. If a match is made to the
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original encrypted text, then the password is valid. (Note: Although you can't
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reverse this to find out what the original password/key was, you can compare
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two encryptions to see if it's the same key.)
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The "One-Time Pad"
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==================
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A long string of random numbers are generated/created. Messages cannot
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be any longer than the string of random numbers, but can be shorter.
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The text is encrypted by XOR'ing the bits in relation to the random string
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of numbers. Bit by bit. So, anyone not knowing the original key wouldn't know
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whether the string, "123" was really "456" or "789" because in fact the
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originator and the intended receiver know it's really, "012" (wrap around
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9->0). This is the best explanation I can come up with for this.
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It's a proven technique and is considered quite secure.
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Single-Key Encryption
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=====================
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This is what most non-crypto-speak people would understand as an
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encryption system. You enter one string of characters (or whatnot - The KEY)
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and encrypt your plaintext with this key. Anyone with knowledge of what this
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key is can decrypt and read the plaintext.
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Public-Key Encryption
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=====================
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This is gaining a large following during the time of this writing with
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such programs as RIPEM, PGP, and the availability of RSAREF, a RSA Public Key
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algorithm library. RIPEM, and PGP (Pretty Good Privacy by Phil Zimmerman) are
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both examples of RSA Public Key systems. There are two distinct parts to a
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public key system, the PUBLIC key and the PRIVATE key.
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o The PUBLIC key is given out to everyone you know who would want to send
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you an encrypted message.
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o The PRIVATE key you keep secret and do not disclose to anyone.
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How it works: User A (Iskra) wants to send a message to User B (B00gerHed)
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so Iskra encrypts a message to B00gerHed using BH's public key that was given
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out at the last HoHoCon. No one except B00gerHed has the private key to
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decrypt the message. So he takes his private key, the counterpart to his
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public key, and decrypts the message sent to him by Iskra. Viola. He now sees
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that the new red boxes are no longer working because AT&T has cinched up the
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timing checks. However, Veggie (User C) has intercepted the encrypted message
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and is trying to figure out what they are talking about. But because he
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doesn't have B00gerHed's private key, he cannot read it. A successful use of
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public key encryption.
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There are a LOT of books on this, so that's all I'm going to say.
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% Books, journals et al... %
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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NOTE: A lot of the best and most complete sources of cryptography and some
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algorithms are classified by the United States Government. However, there are
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still a decent number I can suggest. Also, the NSA has been pushing for
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legislation to require all encryption schemes to be "breakable" in a reasonable
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matter of time with back doors or weaknesses so THEY can decrypt your messages.
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This is a violation of your rights. I hope you would oppose such things.
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Thanks to the following people for some info:
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Larry Loen - lwloen@rchland.vnet.ibm.com 11/92)
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cme@ellisun.sw.stratus.com (Carl Ellison) 11/92)
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Alec Chambers (jac54@cas.org)
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mrr@scss3.cl.msu.edu (Mark Riordan)
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David Kahn, The Codebreakers, Macmillan, 1967 [history; excellent]
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H.F. Gaines, Cryptanalysis, Dover, 1956 [originally 1939, as
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Elementary Cryptanalysis].
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Abraham Sinkov, Elementary Cryptanalysis, Math. Assoc. of Amer., 1966.
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D. Denning, Cryptography and Data Security, Addison-Wesley, 1983.
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[ Dorothy Denning, also wrote a paper proposing all public key ]
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[ systems be required to "register" their private keys with the ]
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[ NSA or other agency for decryption should the gov't feel it ]
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[ necessary. ]
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Alan G. Konheim, Cryptography: A Primer, Wiley-Interscience, 1981.
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Meyer and Matyas, Cryptography: A New Dimension in Computer Data Security,
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John Wiley & Sons, 1982.
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Books can be ordered from Aegan Park Press. They aren't cheap, but they
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are the only known public source for most of these and other books of
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historical and analytical interest.
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Write for catalog to:
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Aegean Park Press
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P.O. Box 2837
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Laguna Hills, CA 92654-0837
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Cryptologia: a cryptology journal, quarterly since Jan 1977.
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Cryptologia; Rose-Hulman Institute of Technology; Terre Haute,
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Indiana 47803 [general: systems, analysis, history, ...]
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Gordon Welchman, The Hut Six Story, McGraw-Hill, 1982.
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[excellent description of his WW-II crypto work (breaking the German
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Enigma); discussion of modern cryptological implications]
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--
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Various books available from Artech House, 610 Washington St., Dedham, MA
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02026; including:
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Deavours & Hruh, Machine Cryptography and Modern Cryptanalysis.
