naruyaizumi
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A WebSockets library for interacting with WhatsApp Web
155 lines (154 loc) • 6.24 kB
JavaScript
import { createCipheriv, createDecipheriv, createHash, createHmac, randomBytes } from "crypto";
import * as curve from "libsignal/src/curve.js";
import { KEY_BUNDLE_TYPE } from "../Defaults/index.js";
// insure browser & node compatibility
const { subtle } = globalThis.crypto;
/** prefix version byte to the pub keys, required for some curve crypto functions */
export const generateSignalPubKey = (pubKey) =>
pubKey.length === 33 ? pubKey : Buffer.concat([KEY_BUNDLE_TYPE, pubKey]);
export const Curve = {
generateKeyPair: () => {
const { pubKey, privKey } = curve.generateKeyPair();
return {
private: Buffer.from(privKey),
// remove version byte
public: Buffer.from(pubKey.slice(1)),
};
},
sharedKey: (privateKey, publicKey) => {
const shared = curve.calculateAgreement(generateSignalPubKey(publicKey), privateKey);
return Buffer.from(shared);
},
sign: (privateKey, buf) => curve.calculateSignature(privateKey, buf),
verify: (pubKey, message, signature) => {
try {
curve.verifySignature(generateSignalPubKey(pubKey), message, signature);
return true;
} catch (error) {
return false;
}
},
};
export const signedKeyPair = (identityKeyPair, keyId) => {
const preKey = Curve.generateKeyPair();
const pubKey = generateSignalPubKey(preKey.public);
const signature = Curve.sign(identityKeyPair.private, pubKey);
return { keyPair: preKey, signature, keyId };
};
const GCM_TAG_LENGTH = 128 >> 3;
/**
* encrypt AES 256 GCM;
* where the tag tag is suffixed to the ciphertext
* */
export function aesEncryptGCM(plaintext, key, iv, additionalData) {
const cipher = createCipheriv("aes-256-gcm", key, iv);
cipher.setAAD(additionalData);
return Buffer.concat([cipher.update(plaintext), cipher.final(), cipher.getAuthTag()]);
}
/**
* decrypt AES 256 GCM;
* where the auth tag is suffixed to the ciphertext
* */
export function aesDecryptGCM(ciphertext, key, iv, additionalData) {
const decipher = createDecipheriv("aes-256-gcm", key, iv);
// decrypt additional adata
const enc = ciphertext.slice(0, ciphertext.length - GCM_TAG_LENGTH);
const tag = ciphertext.slice(ciphertext.length - GCM_TAG_LENGTH);
// set additional data
decipher.setAAD(additionalData);
decipher.setAuthTag(tag);
return Buffer.concat([decipher.update(enc), decipher.final()]);
}
export function aesEncryptCTR(plaintext, key, iv) {
const cipher = createCipheriv("aes-256-ctr", key, iv);
return Buffer.concat([cipher.update(plaintext), cipher.final()]);
}
export function aesDecryptCTR(ciphertext, key, iv) {
const decipher = createDecipheriv("aes-256-ctr", key, iv);
return Buffer.concat([decipher.update(ciphertext), decipher.final()]);
}
/** decrypt AES 256 CBC; where the IV is prefixed to the buffer */
export function aesDecrypt(buffer, key) {
return aesDecryptWithIV(buffer.slice(16, buffer.length), key, buffer.slice(0, 16));
}
/** decrypt AES 256 CBC */
export function aesDecryptWithIV(buffer, key, IV) {
const aes = createDecipheriv("aes-256-cbc", key, IV);
return Buffer.concat([aes.update(buffer), aes.final()]);
}
// encrypt AES 256 CBC; where a random IV is prefixed to the buffer
export function aesEncrypt(buffer, key) {
const IV = randomBytes(16);
const aes = createCipheriv("aes-256-cbc", key, IV);
return Buffer.concat([IV, aes.update(buffer), aes.final()]); // prefix IV to the buffer
}
// encrypt AES 256 CBC with a given IV
export function aesEncrypWithIV(buffer, key, IV) {
const aes = createCipheriv("aes-256-cbc", key, IV);
return Buffer.concat([aes.update(buffer), aes.final()]); // prefix IV to the buffer
}
// sign HMAC using SHA 256
export function hmacSign(buffer, key, variant = "sha256") {
return createHmac(variant, key).update(buffer).digest();
}
export function sha256(buffer) {
return createHash("sha256").update(buffer).digest();
}
export function md5(buffer) {
return createHash("md5").update(buffer).digest();
}
// HKDF key expansion
export async function hkdf(buffer, expandedLength, info) {
// Normalize to a Uint8Array whose underlying buffer is a regular ArrayBuffer (not ArrayBufferLike)
// Cloning via new Uint8Array(...) guarantees the generic parameter is ArrayBuffer which satisfies WebCrypto types.
const inputKeyMaterial = new Uint8Array(
buffer instanceof Uint8Array ? buffer : new Uint8Array(buffer)
);
// Set default values if not provided
const salt = info.salt ? new Uint8Array(info.salt) : new Uint8Array(0);
const infoBytes = info.info ? new TextEncoder().encode(info.info) : new Uint8Array(0);
// Import the input key material (cast to BufferSource to appease TS DOM typings)
const importedKey = await subtle.importKey("raw", inputKeyMaterial, { name: "HKDF" }, false, [
"deriveBits",
]);
// Derive bits using HKDF
const derivedBits = await subtle.deriveBits(
{
name: "HKDF",
hash: "SHA-256",
salt: salt,
info: infoBytes,
},
importedKey,
expandedLength * 8 // Convert bytes to bits
);
return Buffer.from(derivedBits);
}
export async function derivePairingCodeKey(pairingCode, salt) {
// Convert inputs to formats Web Crypto API can work with
const encoder = new TextEncoder();
const pairingCodeBuffer = encoder.encode(pairingCode);
const saltBuffer = new Uint8Array(salt instanceof Uint8Array ? salt : new Uint8Array(salt));
// Import the pairing code as key material
const keyMaterial = await subtle.importKey(
"raw",
pairingCodeBuffer,
{ name: "PBKDF2" },
false,
["deriveBits"]
);
// Derive bits using PBKDF2 with the same parameters
// 2 << 16 = 131,072 iterations
const derivedBits = await subtle.deriveBits(
{
name: "PBKDF2",
salt: saltBuffer,
iterations: 2 << 16,
hash: "SHA-256",
},
keyMaterial,
32 * 8 // 32 bytes * 8 = 256 bits
);
return Buffer.from(derivedBits);
}
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