Wikipedia :
Cipher
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Cryptography
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History of cryptography
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One-time pad
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Public-key cryptography
Elliptic curve cryptography (ECC)
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RSA
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Olive Hazlett (1890-1974,
PhD 1915)
Lock Picking 101 (1:04:09)
by Andrews Roy (2012年07月17日)
Shamir's Secret Sharing (10:35)
by Matt Parker (standupmaths, 2019年12月31日)
Strictly speaking, Caesar's cipher was a fixed monalphabetic substitution method based on the Roman alphabet (Classical Latin alphabet) of 23 letters (omitting J, U and W from the modern Latin alphabet of 26 letters). It consisted in replacing every letter by the letter appearing three ranks further in the alphabet:
Wikipedia : Caesar cipher | ROT13
Frequency analysis is almost enough to break such a code.
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Wikipedia : Substitution cipher | Frequency analysis | Al-Kindi (c.801-873)
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How to Write in Tri Code
Wikipedia :
Classical cipher
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Transposition cipher
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The device designed by Leon Battista Alberti (1404-1472) was used for secret transmission within the Vatican. It uses two different extensions of the Latin alphabet for the plain text and the cipher text.
It was once known as le chiffre indéchiffrable (the unbreakable cipher). It was re-invented many times and its good reputation is not deserved: The so-called Babbage-Kasisky method cab easily crack it, at least if the encoding key is much shorter than the text.
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Vigenère cipher
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Giovan Battista Bellaso (b. 1505)
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Blaise de Vigenère (1523-1595)
Babbage-Kasiski method
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Friedrich Kasiski (1805-1881)
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Charles Babbage (1791-1871)
Codebreaking challenge &
solution by
James Grime.
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Wikipedia : Cylinder cipher | Etienne Bazerie (1846-1931) | M-94 (1922-1945)
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Wikipedia : Rotor machines
The enigma machine was invented in 1918 by Arthur Cherbius (1878-1929). In spite of its high cost, it was eventually adopted by the German military once it was revealed that the British had been able to crack the military German codes during WWI (that revelation was published in a book by Winston Churchill).
Instrumental in that German decision to adopt a new coding technology was the future Panzer General Rudolf Schmidt (1886-1957) whose younger brother Hans-Thilo Schmidt (1888-1943) would eventually sell enigma secrets to a French operative codenamed Rex, under the cryptonym of Asché or Source-D.
The information received from Asché was communicated to the Polish cipher-bureau who could use it to figure out the internal wiring of the enigma rotors. The Polish mathematician Marian Rejewski (1905-1980) used this, together with the weakness introduced by the systematic repetition of the first trigram in the original standard Enigma protocol, to crack enigma codes in 1932.
Poland communicated that information back to France and the UK, where Alan Turing (1912-1954) could crack the codes even after the Germans had stopped repeating the first trigrams in their messages (in a way, Rejewski's ultimate contribution was to convince the British that enigma codes were breakable even if fewer weaknesses could be exploited).
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The Enigma Code
by David Perry (NSA).
Turing: Pioneer of the Information Age
by Jack Copeland
A genuine WWII Enigma machine presented by James Grime.
Wikipedia :
Enigma machine
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Enigma rotors
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Lorenz SZ (Tunny)
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Ultra
On 1945年09月01日, Claude Shannon published a classified paper demonstrated that a truly random one-time pad achieves perfect secrecy.
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One-time pad (1882) | Frank Miller (1842-1925) | Gilbert Vernam (1890-1960) | Joseph Mauborgne (1881-1971)
Elliptic curve cryptography.
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NSA Surveillance (10:58) Controversy (4:19) by Edward Frenkel (Numberphile, 2013年12月22日).
In 1912, this 200-page manuscript was acquired from Villa Mondragone, near Rome, by an antiques dealer from London who would move to New-York in 1914, Wilfrid Voynich (1865-1930). Né Michal Habdank-Wojnicz, he was a Polish-Lithuanian revolutionary who had escaped from penal servitude in Siberia and established himself in London in 1890. In 1898, he married Ethel Lilian Boole (1864-1960) daughter of Mary Everest Boole (1862-1916, niece of George Everest) and of the great mathematician George Boole (1815-1864) who died when she was 4 months old...
This mathematical connection may have played a rôle in building the early belief that the manuscript was written in some common language but encoded with a secret cipher to hide sensitive information not meant for the uninituated. This hypothesis is all but abandonned now.
What's now believed by an increasing number of scholars and amateurs alike is that the manuscript is a unique sample of a script invented to transcribe an unidentified Indo-European language or dialect for which no other script is known. The many botanical and astronomical illustrations in the Voynich manuscript offer some hope of identifying some scientific words and their Indo-European roots. This leads to a partial decoding of the Voynich alphabet in terms of associated sounds.
Along those promising lines, Stephen Bax has tentatively identified 10 words and 14 letters (or groups of letters). (video 47:11).
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National Geographic's "Naked Science"
The book that can't be read
by Walter Köhler and Martin Mészàros.
Arbëreshë people and Arbërisht, or extinct slavic language:
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update
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by Amy Michelle Mosier.
How to solve the Voynich manuscript, by Volder Z. :
phonetics & alphabet |
putting the pieces together
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Diffie-Hellman key exchange
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Whit Diffie (1944-)
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Martin Hellman (1945-)
The Mathematics of Diffie-Hellman Key Exchange (13:32)
by Gabe Perez-Giz
(PBS Infinite Series, 2018年01月11日).
