CaCC-Challenge-bar

In May 2014 the NSA published four crypto challenges via Twitter. To my knowledge, the fourth one is still unsolved.

You want to win a copy of Helen Fouché Gaines’ book Cryptanalysis? If so, try to solve one of the following crypto challenges:

https://www.facebook.com/groups/763282653806483/permalink/1278354768965933/

CC-Competition

Send your solutions to classical.ciphers.group@gmail.com by the end of January with your name to be in to win. Early February two random entries will be drawn. The competition is organized by blog reader Bart Wenmeckers on the occasion of the second aniversary of the Cryptograms & Classical Ciphers FaceBook group. Please don’t publish the solutions before the competition is finished.

 

NSA’s Monday challenges from 2014

Let’s now turn to four other crypto challenges. They were published by the NSA on Twitter (@NSACareers, #MissionMonday) in May 2014. The first three challenges were of medium difficulty, at best:

 

Challenge #1 (Monday, May 5th, 2014)

NSA-Tweet-Mission-Monday

tpfccdlfdtte pcaccplircdt dklpcfrp?qeiq lhpqlipqeodf gpwafopwprti izxndkiqpkii krirrifcapnc dxkdciqcafmd vkfpcadf.

Solution (letter substitution): want to know what it takes to work at nsa? check back each monday in may as we explore careers essential to protecting our nation.

 

Challenge #2 (Monday, May 12th, 2014)

NSA-Monday-Challenge-2

Rimfinnpeqcnvqauuagcrdokvdisndrdcrpigaisacpsdffaicvhakcfdqfpqdetrkilfaecnpqacakqisacpfampoacfimannicfakdumfalddnraprf

Solution (letter substitution, plaintext has to be read backwards): NSA is looking for intelligent, imaginative critical thinkers who can contribute innovative ideas to solve our most difficult challenges.

 

Challenge #3 (Monday, May 19th, 2014)

nbylcrhspclbyxrnmlbzevsmlchscrhrhnmbebfs
vhcxmxxrmzencmfyvychclcmscgmyimkcncxm
xrydsmnrhsbyemfmmefrhxrfdyrfczmtchmscgby 

Solution (letter substitution, plaintext in Spanish): Los cient(i)ficos de la computaci(o)n tienen la oportunidad de ampliar sus iniciativas, habilidades y talentos para aprender y ser imaginativos.

As can be seen, all three solutions explain the purpose of these challenges. The NSA published them in order to attract skilled codebreakers that might be interested in a career at the agency. However, the first three cryptograms were not difficult enough to challenge the really good ones. This changed with the fourth challenge.

 

Still unsolved: challenge #4

The fourth ciphertext (Monday, May 26th) proved quite difficult. Here it is:

pjbbfcklerfebjppjjlboumcuppelqpfezbjruoqlerdjbcuddbu
kulfjojprfebjbjzfrtmloupraublxpepkurtppdbjcbelfrfebkj

I blogged about this challenge in 2014 (in German). Though there were a number of comments, nobody could break this cryptogram. Almost four years later, I’m still not aware of a solution. When searching via Google, I can’t even find a page describing the challenge, let alone the cleartext.

Here’s a frequency analysis made with CrypTool 2:

CaCC-Frequency-Analysis

This looks like an ordinary MASC (monoalphabetic substitution cipher). The Index of Coincidence (IoC) is 6.7 percent, which is consistent with the English language. As the B is the most frequent letter, it might stand for the E. However, I don’t think that it is that simple – otherwise the challenge would have been long solved.

Does a reader know whether the solution of this challenge is available somewhere? If not, can a reader break it?


Further reading: A few videos and crypto puzzles from the NSA Symposium on Cryptologic History

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Kommentare (5)

  1. #1 Gerd
    28. Dezember 2017

    As reader Peter commented in the german blog, the letters G, H, I, N, S, V, W, Y are missing in the text. So if it is MASC, only 18 different letters are used. Maybe a “special” english text or a language that uses less letters? (Italian has 21 letters)

    Gerd

  2. #2 Klaus Schmeh
    28. Dezember 2017

    Nils Kopal via Facebook:
    Nice! Cool idea to also promote Bart’s challenge of the cryptogram & classical ciphers group :)

  3. #3 Thomas
    29. Dezember 2017

    Italian is a good idea, as not only the low number of letters but also the index of coincidence (0,072) would be consistent with a monoalphabetic substitution of an Italian plaintext. But neither a forward nor a backward substitution yields meaningful results, so that probably a more complicated transposition component was used before or after the substitution.

  4. #4 Klaus Schmeh
    5. Januar 2018

    Bart Wenmeckers via Facebook:

    Here are the transcribes of the challenges on Facebook:

    Cryptogram #1
    35440 98414 44956 91984 99297 97269 89410 98447
    04944 91689 84096 98356 98419 24017 98049 96984
    11069 84842 98177 98474 87360 98945 44415 98941
    09849 48036 89848 79835 69841 21004 44112 98414
    44956 91098 43914 89249 98447 98491 03983 54409
    84992 97972 69844 09894 48913 59842 44936 98494
    84473 0

    Cryptogram #2
    BAUSY DRFUS WHSBY BWBYI XQYRA UVPFR APHUB YSXIB SYDRF TSAYM BUGFY NUBAU QPUSP VQYRA UVYBY SQIDR FUBUF TLWDH FUG

    Cryptogram #3
    IEMNN AITIA RYICO MSAMN CARSC HFAER CTREG SDTOP SNBIN RPHNN DPVES
    CAILU ORNEI STEER TECIL TESTW THTOT TOSAE LHISA MAITO TIETT HORDM
    SPNSI NGRRA NMEAO MARWI IGGOI AFCLE PTHLA PMTS

    Cryptogram #4
    PRAMV BQGEK MCIKS AGIWQ HQPIJ ALDWT RBXSS ZIKEK GBSEP UDOWX MVXLM
    DTSKC YVXEE HSGWV JOKMM HQBES ZDSMV XTFKC CAJOT MBDAX KFWOV MHDEA
    PTZMH VIMKT QHTLP WUIWF SWSEP IESVE QIAXA DAGMI PIEPD HWSSC QWHIF
    OSLBS UMWXD HKNLI YOWJQ HQPAU BLRIX OEBOA LMVGW VASYK YTGUR IRZEE
    YMWBA WMWYE QXCJG HDMHR SUXGL PWCIQ BKQIL WBLOZ WIEMN IFOLY ZIMEM
    DEVOJ YCTPI ZDHWK AZPIO TQHT

    Cryptogram #5
    %);>=;z-=4+7z.=61=%;3!z-.;%%;9=6=1z6+(;!6+;1%%z594(%313.4=6=

    or (depending on preference)

    ABCDECFGEHIJFKELMEACNOFGKCAACPELEMFLIQCOLICMAAFRPHQANMNKHELE

    Quiz #1
    Name the Structure (where in the site) and site location of the main image.

  5. #5 Klaus Schmeh
    8. Januar 2018

    Bart Wenmeckers via Facebook:
    Thanks for promoting the classical ciphers group competition.