100 Fun Facts About Cryptography

Which Roman general guarded military messages by shifting each letter three places, so A became D?

Julius Caesar's shift is easy to undo, and its 13-place cousin ROT13 was later used on Usenet to hide joke punchlines and spoilers.

The word cryptography pairs an ancient root for 'writing' with one meaning what?

Hidden is the sense of kryptos, the root that opens the word, so cryptography literally means hidden writing; the CIA's Kryptos sculpture borrows the same root.

Which scholar announced in Paris in 1822 that he could read the Egyptian scripts on the Rosetta Stone?

Jean-François Champollion showed that hieroglyphs spelled sounds as well as pictures, a trick the stone's Demotic text had already revealed for foreign names in 1802.

Which German engineer's firm patented the rotor cipher machine in 1918 that went on sale as Enigma?

Arthur Scherbius co-founded Scherbius & Ritter, which patented the design in 1918 and began selling the finished machine under the Enigma name in 1923.

When Enigma went on sale in 1923, which buyers was the machine first aimed at?

Commercial firms were the first target: the machine was pitched to businesses wanting to shield telegrams from rivals, and only later did the German armed forces adopt and modify it.

Because of its reflector, an Enigma machine could never encrypt a letter as what?

Itself was the one output Enigma could never give a pressed key, a patented side-effect of the reflector that Allied codebreakers learned to exploit.

Bletchley Park, bought by MI6's chief with his own money in 1938, lies in which English county?

Buckinghamshire's Bletchley, now inside Milton Keynes, got the codebreakers because Admiral Hugh Sinclair paid £6,000 of his own money when the government said it had no budget.

Churchill called Bletchley Park's staff 'the geese that laid the golden eggs' and never did what?

Cackled is the word: the codebreakers kept quiet for decades, and many families never learned that a parent had done secret war work.

Eight soldiers of which tribe used their language on Army phones in the 1918 Meuse-Argonne fighting?

Choctaw men of the 36th Infantry Division were among the first code talkers, a generation before the Marines recruited Navajo speakers for the Pacific.

Which Los Angeles city civil engineer proposed the Navajo language to the Marines in World War II?

Philip Johnston pitched the idea at the start of the war, and the first 29 Navajo recruits began boot camp in May 1942.

In the Zimmermann Telegram of January 1917, Germany proposed a wartime alliance with which country?

Mexico was offered German help to recover Texas, Arizona and New Mexico, and the telegram's publication helped push the United States into the war in April 1917.

Which Admiralty codebreaking section, named for its office, decoded the Zimmermann Telegram?

Room 40's Nigel de Grey had partly decoded the message by the next day, in what is called Britain's greatest intelligence triumph of the First World War.

Deciphered letters from the 1586 Babington Plot led to whose execution in 1587?

Mary, Queen of Scots replied in cipher on 17 July 1586 endorsing the killing of Elizabeth I, and that decoded reply became the evidence that sent her to the block.

The Vigenère cipher, once called 'indecipherable', was first described in 1553 by which Italian?

Giovan Battista Bellaso laid out the key-word system in his 1553 book, but 19th-century writers pinned it on the French diplomat Blaise de Vigenère, and the wrong name stuck.

Which Prussian infantry officer published the first general attack on the Vigenère cipher in 1863?

Friedrich Kasiski's 95-page book of 1863 ended three centuries of the cipher's 'unbreakable' reputation, though Charles Babbage had quietly broken a version around 1854 without publishing.

Atbash reverses an alphabet end to end; its name comes from four letters of which alphabet?

Hebrew's Aleph, Taw, Bet and Shin spell the name, and the Book of Jeremiah uses the trick to disguise Babylon as 'Sheshach'.

Spartan commanders read a scytale message by winding its strip of parchment around what?

A rod of exactly the same diameter as the sender's lines the letters up again; Plutarch gave the earliest surviving description of the device.

Which 9th-century Baghdad scholar first described breaking ciphers by counting letter frequencies?

Al-Kindi's Manuscript on Deciphering Cryptographic Messages introduced frequency analysis, building on the work of al-Khalil, and counts as the birth of cryptanalysis.

Which Renaissance architect's 1467 cipher disk was one of the first polyalphabetic ciphers?

Leon Battista Alberti's device, two concentric disks on a pin that could be turned mid-message, changed the substitution alphabet as it went.

In 1952 architect Michael Ventris showed that Linear B tablets held an early form of which language?

Greek in its Mycenaean form is what the tablets hold, centuries older than Homer; Ventris died in a car crash in 1956, weeks before his book on the script appeared.

