Cryptiana: Articles on Historical Cryptography

Table of Contents:
General Topics
Codes and Ciphers in 16th-Century England
Italian Ciphers
Spanish Ciphers
Early French Ciphers
Codes and Ciphers in 17th-Century England
French Ciphers during the Age of Louis XIV
German (and Germanic) Ciphers
British Ciphers: 18th Century
Authors on Cryptology
Codes and Ciphers during the American Revolutionary War
Codes and Ciphers during the First Decades of the United States
French Ciphers in the 18th and 19th centuries
US Civil War Ciphers
US Codes of Telegraphic Age
A Russian Cipher
Telegraph Codes
Early Japanese Codes and Ciphers
Japanese Codes and Ciphers in the 1920s-1930s
Chinese Cryptography

Various codes and ciphers used through history are described. See also my blog.

General Topics

Code, Cipher, Nomenclator -- Notes on Terms in Cryptology
Unsolved Historical Ciphers
How to Break a Code (Not a Cipher)
Is Codebreaking Possible without Knowing the Language?
Do Ciphering in Rome as the Romans Do.
Paleography in Examples: Tips for Reading Old Handwriting

Codes and Ciphers in 16th-Century England

Earliest English Diplomatic Ciphers
Ciphers during the Reign of Henry VIII
Cardinal Wolsey's Cipher (1524)
A Misplaced? English Cipher Letter in French Archives
Ciphers during the Reign of Queen Elizabeth I
Ciphers of Mary, Queen of Scots
Deciphering Mary Stuart's lost letters from 1578-1584 (Coauthored by George Lasry, Norbert Biermann, Satoshi Tomokiyo) (Cryptologia)
メアリー・ステュアートの暗号の手紙(1578-1584):50通以上を発見・解読 (Mary, Queen of Scots)
Discovery and Codebreaking of 50+ Letters of Mary, Queen of Scots (1578-1584)
Simulated Paper-and-Pencil Codebreaking of a Ciphered Letter of Mary, Queen of Scots
What Encryption Errors Can Reveal: Cross-Cipher Errors in Mary Queen of Scots' Letters (Coauthored by Norbert Biermann, Satoshi Tomokiyo, and George Lasry) (HistoCrypt2024) NEW

Italian Ciphers

Ciphers of Isabella d'Este (1510)
An Early Vatican Cipher (1520)
A Cipher with Vowel Indicators Used by Papal Nuncio Castiglione (1527)
Variable-Length Symbols in Italian Numerical Ciphers
Identifying Italian ciphers from continuous-figure ciphertexts (1593) (Cryptologia)
Intercalary Nulls in Italian and French Ciphers
Polyphonic Substitution in Italian Numerical Ciphers
Venetian Ciphers with Superscripts (1519-1587)
The Gronsfeld Cipher before Count Gronsfeld (1560s-1570s, Mantua)
Vatican Substitution Ciphers Designed on Alphabetical Matrices (1550s-1560s)
Ciphertext-only Attack on a Vatican Cipher (1573) by Albert C. Leighton
Florentine Ciphers of Guicciardini (ca.1590-1593)
Reading an Undeciphered Letter of the Duke of Mantua (1590, 1593)
Reading Undeciphered Letters to the Duke of Savoy (1593)
A Cipher of the Duke of Savoy (1606)
Ciphertext-only Attack on "Vatican Challenge" Ciphers (1625, 1628)
ルネサンス期の暗号,450年ぶりに解読(ベラソの暗号) (1553, 1555, 1564) (Bellaso)
Anagram and Gergo (Jargon): Galileo's Secret Communication

Spanish Ciphers

Spanish Ciphers before Accession of King Ferdinand: 1470-1479 (
Spanish Ciphers during the reign of Ferdinand and Isabella
Solution of Ciphertext of Catherine of Aragon to King Ferdinand (1509)
Bergenroth's Papers on Spanish Ciphers in PRO 31/11/11
Ciphers during the Reign of Emperor Charles V
Codebreaking of a Spanish Cipher with Vowel Indicators (1529)
Philip II's First Cipher (1543)
Spanish Ciphers during the Reign of Philip II
Major Types of Ciphers during the Reign of Philip II
Tracing the Origin of Vowel Indicators in Spanish Ciphers
Thomas Phelippes' Deciphering of Spanish Ciphers Found in French Archives
Spanish Codebreaking under Phillip II
Finding the Keys to Philip II's Cipher Letters to Juan de Vargas Mexia
Reading an Undeciphered Letter of Philip II to Juan de Vargas Mexia (1577) (
Did Philip II Call Codebreaking "Black Magic"? (summary version at
How I reconstructed a Spanish cipher from 1591 (Cryptologia)
Philip II's Trivial Substitution Cipher
A Jesuit Cipher Found in Peru (1601)
A Memorial in Line Segment Cipher from Peru (1604)
Spanish Ciphers in the Seventeenth Century

