131-602: In the history of cryptography , the "System 97 Typewriter for European Characters" (九七式欧文印字機 kyūnana-shiki ōbun injiki ) or "Type B Cipher Machine" , codenamed Purple by the United States, was an encryption machine used by the Japanese Foreign Office from February 1939 to the end of World War II . The machine was an electromechanical device that used stepping-switches to encrypt the most sensitive diplomatic traffic. All messages were written in
262-645: A glossing system to add readings or explanations to Buddhist sutras . Both of these systems were simplified to make writing easier. The shapes of many hiragana resembled the Chinese cursive script , as did those of many katakana the Korean gugyeol , suggesting that the Japanese followed the continental pattern of their neighbors. Kana is traditionally said to have been invented by the Buddhist priest Kūkai in
393-472: A hybrid of the two schemes became the most accepted way for e-commerce operations to proceed. Additionally, the creation of a new protocol known as the Secure Socket Layer, or SSL, led the way for online transactions to take place. Transactions ranging from purchasing goods to online bill pay and banking used SSL. Furthermore, as wireless Internet connections became more common among households,
524-504: A CVV syllable with complex nucleus (i.e. multiple or expressively long vowels), or a CCV syllable with complex onset (i.e. including a glide , C y V, C w V). The limited number of phonemes in Japanese, as well as the relatively rigid syllable structure, makes the kana system a very accurate representation of spoken Japanese . 'Kana' is a compound of kari ( 仮 , 'borrowed; assumed; false') and na ( 名 , 'name') , which eventually collapsed into kanna and ultimately 'kana'. Today it
655-529: A German clerk. This was the greatest breakthrough in cryptanalysis in a thousand years and more, according to historian David Kahn . Rejewski and his mathematical Cipher Bureau colleagues, Jerzy Różycki and Henryk Zygalski , continued reading Enigma and keeping pace with the evolution of the German Army machine's components and encipherment procedures for some time. As the Poles' resources became strained by
786-484: A Type 97 Japanese machine on display at the National Cryptologic Museum, the largest piece known in existence, has three 7-layer stepping switches (see photo). The U.S. Army developed an improved analog in 1944 that has all the layers needed for each stage on a single shaft. An additional layer was used in the improved analog to automatically set each switch bank to the initial position specified in
917-537: A competition among, candidates for such a cypher algorithm. DES was approved for a short period, but saw extended use due to complex wrangles over the use by the public of high quality encryption. DES was finally replaced by the AES after another public competition organized by the NBS successor agency, NIST. Around the late 1990s to early 2000s, the use of public-key algorithms became a more common approach for encryption, and soon
1048-672: A famous story, The Gold-Bug , in which cryptanalysis was a prominent element. Cryptography, and its misuse, were involved in the execution of Mata Hari and in Dreyfus' conviction and imprisonment, both in the early 20th century. Cryptographers were also involved in exposing the machinations which had led to the Dreyfus affair; Mata Hari, in contrast, was shot. In World War I the Admiralty 's Room 40 broke German naval codes and played an important role in several naval engagements during
1179-407: A limited set of characters, such as Wabun code for Morse code telegrams and single-byte digital character encodings such as JIS X 0201 or EBCDIK , likewise dispense with kanji, instead using only katakana. This is not necessary in systems supporting double-byte or variable-width encodings such as Shift JIS , EUC-JP , UTF-8 or UTF-16 . Old Japanese was written entirely in kanji, and
1310-401: A machine that duplicated the behavior (was an analog ) of the Japanese machines, even though no one in the U.S. had any description of one. The Japanese also used stepping-switches in systems, codenamed Coral and Jade , that did not divide their alphabets. American forces referred to information gained from decryptions as Magic . The Imperial Japanese Navy did not fully cooperate with
1441-401: A major part in bringing the United States into the war. In 1917, Gilbert Vernam proposed a teleprinter cipher in which a previously prepared key, kept on paper tape, is combined character by character with the plaintext message to produce the cyphertext. This led to the development of electromechanical devices as cipher machines, and to the only unbreakable cipher, the one time pad . During
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#17327721432751572-438: A meaning . Apart from the five vowels, it is always CV (consonant onset with vowel nucleus ), such as ka , ki , sa , shi , etc., with the sole exception of the C grapheme for nasal codas usually romanised as n . The structure has led some scholars to label the system moraic , instead of syllabic , because it requires the combination of two syllabograms to represent a CVC syllable with coda (e.g. CV n , CV m , CV ng ),
1703-415: A message (theoretical secrecy, now unconditional security), and the second are those designed to protect against hackers and attacks with finite resources with which to decode a message (practical secrecy, now computational security). Most of Shannon's work focused around theoretical secrecy; here, Shannon introduced a definition for the "unbreakability" of a cipher. If a cipher was determined "unbreakable", it
1834-402: A pair of mathematically related keys, each of which decrypts the encryption performed using the other. Some, but not all, of these algorithms have the additional property that one of the paired keys cannot be deduced from the other by any known method other than trial and error. An algorithm of this kind is known as a public key or asymmetric key system. Using such an algorithm, only one key pair
1965-455: A poem which uses each kana once. However, hiragana and katakana did not quickly supplant man'yōgana . It was only in 1900 that the present set of kana was codified. All the other forms of hiragana and katakana developed before the 1900 codification are known as hentaigana ( 変体仮名 , "variant kana") . Rules for their usage as per the spelling reforms of 1946, the gendai kana-zukai ( 現代仮名遣い , "present-day kana usage") , which abolished
2096-413: A poetry anthology assembled sometime after 759 and the eponym of man'yōgana , exemplifies this phenomenon, where as many as almost twenty kanji were used for the mora ka . The consistency of the kana used was thus dependent on the style of the writer. Hiragana developed as a distinct script from cursive man'yōgana , whereas katakana developed from abbreviated parts of regular script man'yōgana as
2227-672: A prototype of Red, "Roman-typewriter cipher machine". The prototype used the same principle as the Kryha cipher machine, having a plug-board , and was used by the Japanese Navy and Ministry of Foreign Affairs at negotiations for the London Naval Treaty in 1930. The prototype machine was finally completed as "Type 91 Typewriter" in 1931. The year 1931 was year 2591 in the Japanese Imperial calendar . Thus it
