Otto Leiberich (5 December 1927 in

Crailsheim Crailsheim is a town in the German state of Baden-Württemberg. Incorporated in 1338, it lies east of Schwäbisch Hall and southwest of Ansbach in the Schwäbisch Hall district. The city's main attractions include two Evangelical churches, ...

- 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) bo ...

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, structure, space, models, and change. History On ...

. Leiberich is most notable for establishing the

Bundesamt für Sicherheit in der Informationstechnik The Federal Office for Information Security (german: Bundesamt für Sicherheit in der Informationstechnik, abbreviated as BSI) is the German upper-level federal agency in charge of managing computer and communication security for the German g ...

in 1991.

Life

Leiberich started his career during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

, 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 (german: Universität zu Köln) is a university in Cologne, Germany. It was established in the year 1388 and is one of the most prestigious and research intensive universities in Germany. It was the sixth university to ...

, Leiberich earned a Dr. phil. in 1953 at the same university with a topic on algebra; his thesis (german: "Über Systeme von Jardenschen Folgen", On systems of Jarden sequences) was supervised by Guido Hoheisel. Leiberich joined the newly established post war German cipher bureau that from 1956 on was called the ''Central Cryptography Office'' (german: Zentralstelle für das Chiffrierwesen (ZfCh)). Dr

Erich Hüttenhain Erich Hüttenhain (26 January 1905 in Siegen – 1 December 1990 in Brühl (Rhineland), Brühl) was a German academic mathematician and cryptographer (Cryptography) and considered a leading Cryptanalysis, cryptanalyst in the Third Reich. He w ...

was his director, both in OKW/Chi and in the new bureau.

Career

During the Cold War Leiberich and his team worked intensively on the cryptanalysis of double transposition ciphers. One of their results led in 1974 to the discovery of the spying activities of

Günter Guillaume Günter Guillaume (1 February 1927 – 10 April 1995) was a German spy who gathered intelligence as an agent for East Germany's secret service, the Stasi, in West Germany. Guillaume became West German chancellor Willy Brandt's secretary, a ...

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 served as the chancellor of West Ge ...

, the statesman who served as Chancellor of the

Federal Republic of Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated between ...

(West Germany) from 1969 to 1974. In 1972, Leiberich was the successor to

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 famous scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it. In print since 1845, it ...

Cipher challenge

In order to encourage research on the double

transposition cipher In cryptography, a transposition cipher is a method of encryption which scrambles the positions of characters (''transposition'') without changing the characters themselves. Transposition ciphers reorder units of plaintext (typically characters or ...

, 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 inclduding 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 o ...

that also solved it.

Publications

* *

References

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