The only solved Beale cipher, describing treasure buried in Virginia, used which document as its key?

Declaration of Independence word numbers unlock the second of three ciphertexts from a pamphlet sold in the 1880s; the two naming the spot and the owners remain unsolved.

Because it is the most common letter in English, which letter is a single dot in Morse code?

E got the shortest code because Alfred Vail sized each symbol to letter frequency, which he estimated by counting the type in a Morristown printer's cases.

Which 1906 international distress call was picked as a simple Morse rhythm, not as an abbreviation?

SOS never stood for 'save our souls'; German maritime rules adopted it in 1905, the 1906 convention made it worldwide, and it stayed the radio distress signal until 1999.

Which AT&T engineer invented the 1917 teleprinter cipher that became the unbreakable one-time pad?

Gilbert Vernam's patent was granted in 1919, but Army captain Joseph Mauborgne added the rule that made it unbreakable: a truly random key used only once.

Diffie and Hellman published public-key cryptography in 1976; which British agency had secretly found the idea first?

GCHQ's James Ellis proposed 'non-secret encryption' in 1970, but the agency kept the work classified until 1997.

Which MIT mathematician kept finding flaws in Rivest and Shamir's proposals until one held in 1977?

Leonard Adleman could not break the scheme Rivest wrote up after a sleepless Passover night, and it became RSA, named for all three.

Which Secretary of State shut down the Cipher Bureau in 1929, reputedly calling codebreaking ungentlemanly?

Henry Stimson is quoted as saying 'Gentlemen do not read each other's mail', and he was reportedly most offended by Herbert Yardley's boast that he could read the Vatican's traffic.

In 'The Adventure of the Dancing Men', a stick figure holding what marks the end of a word?

A flag in a figure's hand ends a word, a rule Sherlock Holmes spots in the 1903 story after Norfolk squire Hilton Cubitt brings him the scrawled messages.

In whose 1843 story 'The Gold-Bug' does William Legrand decode a cipher to find buried treasure?

Edgar Allan Poe won the Philadelphia Dollar Newspaper's $100 prize with the story, probably the largest single sum he ever earned for a piece of writing.

Which French officer cracked Louis XIV's Great Cipher around 1893 by spotting it encoded syllables?

Étienne Bazeries took three years over the task, reading messages the Rossignol family had enciphered for the Sun King two centuries earlier.

Which scientist invented the Playfair cipher in 1854, which ended up named after the friend who promoted it?

Charles Wheatstone devised it for telegraph secrecy, but Lord Playfair's promotion won it his name, and militaries used it through at least World War I.

Why did Germany's 1918 ADFGVX cipher use only the letters A, D, F, G, V and X?

Distinct radio signals were the aim, since the six letters sound very different in Morse code; France's Georges Painvin still broke the cipher and fell ill from the strain.

Which colour codename did US codebreakers give Japan's Type B diplomatic cipher machine?

Purple's stepping-switch machine was rebuilt by William Friedman's Army team in September 1940 without anyone having seen the original, and its decrypts were codenamed Magic.

To prove 'AF' meant Midway in 1942, US codebreakers had the island radio a fake breakdown of what?

Its water plant was the bait: Joseph Rochefort's Station Hypo team had the order sent by undersea cable, and the shortage then surfaced in Japanese traffic under the 'AF' label.

Which Founding Father's wheel cipher of 36 lettered disks was reinvented as the US Army's M-94?

Thomas Jefferson described the device in a manuscript that lay forgotten until 1922, and the Army had arrived at the M-94 on its own.

Which secret-writing aid, invented by John Jay's brother, did Washington's Culper spy ring use?

Invisible ink, a 'sympathetic stain', hid reports between the lines of ordinary letters, and the ring's codebook gave Washington the number 711.

The pigpen cipher, which turns letters into grid fragments, is often named for which fraternal order?

Freemasons used it so often from the early 18th century, for lodge records and even tombstone engravings, that it is frequently called the Freemason's cipher.

Which English statesman devised a 1605 cipher that hides a message in the choice between two typefaces?

Francis Bacon's method turns every letter into a five-symbol pattern of As and Bs, then prints an innocent cover text in two typefaces to carry it.

Which composer sent a friend the still-unsolved Dorabella Cipher of 87 symbols in 1897?

Edward Elgar wrote the three lines of squiggles to Dora Penny, who never worked out what they said, and nobody has convincingly read them since.

The 2008 white paper that invented Bitcoin was published under which name?

Satoshi Nakamoto released the Bitcoin software in January 2009, and the currency's smallest unit, one hundred-millionth of a bitcoin, is named a satoshi.

