Major Friedrich Wilhelm Kasiski (29 November 1805 – 22 May 1881) was a German

infantry Infantry is a military specialization which engages in ground combat on foot. Infantry generally consists of light infantry, mountain infantry, motorized infantry & mechanized infantry, airborne infantry, air assault infantry, and mar ...

officer An officer is a person who has a position of authority in a hierarchical organization. The term derives from Old French ''oficier'' "officer, official" (early 14c., Modern French ''officier''), from Medieval Latin ''officiarius'' "an officer," f ...

cryptographer Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adver ...

and

archeologist Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscap ...

. Kasiski was born in Schlochau,

Kingdom of Prussia The Kingdom of Prussia (german: Königreich Preußen, ) was a German kingdom that constituted the state of Prussia between 1701 and 1918. Marriott, J. A. R., and Charles Grant Robertson. ''The Evolution of Prussia, the Making of an Empire''. ...

(now

Człuchów Człuchów (, ''Człochòwo'', or ''Człëchòwò''; formerly ) is a town in the region of Gdańsk Pomerania, northwestern Poland, with 13,350 inhabitants as of December 2021. Człuchów has been the capital of Człuchów County in the Pomerani ...

, Poland).

Military service

Kasiski enlisted in East Prussia's 33rd Infantry

Regiment A regiment is a military unit. Its role and size varies markedly, depending on the country, service and/or a specialisation. In Medieval Europe, the term "regiment" denoted any large body of front-line soldiers, recruited or conscript ...

on 20 March 1823 at the age of 17. In May 1824, he was promoted to the

rank Rank is the relative position, value, worth, complexity, power, importance, authority, level, etc. of a person or object within a ranking, such as: Level or position in a hierarchical organization * Academic rank * Diplomatic rank * Hierarchy * ...

of Master Sergeant, and eight months later was commissioned as a Second Lieutenant in February 1825. It took fourteen years to earn his next

promotion Promotion may refer to: Marketing * Promotion (marketing), one of the four marketing mix elements, comprising any type of marketing communication used to inform or persuade target audiences of the relative merits of a product, service, brand or i ...

when, in May 1839, he advanced to the rank of

First Lieutenant First lieutenant is a commissioned officer military rank in many armed forces; in some forces, it is an appointment. The rank of lieutenant has different meanings in different military formations, but in most forces it is sub-divided into a ...

. His next advancement was quicker, promoted to Captain in November 1842. Kasiski finally retired from active service with the rank of Major on 17 February 1852. Between 1860 and 1868 he was the commander of a

National Guard National Guard is the name used by a wide variety of current and historical uniformed organizations in different countries. The original National Guard was formed during the French Revolution around a cadre of defectors from the French Guards. Nat ...

battalion A battalion is a military unit, typically consisting of 300 to 1,200 soldiers commanded by a lieutenant colonel, and subdivided into a number of companies (usually each commanded by a major or a captain). In some countries, battalions a ...

Cryptography

In 1863, Kasiski published a 95-page book on

cryptography Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adver ...

, ''Die Geheimschriften und die Dechiffrir-Kunst'' (German, "Secret writing and the Art of Deciphering"). This was the first published account of a procedure for attacking

polyalphabetic substitution A polyalphabetic cipher substitution, using multiple substitution alphabets. The Vigenère cipher is probably the best-known example of a polyalphabetic cipher, though it is a simplified special case. The Enigma machine is more complex but is sti ...

ciphers, especially the

Vigenère cipher The Vigenère cipher () is a method of encrypting alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword. It employs a form of polyalphabetic substitution. First described by Giovan Battista Bella ...

(although it is possible Charles Babbage was already aware of a similar method but had not published it). The method relied on the analysis of gaps between repeated fragments in the

ciphertext In cryptography, ciphertext or cyphertext is the result of encryption performed on plaintext using an algorithm, called a cipher. Ciphertext is also known as encrypted or encoded information because it contains a form of the original plaintext ...

; such analysis can give hints as to the length of the key used. This technique is known as

Kasiski examination In cryptanalysis, Kasiski examination (also referred to as Kasiski's test or Kasiski's method) is a method of attacking polyalphabetic substitution ciphers, such as the Vigenère cipher. It was first published by Friedrich Kasiski in 1863, but se ...

. The significance of Kasiski's cryptanalytic work was not widely realised at the time, and he turned his mind to

archaeology Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landsca ...

instead. The later years of his life were spent at Neustettin (

Szczecinek Szczecinek ( ; German until 1945: ''Neustettin'') is a historic city in Middle Pomerania, northwestern Poland, with a population of more than 40,000 (2011). Formerly in the Koszalin Voivodeship (1950–1998), it has been the capital of Szczecine ...

); the 11th edition of Encyclopædia Britannica cited a scholarly article by Kasiski in its entry on the town. Historian David Kahn notes, "Kasiski died on May 22, 1881, almost certainly without realizing that he had written a revolution in cryptology" (''

The Codebreakers ''The Codebreakers – The Story of Secret Writing'' () is a book by David Kahn, published in 1967, comprehensively chronicling the history of cryptography from ancient Egypt to the time of its writing. The United States government attempted to h ...

'').

Publication

* F. W. Kasiski
''Die Geheimschriften und die Dechiffrir-Kunst''
(Berlin, (Germany): E. S. Mittler und Sohn, 1863).

References

* David Kahn, ''

– The Story of Secret Writing'', revised ed, Scribner, 1996. pp. 207–209. * M. W. Bowers (pseudonym ''Zembie''), "Major F. W. Kasiski – Cryptologist", ''The Cryptogram'', Vol. XXXI(3) (January–February 1964) pp. 53,58–59.

Military service

Cryptography

Publication

References

See also