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Topic: Playfair cipher

Related Topics

Caesar cipher

Substitution cipher

Book cipher

Running key cipher

Trifid cipher

Frequency analysis

Transposition cipher

Polyalphabetic substitution

Tabula recta

ADFGVX cipher

Straddling checkerboard

Pigpen cipher

Asymmetric key algorithm

List of famous ciphertexts

Topics in cryptography

	Playfair cipher - Definition, explanation
		The Playfair cipher or Playfair square is a manual symmetric encryption technique and was the first literal digraph substitution cipher.
		The Playfair is thus significantly harder to break since the frequency analysis used for simple substitution ciphers does not work with it.
		When only the ciphertext is known, brute force cryptanalysis of the cipher involves searching through the key space for matches between the frequence of occurrence of digrams (pairs of letters) and the known frequency of occurrence of digrams in the assumed language of the original message.
	www.calsky.com /lexikon/en/txt/p/pl/playfair_cipher.php (1255 words)

	Playfair Cipher
		The Playfair Cipher was invented by the physicist Sir Charles Wheatstone (1802-1875) in 1854.
		It was probably first used by the British Army in the Boer War and was still in use in World War I. Playfair Cipher uses a 5 by 5 square, in which the letters of an agreed key word or phrase are entered (suppressing duplicates), followed by the rest of the alphabet in order.
		Playfair Crossword by Beetlejuice is an example puzzle using Playfair as a gimmick.
	www.bryson.ltd.uk /cgi-bin/playfair (404 words)

	NOVA Online \| Decoding Nazi Secrets \| The Playfair Cipher
		Its simplicity and its cryptographic strength compared to simple substitution and Vigènere (a polyalphabetic substitution cipher) made it an immediate success as a field cipher, used by the British in the Boer War and the First World War, and by several armed forces as an emergency back-up cipher in the Second World War.
		When Lt. John F. Kennedy's PT-109 was sunk by a Japanese cruiser in the Solomon Islands, for instance, he made it to shore on Japanese-controlled Plum Pudding Island and was able to send an emergency message in Playfair from an A llied coast-watcher's hut to arrange the rescue of the survivors from his crew.
		To encipher a message in Playfair, pick a keyword and write it into a five-by-five square, omitting repeated letters and combining I and J in one cell.
	www.pbs.org /wgbh/nova/decoding/playfair.html (497 words)

	Fred Cohen & Associates
		We begin with a classification scheme for ciphers given by Gary Knight [Knight78] in the first of a series of articles which posed ciphers to the reader, and after a given period of time demonstrated reader solutions along with explanations of how they solved the ciphers.
		The general case of this sort of cipher is the "monoalphabetic substitution cipher" wherein each letter is mapped into another letter in a one to one fashion.
		At first, the military used a Vigenere cipher with a short repeating keyword, but in 1863, a solution was discovered by Friedrich W. Kasiski for all periodic polyalphabetic ciphers which up until this time were considered unbreakable, so the military had to search for a new cipher to replace the Vigenere.
	www.all.net /books/ip/Chap2-1.html (5872 words)

	Playfair cipher
		The Playfair cipher is a manual symmetric encryption technique invented in 1854 by Charles Wheatstone for telegraph secrecy and was the first literal digraph substitution cipher.
		The usual form of the cipher used a 5 by 5 table and a key word or phrase.
		When only the ciphertext is known, cryptanalysis of the cipher involves searching through the key space for matches between the frequence of occurrence of digrams (pairs of alphabets) and the known frequency of occurrence of digrams in the English language.
	www.ebroadcast.com.au /lookup/encyclopedia/pl/Playfair_cipher.html (674 words)

	Playfair cipher - Wikipedia, the free encyclopedia
		The Playfair system was invented by Charles Wheatstone, who first described it in 1854.
		Playfair is now regarded as insecure for any purpose – even an obsolete Intel 80386 PC can break Playfair within a short time.
		A different approach to tackling a Playfair cipher is the shotgun hill climbing method.
	en.wikipedia.org /wiki/Playfair_cipher (1526 words)

	The Playfair Cipher (Site not responding. Last check: )
		Playfair was a scientist and a public figure of Victorian England.
		Playfair demonstrated what he called "Wheatstone's newly discovered symmetrical cipher", at a dinner in January of 1854, to associates in the British Aristocracy as well as in the Foreign office.
		The Playfair cipher was developed for telegraph secrecy and it was the first literal digraph substitution cipher.
	www.geocities.com /CapeCanaveral/8341/playfair.htm (483 words)

	Murky.org » Playfair (Site not responding. Last check: )
		The Playfair cipher was invented by a rather clever chap by the name of Wheatstone.
		Playfair’s name is attached to it as he is the one who was a vocal supporter of it in government circles.
		The cipher had many advantages, no cumbersome tables or apparatus was required, it had a keyword which could be easily changed and remembered and it was very simple to operate.
	www.murky.org /blg/2004/09/07/playfair (976 words)

