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Topic: Substitution cipher

Related Topics

Simple substitution cipher

Playfair cipher

Permutation cipher

Polyalphabetic cipher

Transposition cipher

Classical cipher

Atbash

Caesar cipher

Monoalphabetic substitution cipher

Autokey cipher

Product cipher

Ciphertext

Bifid cipher

Encryption

Atbash cypher

	Substitution Cipher
		Wiki says: In cryptography, a substitution cipher is a method of encryption by which units of plaintext are substituted with ciphertext according to a regular system; the "units" may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth.
		The cipher alphabet may be shifted or reversed (creating the Caesar and Atbash ciphers, respectively) or scrambled in a more complex fashion, in which case it is called a mixed alphabet or deranged alphabet.
		It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions further down the alphabet.
	substitution.webmasters.sk (254 words)

	The Knights Templar \| Baphomet: The Atbash Cipher Theory \| www.templarhistory.com
		In order to understand the Atbash Cipher theory, as it relates to the Baphomet mythos, it is first important to examine the origins of the code.
		In the case of the Atbash cipher, the first letter of the alphabet is substituted for the last, the second for the second last and so on.
		Whether the Templars were devoted to the goddess or simply respectful of wisdom, it cannot be argued that Schonfield's Atbash cipher theory is among the most plausible explanations of the etymology of Baphomet.
	www.templarhistory.com /atbash.html (455 words)

	Substitution Cipher
		To prevent other companies from revealing his secret, he decided to use a substitution cipher in all the letters mentioning the new play.
		Substitution cipher is defined by a substitution table assigning each character of the substitution alphabet another character of the same alphabet.
		The director is afraid of disclosing the substitution table and therefore he changes it frequently.
	acm.uva.es /p/v7/715.html (383 words)

	Cryptography -- Vigenere Cipher (Site not responding. Last check: 2007-10-07)
		A variation of it, known as the Gronsfeld cipher, did catch on in Germany and was widely used in Central Europe.
		Vigenere-like substitution ciphers were regarded by many as practically unbreakable for 300 years.
		Given the structure of the Vigenere tableau, this is equivalent to using 9 distinct simple substitution ciphers, each of which was derived from 1 of the 26 possible Caesar shifts given in the tableau.
	www.trincoll.edu /depts/cpsc/cryptography/vigenere.html (1337 words)

	Cryptography -- Simple Substitution (Site not responding. Last check: 2007-10-07)
		A cipher is a method for encrypting a message -- i.e., for transforming the message into one that can't be easily read.
		A substitution cipheris one in which each letter of the plaintext is replaced by some other symbol.
		A simple substitution is one in which each letter of the plaintext is always replaced by the same ciphertext symbol.
	www.trincoll.edu /depts/cpsc/cryptography/substitution.html (965 words)

	History of Cryptography and Secrecy Systems
		Substitution is a cryptographic technique where each letter of the plaintext message is replaced by a different letter.
		A simple substitution cryptographic technique where the cipher alphabet is shifted a certain number of spaces relative to the original plain alphabet.
		In the case of a substitution cipher, the algorithm would be replacing plain text letters with cipher text letters and the key would be the actual cipher text alphabet.
	www.dsm.fordham.edu /~mathai/crypto.html (2428 words)

	Dynamic substitution combiner and extractor - Patent 4979832
		Substitution is generally easy to solve or penetrate because the different letters in a written language are used with different characteristic frequencies, and substitution does not change those relationships.
		The extractor substitution 30 translates the extractor substitution changes input 28 data into the extractor substitution output 32 data; extractor substitution 30 is the same as combiner substitution 12, and is used to develop translated pseudo-random data to change inverse substitution 24.
		The method of the present development is to revive and generalize the venerable substitution cipher, with the addition of a new data input which is used, along with the substitution input, to alter the contents of the translation table during operation.
	www.freepatentsonline.com /4979832.html (6166 words)

	The Dynamic Substitution Combiner (Site not responding. Last check: 2007-10-07)
		Simple substitution is normally considered to be a very weak cryptographic operation [22], mainly because substitution in no way obscures the letter- frequency distribution of the source text.
		The combination of substitution and a strategy for changing the contents of the substitution tables yields a cryptographic combining function; such a function may be used to combine plaintext data with a pseudo-random sequence to generate enciphered data.
		The simple substitution function is a monoalphabetic substitution cipher, and is easily penetrated since a mapping preserves the frequency distributions of the source material (the message).
	www.ciphersbyritter.com /ARTS/DYNSUB2.HTM (4264 words)

