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Topic: Classical cipher

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Bifid cipher

Substitution cipher

Encryption

Caesar cipher

Famous ciphertexts

Stream cipher

Rotor machine

Cryptography

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	Classical cipher - Wikipedia, the free encyclopedia (Site not responding. Last check: 2007-10-22)
		In general, classical ciphers operate on an alphabet of letters (such as "A-Z"), and are implemented by hand or with simple mechanical devices.
		Classical schemes are often susceptible to ciphertext-only attacks, sometimes even without knowledge of the system itself, using tools such as frequency analysis.
		Classical ciphers are often divided into transposition ciphers and substitution ciphers.
	en.wikipedia.org /wiki/Classical_cipher (214 words)

	Encryption - Biocrawler definition:Encryption - Biocrawler (Site not responding. Last check: 2007-10-22)
		Ciphers are usually parameterized by a piece of auxiliary information, called a key.
		Historical pen and paper ciphers used in the past are sometimes known as classical ciphers.
		Symmetric key ciphers can be distinguished into two types, depending on whether they work on blocks of symbols usually of a fixed size (block ciphers), or on a continuous stream of symbols (stream ciphers).
	www.biocrawler.com /biowiki/Cipher (704 words)

	United States Patent 4,979,832
		This is a substitution-permutation product cipher which applies a sequence of substitutions and permutations to the plaintext data, with each substitution selected by the key from a set of pre-defined tables.
		The arrangement of ciphering modules might be fixed by design, or selected by the key, or might even change dynamically as a result of a pseudo-random sequence, or even cipher-network values.
		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.ciphersbyritter.com /PATS/DYNSBPAT.HTM (6262 words)

	Cryptology Lecture Notes 2
		In a transposition cipher the letters of the original message remain the same, but their positions are scrambled in some systematic way.
		Recognizing transposition ciphers is easily done by considering the fact that the vowel percentage in English is 40% and almost never varies outside of the range 35% - 45%.
		Transposition ciphers are easily recognized by their letter frequencies but remain hard to decipher since there are many ways to systematically encrypt.
	www-math.cudenver.edu /~wcherowi/courses/m5410/m5410cc.html (2236 words)

	HIGH-SECURITY CIPHER (Site not responding. Last check: 2007-10-22)
		The process is simple: you start with a basic cipher, then you examine all of the known ways that such ciphers have been broken in the past, and you devise ways to defeat those attacks.
		Such a cipher was invented in 1563 by Giovanni Batista Porta, and is now known as a Type IV Quagmire cipher by hobbyists in the American Cryptogram Association.
		The basis for cracking such a polyalphabetic cipher is to discover several sections of text that have been enciphered with the same part of the key stream.
	www.contestcen.com /crypt003.htm (3667 words)

	wikien.info: Main_Page (Site not responding. Last check: 2007-10-22)
		The Greeks of Classical times are said to have known of ciphers (e.g., the scytale transposition cipher claimed to have been used by the Spartan military).
		Allied cipher machines used in WWII included the British TypeX and the American SIGABA; both were electromechanical rotor designs similar in spirit to the Enigma, though with major improvements.
		British SOE agents initially used 'poem ciphers' (memorized poems were the keys), but later in the war, they began to switch to one time pads.
	www.alanaditescili.net /index.php?title=History_of_cryptography (2887 words)

	INI : Abstracts : QIS_FOCUS : On the Key-Uncertainty of Quantum Ciphers and the Computational Security of One-way ... (Site not responding. Last check: 2007-10-22)
		In this direction, we show that there exist ciphers with perfect security producing quantum ciphertext where, even if an adversary knows the plaintext and applies an optimal measurement on the ciphertext, his Shannon uncertainty about the key used is almost maximal.
		This is in contrast to the classical case where the adversary always learns $n$ bits of information on the key in a known plaintext attack.
		We also show that there is a limit to how different the classical and quantum cases can be: the most probable key, given matching plain- and ciphertexts, has the same probability in both the quantum and the classical cases.
	www.newton.cam.ac.uk /programmes/QIS/Abstract3/pederson.html (303 words)

	The Penknife Cipher Design
		Penknife builds on the basic concepts of a conventional stream cipher: The classical stream cipher combines a confusion stream with a data stream to produce a ciphertext stream.
		The cipher is given an alias, finds the "closest" alias file, deciphers that file in memory only (using the same Penknife cipher), and produces the current secret key associated with that alias.
		The Penknife cipher is a serious commercial design, and is part of a growing family of serious ciphers and cipher engines for software developers.
	www.ciphersbyritter.com /PENDESN.HTM (4567 words)

	Encryption (Site not responding. Last check: 2007-10-22)
		Encryption can be used to ensure secrecy, but other techniques are still needed to make communications secure, particularly to verify the integrity and authenticity of a message; for example, a message authentication code (MAC) or digital signatures.
		Ciphers are usually parameterised by a piece of auxillary information, called a key.
		Because of this, codes have fallen into disuse in modern cryptography, and ciphers are the dominant paradigm.
	www.free-download-soft.com /info/encryption.html (634 words)