	CPSC 467b Lecture Notes, Week 2
		A cipher that encrypts two letters at a time is much harder to break than a monoalphabetic cipher since it tends to mask the letter frequencies.
		A stream cipher has two components, the cipher that is used to encrypt a given character, and a keystream generator that produces a different key to be used for each successive letter.
		With a stream cipher, security rests with the keystream generator, for the ciphers used to encrypt the individual characters are all subject to known-plaintext attacks.
	zoo.cs.yale.edu /classes/cs467/2005s/attach/ln_week02.html (2358 words)

	[No title] (Site not responding. Last check: )
		Playfair cryptosystem was usually constructed by using the key phrase (a sentence) in English that not only helps remembering the secret matrix, but also helps distributing it to the trusted parties.
		For the first and third cipher chi value was close to chi value of random English text so that you know that these two ciphers are either simple substitution or transposition.
		Furthermore, frequency distribution of letters would indicate that the first cipher is substitution cipher, while third cipher must be transposition cipher since frequency distribution is identical to that of an English text.
	www.cse.fau.edu /~saeed/cen4540/SolHW5.doc (408 words)

	CRYPTOGRAMS FROM THE CRYPT
		Playfair uses digraphic substitution in a 5 by 5 square alphabetic array omitting one letter, Thouless omitted J. The two letters in each digraph are replaced by letters at the opposite corners of the rectangle they form.
		Playfair ciphers without a crib can be challenging, and the overlapped double Playfair obscures the interesting statistical properties that make longer Playfairs tractable.
		Each of the 1,385 assumed Playfairs resulting from decrypting cipher C with the possible second keywords was tried with all possible first keywords, and the result was scored by finding matches with a reference table of logarithms of English trigraph frequencies derived from several dozen novels.
	members.fortunecity.com /jpeschel/gillog2.htm (1784 words)

	Playfair Cipher - █ FURTHER READING:
		The Playfair cipher is a method of cryptography invented in 1854 by English physicist Sir Charles Wheatstone (1802–1875).
		The Playfair is a block cipher that disguises a message by substituting each pair of letters in the plaintext with a secondary pair of letters.
		The British employed the Playfair in the Boer War in addition to World War I. Several militaries relied on the Playfair as a back-up cipher during the Second World War.
	www.espionageinfo.com /Pa-Po/Playfair-Cipher.html (369 words)

	Bletchley Park Cryptographic Dictionary
		To rearrange the letters of a transposition cipher (usually by trial and error) so as to restore the original plain language.
		To decipher any part of a Playfair cipher, either by utilizing bigram frequencies and a knowledge of the probable plain text, or by using a previously reconstructed Playfair square or squares.
		from 1 upwards) of the letters of a transposition cipher rearranged into the order which these letters have in the clear text, thus showing how the cipher letters are anagramed to restore the original plain language.
	www.codesandciphers.org.uk /documents/cryptdict/page03.htm (213 words)

	Playfair and its Relatives
		If the Playfair cipher is used on a computer, perhaps in combination with other ciphers, it might be more convenient to make a rule for double letters, such as using the letter that is both below and to the right of the plaintext letter, and also doubling it.
		Playfair has inspired some related bigraphic ciphers that, on the one hand, improve security by involving multiple, unrelated alphabets, but on the other hand, are simpler in that they use fewer rules than Playfair.
		Jim Gillogly has noted that declassified NSA documents refer to another cipher of this type, in which the digraphs were enciphered twice by means of the two-square cipher.
	www.quadibloc.com /crypto/pp1321.htm (980 words)

	Playfair Class (Site not responding. Last check: )
		The Playfair is a primitive—by modern reckoning—block cipher.
		Understanding the Playfair will give you a beginning insight into modern cryptography—without all the complex mathematics and number theory.
		Playfair Cipher uses a 5 by 5 square, in which the letters of an agreed key word or phrase are entered (suppressing duplicates), followed by the rest of the alphabet in order.
	www.littlelite.net /llcryptolib/docs/LLCryptoLib.Crypto.Playfair.html (261 words)

	The Playfair Cipher
		Although the Baron Playfair’s name is attached to one of the better-known classical ciphers, the baron’s friend, scientist Charles Wheatstone, actually devised the Playfair cipher.
		Next comes the heart of the Playfair cipher: any pair of letters must both be in the same row, in the same column, or in different rows and columns; no other combinations are possible.
		A modern block cipher can be run in a mode similar to that of Playfair, where the same block (in Playfair, a pair of letters) always encrypts to the same bit of ciphertext: in our example, CO will always come out as OW.
	www.trumpetpower.com /Papers/Crypto/Playfair (1366 words)

	The Playfair Cipher>
		One of the ciphers submitted was 'Playfair's Cipher', a simple mixed-alphabet transposition cipher not invented by Playfair, but by Sir Charles Wheatstone (of Wheatstone Bridge fame) and named for the first Baron Playfair St. Andrews, a friend and fellow scientist; and much more in the public eye.
		The Playfair Cipher was used with great effect through both WWI as a 'trench code' and WWII by Australian coast-watchers.
		A mono-alphabetic cipher is broken by knowing the frequency of letters in the language of the plaintext.
	ozzzy.dyndns.org /playfair.html (473 words)

