Automated Known-Plaintext Cryptanalysis of Short Hagelin M-209 Messages

Lasry, George; Kopal, Nils; Wacker, Arno

doi:10.1080/01611194.2014.988370

Cited by 7 publications

(6 citation statements)

References 2 publications

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“…The second security enhancement has to do with how K affects encryption. In the regular Hagelin C machines, encryption is according to the Beaufort reciprocal formula (p is the plaintext symbol, c the resulting ciphertext symbol, and K the total kick) (Lasry et al, 2016):…”

Section: Complementary Kickmentioning

confidence: 99%

“…Because of the complex stepping mechanism, there are no periodic patterns that would allow statistical attacks to be effective, such as the ciphertextonly and known-plaintext attacks that were developed against Hagelin systems with regular stepping (Lasry et al, 2016;Lasry et al, 2018). Furthermore, the circular dependencies of the wheels with regards to their stepping (as illustrated in Figure 4) make the problem even more challenging.…”

Section: A Novel Known-plaintext Attackmentioning

confidence: 99%

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Modern Cryptanalysis of Schlüsselgerät 41

Lasry¹

2021

Linköping Electronic Conference Proceedings

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The Schlüsselgerät 41 was an highly secure encryption machine developed by Fritz Menzer and used from 1944 by the Abwehr. Bletchley Park could not decipher its traffic. In this article, we provide a functional description of the SG-41 and present a novel cryptanalytic method to recover the key settings from ciphertext and knownplaintext. This attack requires extensive computing power, a testimony to the resilience of the SG-41 even against modern cryptanalysis. We also present an alternative method, based on acoustic cryptanalysis, which allows for the recovery of the key settings in minutes.1 It is also called C-41 in some U.S. documents (Agency, 1947).

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Section: Complementary Kickmentioning

confidence: 99%

Section: A Novel Known-plaintext Attackmentioning

confidence: 99%

Modern Cryptanalysis of Schlüsselgerät 41

Lasry¹

2021

Linköping Electronic Conference Proceedings

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“…We reproduce here the functional description of the device, which we presented in our prior article about a known-plaintext attack [12]. We show the mechanical internals of the M-209 device in Figure 1, and a functional diagram in Figure 2.…”

Section: Functional Descriptionmentioning

confidence: 99%

“…We reproduce here the keyspace analysis of the device, which we presented in our prior publication about a known-plaintext attack [12]. The settings of the device consists of the Wheel Settings which include the wheel pins and the initial position of the wheels, and of the Lug Settings -the settings of the lugs of the 27 bars.…”

Section: Keyspacementioning

confidence: 99%

“…We eventually came up with two novel cryptanalytic attacks on the Hagelin M-209, both based on hillclimbing algorithms. The first one is an automated known-plaintext attack, which we already presented in a separate paper [12]. The second one is a ciphertext-only method, which can recover key settings from messages as short as 750 characters.…”

Section: Introductionmentioning

confidence: 99%

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Ciphertext-only cryptanalysis of Hagelin M-209 pins and lugs

Lasry

Kopal

Wacker³

2015

Cryptologia

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The Hagelin M-209 was a mechanical encryption device used by the US Army during World War 2 and the Korean War, as well as by other armies and in embassy settings. In this paper, we present a 4-stage hillclimbing algorithm for recovering the full key settings from ciphertext only. The two first stages are based on a divide-and-conquer approach developed by Geoff Sullivan. In our performance evaluation, we show that our 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, we solved several M-209 ciphertext-only challenges, including the final exercises in W. Barker's 1977 book, Cryptanalysis of the Hagelin Cryptograph.

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Review of the 2nd Historical Ciphers Colloquium in Kassel, Germany

Schmeh¹

2016

Cryptologia

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Automated Known-Plaintext Cryptanalysis of Short Hagelin M-209 Messages

Cited by 7 publications

References 2 publications

Modern Cryptanalysis of Schlüsselgerät 41

Modern Cryptanalysis of Schlüsselgerät 41

Ciphertext-only cryptanalysis of Hagelin M-209 pins and lugs

Review of the 2nd Historical Ciphers Colloquium in Kassel, Germany

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