	[No title] (Site not responding. Last check: 2007-10-07)
		There are a total of five classical substitution ciphers and they are as follows: ) Simple substitution* cipher - Sometimes called a monoalphabetic cipher, is one in which each character in plaintext is substituted with another in ciphertext.
		Simple substitution cipher's are really not hard to break anyway, considering if they only substituted characters, the cipher does not hide the underlying frequencies of the different letters of the plaintext.
		Homophonic is superior to the simple substitution ciphers and are much more complicated to break, but still do not interrupt all of the stats properties of the plaintext language.
	www.security-protocols.com /whitepapers/cryptography/sub.txt (529 words)

	Codes and Ciphers
		Ciphers have been in use since at least Ancient Rome, and there are indications in ancient writings that they were in use earlier than that.
		The Caesar Substitution cipher, and all like it were called "simple substitution" (to the cryptologist, "monalphabetic substitution") because throughout the message, each character was always replaced by the identical cipher character (e.g., in the Caesar Substitution, "F" would always represent "c" throughout the message).
		Field Ciphers were not intended to be as secure as those between military bases and diplomatic missions, but if they could prevent an adversary from decrypting a message until it was too late, they served their purpose.
	www.otr.com /ciphers.shtml (2124 words)

	Substitution Ciphers
		Substitution Ciphers are ciphers in which each letter is replaced by a different letter.
		Typically in a homophonic substitution cipher, the cipher alphabet (the symbols which can appear in a ciphertext) is larger than the plaintext alphabet.
		Polygram substitution ciphers are ciphers in which ciphertext polygrams (sequences of a few letters) are substituted for plaintext polygrams.
	www.disappearing-inc.com /S/substitutionciphers.html (657 words)

	Cryptography Tutorial - Substitution Ciphers
		Example 1: (Caesar Cipher) The simplest of all substitution ciphers is the one in which the cipher letters results from shifting plain letters by the same distance.
		In Substitution Ciphers, single letters or pairs of letters are replaced with symbols or groups of symbols, which need not be the same as those used in the plaintext.
		We will study three monoalphabetic ciphers in detail and learn that neither the cyclical-shift substitution ciphers nor any other monoalphabetic substitution cipher in which a given plaintext letter is always encrypted into the same ciphertext letter are secure.
	www.antilles.k12.vi.us /math/cryptotut/substitution.htm (1335 words)

	What are substitution and transposition ciphers?
		The Ceasar Cipher was an early substitution cipher.
		An even more complex substitution cipher can be made by having each character of the alphabet correspond to a different letter of the alphabet, without a set pattern.
		The Vernam Cipher, or one time pad, is a simple substitution cipher where the key length equals the message length.
	www.tech-faq.com /substitution-transposition-cipher.shtml (269 words)

	How the Vigenere Cipher Works : A detailed explanation into an important cryptographic historical discovery (Site not responding. Last check: 2007-10-07)
		Substitution Cipher — A method of encryption by which units of plaintext are substituted with cipher text according to a regular system.
		It is a type of substitution cipher in which each letter in plaintext is replaced by a letter some fixed number of positions further down the alphabet.
		The Vigenere cipher is a method of encryption which uses several different Caesar ciphers based on the letters of a keyword and is considered a simple form of polyalphabetic substitution.
	www.xramp.com /resources/vigenerecipherdetails (812 words)

	Codes, Ciphers, & Codebreaking (Site not responding. Last check: 2007-10-07)
		Use of ciphers for military purposes goes back at least to Julius Ceasar, who was skilled in their use.
		This large number of possible monoalphabetic substitution cipher alphabets means that if such a "mixed cipher alphabet" is used, cracking it with a brute-force attack is very difficult.
		This is a simple cipher algorithm, but even if a codebreaker knows that this general scheme was used, the message still cannot be read without the key, and a brute-force approach to cracking it is very difficult.
	www.darkmattermag.com /October2003/dark_science2.htm (679 words)

	Cipher Glossary
		The cipher alphabet can also consist of numbers or any other characters, but in all cases it dictates the replacements for letters in the original message.
		Sometimes the term is used more generally to mean the science of anything connected with ciphers, and is an alternative to the term cryptology.
		substitution cipher : A system of encryption in which each letter of a message is replaced with another character, but retains its position within the message.
	www.fortunecity.com /emachines/e11/86/cipherglos.html (1226 words)

	v7ndotcom elursrebmem v7ndotcoms elursrebmems
		This is a simple cipher algorithm, but even if a codebreaker knows that this general scheme was used, the message still cannot be read without the key, and a brute-force approach to cracking it is very difficult.
		The ancient Spartans used a form of transposition cipher, in which a strip of parchment was wound in a spiral around a wooden cylinder known as a "scytale", and a message was written down the length of the cylinder.
		The frequency of the cipher letters of course is the frequency of their plaintext equivalents, and so at first sight it would be logical to believe that the ciphertext "O" at the top of the list corresponds to plaintext "e", while the ciphertext "N" at the bottom of the list corresponds to plaintext "z".
	www.toprankingcompany.com /code-breaking.htm (4737 words)

