Where results make sense

About us   |   Why use us?   |   Reviews   |   PR   |   Contact us

Substitution cipher   (Site not responding. Last check: 2007-10-18) The simple substitution cipher is one in which each plaintext character is simply replaced by a corresponding one from a cipher alphabet. The earliest practical digraphic substitution was the so-called Playfair cipher, actually invented by Sir Charles Wheatstone in 1854. A digraphic substitution is then simulated by taking pairs of letters as two corners of a rectangle, and using the other two corners as the ciphertext (see the Playfair cipher main article for a diagram). www.sciencedaily.com /encyclopedia/substitution_cipher   (2407 words)

Polyalphabetic cipher - Wikipedia, the free encyclopedia Even Alberti's implementation of his polyalphabetic cypher was rather easy to break (the capitalized letter is a major clue to the cryptanalyst). Polyalphabetic substitution cypher designers seem to have concentrated on obscuring the choice of a few such alphabets (repeating as needed), not on the increased security possible by using many and never repeating any. The principle (particularly Alberti's unlimited additional substitution alphabets) was a major advance -- the most significant in the several hundred years since frequency analysis had been developed. www.wikipedia.org /wiki/Polyalphabetic_substitution   (522 words)

Enigma: Definition and Links by Encyclopedian.com - All about Enigma The cypher was in fact broken, and the reading of information in the messages it didn't protect is generally credited with ending World War II at least a year earlier than it would have otherwise. Simple frequency analysis relies on any one letter always being substituted for another letter in the cypher: if this is not the case the situation is more difficult. The ultimate cypher of this kind would be one in which such a long key could be generated from a simple pattern, just as the polyalphabetic ciphers generate a number of substitution alphabets given a simple key. www.encyclopedian.com /en/Enigma.html   (4650 words)

AMINO ACID SUBSTITUTION If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties. www.websters-online-dictionary.org /definition/AMINO+ACID+SUBSTITUTION   (156 words)

The unbreakable cypher   (Site not responding. Last check: 2007-10-18) In the history of cryptography, le chiffreindéchiffrable (French for 'the unbreakable cypher') was long used to refer, confusedly and incorrectly, to either oftwo hand cyphers named after Blaise de Vigenère (ie, Vigenère cypher). One of the Vigenère cyphers is usually an early exercise in introductory cryptography courses, as is its cryptanalysis. Even though these types of cypher are easily broken, there are products which use them while claiming to have "good security"or "unbreakability" — see snake oil. www.therfcc.org /the-unbreakable-cypher-335211.html   (323 words)

Le chiffre indéchiffrable -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-18) Both are (additional info and facts about polyalphabetic substitution cyphers) polyalphabetic substitution cyphers; neither is unbreakable. One of the Vigenère cyphers is usually an early exercise in introductory cryptography courses, as is its (The science of analyzing and deciphering codes and ciphers and cryptograms) cryptanalysis. Even though these types of cypher are easily broken, there are products which use them while claiming to have "good security" or "unbreakability" — see ((medicine) any of various liquids sold as medicine (as by a travelling medicine show) but medically worthless) snake oil. www.absoluteastronomy.com /encyclopedia/L/Le/Le_chiffre_ind%C3%A9chiffrable.htm   (410 words)

History of computing: Enigma machine   (Site not responding. Last check: 2007-10-18) Cypher users were told to not only use a different substitution for every letter, but also to use a very long key, so both of these techniques would fail (or at least be a lot harder). The ultimate cypher of this kind would be one in which such a long key could be generated from a simple pattern, producing a cypher in which there are so many substitution alphabets that frequency counting and statistical attacks would be effectively impossible. However, unlike the polyalphabetic system, the Enigma had no obvious key length since the rotors generated a new substitution alphabet with each keypress, and the entire sequence of substution alphabets could be changed by spinning one or more rotors, changing rotor order, etc before starting a new encryption. www.theparentingsearch.com /History_of_computing/Enigma.shtml   (4705 words)

Vigenère   (Site not responding. Last check: 2007-10-18) The cypher is a keyword-based system that uses a series of different Caesar ciphers based on the letters of the keyword. It is a simplified version of the more general polyalphabetic substitution cypher, invented by Alberti ca 1465. This use of multiple alphabets in rotation to encrypt a message is why this is called a polyalphabetic cipher; the systematic and repeated use of multiple alphabets (all ordered as in the natural alphabet) is why this cypher is not as secure as polyalphabetic cyphers can be. www.sciencedaily.com /encyclopedia/vigenere   (1263 words)

Cryptography - Part II   (Site not responding. Last check: 2007-10-18) Part II In Part I of this series we mentioned the simple substitution cypher in which each letter of the message is replaced by another letter of the alphabet on a consistent basis throughout the message. The agency creates cypher systems for use by the United States government, evaluates their security, and attempts to read the enciphered communications of other countries. Another type of cypher alphabet which might be used is one which is reciprocal, that is, if "a" translates into "q," then "q" also tranlates into "a," and so on. www25.brinkster.com /ranmath/crypt02.htm   (1182 words)