Mavis Batey's March 1941 break into Italian naval Enigma set up which Royal Navy victory off Greece?

Cape Matapan saw Admiral Andrew Cunningham's British and Australian ships intercept and sink or cripple several Italian warships from 27 to 29 March 1941.

Which Bletchley mathematician deduced the Lorenz machine's full structure without ever seeing one?

Bill Tutte's diagnosis of the twelve-wheel machine was later called one of the greatest intellectual feats of the war; Bletchley saw a real one only in 1945.

The faster Colossus Mark 2 first ran on 1 June 1944, just in time for which Allied operation?

The Normandy landings came five days later, and the Mark 2's shift registers let it run five times faster than the original; ten Colossi were working by the war's end.

Bombe outstations such as Eastcote and Stanmore were staffed mostly by which uniformed organisation?

Women's Royal Naval Service members, the Wrens, ran the machines in shifts; at one point about 70 bombes were expected to be run by some 700 of them.

Which university's Beinecke Library has held the undeciphered Voynich manuscript since 1969?

Yale catalogues it as MS 408; its vellum has been carbon-dated to 1404–1438, and it is named for Wilfrid Voynich, the Polish book dealer who bought it in 1912.

Which artist made Kryptos, the 1990 CIA courtyard sculpture whose fourth passage defied codebreakers for decades?

Jim Sanborn dedicated the piece at Langley on 3 November 1990, and he has hinted that a fifth message will appear once all four are read.

Which honour did the original Navajo code talkers receive in 2001?

Congressional Gold Medals came from President George W. Bush in July 2001, 33 years after the code was declassified in 1968.

Suetonius says Augustus shifted letters by one without wrapping round, writing what in place of Z?

AA replaced Z in the emperor's system, Suetonius writes, because his one-step shift simply ran off the end of the Latin alphabet instead of looping back.

In 2010 Kryptos's sculptor revealed that six letters of its fourth passage decode to which city?

Berlin is what the letters NYPVTT at positions 64 to 69 become, and the artist added that solvers had 'better delve into that particular clock'.

The 1843 treasure-hunt story 'The Gold-Bug' is set on which patch of South Carolina coast near Charleston?

Sullivan's Island is where William Legrand lives in a hut with his servant Jupiter, and the story is often read as an early piece of detective fiction.

Which children's author kept a journal in her own secret cipher that went undecoded until 1958?

Beatrix Potter began the coded diary at about 14 and kept it up for 16 years; collector Leslie Linder needed five years of work to read it.

Codebreakers from which country first cracked Enigma in 1932 and shared the method with Britain in 1939?

Poland's Marian Rejewski reconstructed the machine in December 1932 using permutation theory and material from a German spy. Five weeks before the war, his bureau passed its techniques to the British and French.

The anonymity network Tor wraps traffic in layers of encryption and takes its name from which vegetable?

Onion routing was developed in the mid-1990s at the United States Naval Research Laboratory, and Tor began life in 2002 as The Onion Routing project.

The word 'cipher' came into English from the Arabic 'sifr', a word for which number?

Zero was the word's first meaning in English; it widened to any numeral, then to secret writing in the 1520s, because early codes often swapped numbers for letters.

Which murderer's 340-character cipher, mailed to a California newspaper in 1969, went unsolved for 51 years?

The Zodiac Killer's message was finally read in December 2020 by three private citizens: an American software engineer, an Australian mathematician and a Belgian programmer.

Navajo code talkers had no word for a submarine, so they called it by a phrase meaning what?

Iron fish was typical of the code's plain logic: a bomber aircraft was given the Navajo word for a buzzard.

Which drink brand sponsored radio's Little Orphan Annie and sent its fans cipher-disk membership pins?

Ovaltine's decoders used a simple substitution cipher, and the secret messages read out on air usually previewed the next episode.

In 2016 which company refused an FBI demand to write software unlocking a San Bernardino attacker's phone?

Apple said the software would undermine its products' security; a day before the court hearing, the FBI found a third party able to unlock the phone and withdrew.

Which mathematician headed Bletchley Park's Hut 8 and specified the bombe machines that attacked Enigma?

Alan Turing was also a talented long-distance runner who occasionally ran from Bletchley to London for meetings, at close to world-class marathon standard.

The earliest known cryptography is a set of odd symbols carved into a tomb around 1900 BC in which country?

Egypt's carvers used non-standard hieroglyphs; about 400 years later a Mesopotamian clay tablet enciphered a craftsman's valuable recipe for pottery glaze.