2358-461: A radically new method of distributing cryptographic keys, which went far toward solving one of the fundamental problems of cryptography, key distribution, and has become known as Diffie–Hellman key exchange . The article also stimulated the almost immediate public development of a new class of enciphering algorithms, the asymmetric key algorithms . Prior to that time, all useful modern encryption algorithms had been symmetric key algorithms , in which
2489-453: A set of kanji called man'yōgana were first used to represent the phonetic values of grammatical particles and morphemes. As there was no consistent method of sound representation, a phoneme could be represented by multiple kanji, and even those kana's pronunciations differed in whether they were to be read as kungana ( 訓仮名 , "meaning kana") or ongana ( 音仮名 , "sound kana") , making decipherment problematic. The man'yōshū ,
2620-548: A symmetric session key, and the faster symmetric algorithm takes over for the remainder of the message. Asymmetric key cryptography, Diffie–Hellman key exchange, and the best known of the public key / private key algorithms (i.e., what is usually called the RSA algorithm), all seem to have been independently developed at a UK intelligence agency before the public announcement by Diffie and Hellman in 1976. GCHQ has released documents claiming they had developed public key cryptography before
2751-560: A tool for children), there can be no word-by-word collation; all collation is kana-by-kana. The hiragana range in Unicode is U+3040 ... U+309F, and the katakana range is U+30A0 ... U+30FF. The obsolete and rare characters ( wi and we ) also have their proper code points. Characters U+3095 and U+3096 are hiragana small ka and small ke , respectively. U+30F5 and U+30F6 are their katakana equivalents. Characters U+3099 and U+309A are combining dakuten and handakuten , which correspond to
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#17327721432752882-404: A wire from Alice to Bob. Bob receives the bit stream and decrypts it using his own private key, and then decrypts that bit stream using Alice's public key. If the final result is recognizable as a message, Bob can be confident that the message actually came from someone who knows Alice's private key (presumably actually her if she's been careful with her private key), and that anyone eavesdropping on
3013-533: Is a ligature of koto ( コト ), also found in vertical writing. Additionally, there are halfwidth equivalents to the standard fullwidth katakana. These are encoded within the Halfwidth and Fullwidth Forms block (U+FF00–U+FFEF), starting at U+FF65 and ending at U+FF9F (characters U+FF61–U+FF64 are halfwidth punctuation marks): There is also a small "Katakana Phonetic Extensions" range (U+31F0 ... U+31FF), which includes some additional small kana characters for writing
3144-604: Is also used to represent onomatopoeia and interjections, emphasis, technical and scientific terms, transcriptions of the Sino-Japanese readings of kanji, and some corporate branding. Kana can be written in small form above or next to lesser-known kanji in order to show pronunciation; this is called furigana . Furigana is used most widely in children's or learners' books. Literature for young children who do not yet know kanji may dispense with it altogether and instead use hiragana combined with spaces. Systems supporting only
3275-410: Is an exposition on and a worked example of cryptanalysis, including the use of tables of letter frequencies and sets of letters which cannot occur together in one word. The earliest example of the homophonic substitution cipher is the one used by Duke of Mantua in the early 1400s. Homophonic cipher replaces each letter with multiple symbols depending on the letter frequency. The cipher is ahead of
3406-437: Is commonly accepted that this paper was the starting point for development of modern cryptography. Shannon was inspired during the war to address "[t]he problems of cryptography [because] secrecy systems furnish an interesting application of communication theory". Shannon identified the two main goals of cryptography: secrecy and authenticity. His focus was on exploring secrecy and thirty-five years later, G.J. Simmons would address
3537-426: Is generally assumed that 'kana' were considered "false" kanji due to their purely phonetic nature, as opposed to mana ( 真名 ) which were "true" kanji used for their meanings. Yet originally, mana and kana were purely calligraphic terms with mana referring to Chinese characters written in the regular script ( kaisho ) and kana referring to those written in the cursive ( sōsho ) style (see hiragana ). It
3668-532: Is needed per user. By designating one key of the pair as private (always secret), and the other as public (often widely available), no secure channel is needed for key exchange. So long as the private key stays secret, the public key can be widely known for a very long time without compromising security, making it safe to reuse the same key pair indefinitely. For two users of an asymmetric key algorithm to communicate securely over an insecure channel, each user will need to know their own public and private keys as well as
3799-480: Is stylistic. Usually, hiragana is the default syllabary, and katakana is used in certain special cases. Hiragana is used to write native Japanese words with no kanji representation (or whose kanji is thought obscure or difficult), as well as grammatical elements such as particles and inflections ( okurigana ). Today katakana is most commonly used to write words of foreign origin that do not have kanji representations, as well as foreign personal and place names. Katakana
3930-559: The Advanced Encryption Standard (AES) in 2001 when NIST announced FIPS 197. After an open competition, NIST selected Rijndael , submitted by two Belgian cryptographers, to be the AES. DES, and more secure variants of it (such as Triple DES ), are still used today, having been incorporated into many national and organizational standards. However, its 56-bit key-size has been shown to be insufficient to guard against brute force attacks (one such attack, undertaken by
4061-522: The Army in pre-war cipher machine development, and that lack of cooperation continued into World War II. The Navy believed the Purple machine was sufficiently difficult to break that it did not attempt to revise it to improve security. This seems to have been on the advice of a mathematician, Teiji Takagi , who lacked a background in cryptanalysis . The Ministry of Foreign Affairs was supplied Red and Purple by
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4192-826: The Atlantic Wall fortifications against invasion along the coasts of France and Belgium. On 4 September, Hitler told him that Germany would strike in the West, probably in November. Since those messages were being read by the Allies, they provided valuable intelligence about German military preparations against the forthcoming invasion of Western Europe. He was described by General George Marshall as "our main basis of information regarding Hitler's intentions in Europe." The decrypted Purple traffic and Japanese messages generally were
4323-522: The Enigma rotor machine , provided more sophisticated and efficient means of encryption; and the subsequent introduction of electronics and computing has allowed elaborate schemes of still greater complexity, most of which are entirely unsuited to pen and paper. The development of cryptography has been paralleled by the development of cryptanalysis — the "breaking" of codes and ciphers . The discovery and application, early on, of frequency analysis to
