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Here is a list of past presentations at ICCH. The most recent presentation is at the top. Click on each listing to reveal more information below, including the speaker, presentation description and to access recordings.
Note: Effort has been made to ensure that the information on each presentation is accurate and up-to-date. To suggest a correction please contact the ICCH webmaster Patrick Hayes at .
A successor to the Red Book and Blue Book codes, JN-25 was introduced by the Imperial Japanese Navy on 1 June 1939. It was the primary Japanese naval cipher throughout World War II. JN-25 was a 5-digit code that was enciphered by additives. It evolved through a sequence of codebooks, additive tables, and “Uses.” The cipher was first broken by British codebreaker John Tiltman. US Navy codebreaker Agnes Driscoll broke it soon after. This presentation will explore the evolution of the cipher and give an overview of the attack on JN-25.
May 16, 2021
Here is a list of past presentations at ICCH. The most recent presentation is at the top. Click on each listing to reveal more information below, including the speaker, as well as the presentation date and description. Presentation recordings are available separately, in the ICCH Portal.
To view upcoming ICCH presentations, click here.
Note: Effort has been made to ensure that the information on each presentation is accurate and up-to-date. To suggest a correction please contact the ICCH webmaster Patrick Hayes at info@cryptologichistory.org.
A successor to the Red Book and Blue Book codes, JN-25 was introduced by the Imperial Japanese Navy on 1 June 1939. It was the primary Japanese naval cipher throughout World War II. JN-25 was a 5-digit code that was enciphered by additives. It evolved through a sequence of codebooks, additive tables, and “Uses.” The cipher was first broken by British codebreaker John Tiltman. US Navy codebreaker Agnes Driscoll broke it soon after. This presentation will explore the evolution of the cipher and give an overview of the attack on JN-25.
May 16, 2021
