Files
shannon/login_resources/generate-totp-standalone.mjs
2025-10-03 19:35:08 -07:00

131 lines
3.2 KiB
JavaScript

#!/usr/bin/env node
import { createHmac } from 'crypto';
/**
* Standalone TOTP generator that doesn't require external dependencies
* Based on RFC 6238 (TOTP: Time-Based One-Time Password Algorithm)
*/
function parseArgs() {
const args = {};
for (let i = 2; i < process.argv.length; i++) {
if (process.argv[i] === '--secret' && i + 1 < process.argv.length) {
args.secret = process.argv[i + 1];
i++; // Skip the next argument since it's the value
} else if (process.argv[i] === '--help' || process.argv[i] === '-h') {
args.help = true;
}
}
return args;
}
function showHelp() {
console.log(`
Usage: node generate-totp-standalone.mjs --secret <TOTP_SECRET>
Generate a Time-based One-Time Password (TOTP) from a secret key.
This standalone version doesn't require external dependencies.
Options:
--secret <secret> The base32-encoded TOTP secret key (required)
--help, -h Show this help message
Examples:
node generate-totp-standalone.mjs --secret "JBSWY3DPEHPK3PXP"
node generate-totp-standalone.mjs --secret "u4e2ewg3d6w7gya3p7plgkef6zgfzo23"
Output:
A 6-digit TOTP code (e.g., 123456)
`);
}
// Base32 decoding function
function base32Decode(encoded) {
const alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567';
const cleanInput = encoded.toUpperCase().replace(/[^A-Z2-7]/g, '');
if (cleanInput.length === 0) {
return Buffer.alloc(0);
}
const output = [];
let bits = 0;
let value = 0;
for (const char of cleanInput) {
const index = alphabet.indexOf(char);
if (index === -1) {
throw new Error(`Invalid base32 character: ${char}`);
}
value = (value << 5) | index;
bits += 5;
if (bits >= 8) {
output.push((value >>> (bits - 8)) & 255);
bits -= 8;
}
}
return Buffer.from(output);
}
// HOTP implementation (RFC 4226)
function generateHOTP(secret, counter, digits = 6) {
const key = base32Decode(secret);
// Convert counter to 8-byte buffer (big-endian)
const counterBuffer = Buffer.alloc(8);
counterBuffer.writeBigUInt64BE(BigInt(counter));
// Generate HMAC-SHA1
const hmac = createHmac('sha1', key);
hmac.update(counterBuffer);
const hash = hmac.digest();
// Dynamic truncation
const offset = hash[hash.length - 1] & 0x0f;
const code = (
((hash[offset] & 0x7f) << 24) |
((hash[offset + 1] & 0xff) << 16) |
((hash[offset + 2] & 0xff) << 8) |
(hash[offset + 3] & 0xff)
);
// Generate digits
const otp = (code % Math.pow(10, digits)).toString().padStart(digits, '0');
return otp;
}
// TOTP implementation (RFC 6238)
function generateTOTP(secret, timeStep = 30, digits = 6) {
const currentTime = Math.floor(Date.now() / 1000);
const counter = Math.floor(currentTime / timeStep);
return generateHOTP(secret, counter, digits);
}
function main() {
const args = parseArgs();
if (args.help) {
showHelp();
return;
}
if (!args.secret) {
console.error('Error: --secret parameter is required');
console.error('Use --help for usage information');
process.exit(1);
}
try {
const totpCode = generateTOTP(args.secret);
console.log(totpCode);
} catch (error) {
console.error(`Error: ${error.message}`);
process.exit(1);
}
}
main();