(2024) In the new Edition, as described on page 143, “The silk dress cryptogram“, it is confirmed that this puzzle has been solved! The messages have turned out to be meteorological observations. More information can be found at the following links: Cryptologia article, NOAA.gov, Forbes, Popular Mechanics, The New York Times.

(October 2023, from Günther Waffler) In the new No Starch Edition, published on Sep 19, 2023, the following error appears in pages 18-19. At the top of page 19, the key, instead of 4, should be 22, and in the Plaintext/Ciphertext table, these should be adjusted accordingly. The chart with the arrows should be reversed, meaning the arrows should point to the left instead of to the right.  In other words, the ciphertext JKHQY should decrypt to NOLUC.

(June 2023) The following contains mistakes that were found in the first (2020) edition of Codebreaking. The new Expanded Edition in 2023 should have all of these fixed, though if anything new is found, please let us know!

p. 119 (and others): LOL! First big one: Our book was released on December 10, 2020, but on December 11, 2020, one of the world’s most famous unsolved codes was, well, solved! The Zodiac Killer cipher called “Z340” was cracked. For more information, check here.

p. 15/16: In the appreciation list Jew-Lee Lann-Briere is classified under B instead of L

From Olaf Ostwald:

On page 412 in the fifth line of “Codebreaking – A Practical Guide” it is stated that “The M4 project succeeded in breaking two of the messages in 2006, and the third one was solved two years later.” However, the third one was broken in 2013, thus seven years later.

From Marc Baldwin:

p42: The pigpen diagram is not identical to that on p32, as the Y and Z have been transposed

p43: lines 6 & 7: ‘thut’ should also be ruled out as not making sense
line 13: (‘oUt’) should, I think, read (‘oMt’)
line 14: (‘aetheR’) should, I think, read (‘aetheV’)

pp67 & 68: If all the two-digit numbers are between 01 and 65, how is
the lower-case ‘w’ in, for example, ‘own’ in line 5 of the plain text enciphered,
as the substitution table on p68 gives cipher 66 for plain text ‘w’?

p135: last two lines – for ‘2350’ read ‘2250’ (adding 1016 to 1234)

p282: explanatory letters omitted from right-hand side of the third diagram

p384: line 21: for ‘A YISIL’ read ‘A YISL’

From Richard Bean:

chapter 3. “about 3.9%” 1/26 = 0.03846, I think what’s happened is someone has rounded 3.85% to 3.9% where it should be rounded down to 3.8%.chapter 7. 1016 + 1234 becomes 2350. should be 2240, or possibly 2250 if carrying is used

chapter 8. (twice) “around 3.9%” – should be 3.8%

“seventeen years later” – actually 1998 — https://ep.liu.se/ecp/171/005/ecp2020_171_005.pdf

The search must have been out of sequence, because Book #1469 “Francis Thompson’s poems” has the poem and was first published in Project Gutenberg in July 1998. This is the 1279th book, if only the English language books are considered in sequence. This indicates that Gillogly and Harnisch would have found the keywords if they had waited two or three more years and examined the English books of Project Gutenberg sequentially.

chapter 16. sum 34 -> 36, sum 34 -> 30

Appendix A.

“In 1998 CIA employee David Stein found the three solutions as well. Again, this was not made public; it was just circulated internally at the CIA” … “CIA … kept their [success] secret”

Actually the fact of the CIA (partial) solution, but not the plaintext, was made public on November 16, 1998 in the Atlanta Journal-Constitution, page A2

From Gérard Fetter:

Chapter 3, page 38, the Plain English frequencies, instead of 12.75%, 10.25%, 9.25% and 8.25%, should be 12.7%, 9.1%, 8.2%, and 7.5%.

Chapter 8, page 175, first paragraph: “common trigraphs BLA and CHA” should be, “common trigraphs BLA and HOR”

From Moritz Stocker:

Chapter 12, p. 288, in Figure 12.6, the titles of “General Digraph Substitution” and “Playfair Cipher” are reversed.

Above the figure:, the text:

The frequency distribution of a Playfair cryptogram is flatter – meaning that the frequent letters are less frequent, while the rare ones are less rare – than that of a general digraph substitution (see Figure 12.6). On the other hand, it is flatter than that of a simple substitution cipher.

should be:

The frequency distribution of a Playfair cryptogram is flatter – meaning that the frequent letters are less frequent, while the rare ones are less rare – than that of a simple substitution cipher (see Figure 12.6). On the other hand, it is less flat than that of a general digraph substitution.

The figure 12.6 Caption, instead of:

The frequency distribution of a Playfair cryptogram (middle) is flatter than the distributions of both a general digraph substitution (top) and a simple substitution cipher (bottom).

should be:

The frequency distribution of a Playfair cryptogram (top) is flatter than the distributions of both a general digraph substitution (middle) and a simple substitution cipher (bottom).

The corrected Figure 12.6 is:

Thank you all!

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