Science Fair Projects - Vigenère cipher The Vigenère cipher is a method of encryption that uses a series of different Caesar ciphers based on the letters of a keyword. It is a simplified version of the more general polyalphabetic substitution cipher, invented by Alberti circa 1465. The invention of the Vigenère cipher was misattributed to Blaise de Vigenère in the 19th century; it was originally described by a Giovan Batista Belaso in his 1553 book La cifra del. Sig. www.all-science-fair-projects.com /science_fair_projects_encyclopedia/Vigen%E8re_cipher   (943 words)

frequency analysis These cyphers replace one letter of the plaintext with another to produce the cyphertext, and any particular letter in the plaintext will always, in the simplest and most easily breakable of these cyphers, turn into the same letter in the cypher. The electro-mechanical cypher machines of the first half of the 20th century (eg, the Hebern machine, the various Enigmas, the Japanese Purple machine and its relatives, the SIGABA, the Typex,...) were, if properly used, essentially immune to straightforward frequency analysis attack, being fundamentally polyalphabetic cyphers. Several of the cyphers used by the Axis were breakable using frequency analysis (eg, some of the 'consular' cyphers used by the Japanese). textalyser.net /frequency_analysis.html   (715 words)

Bungie.net : Resources : Article We're hoping translation at this time is a simple substitution cypher - if it's not, we're going to be staring at it for a *long* time. Substitution method guessed one word to be November, but nothing fit for the other. Given the nature of substitution cyphers, accuracy is limited until you actually assure yourself of some of the code - then, we're rockin'. www.bungie.net /fanclub/beekeepers/Resources/Article.aspx?cid=64914   (181 words)

Frequency analysis   (Site not responding. Last check: 2007-10-18) These cyphers replace one letter of the plaintext with another to produce the cyphertext, and any particular letter in the plaintext will always, in the simplest and most easily breakable ofthese cyphers, turn into the same letter in the cypher. Poe was overconfident in his proclamation, however, for polyalphabetic substitution ciphers (invented by Alberti around 1467) are immune to simple frequency analysis attacks. The cypher in the Poe story is encrustedwith several deception measures, but this is more a literary device than anything significant cryptographically. www.therfcc.org /frequency-analysis-72541.html   (857 words)

Cryptogimp   (Site not responding. Last check: 2007-10-18) Substitution Box, an array of values that are used to find which character is substituted for some other character. The symmetric cypher is chosen by the browser from a selection provided by the server which it can use. A type of Symmetric cypher where the cypher generates a stream of Pseudo-Random bits that are combined with the Plaintext. www.cryptogimp.co.uk /whisper/glossary/s.html   (902 words)

Reflect : Codes and Cyphers Main Page   (Site not responding. Last check: 2007-10-18) Having solved a cypher of any type it is good practise to reconstruct the keyword, which may assist in the solution of future cyphers from the same source, or may yield other useful information. This is common to most cyphers, normally letters are blocked into 'words' of three or five letters, any remaining spaces are replaced with X's (or Nulls as they are known). In a Transposition Cypher the sequence of the letters is scrambled, normally using a matrix to determine the new order. home.att.net /~stephen821/cyphers/codesgen.htm   (1969 words)

Cryptography - Part V   (Site not responding. Last check: 2007-10-18) This is known as a polyalphabetic substitution cypher. The shorter the key relative to the length of the message the more the encypherment approaches a simple monoalphabetic cypher and the easier it is to solve and vice versa. A compromise may be reached by using a short key and having a number of sets of substitution alphabets, using a different one for each repetition of the key. www25.brinkster.com /ranmath/crypt05.htm   (772 words)

Button Instructions   (Site not responding. Last check: 2007-10-18) Cypher defaults to monoalphabetic substitution cipher as the cipher guessed in use. Besides the simple monoalphabetic substitution cipher there is shift monoalphabetic substitution cipher. Data will be calculated, a report made, and the number figured by Cypher which may or may not be appropriate for the Space Value. www.cs.unc.edu /~stotts/145/homes/crypt/userManual/user_button.html   (382 words)

Cryptography:Frequency analysis - Wikibooks Poe was overconfident in his proclamation, however, for polyalphabetic substitution cyphers (invented by Alberti around 1467) defy simple frequency analysis attacks. Several of the cyphers used by the Axis were breakable using frequency analysis (eg, the 'consular' cyphers used by the Japanese). No mere substitution cypher can be thought credibly safe in modern times. en.wikibooks.org /wiki/Cryptography:Frequency_analysis   (755 words)

History of Cryptography   (Site not responding. Last check: 2007-10-18) Messages were encoded by substituting the letter in the text by one that is three positions to the right. There was however a weakness in this cypher waiting to be exploited because the cyphertext produced by this method was vulnerable to the yet undiscovered statistical attack. Unfortunately for the WWI allies their decryption of almost all German cypher traffic had ceased by early 1930 because of the introduction of the Enigma. www.cypher.com.au /crypto_history.htm   (3944 words)