Early French Ciphers

French Ciphers during the Reign of Francis I (1515-1547)
French Ciphers during the Reign of Henry II of France (1550-1557)
Duke of Guise's Ciphers (1556) in BnF fr.20974
Reading an Undeciphered French Letter from Antwerp (1580)
French Ciphers during the Reigns of Charles IX and Henry III (1561-1574, 1574-1589)
A Polyphonic Substitution Cipher of the Catholic League (1592-1593)
Catalogue of Ciphers (Mainly Related to Duke of Nevers) in BnF fr.3995 (1580-1595)
A List of Cipher Materials in Mémoires de la Ligue in the French Archives (1585-1595)
Undeciphered Letters in BnF fr.4715 (c.1586-1593)
A Decoding Table Sorted by Symbol Similarity in a French Cipher for Henry IV, Duke of Nevers, etc. (1593-1594)
A Cipher of Henry of Navarre before Accession to the French Throne (1587)
French Ciphers during the Reign of Henry IV of France (1589-1610)
Catalogue of Ciphers Related to Jacques Bongars in BnF fr.7125-7132 (1590-1611)
Development of Ciphers under Henry IV of France: A Case of Jacques Bongars: 1590-1611 (
Ciphers Broken by François Viète
French Ciphers during the Reign of Louis XIII (1610-1643)
Variable-Length Figure Cipher of Duke of Lorraine (ca.1620?)
Codebreaking through Comparison of Two Independently Enciphered Texts (1632)
Decipherment of Hitherto Unsolved Historical Ciphers (by George Lasry)

Codes and Ciphers in 17th-Century England

Ciphers in Early Stuart England before the Civil War
A Polyalphabetic Cipher of Lord Feilding (1634-1639)
King Charles I's Ciphers
What It Takes to Break Charles I's Cipher Used in the Isle of Wight
An Ormonde-Clanricairde Cipher -- An Example of Codebreaking
Duke of York's Intercepted Letter Reveals His Escape Plan
Charles I's Cipher Revealed: Sir Charles Wheatstone's Codebreaking
Lord Digby's Ciphers (1645)
Colonel Bampfield as Charles I's Agent
Glamorgan's Line Segment Cipher (1645)
Quest for "Trevanion's Cipher" (トレヴァニオンの暗号)
Musical Notes Concealing A Warning to Fleeing Prince Charles
King Charles II's Ciphers during Exile
Codes and Ciphers of Thurloe's Agents
大法官ハイド,暗号の安全性を語る (1660)
Some Orangist Ciphers (1662)
English Ciphers during the Restoration Period
Clarendon's Correspondence Decoded by John Wallis (c.1669) and Re-decoded by His Grandson
Polyalphabetic Cipher Exercise by Royalist Minister Edward Nicholas
An English Polyalphabetic Cipher from the Seventeenth Century
Samuel Morland's "New Method" Used for Charles II's Ambassador
Ciphers of Coleman's Correspondence Discovered in the Popish Plot
Earl of Argyll's Ciphers (1683) (アーガイルの暗号)
John Wallis and Cryptanalysis
Secret Letters Left Unbroken by John Wallis Solved After 400 Years
William Blencowe's "Safest and Most Expeditious" Cipher
Diplomatic Codes after the Glorious Revolution and Use of Printed Templates

French Ciphers during the Age of Louis XIV

French Ciphers at the time of the Fronde (1639-1651)
Cardinal Mazarin and Ciphers
Ciphers Early in the Reign of Louis XIV
French Ciphers during the Reign of Louis XIV
Specimens of French Cipher (1689) Printed in John Wallis' Opera Mathematica
Decoding Louis XIV's Secret Instructions to His Ambassador in Constantinople (1690)
Commandant Bazeries' Codebreaking and His Candidate of the Man in the Iron Mask
Specimens of Louis XIV's Great Cipher (1691)
Code Switching in French Diplomatic Correspondence during the Peace Negotiation at Rijswijk (1696-1697)