Which 2014 film stars Benedict Cumberbatch as a Bletchley Park codebreaker racing to crack Enigma?

The Imitation Game earned eight Oscar nominations, including Best Picture, and won for Best Adapted Screenplay.

Which 2002 John Woo war film stars Nicolas Cage as a Marine guarding a Navajo radioman on Saipan?

Windtalkers, based on the real Navajo code talkers of the Pacific war, cost about $115 million and took under $78 million worldwide.

In Dan Brown's The Da Vinci Code, forcing open a cryptex breaks a vial of what, dissolving the papyrus inside?

Vinegar would destroy the papyrus message, so the hand-held cylinder has to be opened properly, by lining up five lettered dials to spell a password.

In Jules Verne's 'Journey to the Center of the Earth', a decoded runic note points to a volcano in which country?

Iceland's Snæfellsjökull crater is the way in; the travellers are finally blown back out through Stromboli, a volcanic island off Sicily.

The security of RSA encryption rests on the difficulty of factoring a huge number built from two of what?

Prime numbers are the secret: an RSA user picks two large primes at random and keeps them hidden, while publishing their product as part of the public key.

Peter Shor's 1994 algorithm showed that which kind of computer could one day break RSA encryption?

Quantum computers could factor huge numbers far faster than ordinary ones, a threat that led the United States to publish its first quantum-resistant encryption standards in 2024.

Which messaging app finished switching on end-to-end encryption for over a billion users in April 2016?

WhatsApp built in the Signal Protocol with Open Whisper Systems, then announced that every form of communication on the app was end-to-end encrypted.

Which ancient Indian text lists writing in cipher among 64 arts recommended for a better life?

The Kama Sutra recommends cipher for private messages between lovers but only names the skill; step-by-step substitution ciphers appear in commentaries written between the tenth and thirteenth centuries.

Herodotus tells how Histiaeus smuggled an order to revolt by marking it on which part of a trusted servant?

Scalp was the spot: Histiaeus shaved the man's head, wrote the message, waited for the hair to regrow, then sent him to Miletus to be shaved again.

Which art of concealing a message's very existence took its name from a 1499 treatise by the abbot Trithemius?

Steganography, unlike encryption, leaves nothing that looks secret; Trithemius disguised his own treatise on the subject as a book on magic.

Which Victorian computing pioneer broke the Vigenère cipher during the Crimean War but never published the method?

Charles Babbage first cracked a cipher set as a challenge by his nephew in 1845, and planned a book called The Philosophy of Deciphering that never appeared.

Which future novelist in Naval Intelligence devised Operation Ruthless, a 1940 plan to seize Enigma codebooks?

Ian Fleming proposed ditching a captured German bomber in the Channel so that its disguised crew could overpower their rescuers and take the boat's codebooks. No suitable German vessel appeared, and it was called off.

Bletchley Park scouted for codebreakers through a wartime crossword contest run by which newspaper?

The Daily Telegraph was asked to stage the contest, and promising solvers were then discreetly approached about a particular type of war work.

Decrypted Japanese orders let US fighters ambush which admiral's plane near Bougainville in April 1943?

Isoroku Yamamoto was the man US leaders blamed for Pearl Harbor; the decoded message gave the day and route of his inspection flight from Rabaul.

Which codename did Britain adopt in June 1941 for intelligence from broken Enigma and other high-level ciphers?

Ultra got its name because the material was judged more important than anything in Britain's highest classification, Most Secret.

The undeciphered Phaistos Disc, a clay disc stamped with a spiral of signs, was unearthed in 1908 on which island?

Crete's disc carries more than 240 signs of 45 different kinds, each pressed into the soft clay with a separate stamp before the disc was fired.

Rongorongo, an undeciphered script carved on about two dozen wooden objects, comes from where in the Pacific?

Easter Island keeps none of the surviving pieces: they were collected in the late 19th century and scattered among museums and private collections.

Which pair of names, introduced in the 1978 RSA paper, stands for the two parties in a cryptography example?

Alice and Bob replaced the plain A and B of earlier papers, and later writers added a supporting cast that includes the malicious Mallory.

Which simple text-scrambling scheme did 1980s Usenet users adopt to mask joke punchlines and puzzle spoilers?

ROT13 moves each letter 13 places, exactly half the alphabet, so running the same scramble a second time restores the original text.

The National Cryptologic Museum, housed in a former motel beside NSA headquarters, is in which US state?

Maryland's Fort Meade is home to the NSA, which bought the old Colony Seven Motel to create a buffer between its high-security buildings and a highway.

