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Hebern's machines
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Introduction
In 1934, Friedman published a report
internal to the cipher service of the American army in which he
described the first version of the Hebern cipher machine equipped
with 5 rotors as well as the cryptanalysis methods that he invented
to
notably winning the naval challenge of 1924. This report is
undoubtedly an evolution of a draft dating from 1924 written following
his
feat.
Notes:
-
If the reader wants to know the real methods used by
Friedman, I advise
him to read his report directly, one of which
copy is available on this
site (cf. Web links below).
In this web page I give my view of Friedman's
methods using what I think is a more "modern" approach. Likewise I do
not have
not repeated the same examples always with the aim of clarity.
-
Friedman's report does not deal exclusively with the methods he used to
win the 1924 Navy challenge.
Other topics are covered in my page dedicated
to the cryptanalysis of the Hebern 5 rotor v1 machine
(link).
The different stages of resolution
Friedman's resolution of the 10 messages is divided into several
steps:
- 1. Find the rotor wiring in position V
(link).
- 2. Find the plain text of a few lines of the cryptogram
(link).
- 3. Find the rotor wiring in position I.
(link).
- 4. Find the wiring of pseudo-rotor S equivalent to rotors II, III, IV.
Find the plain text of the cryptograms (after steps 3 and/or 4)
(link).
- 5. Find the wiring of the rotors in position II, III and IV.
(link).
Web Links
- ANALYSIS OF A MECHANICO-ELECTRICAL CRYPTOGRAPH,
PART I, TECHNICAL PAPER,
BY WILLIAM F. FRIEDMAN
Cryptanalyst, Chief of Signal Intelligence Section
UNITED STATES GOVERNMENT PRINTING OFFICE,
WASHINGTON: 1934, Secret.
(link)
- NSA - Friedman's Original Worksheets of Hebern Solution, 11 Nov 1936
(PDF)
Note: The solution dates from 1924.
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