	Maple worksheets for Cryptography
		This is done before the more typical symmetric block ciphers since the public key systems are typically easier to understand mathematically.
		HillCipher.mws is a variant of the multiplicative cipher, but vectors of characters are multiplied by an invertible matrix over the appropriate modulus.
		BabyDes-Intro.mws &endash; introduces a symmetric block cipher which is a simplified version of DES.
	euler.slu.edu /courseware/CryptoSubmissionSet/Cryptography.html (931 words)

	Lanaki Lesson 3
		Ciphers in which one plain text letter is represented by cipher characters of two or more elements are classed as multiliteral.
		One of the first steps to solving a multiliteral cipher with a cipher matrix, is to anagram the letters comprising the row and column indicators in an attempt to disclose the key words used.
		Mixed numerical cipher alphabets are those that have been keyed by a key word turned into numerical cipher equivalents or have a random combination of two or more digits for each letter of plain text.
	www.fortunecity.com /skyscraper/coding/379/lesson3.htm (6167 words)

	Homework 1 (Site not responding. Last check: 2007-10-22)
		Decipher ycxkhld knowing that an affine cipher with additive constant 7 was used and that it is an English word.
		This is a substitution cipher where the key is a word or phrase P together with a letter L. Starting at L the substitution is made with the corresponding letter of P. At the end of P all the other letters, those not in P, are placed alphabetically.
		SO for example if the phrase is computer and the letter is d, then the substitution is: a b c d e f g h i j k l m n o p...
	www.cs.bu.edu /faculty/homer/538/homework/hw1.html (407 words)

	USS Pampanito - ECM Mark II (Site not responding. Last check: 2007-10-22)
		The 10 cipher and control rotors are large 26 contact rotors that may be used interchangeably in the cipher or control bank and are reversible.
		Control and cipher rotors are also reassembled once a day from the secret daily keylist, their alignment however, was changed with each message.
		The rotors are zeroized, (cipher and control rotors positioned on "O") and the letter A is repeatedly encrypted until 30 cipher text characters are printed.
	www.maritime.org /ecm2.htm (3822 words)

	Electronic Sample Issue of The Cryptogram
		Although they might be called puzzle ciphers today, it was not so many years ago that some of these ciphers were used in earnest.
		All the ciphers we work with are constructed and edited to be suitable for solving with pencil and paper.
		Each cipher has a number like (A-1), title, keyword indicator, letter count in parentheses, and the constructor's "nom de plume." There may also be a tip given in parentheses.
	www.und.nodak.edu /org/crypto/crypto/.sample-issue.html (1512 words)

	HNF - Heinz Nixdorf MuseumsForum (Site not responding. Last check: 2007-10-22)
		During the 17th century, the first professional cipher bureaus appeared at the courts in England, Sweden, France, and Austria.
		The machine era of the 18th and 19th century saw the construction of the first mechanical cipher machines, which were all based on age-old principles.
		Until the mid-1970s cipher machines were almost exclusively used by order of diplomats, spies and the military.
	www.hnf.de /museum/codes_und_chiffren_en.html (337 words)

	Making, Breaking Codes: Introduction to Cryptology by Paul B. Garrett - BestBookDeal.com
		Rather, it is now demanded that 'strong' ciphers be resistant to types of attacks which might have seemed irrelevant in the past.
		One interesting idea that pervades both the classical and modern cryptanalysis and underlying mathematics is that of stochastic algorithm or probabilistic algorithm, by contrast to the more traditional and usual deterministic algorithms used in elementary mathematics.
		So at first we'll discuss some representative 'classical' cryptosystems, and the mathematics on which they are based, or which can be used to understand or break them.
	www.bestbookdeal.com /book/0130303690 (1546 words)

	Classical Cryptography: Substitution Ciphers (Site not responding. Last check: 2007-10-22)
		The Caesar cipher is the one most famous and simplest of all ciphers.
		It is classified as a substitution cipher because the sender replaces the letters in the actual message with a new set of letters.
		Note that the key to deciphering a message encoded with a Caesar cipher (also called a Caesar shift) is knowing the number of letters by which the alphabet is shifted.
	www.ece.utexas.edu /~gng/crypto/class_sub.shtml (704 words)

	Zodiackiller.com Message Board
		The fourth cipher was a whopping 32 characters long by comparison, and supposedly contained the location of a bomb which was set to destroy a school bus full of children.
		I agree glen the 340 cipher was not a "hoax".
		These could simply be artifacts of the cipher itself, but when I consider that digraph and separated pairs of characters tend to reverse themselves in the second half of the cipher, I'm inclined to watch for some sort of system reversal in the second half.
	www.zodiackiller.com /mba/zc/20.html (15554 words)

	Aegean Park Press: Browse
		A section of the text is devoted to cipher machines, with discussion as to their importance, types of machines, and advantages and disadvantages of cipher machines.
		One example deals with a substitution cipher wherein a series of messages employing up to 125 random mixed secondary alphabets can be solved without assuming a plaintext value for a single cipher letter.
		Classic, well-written text was used by the author to introduce cryptography to students at New York University in 1943.
	www.aegeanparkpress.com /desc.html (11829 words)

