11/07/2020

Cardinal Richelieu's Cipher (1641) Identified

I mentioned a recent solution (by Norbert) of Cardinal Richelieu's cipher letter from 1641 in "Unsolved Historical Ciphers". While Richelieu is said to have used the Cardan grille, this is the first specific cipher used in Richelieu's correspondence known to me. Basically, it is a homophonic substitution cipher that has numbers, letters, and other symbols to represent the letters of the alphabet.

01/05/2020

Complementing Transcription of Ambassador Vivonne's Letter by Decipherment

Old handwriting is hard to read. Crypto-people often find deciphering a ciphertext is easier than reading its decipherment.
Now, I added my decipherment of an enciphered passage from a letter from French ambassador Vivonne to King Henry III dated 17 September 1586 (BnF fr.16045, f.244) in "French ciphers during the Reign of Henry III of France". The letter is printed in a scholarly article, but the transcription of the ciphertext from the decipherment in the margin is incomplete. My decipherment from the ciphertext complements the reading (albeit yet not complete).

By the way, I'm glad to find that my transcription of cipher symbols can be used to read actual ciphertext.

28/03/2020

Unsolved Ciphers in BnF fr.4712 (ca.1592?)

I added references to BnF fr.4712 in "Catalogue of Ciphers (Mainly Related to Duke of Nevers) in BnF fr.3995" and "Unsolved Historical Ciphers". The volume contains some cipher letters, of which some are undeciphered. I found one cipher with interlined decipherment is no.71 of the Nevers Collection.

19/03/2020

Duke of Guise's Ciphers (1556)

I uploaded "Duke of Guise's Ciphers (1556) in BnF fr.20974". It includes some undeciphered ciphertexts. I solved one cipher, but two remain unsolved. I added a section on this in "Unsolved Historical Ciphers".

05/03/2020

Undecoded Chinese Telegrams (1916 and ca.1938)

I added undecoded Chinese telegrams to "Unsolved Historical Ciphers":
Telegram to Sun Yat-sen (1916)
Telegram from Huang Xing to Lin Hu and Li Genyuan (1916)
Telegrams Found in a Sunken Ship Zhongshan (ca.1938) (sorry, this is hearsay)

04/03/2020

Chinese Cryptography: 1871-1945

I uploaded an article on Chinese cryptography from 1871 to 1945 in Japanese and English. When I wrote about Chinese telegraphic codes in 2014 in Japanese and English, it was commonly believed that there was nothing to discuss about Chinese cryptography during this period. Since then, new light has been shed on this neglected field by materials published in 2014-2018.
Five points I learned from these new materials:
(1) Revisions of Dianxin Xinfa (電信新法) (not to be confused with Dianbao Xinshu (電報新書) or Dianbao Xinbian (電報新編)) were used as official secret codebooks.
(2) Before the "Ming mi" (Plain/Secret) format of a 1908 codebook published by the Commercial Press, a similar format "Mi zhi" was used in official secret codebooks.
(3) There were many versions of official secret codebooks with different ordering of characters. (About the character ordering of the Zhou Code (1900 or 1902), there are conflicting descriptions, and it is desired to re-check the original copy.)
(4) Secret codebooks were used with the conventional (public) codebook (see the examples of "Qing Mi" and "Liang Mi" (1930-1931)).
(5) Official secret codebooks had long used the word dianma (電碼) in the title before 1929.

01/03/2020

Codebreaking as opposed to Cipher-breaking (1926)

Codebreaking through logical reasoning would be the most exciting topic for crypto-enthusiasts. But breaking code, as opposed to cipher, cannot be achieved by techniques such as letter frequency analysis. I'm collecting specimens of breaking codes in "How to Break a Code (Not a Cipher)".
I now added a specimen of solving a Peruvian diplomatic code (1926) described by Yardley.