const crypto = require('crypto'); const fs = require("fs").promises; class Helpers { /** * Generates a random long integer (8 bytes), which is optionally signed * @returns {number} */ static generateRandomLong() { let buf = Buffer.from(this.generateRandomBytes(8)); // 0x12345678 = 305419896 return buf.readUInt32BE(0); } /** * Generates a random bytes array * @param count * @returns {Buffer} */ static generateRandomBytes(count) { return crypto.randomBytes(count); } /** * Loads the user settings located under `api/` * @param path * @returns {Promise} */ static async loadSettings(path = "../api/settings") { let settings = {}; let left, right, value_pair; let data = await fs.readFile(path, 'utf-8'); for (let line of data.toString().split('\n')) { value_pair = line.split("="); if (value_pair.length !== 2) { break; } left = value_pair[0].replace(/ \r?\n|\r/g, ''); right = value_pair[1].replace(/ \r?\n|\r/g, ''); if (!isNaN(right)) { settings[left] = Number.parseInt(right); } else { settings[left] = right; } } return settings; } /** * Calculate the key based on Telegram guidelines, specifying whether it's the client or not * @param shared_key * @param msg_key * @param client * @returns {[*, *]} */ static calcKey(shared_key, msg_key, client) { let x = client !== null ? 0 : 8; let iv, key, sha1a, sha1b, sha1c, sha1d; sha1a = this.sha1((msg_key + shared_key.slice(x, (x + 32)))); sha1b = this.sha1(((shared_key.slice((x + 32), (x + 48)) + msg_key) + shared_key.slice((x + 48), (x + 64)))); sha1c = this.sha1((shared_key.slice((x + 64), (x + 96)) + msg_key)); sha1d = this.sha1((msg_key + shared_key.slice((x + 96), (x + 128)))); key = ((sha1a.slice(0, 8) + sha1b.slice(8, 20)) + sha1c.slice(4, 16)); iv = (((sha1a.slice(8, 20) + sha1b.slice(0, 8)) + sha1c.slice(16, 20)) + sha1d.slice(0, 8)); return [key, iv]; } /** * Calculates the message key from the given data * @param data * @returns {Buffer} */ static calcMsgKey(data) { return this.sha1(data).slice(4, 20); } /** * Generates the key data corresponding to the given nonces * @param serverNonce * @param newNonce * @returns {{ivBuffer: Buffer, keyBuffer: Buffer}} */ static generateKeyDataFromNonces(serverNonce, newNonce) { let hash1 = this.sha1(Buffer.concat([newNonce, serverNonce])); let hash2 = this.sha1(Buffer.concat([serverNonce, newNonce])); let hash3 = this.sha1(Buffer.concat([newNonce, newNonce])); let keyBuffer = Buffer.concat([hash1, hash1.slice(0, 12)]); let ivBuffer = Buffer.concat([hash2.slice(12, 20), hash3, newNonce.slice(0, 4)]); return {keyBuffer: keyBuffer, ivBuffer: ivBuffer} } /** * Calculates the SHA1 digest for the given data * @param data * @returns {Buffer} */ static sha1(data) { let shaSum = crypto.createHash('sha1'); shaSum.update(data); return shaSum.digest(); } } exports.helpers = Helpers;