4454-691: The Fish ciphers ; Max Newman and colleagues designed and deployed the Heath Robinson , and then the world's first programmable digital electronic computer, the Colossus , to help with their cryptanalysis. The German Foreign Office began to use the one-time pad in 1919; some of this traffic was read in World War II partly as the result of recovery of some key material in South America that
4585-572: The German push to Moscow in December. History of cryptography Cryptography, the use of codes and ciphers to protect secrets, began thousands of years ago. Until recent decades, it has been the story of what might be called classical cryptography — that is, of methods of encryption that use pen and paper, or perhaps simple mechanical aids. In the early 20th century, the invention of complex mechanical and electromechanical machines, such as
4716-512: The NSA , acting behind the scenes, it was adopted and published as a Federal Information Processing Standard Publication in 1977 (currently at FIPS 46-3 ). DES was the first publicly accessible cipher to be 'blessed' by a national agency such as the NSA. The release of its specification by NBS stimulated an explosion of public and academic interest in cryptography. The aging DES was officially replaced by
4847-708: The Renaissance , citizens of the various Italian states—the Papal States and the Roman Catholic Church included—were responsible for rapid proliferation of cryptographic techniques, few of which reflect understanding (or even knowledge) of Alberti's polyalphabetic advance. "Advanced ciphers", even after Alberti, were not as advanced as their inventors/developers/users claimed (and probably even they themselves believed). They were frequently broken. This over-optimism may be inherent in cryptography, for it
4978-760: The Soviet Union attacked Poland from the East, they crossed into Romania . From there they reached Paris, France; at PC Bruno , near Paris, they continued working toward breaking Enigma, collaborating with British cryptologists at Bletchley Park as the British got up to speed on their work breaking Enigma. In due course, the British cryptographers – whose ranks included many chess masters and mathematics dons such as Gordon Welchman , Max Newman , and Alan Turing (the conceptual founder of modern computing ) – made substantial breakthroughs in
5109-535: The attack on Pearl Harbor . US cryptanalysts decrypted and translated Japan's 14-part message to its Washington embassy to break off negotiations with the United States at 1 p.m., Washington time, on 7 December 1941, before the Japanese Embassy in Washington had done so. Decryption and typing difficulties at the embassy, coupled with ignorance of the importance of it being on time, were major reasons for
5240-416: The message indicator . The U.S. improved analog has a six-position switch for making this assignment, see photo. The message indicator also specified the initial positions of the twenties switches. The indicator was different for each message or part of a message, when multi-part messages were sent. The final part of the key, the alphabet plugboard arrangement, was changed daily. The twenties switch stepping
5371-620: The tabula recta , a critical component of the Vigenère cipher. Trithemius also wrote the Steganographia . Giovan Battista Bellaso in 1553 first described the cipher that would become known in the 19th century as the Vigenère cipher , misattributed to Blaise de Vigenère . In Europe, cryptography became (secretly) more important as a consequence of political competition and religious revolution. For instance, in Europe during and after
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5502-567: The " Nomura Note " to be delivered late. During World War II, the Japanese ambassador to Nazi Germany , General Hiroshi Oshima , was well-informed on German military affairs. His reports went to Tokyo in Purple-enciphered radio messages. One had a comment that Hitler told him on 3 June 1941 that "in every probability war with Russia cannot be avoided." In July and August 1942, he toured the Eastern Front, and in 1944, he toured
5633-504: The 1840s. In particular he placed a notice of his abilities in the Philadelphia paper Alexander's Weekly (Express) Messenger , inviting submissions of ciphers, most of which he proceeded to solve. His success created a public stir for some months. He later wrote an essay on methods of cryptography which proved useful as an introduction for novice British cryptanalysts attempting to break German codes and ciphers during World War I, and
5764-836: The 1920s, Polish naval-officers assisted the Japanese military with code and cipher development. Mathematical methods proliferated in the period prior to World War II (notably in William F. Friedman 's application of statistical techniques to cryptanalysis and cipher development and in Marian Rejewski 's initial break into the German Army's version of the Enigma system in 1932). By World War II, mechanical and electromechanical cipher machines were in wide use, although—where such machines were impractical— code books and manual systems continued in use. Great advances were made in both cipher design and cryptanalysis , all in secrecy. Information about this period has begun to be declassified as
5895-411: The 1970s, as the public-key cryptography developers, M. E. Hellman and W. Diffie cited Shannon's research as a major influence. His work also impacted modern designs of secret-key ciphers. At the end of Shannon's work with cryptography, progress slowed until Hellman and Diffie introduced their paper involving "public-key cryptography". The mid-1970s saw two major public (i.e., non-secret) advances. First
6026-478: The 26-letter English alphabet , which was commonly used for telegraphy. Any Japanese text had to be transliterated or coded. The 26-letters were separated using a plug board into two groups, of six and twenty letters respectively. The letters in the sixes group were scrambled using a 6 × 25 substitution table, while letters in the twenties group were more thoroughly scrambled using three successive 20 × 25 substitution tables. The cipher codenamed "Purple" replaced
6157-486: The Allies and Axis made a strategic difference in the war. Encryption in modern times is achieved by using algorithms that have a key to encrypt and decrypt information. These keys convert the messages and data into "digital gibberish" through encryption and then return them to the original form through decryption. In general, the longer the key is, the more difficult it is to crack the code. This holds true because deciphering an encrypted message by brute force would require
6288-622: The Deciphering Cryptographic Messages ), in which he described the first cryptanalytic techniques, including some for polyalphabetic ciphers , cipher classification, Arabic phonetics and syntax, and most importantly, gave the first descriptions on frequency analysis. He also covered methods of encipherments, cryptanalysis of certain encipherments, and statistical analysis of letters and letter combinations in Arabic. An important contribution of Ibn Adlan (1187–1268)
6419-578: The Japanese used three 7-level switches. Both represented the 20s cipher identically. Note however that these were not two-motion or Strowger switches as sometimes claimed: "twenty-five Strolger-type (sic) stepper switches ...". Apparently, all other Purple machines at Japanese embassies and consulates around the world (e.g. in Axis countries, Washington, London, Moscow, and in neutral countries) and in Japan itself, were destroyed and ground into small particles by