	The secret code machine.
		Indeed, several days later, while Playfair was visiting Dublin, he received letters from several of that night's guests, encoded, naturally, in the new cipher which had proved so easy to master.
		The power of the cipher can be seen in the way that O is enciphered S in one place and T another, while A in the ciphertext stands for P in one case and L in the other.
		In the heart of Japanese-controlled territory, with the radio waves continuously monitored, the use of a simple Playfair cipher kept the proceedings secret until the rescue could be effected.
	www.atarimagazines.com /creative/v9n5/166_The_secret_code_machine.php (1517 words)

	IM-QPP: REF GAINES ARTICLE
		We might say that the Playfair is, in effect, a "simple substitution" based on an "alphabet" of 600 pairs; and, just as in simple substitution proper, the Playfair cryptograms will very often contain long repeated sequences which represent whole words.
		The Playfair shows this a little less distinctly than some of the others, because of the fact that substitutes for single letters are so limited in number.
		Once a beginning is made, the cipher is broken, though just how rapidly we may proceed with the solution depends chiefly upon the manner in which the square has been filled.
	members.tripod.com /~ironmouth/mp-ref-hga.html (3706 words)

	Braingle: Playfair Cipher
		This is significantly harder to break since the frequency analysis used for simple substitution ciphers is considerably more difficult.
		Memorization of the keyword and 4 simple rules is all that is required to create the 5 by 5 table and use the cipher.
		The Playfair cipher uses a 5 by 5 table containing a key word or phrase.
	www.braingle.com /brainteasers/codes/playfair.php (398 words)

	The Computer Era
		The era of computers and electronics has meant an unprecedented freedom for cipher designers to use elaborate designs which would be far too prone to error if handled by pencil and paper, or far too expensive to implement in the form of an electromechanical cipher machine.
		As a block cipher obtains its strength from operating on a large group of bits of fixed size, it belongs to the class of polygraphic ciphers, such as Playfair.
		The most common case of Playfair, where the two letters are neither in the same row or column, would also have the same structure, but the other possible cases make it more complicated.
	www.quadibloc.com /crypto/comp04.htm (334 words)

	CS 456 Assignment 1
		The Playfair cipher uses a 5 by 7 grid filled with characters to encode a message written with those 35 characters.
		Because we are using a substitution cipher, the histogram of the frequencies of letter pairs occuring in the encrypted text should be similar to the histogram of the frequencies of letter pairs in the plaintext.
		Also, in the Playfair cipher grid, the letters t and space are in the same row.
	www.clarkson.edu /class/cs456/assignment1/assignment1.html (721 words)

	[No title]
		At the intersection of the first row and sixth column is the digit 3, so this is the symbol we use for H. The cipher text for TH is 73.
		The ciphered code is put into “pairs of pairs”, making a “word” four symbols long.
		It is 26CY 3CGK 2SY5 3AJP 7QBL It is deciphered in the same way it is written except for a slight modification when the two letters of a pair are in the same row and column.
	www.usca.edu /math/~mathdept/sjcb/codetalk/THEPLAYFAIRCIPHER.doc (445 words)

	Initial Knowledge
		However, several properties of the ciphertext suggested that this cipher was a Playfair cipher.
		The chronological order in which the ciphers tend to appear made a Playfair cipher seem probable.
		The Playfair cipher seemed connected with Great Britain so our approach was that the plaintext should be written in English.
	codebook.org /node33.html (101 words)

	Problem G - Playfair Cypher
		The Playfair cipher was invented more than one and a half century ago by Sir Charles Wheatsone, one of the pioneers of the electric telegraph.
		The cipher's main advantages were that it is quite easy to use, both for encryption and decryption, and that it was relatively secure compared to other ciphers of that age.
		The key was taken from Appendix E that contains the explanation of the Playfair cipher.
	acm.uva.es /p/v109/10955.html (1090 words)

	Data Encryption - Computer Forensic
		A cipher is the algorithm that is used to encrypt the file.
		There are many ciphers that are used for encryption of the information.
		In case of transposition ciphers the examples are Scytale, Grille cipher, as well as VIC cipher.
	www.computerforensics1.com /data-encryption.html (522 words)

	Cipher Challenge
		The Cipher Challenge was a set of ten encrypted messages to be found at the end of The Code Book, a history of codes and code breaking that I published last year.
		For example, in stage 2 a Latin message was encrypted with the Caesar cipher, and in stage 4 a French message was encrypted with the Vigenère cipher.
		I wondered if the winner might be a team made up of an amateur who had cracked the ancient ciphers and a computer expert who had cracked the latter two ciphers.
	www.simonsingh.net /Cipher_Challenge.html (2021 words)

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