CS 321 Lecture Notes   (Site not responding. Last check: 2007-10-18) Caeser's cyper, or any similar ``substitution cypher'' is painfully insecure- if you can work out one letter (e.g., based on formatting, frequency analysis, or just repetition), you can recognize it anytime that letter appears again. Useful examples of symmetric cyphers are the older DES (56-bit key, 64-bits of data at a time), and the more modern AES (128-bit to 256-bit key, 128 bits at a time). Both of these are ``block cyphers'', where they take the input one block (64 or 128 bits) at a time, mix it up thoroughly, spit it out, keep the mixed copy, and move to the next block. lawlor.cs.uaf.edu /2005/cs321/lecture/2005_04_27/lecture/lecture.html   (666 words)

Enigma machine   (Site not responding. Last check: 2007-10-18) In the frequency analysis technique, letters and letter patterns are counted. It took several hundred years before methods to reliably break these cyphers were found. The effort which broke the German cypher began in 1929 when the Poles intercepted an Enigma machine being shipped from Berlin to Warsaw and mistakenly not protected as diplomatic baggage. www.portaljuice.com /enigma_machine.html   (5000 words)

Comments on 6265 | Ask MetaFilter It is a neat encryption idea, though, vacapinta, and something that might take a few minutes to crack for those used to straight substitution cyphers. Thus the particular cypher is very random-seeming, but always ties back to a single unguessable structure. Of course, cyphers are computational child's play, and practically meaningless as a way of really hiding information. ask.metafilter.com /mefi/6265   (1217 words)

Communication, Codes and Cyphers The way it works is that you simply mix-up (or permute) the letters of your alphabet and replace each letter in your message by the corresponding letter in the permuted alphabet. In fact, using a little educated guesswork and knowledge of English, it is often possible to work out what the unencrypted version must be for a message with as few as 50 letters. Needless to say, you do not want to be using a substitution cypher to transmit national secrets. www.nevada.edu /~cwebster/Teaching/Notes/Codes/Introduction/examples.html   (1254 words)

[No title]   (Site not responding. Last check: 2007-10-18) Please enter the time at which the population is to be estimated... Substitution Cypher ######################## Inputs encodingShift - shift in alphabet position for cypher message - the message (string) to be encoded continuation - whether user wishes to continue with another subst. The encoded message is #@$%%^&&(&*!%($@$^ Would you like to perform another substitution?... www.itee.adfa.edu.au /courses/ZITE7103/work/Solutions/soln02S1_1.txt   (209 words)

jambeCodec_Enigma - JAMBE's Online Enigma Machine This does make it easier to understand, and it is compatible with my buggy c++ code and my paper and scissors enigma machine. Enigma machines basicly works like a substitution cypher except that the cypher changes for each letter. When that rotor is completing one whole turn you turn the middle rotor as well, so that the next time through you get a different set of cyphers again. homepages.maxnet.co.nz /brunnies/EnigmaApplet.html   (358 words)

[No title]   (Site not responding. Last check: 2007-10-18) Compression technique that substitutes a "count" for a string of repeated symbols. A secret-key block substitution cypher using a 56-bit secret key, 64-bit blocks, and bit twiddleing step that is repeated 16 times. A secret-key block substitution cypher using a 128-bit secret key, 64-bit blocks, and bit twiddleing step that is repeated 8 times. www.cis.temple.edu /~stafford/thunder9899/cis741/week15/pfinal00.txt   (2027 words)

[No title]   (Site not responding. Last check: 2007-10-18) The first one is encrypted with a substitution cypher - the second string is the key of the cypher. The slashes are not in the cypher key; they are used to divide the encrypted string into a sequence of substrings. I realized that it was doing a substitution cypher and wrote a small program to print the decrypted string Source Output sigbeer.org /%7Emike/old/virginia/xmassong   (959 words)

Classes -- CSCI 200: Assignment #6   (Site not responding. Last check: 2007-10-18) A simple type of encryption is a substitution cipher. In a substitution cypher, a table is maintained for each character that might appear in an unencrypted message (called the "plaintext"). Write two similar programs: one which uses a simple substitution cipher to encode a plaintext character into an encrypted character, and one which decodes an encrypted character into a plaintext character. www.cs.ulm.edu /~smith/fall00/cs200/assign6.html   (585 words)

Secret Codes and Cyphers   (Site not responding. Last check: 2007-10-18) The simplest way to do this is to use a plain substitution code or cypher. The weakness of a simple substitution cypher is that each original letter is always replaced with the same cypher symbol. This can be done in various ways, but in practice these are always based on the ideas of the one time pad and a extended form of substitution code where we encrypt groups of characters - perhaps as many as a few dozen at a time. www.st-andrews.ac.uk /~jcgl/Scots_Guide/info/signals/digital/codes/secret/cyphers.html   (389 words)

[No title] Or if -o is the first command line */ /* parameter, the program generates a puzzle from the fortune */ /* command. The encryption must be a simple substitution cypher. It will allow you to */ /* substitute non-letters into the puzzle. www.cs.uakron.edu /~hennings/progs/cypher.c   (134 words)

Try your search on: Qwika (all wikis)

About us   |   Why use us?   |   Reviews   |   Press   |   Contact us   Copyright © 2005-2007 www.factbites.com Usage implies agreement with terms.