6550-472: The Japanese. American occupation troops in Japan in 1945–52 searched for any remaining units. A complete Jade cipher machine, built on similar principles but without the sixes and twenties separation, was captured and is on display at NSA's National Cryptologic Museum . The Purple machine itself was first used by Japan in June 1938, but American and British cryptanalysts had broken some of its messages well before
6681-573: The Latin vowels AEIOUY. Thus US Army SIS was able to break the cipher used for the six letters before it was able to break the one used for the 20 others. The Type B Cipher Machine consisted of several components. As reconstructed by the US Army, there were electric typewriters at either end, similar to those used with the Type A Machine. The Type B was organized for encryption as follows: For decryption,
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#17327721432756812-669: The Mongols brought about the end of the Islamic Golden Age , cryptography remained comparatively undeveloped. Cryptography in Japan seems not to have been used until about 1510, and advanced techniques were not known until after the opening of the country to the West beginning in the 1860s. Although cryptography has a long and complex history, it wasn't until the 19th century that it developed anything more than ad hoc approaches to either encryption or cryptanalysis (the science of finding weaknesses in crypto systems). Examples of
6943-602: The Navy. No one in Japanese authority noticed the weak points in both machines. Japanese diplomatic communications at negotiations for the Washington Naval Treaty were broken by the American Black Chamber in 1922, and when this became publicly known, there was considerable pressure to improve their security. In any case, the Japanese Navy had planned to develop their first cipher machine for
7074-610: The Type A Red machine previously used by the Japanese Foreign Office. The sixes and twenties division was familiar to U.S. Army Signals Intelligence Service (SIS) cryptographers from their work on the Type A cipher and it allowed them to make early progress on the sixes portion of messages. The twenties cipher proved much more difficult, but a breakthrough in September 1940 allowed the Army cryptographers to construct
7205-531: The U.S. That Purple analog was accompanied by a team of four American cryptologists, two Army, two Navy, who received information on British successes against German ciphers in exchange. This machine was subsequently sent to Singapore, and after Japanese moves south through Malaya, on to India. A fourth Purple analog was sent to the Philippines and a fifth was kept by the SIS. A sixth, originally intended for Hawaii,
7336-708: The US victory in the Battle of Midway ; and to the publication of that fact in the Chicago Tribune shortly after the battle, though the Japanese seem not to have noticed for they kept using the JN-25 system. The Americans referred to the intelligence resulting from cryptanalysis, perhaps especially that from the Purple machine, as ' Magic '. The British eventually settled on ' Ultra ' for intelligence resulting from cryptanalysis, particularly that from message traffic protected by
7467-724: The War. The Poles used the Lacida machine, but its security was found to be less than intended (by Polish Army cryptographers in the UK), and its use was discontinued. US troops in the field used the M-209 and the still less secure M-94 family machines. British SOE agents initially used 'poem ciphers' (memorized poems were the encryption/decryption keys), but later in the War, they began to switch to one-time pads . The VIC cipher (used at least until 1957 in connection with Rudolf Abel 's NY spy ring)
7598-589: The West. Ahmad al-Qalqashandi (AD 1355–1418) wrote the Subh al-a 'sha , a 14-volume encyclopedia which included a section on cryptology. This information was attributed to Ibn al-Durayhim who lived from AD 1312 to 1361, but whose writings on cryptography have been lost. The list of ciphers in this work included both substitution and transposition , and for the first time, a polyalphabetic cipher with multiple substitutions for each plaintext letter (later called homophonic substitution). Also traced to Ibn al-Durayhim
7729-580: The attacker to try every possible key. To put this in context, each binary unit of information, or bit, has a value of 0 or 1. An 8-bit key would then have 256 or 2^8 possible keys. A 56-bit key would have 2^56, or 72 quadrillion, possible keys to try and decipher the message. With modern technology, cyphers using keys with these lengths are becoming easier to decipher. DES, an early US Government approved cypher, has an effective key length of 56 bits, and test messages using that cypher have been broken by brute force key search. However, as technology advances, so does
7860-596: The changes being introduced by the Germans, and as war loomed, the Cipher Bureau , on the Polish General Staff 's instructions, on 25 July 1939, at Warsaw , initiated French and British intelligence representatives into the secrets of Enigma decryption. Soon after the invasion of Poland by Germany on 1 September 1939, key Cipher Bureau personnel were evacuated southeastward; on 17 September, as
7991-488: The channel will need Bob's private key in order to understand the message. Asymmetric algorithms rely for their effectiveness on a class of problems in mathematics called one-way functions, which require relatively little computational power to execute, but vast amounts of power to reverse, if reversal is possible at all. A classic example of a one-way function is multiplication of very large prime numbers. It's fairly quick to multiply two large primes, but very difficult to find
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#17327721432758122-479: The controversy and the investigations.) The Soviets also succeeded in breaking the Purple system in late 1941, and together with reports from Richard Sorge , learned that Japan was not going to attack the Soviet Union . Instead, its targets were southward, toward Southeast Asia and American and British interests there. That allowed Stalin to move considerable forces from the Far East to Moscow in time to help stop
8253-459: The corresponding unvoiced columns ( k , s , t and h ) and the voicing mark, dakuten . Syllables beginning with [p] are spelled with kana from the h column and the half-voicing mark, handakuten . Syllables beginning with palatalized consonants are spelled with one of the seven consonantal kana from the i row followed by small ya , yu or yo . These digraphs are called yōon . The difference in usage between hiragana and katakana
8384-546: The cyber civil-rights group Electronic Frontier Foundation in 1997, succeeded in 56 hours. ) As a result, use of straight DES encryption is now without doubt insecure for use in new cryptosystem designs, and messages protected by older cryptosystems using DES, and indeed all messages sent since 1976 using DES, are also at risk. Regardless of DES' inherent quality, the DES key size (56-bits) was thought to be too small by some even in 1976, perhaps most publicly by Whitfield Diffie . There
8515-422: The data flow is reversed. The keyboard on the second typewriter becomes the input and the twenties letters pass through the stepping switch stages in the opposite order. A stepping switch is a multi-layer mechanical device that was commonly used at the time in telephone switching systems. Each layer has a set of electrical connects, 25 in the Type B, arranged in a semicircular arc. These do not move and are called
