Chapter 2: Herbert Yardley’s first challenge
Chapter 2: A series of newspaper advertisements from 1900
The following encryption table was used:
ABCDEFGHIJKLMNOPQRSTUVWXYZ OPQRSTUVWXYZABCDEFGHIJKLMN
Â
Cipher: A Caesar cipher with key 14 (A->O, B->P, C->Q, …) was used for the encrypted passages.
Plaintexts:
ALICE R.P. Congratulate you. I do not forget but think of you very much and wonder if we shall meet in six or seven weeks. Tuesday 27th March 1900
ALICE R.P. How nice of you to remember. Will certainly meet you. Always thinking of you. Thursday 29th March 1900
ALICE R.P. Am so looking forward to it. Want to see you more than i can tell you. Will let know in about five weeks time. Monday 2nd April 1900
ALICE R.P. Shall wait portland dp station thursday five clock should much like see you. Thursday 17th May 1900
Chapter 3: A prison code

Hey Mark,
So I could not find a generator online but there is an Aurebesh font you can download for both Mac and PC and install. I’ve been reading into how to take pictures of individual snowflakes. It is an amazing process. After the Holiday I’ll send you in an article about it with some examples.
Chapter 3: A postcard
Â
Plaintext:
Fri Night
How are you Ethel
Suppose you are
st(u)dying ton(i)ght
I have been trying
to flourish a
little. Have
been out breaking
roads this
afternoon for the
wagons. Good night (RR)LW
Â
Chapter 3: Another postcard
The following word stands for HELLO:
Key:
Plaintext:
Hello Nellie This rose was raised in our backyard. Is it not beautiful? Elizabeth is in two places at once, on running creek, and on the map.
Ta-Ta – F.M.S.
Chapter 3: Friedman's wedding centennial nickel
The keyword BANDJ was used to scramble the alphabet. BANDJ is derived from “Bill and Jew-Lee”, the first names of Bill Briere and Jew-Lee Lann-Briere, who created this puzzle.
The ciphertext trigraph KZW stands for THE.
The following substitution table was used:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
STUVWXYZBANDJCEFGHIKLMOPQR
Plaintext:
CENTENNIAL OF THE
WEDDING
OF ELIZEBETH AND
WILLIAM
1917 * FRIEDMAN * 2017
Chapter 3: An aristocat from the ACA
The keyword DEBIAN was used to scramble the alphabet.
The ciphertext trigraph JYV stands for THE.
The following substitution table was used:
ABCDEFGHIJKLMNOPQRSTUVWXYZ RSTUVWXYZDEBIANCFGHJKLMOPQ
Chapter 4: Rudyard Kipling’s encrypted message
The word
stands for THE.
The following substitution table was used:
Â
Plaintext:
Left side:
This is the stori of Taffimai all ritten out on an old tusk. If u begin at the top left hand corner and go on to the right u can see for urself things as the happened.
Right side:
The reason that I spell so queerli is becase there are not enough letters in the Runic alphabet for all the ourds that I ouant to use to u o beloved.
Â
Chapter 4: NSA’s second Monday challenge
The ciphertext trigraph FRP stands for NSA. As the text needs to be read backwards, this means that actually PRF stands for ASN.
ABCDEFGHIJKLMNOPQRSTUVWXYZ
PHQGIUMEAJLNOFDXBKRCVSTZWY
Plaintext:
NSA is looking for intelligent, imaginative critical thinkers who can contribute innovative ideas to solve our most difficult challenges.
Chapter 5: An encrypted postcard
6
GT stands for the French word MA (“my”).
Key:
ABCDEFGHIJKLMNOPQRSTUVWXYZ GHIJKLMNOPQRSTUVWXYZABCDEF
Plaintext:
MA CHERE PETITE IDA,
AI JE MANQUE DE PAROLE. TU VOIS QUE JE PENSE A TOI. ET TOI M’AS TU OUBLIE. JE T’ENVOIE DES MILLIERS DE BAI[S]ERS SUR TES PETITES LEVERES ET SUR TOUT DE QUE J’AIME. ECRIS MOI
Translation:
My dear little Ida,
Have I broken my promise. You see that I have thought of you. And you, have you forgotten me? I send you thousands of kisses on your little lips and on everything I love. Write me.
Chapter 5: The third NSA Monday challenge
“nby” stands for “los”.
ABCDEFGHIJKLMNOPQRSTUVWXYZ
?OIYPRVNH?BCAL?F?ETG?U?DSM
Plaintext:
Los cient(i)ficos de la computaci(o)n tienen la oportunidad de ampliar sus iniciativas, habilidades y talentos para aprender y ser imaginativos.
