Articles on Historical Cryptography

To those who have been redirected here from the old domain:
The old domain ( will stop working as of 31 October 2017. Please update your bookmark.

Various codes and ciphers used through history are described.

Unsolved Historical Ciphers
How to Break a Code (Not a Cipher)
Paleography in Examples: Tips for Reading Old Handwriting

Codes and Ciphers in 16th-Century England

Earliest English Diplomatic Ciphers
Cardinal Wolsey's Cipher (1524)
Ciphers during the Reign of Queen Elizabeth I

Italian Ciphers

Variable-Length Symbols in Italian Numerical Ciphers
Intercalary Nulls in Italian and French Ciphers NEW
Polyphonic Substitution in Italian Numerical Ciphers
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)

Spanish Ciphers

Spanish Ciphers during the reign of Ferdinand and Isabella
Ciphers during the Reign of Emperor Charles V
Spanish Ciphers during the Reign of Philip II
Thomas Phelippes' Deciphering of Spanish Ciphers Found in French Archives
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 Henry II of France (1550-1557)
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 Decoding Table Sorted by Symbol Similarity in a French Cipher for Henry IV, Duke of Nevers, etc. (1593-1594)
French Ciphers during the Reign of Henry IV of France (1589-1610)

Codes and Ciphers in 17th-Century England

Ciphers in Early Stuart England before the Civil War
King Charles I's Ciphers
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)
Clarendon's Correspondence Decoded by John Wallis (c.1669) and Re-decoded by His Grandson
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

French Ciphers during the Age of Louis XIV

French Ciphers during the Reign of Louis XIV
Specimens of French Cipher (1689) Prited 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)

Prince of Orange's Columnar Transposition Cipher (c.1675)
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
Porta's De Furtivis Literarum Notis (1563)
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
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
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)
Principles of William Blair's Ciphers (1807)
Solution of Tyler's Cryptograms Published in Poe's Article

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
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 (in Japanese)
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 (in Japanese)
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 (in Japanese)
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 (in Japanese)
XYZ事件と暗号 (in Japanese)
State Department Code: 1797-1866

French Ciphers in the 18th and 19th centuries

Code Switching in French Diplomatic Correspondence and Intercepted Letter of Barbé-Marbois (1782)
マリー・アントワネットフェルゼンの暗号 (in Japanese)
Ciphers of Marie-Antoinette and Axel von Fersen
Great Ciphers of Napoleon's Grande Armée
A Specimen of Napoleon's Small Cipher (1813)
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
American Army Field Codes during World War I

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
Japanese Telegraph Codes
Chinese Telegraph Code (CTC), or A Brief History of Chinese Character Code (CCC)
Figure Codes and Code Condensers -- Data Compression Before Computer Age
Mutilation Table and Error-Correcting Code Before Computer Age

Early Japanese Codes and Ciphers

Codes and Ciphers of Imperial Japanese Army and Navy in the Meiji Period: 1874-1912
Early Japanese Diplomatic Codes: 1874-1933

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)
Development of the First Japanese Cipher Machine: RED (1927-1932)
映画紹介:The Red Machine(「レッド暗号機」)

『大脱走』の暗号 Cipher behind The Great Escape (in Japanese)

My postings at

Search This Site
SINCE 2008 © S.Tomokiyo (友清理士)
(originally at and and moved to this fc2 domain on 21 September 2014)

inserted by FC2 system