// FIELD MANUAL — AGENT REFERENCE
Everything you need to operate in the field. No spoilers. No shortcuts. Use this to learn the methods — the application is yours to find.
// SECTION 1 — CLASSICAL CIPHERS
Each letter in the plaintext is shifted a fixed number of positions along the alphabet. A shift of 3 turns A into D, B into E, and so on. To decode, shift in the opposite direction by the same amount.
Common shifts: 3, 13 (ROT13), 1–25. Try all 25 shifts if the key is unknown — this is called brute force.
Cipher: KHOOR
Plain: HELLO
The alphabet is reversed. A maps to Z, B maps to Y, C maps to X, and so on. It is its own inverse — encoding and decoding use the same operation.
A=Z · B=Y · C=X · D=W · E=V · F=U · G=T · H=S · I=R · J=Q · K=P · L=O · M=N
A polyalphabetic cipher that uses a keyword to shift each letter by a different amount. Each letter of the keyword sets the shift for its corresponding plaintext letter, cycling through the keyword as needed.
To decode: subtract the key letter's value from the cipher letter's value (mod 26). The keyword must be known or discovered from context.
Each letter x is encrypted as (ax + b) mod 26 where a and b are the key parameters. Frequency analysis can help identify b once a is known. E is the most common letter in English.
Valid values of a: 1, 3, 5, 7, 9, 11, 15, 17, 19, 21, 23, 25 (must be coprime with 26).
The plaintext is written in a zigzag pattern across a number of "rails", then read off row by row. To decode, determine the number of rails, reconstruct the grid, and fill the rails with the ciphertext before reading diagonally.
H . . . O . . . N . . E . L . A . E . T . . L . . . G . . .
Cipher (read rows): HON ELAET LG
Letters and numbers are represented by sequences of dots (·) and dashes (−). A space separates letters. A slash (/) separates words.
// SECTION 2 — ENCODING FORMATS
Data represented using only 0 and 1. ASCII text uses 8-bit groups. Convert each group of 8 binary digits to a decimal number, then to its ASCII character.
Base-16 encoding using digits 0–9 and letters A–F. ASCII text is commonly represented as pairs of hex digits. Two hex digits = one byte = one character.
41=A 42=B 43=C 44=D 45=E 46=F 47=G 48=H 49=I 4A=J
53=S 54=T 55=U 56=V 57=W 58=X 59=Y 5A=Z 2D=− 20=space
A binary-to-text encoding that represents data using 64 characters: A–Z, a–z, 0–9, + and /. Output is padded with = characters to make the length a multiple of 4. Commonly used to encode binary data for transmission.
Recognise it by: appears as alphanumeric characters with occasional + / = characters. Length is always a multiple of 4.
Data may be encoded multiple times using different formats. Apply each decode step in sequence. Look for recognisable patterns at each stage to identify the next format.
Example chain: Hex → Base64 → ASCII plaintext
// SECTION 3 — INSPECTION TECHNIQUES
Web pages contain more than what is visible. Agents should inspect the raw HTML source of any page that appears incomplete or unusual.
How to view source: right-click → View Page Source, or press Ctrl+U / Cmd+U. Use Ctrl+F to search within the source.
Look for: HTML comments <!-- ... -->, hidden elements, data attributes, unusual metadata, embedded strings.
Content between <!-- and --> is not rendered in the browser but is visible in the page source. Operational data is sometimes embedded here.
HTML elements can carry hidden data in attributes prefixed with data-. These are not rendered visibly but appear in the source.
<div data-node="station-alpha" data-ref="7K">
CSS files and inline style blocks can contain comments. These are not displayed to the user but are present in the source. Inspect all style blocks when other sources have been exhausted.
Information may be distributed across multiple source elements. Look for: first letter of each element, every Nth character, numbered entries, capitalised keywords within otherwise lowercase text.
// SECTION 4 — ANALYSIS METHODS
In any sufficiently long English text, certain letters appear far more often than others. E is the most common, followed by T, A, O, I, N, S, H, R.
In a monoalphabetic substitution cipher, the most frequent letter in the ciphertext likely maps to E. Use this to identify the substitution rule.
A reference document is used as a key. Coordinates (line, word) or (page, line, word) point to specific words or letters. Extract them in sequence to reveal the message.
The reference document will always be provided or discoverable within the mission context.
A grid of letters is provided alongside a list of coordinates. Read each coordinate to extract a letter. Common formats: (row, column) using letter rows and number columns.
When two sources conflict, one is authentic and one has been tampered with. Look for: authentication codes, timestamps, formatting inconsistencies, internal contradictions. Identify and trust the verified source.
Transmission logs or node hops may arrive out of sequence. Chain them by matching each destination to the next origin. The final destination in the correct chain is your objective.
// SECTION 5 — RECOMMENDED TOOLS