	CCB catalogue Part 1
		Hired by George Fabyan, a wealthy textile merchant, to conduct research in genetics, he quickly developed an interest in the activities of Riverbank's Department of Ciphers, and a particular interest in one of its staff, Elizebeth Smith, the future Mrs.
		Starting with the Caesar cipher, this slim volume moves rapidly through simple substitution (with and without word divisions), null, Baconian, ADFGX, and transposition cipher systems (columnar, Nihilist, and route).
		Included are sections on transposition and substitution ciphers, codes, and cryptanalysis.
	www.cvni.net /ccb/ccb1.html (1984 words)

	NOVA Online \| Decoding Nazi Secrets \| Resources
		Founded in the 1920's, this nonprofit volunteer organization is devoted to disseminating cryptographic knowledge.
		Members construct problems in classical cipher systems for other members to solve without knowing the secret key.
		Includes a Cipher Challenge with a $15,000 award (deadline 10/1/2000).
	www.pbs.org /wgbh/nova/decoding/resources.html (485 words)

	Making, Breaking Codes: Introduction to Cryptology (Site not responding. Last check: 2007-10-22)
		Some parts of the present text are an outgrowth of notes I've written for undergraduate courses in which I coordinated number theory and abstract algebra, using number theory as a tangible entry point to algebra and as a beneficiary of basic results from it.
		Thus, a one-semester course in number theory could skip over the first six chapters on classical ciphers and probability, and also skip the chapter on the Hill ciphers.
		The chapter on public-key ciphers could be skipped, but this is one of the chief applications of mathematics to communication.
	www.pcprotection.ca /books-reviewed/0130303690.html (5214 words)

	Cryptology ePrint Archive (Site not responding. Last check: 2007-10-22)
		In this paper, we show several known-plaintext attacks on the stream cipher HBB which was proposed recently at INDOCRYPT 2003.
		The cipher can operate either as a classical stream cipher (in the B mode) or as an asynchronous stream cipher (in the SS mode).
		All attacks need only a small part of the plaintext to be known.
	eprint.iacr.org /2005/003 (120 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		Both ciphers are insecure.ó#¨Perfect Secrecy A cryptosystem is computationally secure if the best algorithm for breaking it requires at least N operations, where N is some specified , very large number.Problems& A cryptosystem is unconditionally secure if it cannot be broken with infinite computational resources.¡d9D>ó$¨Perfect Secrecyª¨óNone of the classical cryptosystems is even computationally secure.
		Suppose the 26 keys in the Shift Cipher are used with equal probability 1/26.
		The Shift Cipher (Caesar Cipher) The Substitution Cipher The Affine Cipher ¡V”Kg&K ª6x?ó ¨Classical Cryptography¨ãPolyalphabetic CiphersEach alphabetic character of a plaintext can be mapped onto m alphabetic characters of a ciphertext.
	www2.semo.edu /jwojdylo/Research/cryptoclassic.ppt (707 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		This gives the attacker more work, since many alphabets need to be guessed, and because the frequency distribution is more complex, since the same plaintext letter could be replaced by several ciphertext letters, depending on which alphabet is used.
		As a result of a challenge, it was broken by Charles Babbage (the inventor of the computer) in 1854 but kept secret (possibly because of the Crimean War - not the first time governments have kept advances to themselves!).
		In general the approach is to find a number of duplicated sequences, collect all their distances apart, look for common factors, remembering that some will be random flukes and need to be discarded.
	www.wku.edu /~leyla.zhuhadar/Cryptography/ch02.ppt (850 words)

	ECS 153, Puzzle for January 17, 1997 (Site not responding. Last check: 2007-10-22)
		The PGP secure mailing system uses both RSA and a classical cipher called IDEA.
		The private key is enciphered with a classical cipher using a user-supplied pass phrase as the key.
		You can also see this document as a Binhex Framemaker version 5 document, Postscript document, or a plain ASCII text document.
	nob.cs.ucdavis.edu /classes/ecs153-1997-01/puz-0117.html (159 words)

	List of cryptography topics (Site not responding. Last check: 2007-10-22)
		Babington Plot -- Baby-step giant-step -- Banburismus -- Bart Preneel -- BATON -- Bazeries cylinder -- Beale ciphers -- Bernstein v.
		FEAL -- Feistel cipher -- Felix Delastelle -- Fialka -- Financial cryptography -- FIPS 140 -- FIREFLY -- FISH (cipher) -- Fish (cryptography) -- FNBDT -- Fortezza -- Fortuna (PRNG) -- Four-square cipher -- Fractal cryptography -- Frank A. Stevenson -- Frank Rowlett -- Frequency analysis -- Friedrich Kasiski -- Fritz-chip -- FROG --
		Ian Goldberg -- IBM 4758 -- ICE (cipher) -- ID-based cryptography -- Identification friend or foe -- IEEE 802.11i -- IEEE P1363 -- I.
	www.worldhistory.com /wiki/L/List-of-cryptography-topics.htm (648 words)

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