# calling all cryptologists! (and puzzle solvers) **URL:** \ **Category:** Factual Questions\ **Created:** [March 20, 2003, 11:17am UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778 "2003-03-20T11:17:25Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![cankerist](https://avatars.discourse-cdn.com/v4/letter/c/bc79bd/32.png) [@cankerist](https://boards.straightdope.com/u/cankerist)\ **Post date:** [March 20, 2003, 11:17am UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/1 "2003-03-20T11:17:25Z")
The Defence Signals Directorate (Australia’s SIGINT and INFOSEC Agency) has a puzzle corner on its website. This little code-breaking one has me stumped :mad: Authorities intercepted the message LJPPV KOUYK OIRWQ HKIQC DPAKB RXHJI, believed transmitted by a gang of smugglers. This was decrypted to: “Password for next month is Bogeyman”. About a month later the message KUVMF PPVLO RVDII EUPUK QLKQS UPRFX was intercepted. This was decrypted to: “New password will be sent on Tuesday”. The following Tuesday the single word EFGMRIHQ was intercepted. What was the new password? ---
**Author:** ![Jabba](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@Jabba](https://boards.straightdope.com/u/Jabba)\ **Post date:** [March 20, 2003, 11:36am UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/2 "2003-03-20T11:36:17Z")
Did you want the answer or a hint? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 20, 2003, 11:37am UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/3 "2003-03-20T11:37:38Z")
Hmmm… Pa **ss** word for next month i **s** Bogeyman LJ **PP** V KOUYK OIRWQ HKIQC D **P** AKB RXHJI Can’t be as simple as a substitution code can it? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 20, 2003, 11:39am UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/4 "2003-03-20T11:39:25Z")
Actually, it is easier to see like this: ```auto Pa **ss** wordfornextmonthi **s** Bogeyman LJ **PP** VKOUYKOIRWQHKIQCD **P** AKBRXHJI ``` ---
**Author:** ![dylan\_73](https://avatars.discourse-cdn.com/v4/letter/d/ecccb3/32.png) [@dylan\_73](https://boards.straightdope.com/u/dylan_73)\ **Post date:** [March 20, 2003, 12:06pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/5 "2003-03-20T12:06:55Z")
Yeah, but then: ```auto newpasswordwillbesentontuesday KUVMFPPVLORVDIIEUPUKQLKQSUPRFX ``` So “s” is still encoded to “P” but “p” is now “M” rather than “L”…and “a” has switched from “J” to “F”…can’t quite figure out how this change works… ---
**Author:** ![Jabba](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@Jabba](https://boards.straightdope.com/u/Jabba)\ **Post date:** [March 20, 2003, 12:10pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/6 "2003-03-20T12:10:49Z")
The change is the key. You need to work out the passwords for the first two messages. Knowing these will suggest an obvious next password. Checking this paaword for the third message should confirm your guess. ---
**Author:** ![dylan\_73](https://avatars.discourse-cdn.com/v4/letter/d/ecccb3/32.png) [@dylan\_73](https://boards.straightdope.com/u/dylan_73)\ **Post date:** [March 20, 2003, 12:31pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/7 "2003-03-20T12:31:25Z")
Well, I was hoping the password for the second message was actually “bogeyman” but I can’t make it fit yet. Don’t have too much time to spend on it just now, but I’ll look later. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 20, 2003, 12:33pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/8 "2003-03-20T12:33:57Z")
Hmmm, well, I see the pattern in the encoding, but applying the next logical key got me nonsense… ---
**Author:** ![Jabba](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@Jabba](https://boards.straightdope.com/u/Jabba)\ **Post date:** [March 20, 2003, 12:36pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/9 "2003-03-20T12:36:10Z")
If you got the right 3rd password, the last message says “hijacker”. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 20, 2003, 12:37pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/10 "2003-03-20T12:37:10Z")
Oops, no, I have it now. hehe. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 20, 2003, 12:53pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/11 "2003-03-20T12:53:43Z")
This is the complete solution, so don’t call me a spoilsport if you click on it: ```auto Natural alphabet: ABCDEFGHIJKLMNOPQRSTUVWXYZ First code: JA URY CD HIKL OPQ V X Second Code: FE RU D I KLM OPQS V X We can tentatively assume that the cipher consists of a key word followed by the remaining letters of the alphabet in proper order; the consecutive keys appear to be 'JANUARY' and 'FEBRUARY', shortened to 'JANURY' and 'FEBRUAY' (as no letter can be repeated in the key) The next cipher should therefore be: Natural alphabet: ABCDEFGHIJKLMNOPQRSTUVWXYZ Third code: MARCHBDEFGIJKLNOPQSTUVWXYZ The coded word EFGMRIHQ decodes thus: E>H F>I G>J M>A R>C I>K H>E Q>R ``` ---
**Author:** ![cankerist](https://avatars.discourse-cdn.com/v4/letter/c/bc79bd/32.png) [@cankerist](https://boards.straightdope.com/u/cankerist)\ **Post date:** [March 20, 2003, 1:05pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/12 "2003-03-20T13:05:48Z")
spoilsport! hehehe. No, acually thanks very much to **Jabba** and **Mangetout**. More important than getting the correct answer I would love to have an action replay of the logical mental steps you took to solve the problem. Did the key words just jump out at you after you did the letter substitutions? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 20, 2003, 1:28pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/13 "2003-03-20T13:28:07Z")
Well… first: noted that the code is the same length as the message noticed the double-letter sequences in the code matched by double-letter sequences in the same positions in the message made a quick substitution grid on paper noticed that the substituted letters were pretty much still in sequence, apart from this chunk at the beginning then I noticed some of the gaps in the coded sequence (for example, HIKL OPQ - the J is missing because it is elsewhere and the single space in the middle is too small to accomodate both M and N so maybe one or the other of those was elsewhere too… then I noticed that if it was the N, it almost spells JANUARY then I realised that the best you can do with single-use letters is JANURY, which would be spot on. then I started on the second message and it was very obvious that the key word was FEBRUARY and it was all downhill from there. ---
**Author:** ![cankerist](https://avatars.discourse-cdn.com/v4/letter/c/bc79bd/32.png) [@cankerist](https://boards.straightdope.com/u/cankerist)\ **Post date:** [March 20, 2003, 1:33pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/14 "2003-03-20T13:33:25Z")
Thanks \*\*Mangetout \*\* - thats exactly what I wanted. You’re a genius.🙂 ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 20, 2003, 1:46pm UTC](https://boards.straightdope.com/t/calling-all-cryptologists-and-puzzle-solvers/162778/15 "2003-03-20T13:46:25Z")
I always wanted to be a genius, now I are one.