@baileys-md/baileys/lib/Signal/Group/sender-chain-key.js

Baileys WhatsApp API

//========================================//
 
import { calculateMAC } from "libsignal-xeuka/src/crypto.js";
import { SenderMessageKey } from "./sender-message-key.js";

export class SenderChainKey {
  constructor(iteration, chainKey) {
    this.MESSAGE_KEY_SEED = Buffer.from([0x01]);
    this.CHAIN_KEY_SEED = Buffer.from([0x02]);
    this.iteration = iteration;
    this.chainKey = Buffer.from(chainKey);
  }
  getIteration() {
    return this.iteration;
  }
  getSenderMessageKey() {
    return new SenderMessageKey(this.iteration, this.getDerivative(this.MESSAGE_KEY_SEED, this.chainKey));
  }
  getNext() {
    return new SenderChainKey(this.iteration + 1, this.getDerivative(this.CHAIN_KEY_SEED, this.chainKey));
  }
  getSeed() {
    return this.chainKey;
  }
  getDerivative(seed, key) {
    return calculateMAC(key, seed);
  }
}