Mishmar Hayarden 5

Giv‘atayim, Israel

Mishmar Hayarden 5

Giv‘atayim, Israel
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Lasry G.,Mishmar Hayarden 5 | Kopal N.,Mishmar Hayarden 5 | Wacker A.,Mishmar Hayarden 5
Cryptologia | Year: 2016

The Hagelin M-209 was a mechanical encryption device used by the U.S. Army during World War II and the Korean War, as well as by other armies and in embassy settings. In this article, the authors present a four-stage hillclimbing algorithm for recovering the full key settings from ciphertext only. The first two stages are based on a divide-and-conquer approach developed by Geoff Sullivan. In the current performance evaluation, the authors show that their method is able to recover key settings from messages as short as 750 letters, compared to 2,000 – 2,500 letters with prior methods. With this method, they solved several M-209 ciphertext-only challenges, including the final exercises in W. Barker’s 1977 book, Cryptanalysis of the Hagelin Cryptograph. © 2016, Copyright © Taylor & Francis Group, LLC.


Lasry G.,Mishmar Hayarden 5 | Kopal N.,Mishmar Hayarden 5 | Wacker A.,Mishmar Hayarden 5
Cryptologia | Year: 2016

The Hagelin M-209 portable encryption device was used by the U.S. Army in World War II and the Korean War, as well as by other armies and in embassy settings. In this article, a fully automated, computerized known-plaintext attack is presented. It is based on hillclimbing and a novel fitness function: the aggregate displacement error. Performance evaluation shows that this attack is able to recover key settings for messages as short as 50 characters. To validate these results, several publicly available challenge messages were solved with this method, including a message with only 40 letters. © 2016, Copyright © Taylor & Francis Group, LLC.

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