Translation:
Computer scientists have the opportunity to broaden their innitiative, skills, and talents to learn and be imaginative.
Chapter 5: Christlieb Funk's challenge cryptogram

With the following table, the ciphertext can be decrypted:
Plaintext:
SOLLTE DIESES MEIN BUCH BEYFALL
FINDEN SO WIRD ES MIR EINE
AUFMUNTERUNG SEYN NOCH MEHR
ÄHNLICHE AUFFALLENDE PHYSEKALISCHE
EXPERIMENTE DIE ZUR ERKLÄRUNG
VERSCHIEDENER PRÄTENDIRTER WUNDER
DIENEN BEKANNT ZU MACHEN DENN DIE
MATERIE IST BEY WEITEN NOCH NICHT
ERSCHÖPFT UND ICH HABE GEGENWÄRTIG
NUR EINIGES ERKLÄREN WOLLEN ES
IST MIR NICHTS MEHR ĂśBRIG ALS
MICH DEM WOHLWOLLEN DES GENEIGTEN
LESERS ZU EMPFEHLEN GESCHRIEBEN IN
DER LEIPZIGER OSTERMESSE IM IAHRE
EIN TAUSEND SIEBEN HUNDERT DREY UND
ACHTZIG
Translation:
If this book should be successful, it will be my pleasure to make known more physical expriments that serve to explain alleged miracles. This matter is by far not exhausted, and I have so far only explained a part of it. Apart from this, I can only send my regards to my readers. Written during the Leipzig Easter Fair in the year 1783.
Chapter 6: A message to the Zodiac Killer
Plaintext:
SODIAC CALL LIBRA FOUR THREE THREE ONE OH SEVEN SEVEN
Chapter 6: Edgar Allan Poe’s second challenge
The third word, OGXEW, stands for EARLY.
Plaintext:
It was early spring, warm and sultry glowed the afternoon. The very breezes seemed to share the delicious langour of universal nature, are laden the various and mingled perfumes of the rose and the -essaerne (?), the woodbine and its wildflower. They slowly wafted their fragrant offering to the open window where sat the lovers. The ardent sun shoot fell upon her blushing face and its gentle beauty was more like the creation of romance or the fair inspiration of a dream than the actual reality on earth. Tenderly her lover gazed upon her as the clusterous ringlets were edged (?) by amorous and sportive zephyrs and when he perceived (?) the rude intrusion of the sunlight he sprang to draw the curtain but softly she stayed him. “No, no, dear Charles,” she softly said, “much rather you’ld I have a little sun than no air at all.”
Chapter 7: Mount Everest telegram
Chapter 8: Schooling challenge
76 69 57 55 65 59 68 87 77 22 75 68 87 88 75 43 67 77 58 65 96
44 54 42 11 33 44 44 54 42 11 33 44 44 54 42 11 33 44 44 54 42
--------------------------------------------------------------
32 15 25 44 32 15 24 33 35 11 42 24 43 34 33 32 34 33 14 11 54
Plaintext:
MEET ME IN PARIS ON MONDAY
Literature: Craig Bauer: Unsolved! Princeton University Press, Princeton 2017, p. 137
Chapter 8: A German radio message from the Second World War
The key length is 7.
Chapter 9: Love in Code
Read each word backwards.
Plaintext:
TRUST ME, BOYS. I QUEEN OF LAMPEDUSA
Â
Chapter 9: The Friedmans’ love messages
Ciphertext 1: Down one column, up the next
Ciphertext 2: Up one column, down the next
Plaintext 1:
I LOVE YOU VERY MUCH I SHOULD SAY SO!!
Plaintext 2:
JE T’ADORE MON MARI!!
Translation: “I admire my husband.”
Chapter 9: Agony column
Lkeoisvstes oeemldyodbv ensedtpliaa naeglmslyhb rmnebemrsea outfWeyrwoi hoaeuvnleye
Ieg rcg cne dhl hdn ihu hao sac ass cbk bis hei e e
Advertisement 1:
When written in lines of 11 (see hint 1), read columns 1, 4, 7, 10, 2, 5, 8, 11, 3, 6, 9:
Love kisses to my beloved deep and lasting shall be my remembranes of you. Write when you leave.
Advertisement 2:
When split and written in lines of 3 (see hint 2), read columns 1, 3, 2 of each part:
Ich habe genossen das irdische gluck ich habe
These are the first eight words of a quote by German poet Friedrich Schiller:
Ich habe genossen das irdische GlĂĽck, ich habe gelebt und geliebet!
Translation: “I have enjoyed the happiness on earth, I have lived and loved.”
Chapter 9: Yardley's 11th ciphergram
After you counted, what is the square root?
