some essential definitions some essential definitions in the field of cryptography are: - cryptoanalysis - cryptology - ciphers "Few false ideas have more firmly gripped the minds of so many intelligent men than the one that, if they just tried, they could invent a cipher that no one could break." (David Kahn) codes plaintext ciphertext to encipher/encode to decipher/decode The variants of encryption systems are endless. For deciphering there exists always the same game of trial and error (first guessing the encryption method, then the code). A help to do so is pruning. Once, after a more or less long or short period a code/cipher breaks. Monoalphabetic ciphers can be broken easily and of course are no longer used today but for games. for further information on codes and ciphers etc. see: http://www.optonline.com/comptons/ceo/01004A.html http://www.ridex.co.uk/cryptology/#_Toc439908851

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Cryptography's Terms and background "All nature is merely a cipher and a secret writing." Blaise de Vigenère In the (dis-)information age getting information but at the same time excluding others from it is part of a power-game (keeping the other uneducated). The reason for it eventually has found an argument called security. Compared to the frequency of its presence in articles, the news and political speeches security seems to be one of the most popular words of the 90's. It must be a long time ago when that word was only used for and by the military and the police. Today one can find it as part of every political issue. Even development assistance and nutrition programs consider it part of its work. The so-called but also real need for information security is widespread and concerning everybody, whether someone uses information technology or not. In any case information about individuals is moving globally; mostly sensitive information like about bank records, insurance and medical data, credit card transactions, and much much more. Any kind of personal or business communication, including telephone conversations, fax messages, and of course e-mail is concerned. Not to forget further financial transactions and business information. Almost every aspect of modern life is affected. We want to communicate with everybody - but do not want anybody to know. Whereas the market already depends on the electronic flow of information and the digital tools get faster and more sophisticated all the time, the rise of privacy and security concerns have to be stated as well. With the increase of digital communication its vulnerability is increasing just as fast. And there exist two (or three) elements competing and giving the term digital security a rather drastic bitter taste: this is on the one hand the growing possibility for criminals to use modern technology not only to hide their source and work secretly but also to manipulate financial and other transfers. On the other hand there are the governments of many states telling the population that they need access to any kind of data to keep control against those criminals. And finally there are those people, living between enlightening security gaps and at the same time harming other private people's actions with their work: computer hackers. While the potential of global information is regarded as endless, it is those elements that reduce it. There is no definite solution, but at least some tools have been developed to improve the situation: cryptography, the freedom to encode those data that one does not want to be known by everybody, and give a possibility to decode them to those who shall know the data. During the last 80 years cryptography has changed from a mere political into a private, economic but still political tool: at the same time it was necessary to improve the tools, eventually based on mathematics. Hence generally cryptography is regarded as something very complicated. And in many ways this is true as the modern ways of enciphering are all about mathematics. "Crypto is not mathematics, but crypto can be highly mathematical, crypto can use mathematics, but good crypto can be done without a great reliance on complex mathematics." (W.T. Shaw) For an introduction into cryptography and the mathematical tasks see: http://www.sbox.tu-graz.ac.at/home/j/jonny/projects/crypto/index.htm http://www.ccc.de/CCC-CA/policy.html

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Timeline BC ~ 1900 BC: Egyptian writers use non-standard Hieroglyphs in inscriptions of a royal tomb; supposedly this is not the first but the first documented example of written cryptography 1500 an enciphered formula for the production of pottery is done in Mesopotamia parts of the Hebrew writing of Jeremiah's words are written down in "atbash", which is nothing else than a reverse alphabet and one of the first famous methods of enciphering 4th century Aeneas Tacticus invents a form of beacons, by introducing a sort of water-clock 487 the Spartans introduce the so called "skytale" for sending short secret messages to and from the battle field 170 Polybius develops a system to convert letters into numerical characters, an invention called the Polybius Chequerboard. 50-60 Julius Caesar develops an enciphering method, later called the Caesar Cipher, shifting each letter of the alphabet an amount which is fixed before. Like atbash this is a monoalphabetic substitution.

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IDEA IDEA is another symmetric-key system. It is a block cipher, operating on 64-bit plaintext blocks, having a key-length of 128 bits.

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