obfuse.js

// @author Carl Kittelberger
// Because I am the only one insane enough to do this voluntarily for a joke.

const n = 0;

function notReallyObfuscateNumber(num) {
	return '0' + num.toString(8);
}

const numberArrayObfuscationUnicodeOffset = 0x29;
function obfuscateNumberArray(nums) {
	const offset = Math.min(...nums);
	const top = Math.max(...nums)-offset;
	const offsetAddition = offset > 0 ? `+${notReallyObfuscateNumber(offset)}` : '';
	return `[...${JSON.stringify(nums.map(num => String.fromCharCode(numberArrayObfuscationUnicodeOffset+num-offset)).join(''))}].map(a=>a.charCodeAt(0)-${notReallyObfuscateNumber(numberArrayObfuscationUnicodeOffset)}${offsetAddition})`
}

function obfuscateString(str) {
	let characterArray = str.split('');
	let characterCodes = [];
	let minCharacterCode = +Infinity;
	let maxCharacterCode = -Infinity;
	for (let i = 0; i < str.length; i++) {
		let code = str.charCodeAt(i);
		characterCodes.push(code);
		if (minCharacterCode > code) {
			minCharacterCode = code;
		} else if (maxCharacterCode < code) {
			maxCharacterCode = code;
		}
	}

	let seed = str.length;
	let offset = minCharacterCode;
	let span = maxCharacterCode;
	let foundSomethingThatWorks = false;
	let activeCharacterSet = [];
	let indices = [];
	for (var c = span; !foundSomethingThatWorks && c > 0; c--) {
		seed = str.length;
		do {
			seed++;
			activeCharacterSet.length = seed;
			activeCharacterSet.fill(undefined);
			activeCharacterSet = activeCharacterSet.map((a,b)=>offset+(b*c)%span);
			//console.log({ c, seed });
			indices = [];
			foundSomethingThatWorks = true;
			for (code of characterCodes) {
				const activeCharacterSetIndex = activeCharacterSet.indexOf(code);
				if (activeCharacterSetIndex < 0) {
					foundSomethingThatWorks = false;
					break;
				}
				indices.push(activeCharacterSetIndex);
			}
		} while (!foundSomethingThatWorks && seed < 1000);
		if (foundSomethingThatWorks) break;
	}

	// DEBUG



	//const seedArray = `[...[${','.repeat(seed)}]]`;
	const seedArray = `(_=[],_[${notReallyObfuscateNumber(seed)}]=0,_.fill(0))`;

	const outputCode=`
	[
		${seedArray}
			.map((_,a)=>
				${notReallyObfuscateNumber(offset)}
				+a
				*${notReallyObfuscateNumber(c)}
				%${notReallyObfuscateNumber(span)}
			),
		${obfuscateNumberArray(indices)}
	].reduce((o,a)=>
		o
			?
				a
					.map(b=>String.fromCharCode(o[b]))
					.join('')
			:
				a
	,0)
	`
		.replace(/[\t\r\n]+/mg,'');

	const actualOutput = eval(outputCode);
	if (actualOutput != str)
	{
		console.error("Invalid code:", outputCode);
		console.error("Output was:", actualOutput);
		throw new Error("Output is not matching input");
	}

	return foundSomethingThatWorks ? outputCode /*indices*/ : undefined;
}

const output = obfuscateString(process.argv[2]);
process.stdout.write(output);