German (and Germanic) Ciphers

Habsburg Codes and Ciphers
Some German Ciphers: 1540-1815
"Triplet" Cipher of Augustus of Brunswick-Lüneburg, a.k.a., Gustavus Selenus
ライプニッツの暗号機構想,初の実機製作 (Leibniz's cipher machine)
オランダ暗号小史 (Dutch ciphers)
Prince of Orange's Columnar Transposition Cipher (c.1675)
A Danish Diplomatic Cipher with Table Swtiching in the 17th Century
数学者オイラーの残した暗号文の解読 (Leonhard Euler) (1744)

British Ciphers: 18th Century

Duke of Marlborough's Codes and Ciphers (1701-1711)
A Cipher during the War of the Spanish Succession (1709)
Cryptologic Aspects of the Atterbury Plot (1722-1723)
Drake-Nelson Code (1796)

Authors on Cryptology (暗号関係の書籍・論者)

Scytale Not As a Transposition Cipher (reorganized summary version at
Porta's De Furtivis Literarum Notis (1563)
Agostino Amadi's Treatise on Cipher (ca.1588)
Vigenere's Introduction of Japanese Characters in Europe (1586)
フランシス・ベーコンの暗号論 (1605, 1623)
Francis Bacon on Cryptology (1605, 1623)
ジョン・ウィルキンズの『マーキュリー』 (1641)
Structured Table of Contents for John Wilkins' Mercury (1641)
"Cipher" mentioned in the Pensées de Blaise de Pascal
ブリュラール・ド・レオンのサイファーディスクと暗号論 (Brulart de Leon)
Brûlart de Léon's Cipher Disk and Treatise on Cipher (
ジョン・フォークナーの『クリプトメニシス・パテファクタ』 (1685)
Notes on John Falconer and Cryptomenysis Patefacta (1685)
ジョン・デーヴィス『暗号解読論』 (1737)
John Davys and the Art of Deciphering (1737)
Conradus' Cryptographia Denudata (1739)
フィリップ・シックネスの『暗号解読および暗号記法の技術に関する論考』 (1782) (Thicknesse)
ウイリアム・ブレア「暗号」(1807)(『リース百科事典』) (William Blair)
Principles of William Blair's Ciphers (1807)
Who Made "the Vigenere Cipher" as Known Today? (
Did Beaufort Really Use the Beaufort Cipher?
ルイス・キャロルの暗号 (Lewis Carroll)
エドガー・アラン・ポーと暗号 (Edgar Allan Poe)
Solution of Tyler's Cryptograms Published in Poe's Article
エティエンヌ・バズリー『暴かれた秘密の暗号』 (Etienne Bazeries)
Cryptologia Articles in Chronological Order of Subjects

Codes and Ciphers during the American Revolutionary War

Decoding Revolutionary Correspondence
First Codebreaking in the American Revolution -- Benjamin Church's Cipher
Dumas' Cipher -- Benjamin Franklin's Favorite Cipher
Benjamin Franklin's Codes and Ciphers
John Jay's Codes and Ciphers
John Jay's Bookcode Formula
Decoding Deane-Jay Code
Lovell's Cipher
John Adams' Troubles with Lovell's Cipher
American Peace Commissioners' Instructions in John Jay's Book Code
Codes and Ciphers under Livingston, the First Secretary of Foreign Affairs
Book Codes between Benedict Arnold and John André (1779-1780)
Sir Henry Clinton's Hourglass Cipher
Cornwallis' Ciphers
Break Cornwallis' Cipher! -- Introductory Codebreaking
コーンウォリスの暗号を解読せよ!――暗号解読入門 (Cornwallis)
James Lovell as a Codebreaker
Codes and Ciphers between Washington and Rochambeau and the Yorktown Campaign
Lafayette's Code
ジョン・アダムズが解読できなかった暗号 (John Adams)
ジョン・アダムズの暗号文:イギリス国王との初謁見の報告 (John Adams)
Rev. William Gordon's Polyalphabetic Cipher for George Washington (1786)

Codes and Ciphers during the First Decades of the United States

Thomas Jefferson's Codes and Ciphers: I (1783-1789)
Thomas Jefferson's Codes and Ciphers: II (1790-1803)
Thomas Jefferson's Codes and Ciphers: III (Miscellaneous)
Jefferson Studies Livingston-Jay Code
James Madison's Codes and Ciphers
Italian Cipher Letter to Madison (1780) Deciphered
Rotating Grille for Alexander Hamilton
Patterson's Cipher for Jefferson -- Challenge Solved After 200 Years
200年を経て解読――パターソンからジェファソンへの暗号 (Patterson)
XYZ事件と暗号 (XYZ Affair)
State Department Code: 1797-1866