	Monoalphabetic Cipher
		Ciphers in which the cipher alphabet remains unchanged throughout the message are called Monoalphabetic Substitution Ciphers.
		If we permit the cipher alphabet to be any rearrangement of the plain alphabet, then we can generate an enormous number of distinct modes of encryption.
		If our message is intercepted by the enemy, who correctly assumes that we have used a monoalphabetic substitution cipher, they are still faced with the impossible challenge of checking all possible keys.
	www.simonsingh.net /The_Black_Chamber/generalsubstitutionWithMenu.html (177 words)

	Cryptography Workshop Outline
		A shift cipher is implemented by adding a constant to each plaintext letter, and its inverse by subtracting the same constant.
		A simple shift uses a one-element key, and the cipher is broken by fixing just one letter; an affine code uses a two-element key and may be broken by fixing as few as two letters; a word-key substitution cipher has a variable-length key, and requires more work to break.
		An astonishingly simple machine implements a substitution cipher in which the alphabets move irregularly, and the cycle of alphabets is the GCD of the sizes of two wheels.
	www.mtholyoke.edu /courses/quenell/s2002/crypto/outline.html (1561 words)

	Monoalphabetic Substitution Cipher Applet (Site not responding. Last check: 2007-10-07)
		The letters A-Z are substituted according to the characters specified in the "Cipher alphabet".
		The cipher alphabet present when the applets starts up implements a "Caesar-shift" substitution cipher, whereby the normal, in this case English, alphabet is "shifted" a certain number of places to the right.
		The Caesar-shift substitution cipher was used by Julius Caesar to deliver secret messages, for example, to Cicero.
	people.reed.edu /~mcphailb/applets/crypto (200 words)

	IM-QPP: REF IRON MOUTH ARTICLE
		In Figure 7 are listed the repeated letter combinations in the ciphered message, together with the distances they are from each other. The next step is to take the distances and break them down into their factors. Doing so, we obtain the values in Figure 8.
		To test the period you've chosen, you need to segment the cipher into six portions. For the test period six, this has been done in Figure 9. The next step is to do a frequency count for each of the six message segments, which we've done in Figure 10.
		I have tested the Kasiski method out on this month's Vigenere cipher and it should, relatively easily, enable you to guess the correct period for the cipher. From there, you're on your own, although as I have said, the most difficult part of cryptanalysis of periodic ciphers is the determination of the keyword's period.
	members.tripod.com /~ironmouth/mp-ref-ima.html (362 words)

	Monoalphabetic Substitution Cipher Applet (Site not responding. Last check: 2007-10-07)
		The letters A-Z are substituted according to the characters specified in the "Cipher alphabet".
		The cipher alphabet present when the applets starts up implements a "Caesar-shift" substitution cipher, whereby the normal, in this case English, alphabet is "shifted" a certain number of places to the right.
		The Caesar-shift substitution cipher was used by Julius Caesar to deliver secret messages, for example, to Cicero.
	www.reed.edu /~mcphailb/applets/crypto (200 words)

	Analysis of Criminal Codes and Ciphers by Olson (Forensic Science Communications, January 2000)
		Ciphers involve the replacement of true letters or numbers (plain text) with different characters (cipher text) or the systematic rearrangement of the true letters without changing their identities to form an enciphered message.
		This complex cipher used more than fifty shapes and symbols to represent the 26 letters of the alphabet but was broken in hours by a high school history teacher and his wife.
		Ciphers can be made more secure by using a keyword to scramble one of the alphabets.
	www.fbi.gov /hq/lab/fsc/backissu/jan2000/olson.htm (2118 words)

	Cryptography Workshop Outline
		A shift cipher is implemented by adding a constant to each plaintext letter, and its inverse by subtracting the same constant.
		A simple shift uses a one-element key, and the cipher is broken by fixing just one letter; an affine code uses a two-element key and may be broken by fixing as few as two letters; a word-key substitution cipher has a variable-length key, and requires more work to break.
		An astonishingly simple machine implements a substitution cipher in which the alphabets move irregularly, and the cycle of alphabets is the GCD of the sizes of two wheels.
	users.bestweb.net /~quenell/s2002/crypto/outline.html (1561 words)

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