hackjs

Functional programs for hacking in node.

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Intro

Programs and solvers are written by the author to practice writing FP programs for hacking and solving CTFs ⛳️.

Programs are usually curried, which allows for composition and reuse, as shown in the examples below.

Use

Requires at least v13 Node to be installed.

Import and alias to h

import * as h from 'hackjs';

// pipe files
const flagRegexp = /flag{.*}/;
h.pipeFile([
  h.toString('utf8'),
  h.lines,
  h.filter(h.test(flagRegexp)),
  h.head,
  h.match(flagRegexp),
  h.prop('match'),
])('./leet.jpg'); // 'flag{1337}'

// modular ciphers
const rot13 = h.caesarCipher(13);
rot13('synt{1337}'); // 'FLAG{1337}'

h.substitutionCipher(h.MORSE_CODE_MAPPING)('..-. .-.. .- --. { .---- ...-- ...-- --... }'); // 'flag{1337}'

// string conversions by recoding bases
const decToBinary = recode(16)(2);
recode(16)(10)('a'); // hexadecimal to decimal (10)
recode(16)(8)('a'); // hexadecimal to octal (12)
recode(8)(16)(12); // octal to hex ('a')
decToBinary('a'); // hexadecimal to binary ('1010)

Or import specific named methods

import { lines, map, pipe, toUpper, tap } from 'hackjs';

pipe([
  lines,
  tap('after lines'), // 'tap' the pipe to print the state after an executed program
  map(toUpper),
  tap('after uppercase'),
])('l1w1 l1w2 l1w3\nl2w1 l2w2 l2w3'); // ['L1W1 L1W2 L1W3', 'L2W1 L2W2 L2W3']

CTFs

CTFs are solved using h programs.

Solved CTFs are organized in the ctf folder and can be executed via node.

cd ctf/my-ctf
node index.mjs

Test

Run tests with npm test.

TODOs

• Expand file programs.
• Implement a steganography decoder
• Implement a Vigenere autosolver

Resources

• CTF
• sanctuary
• tape