A six by six table
When written in lines of six, the ciphertext looks as follows:
tskgla atyilt lpasah lmdplg ieneai wtuenn
Now read each column from bottom to top:
will attempt sunday keep signal all night a
The “a” at the end is used for padding.
Chapter 9: Edgar Allan Poe's first challenge
The following three letters stand for DNA (mind that each word is written backwards):
Plaintext:
The soul secure in her existence smiles at the drawn dagger and defies its point. The stars shall fade away, the sun himself grow dim with age and nature sink in years, but thou shall flourish in immortal youth, unhurt amid the war of elements, the wreck of matter and the crush of worlds.
For more information, check here: http://cryptiana.web.fc2.com/code/poe2.htm
Chapter 9: IRA messages
Try lines of 12.
The key word is: INCANDESCENT
INCANDESCENT
------------
TWOTICKETSFO
RHOTELCECILW
ERESECUREDAN
DTHEREFOURBO
MBSWEREIGNIT
EDBUTTHREEFA
ILEDANDTHEOT
HERSIMPLYSPL
UTTEREDANDWA
SINEFFECTIVE
Plaintext:
TWO TICKETS FOR HOTEL CECIL WERE SECURED AND THERE FOUR BOMBS WERE IGNITED BUT THREE FAILED AND THE OTHER SIMPLY SPLUTTERED AND WAS INEFFECTIVE
Â
Chapter 10: IRA message
There are 12 columns in this transposition.
The plaintext contains the following letter string:
PITIABLECONSIDERING
The keyword is: INCANDESCENT
Plaintext:
Â
Chapter 11: The Friedman’s Christmas card
The plaintext contains the word TELEPHOTOGRAM.
Plaintext:
FOR CHRISTMAS GREETINGS IN 28 WE USE A MEANS QUITE UP-TO-DATE. A CRYPTO TELEPHOTOGRAM HERE BRINGS YOU WORD OF X-MAS CHER.
Chapter 11: Jew-Lee and Bill’s Cryptocablegram
Plaintext:
TO THE FRIEDMANS: MILESTONES MEMORIES MOMENTUM CLINKING GLASSES A LUCKY KISS AND AULD LANG SYNE!
Chapter 11: MysteryTwister C3 challenge
Sorry, we can’t provide the solution for this challenge.
We took this cryptogram from the MysteryTwister C3 (MTC3) website. MTC3 participants will get points for solving it. Providing the solution here would enable them to cheat.
Chapter 11: Kerckhoffs' cryptogram
The plaintext contains the word “Attaque”.
Here’s the grille that was used:
Plainext:
Une Attaque Simulee Aura Lieu Demainmatin
Translation: A test attack will take place tomorrow morning.
Chapter 12: National Treasure: Book of Secrets
The plaintext starts with the word LABOULAYE.
The following matrix was used:
DEATH BCFGI KLMNO PQRSU VWXYZ
Plaintext:
LABOULAYE LADY WILL LEAD TO CIBOLA TEMPLES OF GOLD
“Laboulaye Lady” referrers to the French Statue of Liberty in Paris, France.
Chapter 13: A birthday card
The plaintext is taken from the lyrics of a well-known song.
Plaintext:
Happy Birthday to You, Happy Birthday to You. Happy Birthday, Dear Peter, Happy Birthday to You.
Chapter 14: Dan Brown’s book cipher challenge
Chapter 14: Dictionary code challenge
Here’s a list with the 10,000 most common Engish words:
0619 stands for AT
8928 stands for THE
9216 stands for TREE
Plaintext:
START AT THE OAK TREE NEXT TO C A M D E N BRIDGE THREE KILOMETERS SOUTH OF THE POWER PLANT FOLLOW THE ROAD OVER THE BRIDGE AGAIN ABOUT ONE KILOMETER TAKE A LEAVING AND WALK ALONG THE WALLS AFTER SIX HUNDRED METERS YOU WILL REACH A MALL IN THE CENTER OF IT THERE IS A STONE CRYSTAL ON THE REAR SIDE OF IT YOU WILL FIND A WOODEN CASSETTE CONTAINING A DICE THAT WILL HELP YOU TO DECRYPT THE NEXT MESSAGE
Chapter 15: Another steganographic message by the Friedmans
Here’s a hires version of the passage in question:
The Bacon cipher was used:
In the following scan, the marks show that the passage in italics is written in two different fonts:
The two fonts form the following pattern:
ABAAA AAABB ABAAA AAABB ABBAA ABBAB BAABA BABAA BAAAA ABAAA BAABA AABAA BAABA AABBB AABAA ABBBA ABABA BABBA BAAAB AABAB AAAAB AAAAA AAABA ABBAB ABBAA
Plaintext:
I did not write the plays. F. Bacon.