8646-523: The date that the Tripartite Agreement between Nazi Germany, Fascist Italy, and Imperial Japan was announced. There was still a lot of work to do to recover the meaning of the other 119 possible indicators. As of October 1940, one third of the indicator settings had been recovered. From time to time the Japanese instituted new operating procedures to strengthen the Type B system, but these were often described in messages to diplomatic outputs in
8777-689: The earlier "Red" machine used by the Japanese Foreign Ministry, and a related machine, the M-1, used by Naval attachés which was broken by the U.S. Navy's Agnes Driscoll . All the Japanese machine ciphers were broken, to one degree or another, by the Allies. The Japanese Navy and Army largely used code book systems, later with a separate numerical additive. US Navy cryptographers (with cooperation from British and Dutch cryptographers after 1940) broke into several Japanese Navy crypto systems. The break into one of them, JN-25 , famously led to
8908-470: The early U.S. analog. The improved analog organized the wiring more neatly with three matrices of soldering terminals visible above each stepping switch in the photograph. The stages were bi-directional. Signals went through each stage in one direction for encryption and in the other direction for decryption. Unlike the system in the German Enigma machine , the order of the stages was fixed and there
9039-496: The encryption/decryption operations make asymmetric algorithms computationally expensive, compared to most symmetric algorithms. Since symmetric algorithms can often use any sequence of (random, or at least unpredictable) bits as a key, a disposable session key can be quickly generated for short-term use. Consequently, it is common practice to use a long asymmetric key to exchange a disposable, much shorter (but just as strong) symmetric key. The slower asymmetric algorithm securely sends
9170-419: The factors of the product of two large primes. Because of the mathematics of one-way functions, most possible keys are bad choices as cryptographic keys; only a small fraction of the possible keys of a given length are suitable, and so asymmetric algorithms require very long keys to reach the same level of security provided by relatively shorter symmetric keys. The need to both generate the key pairs, and perform
9301-463: The first use of permutations and combinations to list all possible Arabic words with and without vowels. The invention of the frequency analysis technique for breaking monoalphabetic substitution ciphers , by Al-Kindi , an Arab mathematician , sometime around AD 800, proved to be the single most significant cryptanalytic advance until World War II. Al-Kindi wrote a book on cryptography entitled Risalah fi Istikhraj al-Mu'amma ( Manuscript for
9432-635: The following London Naval Treaty . Japanese Navy Captain Risaburo Ito , of Section 10 (cipher & code) of the Japanese Navy General Staff Office, supervised the work. The development of the machine was the responsibility of the Japanese Navy Institute of Technology, Electric Research Department, Section 6. In 1928, the chief designer Kazuo Tanabe and Navy Commander Genichiro Kakimoto developed
9563-403: The huge volume of enemy messages generated in a global conflict. A few women, including Elizabeth Friedman and Agnes Meyer Driscoll , had been major contributors to US code-breaking in the 1930s and the Navy and Army began actively recruiting top graduates of women's colleges shortly before the attack on Pearl Harbor. Liza Mundy argues that this disparity in utilizing the talents of women between
9694-435: The issue of authenticity. Shannon wrote a further article entitled "A mathematical theory of communication" which highlights one of the most significant aspects of his work: cryptography's transition from art to science. In his works, Shannon described the two basic types of systems for secrecy. The first are those designed with the intent to protect against hackers and attackers who have infinite resources with which to decode
9825-492: The kana for wi (ゐ・ヰ), we (ゑ・ヱ), and wo (を・ヲ) (except that the last was reserved as the accusative particle). Kana are the basis for collation in Japanese. They are taken in the order given by the gojūon (あ い う え お ... わ を ん), though iroha (い ろ は に ほ へ と ... せ す (ん)) ordering is used for enumeration in some circumstances. Dictionaries differ in the sequence order for long/short vowel distinction, small tsu and diacritics. As Japanese does not use word spaces (except as
9956-424: The key. However implemented, the 20-layer stepping switch in each stage had 20 rotor connections and 500 stator connections, one wiper and 25 stator contacts on each layer. Each stage must have exactly 20 connections on each end to connect with the adjacent stage or plugboard. On the rotor side, that is not a problem as there are 20 rotors. On the stator end of a stage, every column of stator contacts corresponding to
10087-524: The latter include Charles Babbage 's Crimean War era work on mathematical cryptanalysis of polyalphabetic ciphers , redeveloped and published somewhat later by the Prussian Friedrich Kasiski . Understanding of cryptography at this time typically consisted of hard-won rules of thumb; see, for example, Auguste Kerckhoffs ' cryptographic writings in the latter 19th century. Edgar Allan Poe used systematic methods to solve ciphers in
10218-529: The need for encryption grew, as a level of security was needed in these everyday situations. Claude E. Shannon is considered by many to be the father of mathematical cryptography. Shannon worked for several years at Bell Labs, and during his time there, he produced an article entitled "A mathematical theory of cryptography". This article was written in 1945 and eventually was published in the Bell System Technical Journal in 1949. It
10349-480: The ninth century. Kūkai certainly brought the Siddhaṃ script of India home on his return from China in 806; his interest in the sacred aspects of speech and writing led him to the conclusion that Japanese would be better represented by a phonetic alphabet than by the kanji which had been used up to that point. The modern arrangement of kana reflects that of Siddhaṃ, but the traditional iroha arrangement follows
10480-643: The now-standard hiragana. Katakana, with a few additions, are also used to write Ainu . A number of systems exist to write the Ryūkyūan languages , in particular Okinawan , in hiragana. Taiwanese kana were used in Taiwanese Hokkien as ruby text for Chinese characters in Taiwan when it was under Japanese rule . Each kana character corresponds to one sound or whole syllable in the Japanese language, unlike kanji regular script , which corresponds to
10611-606: The number of participants increases, or when secure channels aren't available for key exchange, or when, as is sensible cryptographic practice, keys are frequently changed. In particular, if messages are meant to be secure from other users, a separate key is required for each possible pair of users. A system of this kind is known as a secret key, or symmetric key cryptosystem. D-H key exchange (and succeeding improvements and variants) made operation of these systems much easier, and more secure, than had ever been possible before in all of history. In contrast, asymmetric key encryption uses
