Otto Leiberich

Otto Leiberich
Otto Leiberich at his desk.
Born December 5, 1927 (1927-12-05)
Berlin, German Empire
Died June 23, 2015(2015-06-23) (aged 87)
Citizenship German
Alma mater University of Cologne
Scientific career
Fields Mathematics
Cryptology
Doctoral advisor Guido Hoheisel

Otto Leiberich (* 5 December 1927 in Crailsheim, † 23 June 2015) was a German cryptologist and mathematician.[1][2] Leiberich is most notable for establishing the Bundesamt für Sicherheit in der Informationstechnik in 1991.[3]

Life

Leiberich started his career during World War II, conscripted as a soldier and working as a cryptanalyst in Chi IV of the OKW/Chi.[4]

In 1953, Leiberich was promoted to D.Phil at the University of Cologne, sponsored by Guido Hoheisel with a topic on algebra. The thesis was titled Über Systeme von Jardenschen Folgen, On systems of Jarden consequences. Leiberich joined the newly established post war German cipher bureau, that from 1956 was called the Central Office for Ciphering (German: Zentralstelle für das Chiffrierwesen). Dr Erich Hüttenhain was his director, both in OKW/Chi and in the new bureau.

Career

During the Cold War Leiberich and his team at BSI 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 who was senior aide to Willy Brandt, the statesman who served as Chancellor of the Federal Republic of Germany (West Germany) from 1969 to 1974.[5] In 1973, Leiberich was the successor to Erich Hüttenhain at the Deputy Director of the Central Office for Encryption (German: Zentralstelle für das Chiffrierwesen).[6]

In 1999, Leiberich wrote a report on the history of cryptography in Germany, which appeared in the international science magazine Spektrum der Wissenschaft[7]

Cipher challenge

In order to encourage research on the double transposition cipher, 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[6] In 2007, the challenge was published by Klaus Schmeh[6], in various media channels inclduding his own books, websites and academic and white papers.[6]

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 that also solved it.[8][9]

References

  1. ↑ Hans Laux (2015). "23". Trilogie meines Lebens (in German). VVW GmbH. pp. 128–136. ISBN 978-3-86298-385-8. Retrieved 12 June 2018.
  2. ↑ Literature by and about Otto Leiberich in the German National Library catalogue
  3. ↑ von Hange, Michael (2015). "Nachruf auf Dr. Otto Leiberich" (PDF). Bundesamt fuer Sicherheit in der Informationstechnik Magazine: 22. Retrieved 12 June 2018.
  4. ↑ The Enigma Bulletin, Source:British Archives document:ADM 223/505. Enigma Press. 1997. p. 78. Retrieved 13 June 2018.
  5. ↑ George Lasry (23 February 2018). A Methodology for the Cryptanalysis of Classical Ciphers with Search Metaheuristics. kassel university press GmbH. p. 175. ISBN 978-3-7376-0458-1.
  6. 1 2 3 4 Friedrich L. Bauer (24 November 2006). Decrypted Secrets: Methods and Maxims of Cryptology. Springer Science & Business Media. p. 415. ISBN 978-3-540-48121-8. Retrieved 12 June 2018.
  7. ↑ Leiberich, Otto (1 June 1999). "Vom diplomatischen Code zur Falltürfunktion". Spektrum der Wissenschaft (in German). Spektrum der Wissenschaft Verlagsgesellschaft mbH. Retrieved 13 June 2018.
  8. ↑ Lasry, George; Kopal, Nils; Wacker, Arno (November 2013). "Solving the Double Transposition Challenge with a Divide and Conquer Approach" (PDF). Retrieved 12 June 2018.
  9. ↑ Lasry, George; Kopal, Nils; Wacker, Arno (2014). "Solving the Double Transposition Challenge with a Divide-and-Conquer Approach". Cryptologia. Taylor & Francis. 38 (3): 197–214. doi:10.1080/01611194.2014.915269.
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