Phi's Cipher Challenge

PhiNotPi

15:35

Sp00k.

in The Nineteenth Byte, 2 mins ago, by PhiNotPi

But I think this puzzle will require a decent amount of thinking and some linguistic-type attacks, it is not enough to just try brute-forcing popular methods (because my exact method is custom although the technique is not).

in The Nineteenth Byte, 58 secs ago, by PhiNotPi

But you should first try to figure some things out: what abnormalities exist (in what ways is the text non-random)?, and then try to figure out substitution vs transposition, block vs stream, and what advanced technique may have been used.

Poke

Are the line numbers there for the reader or are they part of the ciphertext

PhiNotPi

Formatting and line numbers are not part of the text. Look only at the letters themselves.

IRL I told people the same thing.

Poke

since it's in a gist which has the line numbers anyway can you upload a version without them :]

PhiNotPi

Yeah, I'll edit it with a trimmed version....

There, put a condensed version at the top of the gist.

user202729

What about the 5-character blocks?

Character frequency.

PhiNotPi

15:46

5-character blocks are just formatting.

A lot of the time that's how people would physically write out a ciphertext (so when copying it you don't get lost). But that doesn't say anything about the cipher itself.

user202729

What should I expect to get after decryption?

Or 'you will know it's correct if you succeed'?

PhiNotPi

Valid English text, a few short paragraph's worth (several hundred words).

Containing information that would be useful if you were playing my D&D campaign right now.

user202729

Filtered out formatters.
[https://tio.run/##TVZNeuS4Dd3zFDiC699esiRQpAsiZJKSrNoni/nmAnOT3CcHcx5UniSb7rabAoGH98M//vHnn3/9/Pzz3//yPz8/9EbD7BPTmGculHvmkRoPNVHrOs@0pvDdHB3I5zUpdb5UJeXWM/kkOFCHWZ7UUuXB0ZGeJaeZei5jpHvgGOhTfS20auWOSl/uD0cnVNN0p9oXzaj2bJ6s/Eq@y1oopG0rjs4UlOeOvJQuU98iN3zoy4yrZ07UpZhmRxeSeY5MrU8iNGUJTFvhppSCxkoZvS2OrsQt1kih66SSFo6ZStfxQtIrf5FmNODoRs9U@0BJ09rhitkujXnypAujz7EBCUfvlNBpI9UKEFryeaQSuc7E@rChCnN29GGdZKEWs4@UpWI69lwHzFjm/UOu7vBGNT3XjZpuJQCQCiiaLwEj1C5lYuGZ3eFAfQyMA4YIltV@m2@UsMVMceUi7nBE2aCV1piAP4@cCz6JvsNmPY5xj1nd4UTiA5ZeFHCSdD43XJofExALSYiDNBw7k@eGHtJ9WgNJK70nKSVFKkEwTiqbo…

2355 chars.

PhiNotPi

@user202729 Already edited into the gist.

user202729

(= 3 * 5 * 157)

PhiNotPi

15:55

good website to use: dcode.fr/frequency-analysis

or counton.org/explorer/codebreaking/frequency-analysis.php if you like nicer graphics with less functionality

user202729

Apparently there is a quite long repeating block oetdwcciizn

J. Sallé

@PhiNotPi is there any context we need to know to solve this, or just cypher-solving knowledge in general?

user202729

Although, staring at the characters doesn't seem to be useful.

Poke

letter frequencies similar to english

user202729

Why doesn't Hacker's keyboard support Jelly quicks

PhiNotPi

16:03

Also, to level the playing field, I can leak some hints as often as people want/need. In the D&D game I'm playing, I've slowly leaked some hints (which can be somewhat justified because magic). Also there are some important words/phrases in the text that you would not know. I can tell y'all some keywords when you want to know.

I'm gonna work some on a "background knowledge" document for some context.

J. Sallé

Context would help a lot, I think

user202729

Suffixes
https://tio.run/##TVY9liQ5EfZ1ijD2AF3/3Q48VWaopK5IRbakzOwsHwzeXgCXE2BiAyYHYNzd97jHcpHhi6xewJmZ7lGGIr74fvSH3/344x@/f//9z3/xP337@c//@jv98s@/7V5@@Omb/AZ//fDbf//pH/TLt7/SSt@/f6cXuk0@MQ154kK5Zx6o8a0mal3nmZYUPpujHfm8JKXOl6qk3HomnwQH6m2SB7VU@eZoT4@S00Q9lyHSNXAM9K6@Flq0ckelL9e7owOqabpS7YtmVHs0T1Z@Id9lLRTSuhZHRwrKU0deSpepb5EbPvRlwtUTJ@pSTJOjE8k0RabWJxEaswSmtXBTSkFjpYzeZkdn4hZrpNB1UkkLx0yl63gm6ZU/SDMacHShR6p9oKRp6XDFZJfGPHrSmdHn0ICEo1dK6LSRagUILfk8UIlcJ2K921CFOTt6s06yUIvZR8pSMR17rjfMWKbtQ65u90I1PZaVmq4lAJAKKJovASPULmVi4Yndbkd9DIwDhgiW1b6ab5SwxUxx4SJut0fZoJWWmIA/D5wLPom@w2Y9jnGPWd3uQOIDll4UcJ…

user202729

16:17

Repeating 10-char sequences
https://tio.run/##VVZBktxEELzzCh8cwRU@ANHTqlbXTqtKru4erXQniCD8Aa4cORAETzAceQDmaAL@YT6yZLVmbRN72JFGqs7Kysya7755/fr7p6cvv/js3du/fv7ntxfv//j13ZuX796Wr/Dv5df//vD7i/dv37z4@5dvP8d3P47rP3/an56e5h6YFulkMhEtjebKLcZAG6fHFmRjjcGqKrWJApdAde7laFxpPky4T2RLviTK6UFDtU0rRZvscg2ifKmTqSgdZ6UtRFFLvO@WlHoMxaJMLRO@DgYknThy5l56x82JS1mlJNqNmnLSXAXn3qjlmlOMpapRFouRbmVSeqWCMw6uU2LlLUbUayHLGhTvhGWAAICmWgM1DrJYptpJrwBpRIKDpLQseGkU924TW/eHqVY@tr3pAF91awEfuEYWKtRpyomS3ls6ATUGvZI3stIAv26Z8dBCYhpyiI1CEJqAuoREhpvoPAZpAHpdhRMXSsWPbix8WTdc2IQTjLOlosa2A8mmh7xSbxVVJo3FaEsLOtIOwqaT@lCmFSetGNFcDPSEHog…

PhiNotPi

Background/clues: gist.github.com/PhiNotPi/6515c4a645d1600d43e33f3b92f8cbc0

J. Sallé

> Caramalate - name of a "mafia" the party took down prior to the cult. Not to be confused with "caramel latte".

10/10

PhiNotPi

16:36

@user202729 I'm not sure what this is.

J. Sallé

16:49

Well, what I can gather from the information provided so far is that this is likely a variant of the Vigenere cipher. Perhaps a Keyed VC?

@user202729 can you change that code to group the output by which sequence(s) appears more often?

@PhiNotPi also, how was the cipher presented to the party? Just the run of characters that's the first line of the gist?

Might also be a Playfair cipher, but that would take a lot of time to decode

PhiNotPi

@J.Sallé yeah. (I also gave them a formatted version)

J. Sallé

Okay

I'm just throwing ideas out there tbh, not exactly sure how to attack that yet

Transcript for

Phi's Cipher Challenge