10742-664: The official British 50-year secrecy period has come to an end, as US archives have slowly opened, and as assorted memoirs and articles have appeared. The Germans made heavy use, in several variants, of an electromechanical rotor machine known as Enigma . Mathematician Marian Rejewski , at Poland's Cipher Bureau , in December 1932 deduced the detailed structure of the German Army Enigma, using mathematics and limited documentation supplied by Captain Gustave Bertrand of French military intelligence acquired from
10873-550: The older system, giving the Americans warning. Reconstruction of the Purple machine was based on ideas of Larry Clark. Advances into the understanding of Purple keying procedures were made by Navy Lieutenant Francis Raven . After the initial break, Raven discovered that the Japanese had divided the month into three 10-day periods, and, within each period, they used the keys of the first day, with small, predictable changes. The Japanese believed Type B to be unbreakable throughout
11004-420: The one Leo Rosen of SIS had chosen when building a duplicate (or Purple analog machine) in Washington in 1939 and 1940. The stepping switch was a uniselector ; a standard component used in large quantities in automatic telephone exchanges in countries like America, Britain, Canada, Germany and Japan, with extensive dial-telephone systems. The U.S. used four 6-level switches in each stage of its Purple analogs,
11135-413: The other user's public key. Take this basic scenario: Alice and Bob each have a pair of keys they've been using for years with many other users. At the start of their message, they exchange public keys, unencrypted over an insecure line. Alice then encrypts a message using her private key, and then re-encrypts that result using Bob's public key. The double-encrypted message is then sent as digital data over
11266-699: The other. Beginning around 1990, the use of the Internet for commercial purposes and the introduction of commercial transactions over the Internet called for a widespread standard for encryption. Before the introduction of the Advanced Encryption Standard (AES), information sent over the Internet, such as financial data, was encrypted if at all, most commonly using the Data Encryption Standard (DES). This had been approved by NBS (a US Government agency) for its security, after public call for, and
11397-400: The plugboard alphabets changed daily. The cryptographers developed a way to transform messages sent on different days with the same indicator into homologous messages that would appear to have been sent on the same day. This provided enough traffic based on the identical settings (6 messages with indicator 59173) to have a chance of finding some periodicity that would reveal the inner workings of
11528-473: The previous world war. At the end of the War, on 19 April 1945, Britain's highest level civilian and military officials were told that they could never reveal that the German Enigma cipher had been broken because it would give the defeated enemy the chance to say they "were not well and fairly beaten". The German military also deployed several teleprinter stream ciphers . Bletchley Park called them
11659-634: The public domain: the creation of a public encryption standard ( DES ), and the invention of public-key cryptography . The earliest known use of cryptography is found in non-standard hieroglyphs carved into the wall of a tomb from the Old Kingdom of Egypt circa 1900 BC. These are not thought to be serious attempts at secret communications, however, but rather to have been attempts at mystery, intrigue, or even amusement for literate onlookers. Some clay tablets from Mesopotamia somewhat later are clearly meant to protect information—one dated near 1500 BC
11790-870: The publication of Diffie and Hellman's paper. Various classified papers were written at GCHQ during the 1960s and 1970s which eventually led to schemes essentially identical to RSA encryption and to Diffie–Hellman key exchange in 1973 and 1974. Some of these have now been published, and the inventors (James H. Ellis, Clifford Cocks, and Malcolm Williamson) have made public (some of) their work. Kana Kana ( 仮名 , Japanese pronunciation: [kana] ) are syllabaries used to write Japanese phonological units, morae . In current usage, kana most commonly refers to hiragana and katakana . It can also refer to their ancestor magana ( 真仮名 , lit. 'true kana') , which were Chinese characters used phonetically to transcribe Japanese (e.g. man'yōgana ); and hentaigana , which are historical variants of
11921-443: The quality of encryption. Since World War II, one of the most notable advances in the study of cryptography is the introduction of the asymmetric key cyphers (sometimes termed public-key cyphers). These are algorithms which use two mathematically related keys for encryption of the same message. Some of these algorithms permit publication of one of the keys, due to it being extremely difficult to determine one key simply from knowledge of
12052-488: The reading of encrypted communications has, on occasion, altered the course of history. Thus the Zimmermann Telegram triggered the United States' entry into World War I; and Allies reading of Nazi Germany 's ciphers shortened World War II, in some evaluations by as much as two years. Until the 1960s, secure cryptography was largely the preserve of governments. Two events have since brought it squarely into
12183-494: The same cryptographic key is used with the underlying algorithm by both the sender and the recipient, who must both keep it secret. All of the electromechanical machines used in World War II were of this logical class, as were the Caesar and Atbash ciphers and essentially all cipher systems throughout history. The 'key' for a code is, of course, the codebook, which must likewise be distributed and kept secret, and so shares most of
12314-428: The same problems in practice. Of necessity, the key in every such system had to be exchanged between the communicating parties in some secure way prior to any use of the system (the term usually used is 'via a secure channel ') such as a trustworthy courier with a briefcase handcuffed to a wrist, or face-to-face contact, or a loyal carrier pigeon. This requirement is never trivial and very rapidly becomes unmanageable as
12445-407: The same rotor position on each of the 20 layers is connected to the 20 output wires ( leads in the diagram) in a scrambled order, creating a permutation of the 20 inputs. This is done differently for each of the rotor positions. Thus each stator output wire has 25 connections, one from each rotor position, though from different levels. The connections needed to do this created a "rats nest" of wires in
12576-532: The scale and technology of Enigma decryption . German code breaking in World War II also had some success, most importantly by breaking the Naval Cipher No. 3 . This enabled them to track and sink Atlantic convoys. It was only Ultra intelligence that finally persuaded the admiralty to change their codes in June 1943. This is surprising given the success of the British Room 40 code breakers in
12707-405: The scytale was for encryption, authentication, or avoiding bad omens in speech. Herodotus tells us of secret messages physically concealed beneath wax on wooden tablets or as a tattoo on a slave's head concealed by regrown hair, although these are not properly examples of cryptography per se as the message, once known, is directly readable; this is known as steganography . Another Greek method