French Ciphers in the 18th and 19th centuries

A Code of Cardinal of Rohan (1721)
Code Switching in French Diplomatic Correspondence and Intercepted Letter of Barbé-Marbois (1782)
French Code between General Rochambeau and Admiral de Barras (1781)
マリー・アントワネットフェルゼンの暗号 (Marie-Antoinette and Fersen)
Ciphers of Marie-Antoinette and Axel von Fersen
A Letter Code of Emigres in Koblenz
Great Ciphers of Napoleon's Grande Armée
A Specimen of Napoleon's Small Cipher (1813)
Enciphered Proclamation to the Army Attributed to Napoleon in Elba (1814)
Codes from the time of Napoleon III
Panizzardi Telegram: A Cryptologic Sideshow of the Dreyfus Affair (1894)

US Civil War Ciphers

Overview of Civil War Codes and Ciphers (1861-1865)
Development of Stager Ciphers during the Civil War (1861-1865)
A Civil War Dispatch Redeciphered (1865)
Semi-phonetic Reversal Cipher used in Lincoln's Telegram (1865)
Confederate Ciphers during the Civil War: Various Vigenere Keywords (1862-1865)
Confederate Ciphers (Other Than Vigenere) during the Civil War
Keyed Rotating Grille Used by Confederate Agent Sinclair during the Civil War (1863)
Rose Greenhow's Cipher Letter Written after the First Battle of Bull Run (1861)

US Codes of Telegraphic Age

The Last of Pre-Telegraphic Age Codes
"Frugal" Code to Cut Cable Cost (1867-1875)
Red and Blue: First Official Codebooks Adapted for Telegraphy
US War Department Telegraph Codes: 1885-1945
US Navy Secret Code of 1887 Used at the Time of the Spanish-American War (1898)
American Army Field Codes during World War I

A Russian Cipher

Russian Diplomatic Cipher at the time of the Alaska Purchase (1867)

Telegraph Codes

Telegraph Regulations and Telegraph Codes
Nonsecret Code: An Overview of Early Telegraph Codes
日本の電信暗号 (Japanese Telegraph Codes)
Japanese Telegraph Codes
電碼――中国の文字コード (Chinese Character Codes)
Chinese Telegraph Code (CTC), or A Brief History of Chinese Character Code (CCC)
数字暗号とコード・コンデンサー――コンピューター以前の情報圧縮 (Figure Codes and Code Condensers)
Figure Codes and Code Condensers -- Data Compression Before Computer Age
検誤表――コンピューター以前の誤り訂正符号 (Mutilation Table)
Mutilation Table and Error-Correcting Code Before Computer Age

Early Japanese Codes and Ciphers

明治日本の暗号いろいろ (Japanese Codes and Ciphers during the Meiji Period)
明治日本の外交暗号:1874-1885-1904 (Japanese Diplomatic Codes and Ciphers during the Meiji Period)
日露戦争中の日本の一外交暗号の概要判明 (Japanese Diplomatic Code during Russo-Japanese War)
明治・大正期の陸軍暗号 (Japanese Military Codes and Ciphers during the Meiji and Taisho Periods)
明治期の海軍暗号 (Japanese Naval Codes and Ciphers during the Meiji Period)
Codes and Ciphers of Imperial Japanese Army and Navy in the Meiji Period: 1874-1912
Early Japanese Diplomatic Codes: 1874-1933
明治末〜昭和初期の暗号セキュリティー雑録 (Crypto-Security in Late-Meiji to Early-Showa Period)

Japanese Codes and Ciphers in the 1920s-1930s

A Specimen of Yardley's Deciphering of Japanese Diplomatic Code Jp (1921)
Japanese Reaction to Yardley's The American Black Chamber (1931)
ヤードレー『アメリカン・ブラック・チェンバー』の新聞報道(リンク集) (1931) (Newspaper articles on Yardley's American Black Chamber)
Development of the First Japanese Cipher Machine: RED (1927-1932)
映画紹介:The Red Machine(「レッド暗号機」)
昔の特許文献の探し方と戦前の暗号関係の特許(付:戦前の中間処理実例) (Pre-War Japanese Crypto-Patents)

Chinese Cryptography

Chinese Cryptography: 1871-1945


Frequency Count (with Microsoft Excel)
Bigram Count (with Microsoft Excel)
Listing Recurring Polygrams from Ciphertext (with Perl)
Creating a KWIC Index with Microsoft Excel
Creating a Contact Chart with Microsoft Excel

『大脱走』の暗号 Cipher behind The Great Escape (in Japanese)
連続殺人犯「ゾディアック」の暗号Z340、半世紀ぶりに解読 (Zodiac Ciphers) (in Japanese)

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