Which May 2017 ransomware attack encrypted computers in British hospitals and demanded payment in bitcoin?

WannaCry was halted within hours when researcher Marcus Hutchins registered a web address that turned out to be its kill switch.

Swiss cipher-machine maker Crypto AG was exposed in 2020 as secretly owned by West German intelligence and which agency?

CIA ownership dated from 1970 and let the two agencies read the coded traffic of governments that trusted the firm's machines, a scheme called Operation Rubicon.

Which blunt-sounding method did the EFF's Deep Crack machine use in 1998, simply trying every possible key?

Brute force took Deep Crack only 56 hours to find a DES key in July 1998; the machine, named with a nod to IBM's Deep Blue, cost less than $250,000.

Which internet security company films a wall of lava lamps in its office lobby to help generate random numbers?

Cloudflare revived an idea invented at Silicon Graphics in 1996: the chaotic drift of the warm wax blobs is digitised as a source of unpredictability.

From 1954, US export law placed encryption technology on an official government list of what?

Munitions was the legal label, so protesters printed encryption source code on T-shirts, turning each shirt into an export-restricted weapon.

Which encryption program did Phil Zimmermann create in 1991, making him the target of a federal criminal investigation?

PGP's first version used a cipher its author had designed himself and named BassOmatic, after a Saturday Night Live sketch.

Which bug in the widely used OpenSSL encryption library went unnoticed from 2012 until its disclosure in April 2014?

Heartbleed took its name from the heartbeat extension, where a missing bounds check let more data be read out of a server's memory than should be allowed.

Which magazine's Martin Gardner column introduced the RSA cipher to the public in 1977 with a $100 challenge?

Scientific American printed the puzzle in August 1977; when it finally fell, more than 600 volunteers had lent some 1,600 machines, two of them fax machines.

Which 2000 Hollywood film drew protests in Britain's Parliament for showing Americans capturing an Enigma machine?

U-571 was called an affront to British sailors in the Commons; its closing credits acknowledge the Royal Navy crews who seized Enigma material from U-110 and U-559.

Which mysterious group posted elaborate puzzles online from January 2012, saying it sought 'intelligent individuals'?

Cicada 3301 posted three sets of puzzles between 2012 and 2014, the first of them on 4chan, and never revealed who was behind them or why.

Which Dutch cryptographer's 1883 principle says a cipher should stay secure even if all but its key is public?

Auguste Kerckhoffs listed six design rules for military ciphers; Claude Shannon later put this one more bluntly: the enemy knows the system.

Which codebreaker's 1931 book 'The American Black Chamber' told how his bureau had read Japan's diplomatic codes?

Herbert Yardley's team had fed American negotiators decoded Japanese cables during the Washington conference on warship limits in 1921–22.

Which US counterintelligence project ran from 1943 to 1980, decrypting Soviet intelligence messages sent in wartime?

Venona worked because a Soviet factory, pressed by the German advance on Moscow, had printed about 35,000 duplicate pages of one-time pad keys.

Which codebreaker did the US Coast Guard hire during Prohibition to decode liquor smugglers' radio messages?

Elizebeth Friedman was taken on temporarily to clear a backlog of intercepts; in World War II her Coast Guard unit broke the ciphers of German spy networks in South America.

Which ancient historian gives his name to the 5×5 letter grid behind the tap code used by prisoners?

Polybius described the grid as a way to spell out any message with fire signals, where earlier beacons could only send a few prearranged ones.

The 105-page Copiale cipher, decoded in 2011, held the rituals of a German secret society that called its members what?

Oculists was the name of the order from Wolfenbüttel, which used sight as a metaphor for knowledge; the first 16 pages describe an initiation ceremony.

Which officer on Wellington's staff broke the French army's Great Paris Code during the Peninsular War?

George Scovell could read enough by December 1812 to follow a captured letter from Joseph Bonaparte to Napoleon, intelligence that proved vital at Vitoria.

Which schoolroom slang for cheating did Bletchley Park borrow to name known plaintext used to break a cipher?

Crib was also student slang for a word-for-word translation of a classical author, kept for illicit help with Greek or Latin.

Which US government encryption chip, introduced in 1993 with built-in access for law enforcement, was defunct by 1996?

Clipper relied on a classified NSA-designed cipher called Skipjack, which was not declassified and published until 1998.

Which Post Office engineer designed and built Colossus, the first programmable electronic computer, for Bletchley Park?

Tommy Flowers said that when war broke out he was possibly the only person in Britain who realised valves could be used reliably on a large scale for fast computing.