12838-592: The semicircle, the other engages the first contact. This allows the rotor connections to keep cycling through all 25 stator contacts as the electromagnet is pulsed. To encrypt the twenties letters, a 20-layer stepping switch was needed in each of the three stages. Both the Japanese version and the early American analog constructed each stage from several smaller stepping switches of the type used in telephone central offices. The American analog used four 6-level switches to create one 20-layer switch. The four switches in each stage were wired to step synchronously. The fragment of
12969-454: The separate US Army and Navy operations, around Washington, DC. By tradition in Japan and Nazi doctrine in Germany, women were excluded from war work, at least until late in the war. Even after encryption systems were broken, large amounts of work were needed to respond to changes made, recover daily key settings for multiple networks, and intercept, process, translate, prioritize and analyze
13100-411: The spacing characters U+309B and U+309C. U+309D is the hiragana iteration mark , used to repeat a previous hiragana. U+309E is the voiced hiragana iteration mark, which stands in for the previous hiragana but with the consonant voiced ( k becomes g , h becomes b , etc.). U+30FD and U+30FE are the katakana iteration marks. U+309F is a ligature of yori ( より ) sometimes used in vertical writing. U+30FF
13231-402: The stator. A wiper arm on a rotor at the focus of the semicircle connects with one stator contact at a time. The rotors on each layer are attached to a single shaft that advances from one stator contact to the next whenever an electromagnet connected to a ratchet is pulsed. There are actually two wiper arms on each level, connected together, so that when one wiper advances past the last contact in
13362-534: The subject of acrimonious hearings in Congress after World War II in connection with an attempt to decide who, if anyone, had allowed the attack at Pearl Harbor to happen and so should be blamed. It was during those hearings that the Japanese for the first time learned that the Purple cipher machine had indeed been broken. (See the Pearl Harbor advance-knowledge conspiracy theory article for additional detail on
13493-454: The term 'kana' is now commonly understood as hiragana and katakana, it actually has broader application as listed below: The following table reads, in gojūon order, as a , i , u , e , o (down first column), then ka , ki , ku , ke , ko (down second column), and so on. n appears on its own at the end. Asterisks mark unused combinations. Syllables beginning with the voiced consonants [g], [z], [d] and [b] are spelled with kana from
13624-472: The time because it combines monoalphabetic and polyalphabetic features. Essentially all ciphers remained vulnerable to the cryptanalytic technique of frequency analysis until the development of the polyalphabetic cipher, and many remained so thereafter. The polyalphabetic cipher was most clearly explained by Leon Battista Alberti around AD 1467, for which he was called the "father of Western cryptology". Johannes Trithemius , in his work Poligraphia , invented
13755-468: The twenties cipher. William F. Friedman was assigned to lead the group of cryptographers attacking the B system in August 1939. Even with the cribs, progress was difficult. The permutations used in the twenties cipher were "brilliantly" chosen, according to Friedman, and it became clear that periodicities would be unlikely to be discovered by waiting for enough traffic encrypted on a single indicator, since
13886-480: The twenties cipher. On 20 September 1940 at about 2 pm Genevieve Grotjan , carrying a set of work sheets walked up to a group of men engrossed in conversation and politely attempted to get Frank Rowlett 's attention. She had found evidence of cycles in the twenties cipher. Celebration ensued at this first break in the 20s cipher and it soon enabled a replica machine to be built. A pair of other messages using indicator 59173 were decrypted by 27 September, coincidentally
14017-511: The use of a stepping switch instead of the more troublesome half-rotor switch. Clearly, the Purple machine was more secure than Red, but the Navy did not recognize that Red had already been broken. The Purple machine inherited a weakness from the Red machine that six letters of the alphabet were encrypted separately. It differed from Red in that the group of letters was changed and announced every nine days, whereas in Red they were permanently fixed as
14148-611: The various Enigmas. An earlier British term for Ultra had been 'Boniface' in an attempt to suggest, if betrayed, that it might have an individual agent as a source. Allied cipher machines used in World War II included the British TypeX and the American SIGABA ; both were electromechanical rotor designs similar in spirit to the Enigma, albeit with major improvements. Neither is known to have been broken by anyone during
14279-491: The war, and even for some time after the war, even though they had been informed otherwise by the Germans. In April 1941, Hans Thomsen , a diplomat at the German embassy in Washington, D.C., sent a message to Joachim von Ribbentrop , the German foreign minister, informing him that "an absolutely reliable source" had told Thomsen that the Americans had broken the Japanese diplomatic cipher (that is, Purple). That source apparently
14410-585: The war, notably in detecting major German sorties into the North Sea that led to the battles of Dogger Bank and Jutland as the British fleet was sent out to intercept them. However, its most important contribution was probably in decrypting the Zimmermann Telegram , a cable from the German Foreign Office sent via Washington to its ambassador Heinrich von Eckardt in Mexico which played
14541-522: The way it was used. Frequency analysis could often make 6 of the 26 letters in the ciphertext alphabet letters stand out from the other 20 letters, which were more uniformly distributed. This suggested the Type B used a similar division of plaintext letters as used in the Type A. The weaker encryption used for the "sixes" was easier to analyze. The sixes cipher turned out to be polyalphabetic with 25 fixed permuted alphabets, each used in succession. The only difference between messages with different indicators
14672-435: The writing was highly stylized. Some diplomatic messages included the text of letters from the U.S. government to the Japanese government. The English text of such messages could usually be obtained. Some diplomatic stations did not have the Type B, especially early in its introduction, and sometimes the same message was sent in Type B and in the Type A Red cipher, which the SIS had broken. All these provided cribs for attacking
14803-643: Was Antoine Rossignol ; he and his family created what is known as the Great Cipher because it remained unsolved from its initial use until 1890, when French military cryptanalyst, Étienne Bazeries solved it. An encrypted message from the time of the Man in the Iron Mask (decrypted just prior to 1900 by Étienne Bazeries ) has shed some, regrettably non-definitive, light on the identity of that real, if legendary and unfortunate, prisoner. Outside of Europe, after
14934-720: Was Konstantin Umansky , the Soviet ambassador to the US , who had deduced the leak based upon communications from U.S. Undersecretary of State Sumner Welles . The message was duly forwarded to the Japanese; but use of the code continued. The SIS built its first machine that could decrypt Purple messages in late 1940. A second Purple analog was built by the SIS for the US Navy. A third was sent to England in January 1941 on HMS King George V , which had brought Ambassador Halifax to
