Otto Leiberich (5 December 1927 in

Crailsheim Crailsheim () is a town in the States of Germany, German state of Baden-Württemberg. Incorporated in 1338, it lies east of Schwäbisch Hall and southwest of Ansbach in the Schwäbisch Hall (district), Schwäbisch Hall district. The city's mai ...

- 23 June 2015) was a German

cryptologist This is a list of cryptographers. Cryptography is the practice and study of techniques for secure communication in the presence of third parties called adversaries. Pre twentieth century * Al-Khalil ibn Ahmad al-Farahidi: wrote a (now lost) book ...

and

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

. Leiberich is most notable for establishing the

Bundesamt für Sicherheit in der Informationstechnik The Federal Office for Information Security (, abbreviated as BSI) is the German upper-level federal agency in charge of managing computer and communication security for the German government. Its areas of expertise and responsibility include ...

in 1991.

Life

Leiberich started his career during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, conscripted as a soldier and working as a cryptanalyst in Chi IV of the OKW/Chi. After studying mathematics and physics at the

University of Cologne The University of Cologne () is a university in Cologne, Germany. It was established in 1388. It closed in 1798 before being re-established in 1919. It is now one of the largest universities in Germany with around 45,187 students. The Universit ...

, Leiberich earned a Dr. phil. in 1953 at the same university with a topic on algebra; his thesis (, On systems of Jarden sequences) was supervised by

Guido Hoheisel Guido Karl Heinrich Hoheisel (14 July 1894 – 11 October 1968) was a Germans, German mathematician and professor of mathematics at the University of Cologne. Academic life He did his PhD in 1920 from the University of Berlin under the supervis ...

. Leiberich joined the newly established post war German cipher bureau that from 1956 on was called the ''Central Cryptography Office'' ( (ZfCh)). Dr Erich Hüttenhain was his director, both in OKW/Chi and in the new bureau.

Career

During the

Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...

Leiberich and his team worked intensively on the

cryptanalysis Cryptanalysis (from the Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic se ...

of double transposition ciphers. One of their results led in 1974 to the discovery of the spying activities of Günter Guillaume who was senior aide to

Willy Brandt Willy Brandt (; born Herbert Ernst Karl Frahm; 18 December 1913 – 8 October 1992) was a German politician and statesman who was leader of the Social Democratic Party of Germany (SPD) from 1964 to 1987 and concurrently served as the Chancellor ...

, the statesman who served as

Chancellor Chancellor () is a title of various official positions in the governments of many countries. The original chancellors were the of Roman courts of justice—ushers, who sat at the (lattice work screens) of a basilica (court hall), which separa ...

of the

Federal Republic of Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen constituent states have a total population of over 84 ...

(West Germany) from 1969 to 1974. In 1972, Leiberich was the successor to Erich Hüttenhain as the Head of the Central Cryptography Office. In 1999, Leiberich wrote a report on the history of cryptography in Germany, which appeared in ''Spektrum der Wissenschaft'', the German edition of the

Scientific American ''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it, with more than 150 Nobel Pri ...

Cipher challenge

In order to encourage research on the double

transposition cipher In cryptography, a transposition cipher (also known as a permutation cipher) is a method of encryption which scrambles the positions of characters (''transposition'') without changing the characters themselves. Transposition ciphers reorder units ...

, Leiberich suggested during his retirement in 1999, that a double transposition challenge be published. Leiberich's recommendation for the challenge included: * Both transposition keys should be long enough: 20 to 25 elements. * The lengths of the ciphertext should not be a multiple of the length of either key. * A ciphertext of approximately 500 characters, i.e. the product of the lengths of the two keys, should be used. These properties were based on Leiberich's own experience, designed with parameters to ensure its own security In 2007, the challenge was published by Klaus Schmeh, in various media channels including his own books, websites and academic and white papers. In November 2013, George Lasry, Nils Kopal and Arno Wacker solved the double transposition cipher using a ciphertext only hill climbing attack. They also developed a

Dictionary attack In cryptanalysis and computer security, a dictionary attack is an attack using a restricted subset of a keyspace to defeat a cipher or authentication mechanism by trying to determine its decryption key or passphrase, sometimes trying thousands or ...

that also solved it.

Publications

* *

References

{{DEFAULTSORT:Leiberich, Otto 1927 births 2015 deaths German cryptographers 20th-century German mathematicians University of Cologne alumni