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[operation and breaking of cipher machines through about 1955]
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Deavours, et al., CRYPTOLOGY Yesterday, Today, and Tomorrow.
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[Cryptologia reprints - 1st volume]
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Deavours, et al., CRYPTOLOGY: Machines, History & Methods.
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[Cryptologia reprints - 2nd volume]
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--
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Cryptologia
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Rose-Hulman Institute of Technology
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Terre Haute, Indiana 47803
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Cryptologia: a cryptology journal, quarterly since Jan 1977.
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Journal of the International Association for Cryptologic Research.
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[quarterly since 1988]
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The RSA paper: The Comm. of the ACM, Feb 1978, p. 120.
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Claude Shannon's 2 1940's papers in the Bell System Tech Journal.
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Herbert O. Yardley, The American Black Chamber, Bobbs-Merrill, 1931.
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[First hand history - WW-I era]
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Edwin Layton, "And I Was There", William Morrow & Co., 1985.
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[First hand history - WW-II]
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W. Kozaczuk, Enigma, University Publications of America, 1984.
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[First hand history (Rejewski's) - pre-WW-II]
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Journal of Cryptology
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Springer-Verlag New York, Inc.
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Service Center Secaucus
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44 Hartz Way
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Secaucus, NJ 07094
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(201)348-4033
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$87/year + $8 postage & handling. Published three times a year.
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Cryptosystems Journal
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Tony Patti, Editor and Publisher
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P.O. Box 188
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Newtown, PA 18940-0188
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(215)579-9888
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tony_s_patti@cup.portal.com
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$45/year. Published three times a year. Journal dedicated to the
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implementation of cryptographic systems on IBM PC's. Emphasis on
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tutorial/pragmatic aspects. Evidently all articles are written by the
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publisher.
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Forbidden Knowledge
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P.O. Box 770813
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Lakewood, OH 44107
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$18 a year - make check or m/o to Darren Smith (editor). Jack Jeffries
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(cj137@cleveland.Freenet.Edu) says that this is a local publication which has
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articles on cryptology. That's all I know about it.
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The Cryptogram
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Journal of the American Cryptogram Association
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P.O. Box 6454
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Silver Spring, MD 20906
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This is the Journal of the American Cryptogram Assocation, available by
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joining the ACA. Dues are probably about $20/year by now. Published six times
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a year. Contains mostly puzzles for you to solve. No techniques invented after
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1920 are used, with simple substitution being the most common. Also contains
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articles on classical cryptosystems, and book reviews.
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The Cryptogram Computer Supplement
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Dan Veeneman
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P.O. Box 7
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Burlington, IL 60109 USA
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$2.50/issue. Published three times a year for ACA members. Newsletter
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for computer hobbyist members of the ACA.
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The Public Key
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George H. Foot, Editor
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Waterfall, Uvedale Road
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Oxted, Surry RH8 0EW
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United Kingdom
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Cost unknown. Magazine devoted to public key cryptography, especially
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amongst personal computer owners. Note that RSA's patents do not apply in
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Europe, hence the existence of this magazine.
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Surveillant,
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Lock Box Mail Unit 18757
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Washington, DC 20036-8757
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6 issues/year, $48.00. Announces new acquisitions and has some news from
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the intelligence field. Each issue comes with a check-off order form for books
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announced in that issue.
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______________________________________________________________________________
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I suggest if you have the time and access to follow the Usenet groups, as
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they have heaps of info. Also, reading the sci.crypt FAQ and the few online
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publications including Dorothy Denning's work will help you gain a better
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understanding. In fact, probably better than this hack job.
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Exeunt.
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_______ __________________________________________________________________
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/ _ _ \|Demon Roach Undrgrnd.806/794-4362|Kingdom of Shit.....806/794-1842|
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((___)) |Cool Beans!..........510/THE-COOL|Polka AE {PW:KILL}..806/794-4362|
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[ x x ] |The Alcazar..........401/782-6721|Moody Loners w/Guns.415/221-8608|
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\ / |The Works............617/861-8976|Finitopia...........916/673-8412|
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(' ') |ftp - zero.cypher.com in pub/cdc |ftp - ftp.eff.org in pub/cud/cdc|
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(U) |==================================================================|
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.ooM |Copr. 1993 cDc communications by Dave Ferret 04/01/93-#226|
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\_______/|All Rights Drooled Away. [cDc/K-rAd people are we]|
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