15065-458: Was a significant weak point. The Navy also used the 91-shiki injiki Kana -letter model at its bases and on its vessels. In 1937, the Japanese completed the next generation "Type 97 Typewriter". The Ministry of Foreign Affairs machine was the "Type B Cipher Machine", codenamed Purple by United States cryptanalysts. The chief designer of Purple was Kazuo Tanabe . His engineers were Masaji Yamamoto and Eikichi Suzuki . Eikichi Suzuki suggested
15196-517: Was a very complex hand cipher, and is claimed to be the most complicated known to have been used by the Soviets, according to David Kahn in Kahn on Codes . For the decrypting of Soviet ciphers (particularly when one-time pads were reused), see Venona project . The UK and US employed large numbers of women in their code-breaking operation, with close to 7,000 reporting to Bletchley Park and 11,000 to
15327-458: Was considered to have "perfect secrecy". In proving "perfect secrecy", Shannon determined that this could only be obtained with a secret key whose length given in binary digits was greater than or equal to the number of bits contained in the information being encrypted. Furthermore, Shannon developed the "unicity distance", defined as the "amount of plaintext that… determines the secret key." Shannon's work influenced further cryptography research in
15458-593: Was controlled in part by the sixes switch. Exactly one of the three switches stepped for each character. The fast switch stepped for each character except when the sixes switch was in its 25th position. Then the medium switch stepped, unless it too was in its 25th position, in which case the slow switch stepped. The SIS learned in 1938 of the forthcoming introduction of a new diplomatic cipher from decoded messages. Type B messages began to appear in February 1939. The Type B had several weaknesses, some in its design, others in
15589-572: Was developed by Polybius (now called the " Polybius Square "). The Romans knew something of cryptography (e.g., the Caesar cipher and its variations). David Kahn notes in The Codebreakers that modern cryptology originated among the Arabs , the first people to systematically document cryptanalytic methods. Al-Khalil (717–786) wrote the Book of Cryptographic Messages , which contains
15720-562: Was discarded without sufficient care by a German courier. The Schlüsselgerät 41 was developed late in the war as a more secure replacement for Enigma, but only saw limited use. A US Army group, the SIS , managed to break the highest security Japanese diplomatic cipher system (an electromechanical stepping switch machine called Purple by the Americans) in 1940, before the attack on Pearl Harbor. The locally developed Purple machine replaced
15851-569: Was documented in the Kama Sutra for the purpose of communication between lovers. This was also likely a simple substitution cipher. Parts of the Egyptian demotic Greek Magical Papyri were written in a cypher script. The ancient Greeks are said to have known of ciphers. The scytale transposition cipher was used by the Spartan military, but it is not definitively known whether
15982-456: Was found to encrypt a craftsman's recipe for pottery glaze, presumably commercially valuable. Furthermore, Hebrew scholars made use of simple monoalphabetic substitution ciphers (such as the Atbash cipher ) beginning perhaps around 600 to 500 BC. In India around 400 BC to 200 AD, Mlecchita vikalpa or "the art of understanding writing in cypher, and the writing of words in a peculiar way"
16113-428: Was no reflector. However the stepping arrangement could be changed. The sixes switches stepped one position for each character encrypted or decrypted. The motions of the switches in the twenties stages were more complex. The three stages were assigned to step fast, medium or slow. There were six possible ways to make this assignment and the choice was determined by a number included at the beginning of each message called
16244-429: Was not until the 18th century that the early-nationalist kokugaku movement which wanted to move away from Sinocentric academia began to reanalyze the script from a phonological point of view. In the following centuries, contrary to the traditional Sinocentric view, kana began to be considered a national Japanese writing system that was distinct from Chinese characters, which is the dominant view today. Although
16375-488: Was on sample size for use of frequency analysis. In early medieval England between the years 800–1100, substitution ciphers were frequently used by scribes as a playful and clever way to encipher notes, solutions to riddles, and colophons. The ciphers tend to be fairly straightforward, but sometimes they deviate from an ordinary pattern, adding to their complexity, and possibly also to their sophistication. This period saw vital and significant cryptographic experimentation in
16506-481: Was prefixed "91-shiki" from the year it was developed. The 91-shiki injiki Roman-letter model was also used by the Ministry of Foreign Affairs as "Type A Cipher Machine", codenamed "Red" by United States cryptanalysts. The Red machine was unreliable unless the contacts in its half-rotor switch were cleaned every day. It enciphered vowels (AEIOUY) and consonants separately, perhaps to reduce telegram costs, and this
16637-556: Was sent to England for use there. The Purple intercepts proved important in the European theater due to the detailed reports on German plans sent in that cipher by the Japanese ambassador in Berlin. The United States obtained portions of a Purple machine from the Japanese Embassy in Germany following Germany's defeat in 1945 (see image above) and discovered that the Japanese had used a stepping switch almost identical in its construction to
16768-529: Was suspicion that government organizations even then had sufficient computing power to break DES messages; clearly others have achieved this capability. The second development, in 1976, was perhaps even more important, for it fundamentally changed the way cryptosystems might work. This was the publication of the paper New Directions in Cryptography by Whitfield Diffie and Martin Hellman . It introduced
16899-479: Was the publication of the draft Data Encryption Standard in the U.S. Federal Register on 17 March 1975. The proposed DES cipher was submitted by a research group at IBM , at the invitation of the National Bureau of Standards (now NIST ), in an effort to develop secure electronic communication facilities for businesses such as banks and other large financial organizations. After advice and modification by
17030-500: Was the starting position in the list of alphabets. The SIS team recovered the 25 permutations by 10 April 1939. The frequency analysis was complicated by the presence of romanized Japanese text and the introduction in early May of a Japanese version of the Phillips Code . Knowing the plaintext of 6 out of 26 letters scattered throughout the message sometimes enabled parts of the rest of the message to be guessed, especially when
17161-652: Was then – and remains today – difficult in principle to know how vulnerable one's own system is. In the absence of knowledge, guesses and hopes are predictably common. Cryptography, cryptanalysis , and secret-agent/courier betrayal featured in the Babington plot during the reign of Queen Elizabeth I which led to the execution of Mary, Queen of Scots . Robert Hooke suggested in the chapter Of Dr. Dee's Book of Spirits , that John Dee made use of Trithemian steganography, to conceal his communication with Queen Elizabeth I. The chief cryptographer of King Louis XIV of France
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