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Kerckhoffs (part 3) Mystery Cache

Hidden : 03/05/2022
Difficulty:
5 out of 5
Terrain:
2.5 out of 5

Size: Size:   small (small)

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Geocache Description:


This is a puzzle cache. Please do not go to the posted coordinates, nothing is hidden there. For necessary background information please see part one (GC9NT53) and part two (GC9PAWZ).

With the benefit of more experience Cacher Craig realized that some of the design features of his cryptosystem that were meant to aid a human doing the decryption by hand don't really make sense now when computers can simply do it all for you!

There is no reason the first digit of a codeword needs to tell you the length of the codeword. As long as no codeword is a prefix or another codeword (for example you couldn't have both "123" and "1234" as codewords) you can still uniquely determine the boundaries if you know the key. With this change all codewords will still have a length between 2 and 9, but the first digit no longer has any meaning.

There is also no reason the last digit of a codeword needs to tell you the shift applied after that codeword is used. These shifts can also be secret values that are part of the key. With this change all codewords have a secret shift between 0 to 25  (inclusive) with the last digit no longer having any meaning. Some shift values can be repeated and some may not be used at all.

After these two changes Cacher Craig has become overconfident. He is convinced there is no way anyway can break the code now!

8609697278141887164624325591286079833376380054188092092622214633794629441324325591261
0300306489462944138092092630317077243255912064863388773156978969721569783044439661030
0393143261798331424680920926444396317077317077595419121679483763800537638005142463763
8005444396222146337798332432559120273351156978862183686014246610300386009525871646862
1836610300322214633741893781610300361030030648933015697815697887164686061030037812221
4633741844439661030037983361030030952563388773781946294413317077934188608092092609525
3170772432559127811424624325591287164641863388773969723170776103003595419106489462944
1314246860142469309525376380050273351595419122214633724325591215697814326186024325591
2027335196972798338716468600952559541910648300273351444396156978156978862183602733518
7164696972317077969729462944131424661030033170772221463376338877379833306338877387164
6862183693781376380052167948317077095256103003860142462432559123030610300314326102733
5187164624325591244439680920926444396946294413633887730952522214633724325591279833418
9697224325591280920926064814246156978934189462944139697215697806487983363388773444396
4180648317077946294413222146337633887739697214246932432559120273351798337983341806488
6218363037638005064879833871646939321679481432619697286218368609393595419137638005809
2092609525781633887735954191936338877378137638005781809209265954191862183687164609525
3170779386218368621836142461424686094629441306487983302733519697287164602733519697214
2460648216794814326114246143261595419114326131707714326109525969722432559122167948809
2092602733513170772221463371569789697241894629441380920926095258604443969697222214633
7095254182432559122221463374443969697280920926860027335159541911432611432616103003142
4694629441380920926610300337638005610300321679487983344439687164614326114326163388773
0952530595419106488601424679833809209264189462944139697279833809209261424686218361569
7886024325591294629441302733512432559124443968092092680920926222146337143261222146337
1432611569782221463373170770648317077595419161030033763800587164606482221463374443968
6041879833931432610648860871646860142464186338877361030035954191633887738621836156978
8606338877378137638005216794878180920926027335193610300337638005306338877341886086218
3602733514443966338877386002733519393595419178122214633787164693216794863388773781862
1836027335193418862183686063388773969727983380920926633887738609462944138608716460952
5156978142461424630862183686086218362432559129697293376380053015697824325591280920926
2221463371569789697214326187164615697831707741894629441380920926610300393216794844439
6376380052167948969722167948095251569783031707731707714326187164631707724325591214246
8092092678187164614246222146337809209261432612432559122432559128716462432559128600273
3512432559120648798337983386002733513170771432610952514246633887738603093418935954191
8092092686009525216794880920926142467983387164614246860633887730273351809209269363388
7733031707787164622214633737638005860860216794879833610300306488716464443968621836064
8376380050952580920926860781243255912781222146337781418595419178121679480273351216794
8216794802733511569781432619462944138092092641822214633786218364184182167948444396095
2579833143261143261798339462944135954191809209268607983363388773216794837638005969722
1679483041878131707721679489697231707779833969729462944132221463370648862183641831707
78716468092092615697815697830243255912222146337222146337444396

Standard disclaimers: Please replace as found. Online logs may be deleted if physical logbook not signed. NO throwdowns.

Additional Hints (Decrypt)

[Puzzle] Fhogyr pyhrf rkvfg va fbyhgvbaf gb svefg gjb cnegf naq ryfrjurer ba guvf cntr. [Puzzle 2] V'yy trg evtug gb gur Cbvag sbe uvag ahzore Gjb, bayl gur frpbaqf qvssre. [Puzzle 3+] Bhg bs ebbz. Nal nqqvgvbany uvagf jvyy or va pbzzragf.

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)