tweb-i2p/src/lib/mtproto/transports/obfuscation.ts

/*
 * https://github.com/morethanwords/tweb
 * Copyright (C) 2019-2021 Eduard Kuzmenko
 * https://github.com/morethanwords/tweb/blob/master/LICENSE
 */

//import aesjs from 'aes-js';
import AES from "@cryptography/aes";
import { bytesFromWordss } from "../../../helpers/bytes";
import { Codec } from "./codec";

class Counter {
  _counter: Uint8Array;

  constructor(initialValue: Uint8Array) {
    this._counter = initialValue;
  }

  increment() {
    for(let i = 15; i >= 0; i--) {
      if(this._counter[i] === 255) {
        this._counter[i] = 0;
      } else {
        this._counter[i]++;
        break;
      }
    }
  }
}

class CTR {
  _counter: Counter;
  _remainingCounter: Uint8Array = null;
  _remainingCounterIndex = 16;
  _aes: AES;

  constructor(key: Uint8Array, counter: Uint8Array) {
    this._counter = new Counter(counter);
    this._aes = new AES(key);
  }

  update(payload: Uint8Array) {
    const encrypted = payload.slice();

    for(let i = 0; i < encrypted.length; i++) {
      if(this._remainingCounterIndex === 16) {
        this._remainingCounter = new Uint8Array(bytesFromWordss(this._aes.encrypt(this._counter._counter)));
        this._remainingCounterIndex = 0;
        this._counter.increment();
      }

      encrypted[i] ^= this._remainingCounter[this._remainingCounterIndex++];
    }

    return encrypted;
  }
}

/* 
@cryptography/aes не работает с массивами которые не кратны 4, поэтому использую intermediate а не abridged
*/
export default class Obfuscation {
  /* public enc: aesjs.ModeOfOperation.ModeOfOperationCTR;
  public dec: aesjs.ModeOfOperation.ModeOfOperationCTR; */

  public encNew: CTR;
  public decNew: CTR;

  public init(codec: Codec) {
    const initPayload = new Uint8Array(64);
    initPayload.randomize();
    
    while(true) {
      let val = (initPayload[3] << 24) | (initPayload[2] << 16) | (initPayload[1] << 8) | (initPayload[0]);
      let val2 = (initPayload[7] << 24) | (initPayload[6] << 16) | (initPayload[5] << 8) | (initPayload[4]);
      if(initPayload[0] !== 0xef &&
          val !== 0x44414548 &&
          val !== 0x54534f50 &&
          val !== 0x20544547 &&
          val !== 0x4954504f &&
          val !== 0xeeeeeeee &&
          val !== 0xdddddddd &&
          val2 !== 0x00000000) {
          //initPayload[56] = initPayload[57] = initPayload[58] = initPayload[59] = transport;
          break;
      }
      initPayload.randomize();
    }

    ////////////////////////initPayload.subarray(60, 62).hex = dcId;
    /* initPayload.set(new Uint8Array([161, 208, 67, 71, 118, 109, 20, 111, 113, 255, 134, 10, 159, 241, 7, 44, 217, 82, 187, 76, 108, 131, 200, 186, 33, 57, 177, 251, 52, 34, 18, 54, 65, 105, 37, 89, 38, 20, 47, 168, 126, 181, 24, 138, 212, 68, 60, 150, 225, 37, 181, 4, 201, 50, 72, 151, 168, 143, 204, 169, 81, 187, 241, 23]));
    console.log('initPayload', initPayload); */

    const reversedPayload = initPayload.slice().reverse();

    const encKey = initPayload.slice(8, 40);
    const encIv = initPayload.slice(40, 56);
    const decKey = reversedPayload.slice(8, 40);
    const decIv = reversedPayload.slice(40, 56);

    /* this.enc = new aesjs.ModeOfOperation.ctr(encKey, new aesjs.Counter(encIv as any));
    this.dec = new aesjs.ModeOfOperation.ctr(decKey, new aesjs.Counter(decIv as any)); */

    // console.log('encKey', encKey.hex, encIv.hex);
    // console.log('decKey', decKey.hex, decIv.hex);

    this.encNew = new CTR(encKey, encIv);
    this.decNew = new CTR(decKey, decIv);

    initPayload.set(codec.obfuscateTag, 56);
    const encrypted = this.encode(initPayload);

    //console.log('encrypted', encrypted);

    initPayload.set(encrypted.slice(56, 64), 56);

    return initPayload;
  }

  /* public encode(payload: Uint8Array) {
    let startTime = performance.now();
    let res = this.enc.encrypt(payload);
    let time = performance.now() - startTime;

    try {
      startTime = performance.now();
      let arr = this.encNew.encrypt(payload);
      //let resNew = bytesFromWords({words: arr, sigBytes: arr.length});
      let resNew = new Uint8Array(bytesFromWordss(arr));
      let time2 = performance.now() - startTime;
      console.log('Obfuscation: encode comparison:', res, arr, resNew, res.hex === resNew.hex, time2 < time);
    } catch(err) {
      console.error('Obfuscation: error:', err);
    }
    
    return res;
  }

  public decode(payload: Uint8Array) {
    let res = this.dec.encrypt(payload);

    try {
      let arr = this.decNew.decrypt(payload);
      //let resNew = bytesFromWords({words: arr, sigBytes: arr.length});
      let resNew = new Uint8Array(bytesFromWordss(arr));
      console.log('Obfuscation: decode comparison:', res, arr, resNew, res.hex === resNew.hex);
    } catch(err) {
      console.error('Obfuscation: error:', err);
    }
    
    return res;
  } */
  public encode(payload: Uint8Array) {
    return this.encNew.update(payload);
  }

  public decode(payload: Uint8Array) {
    return this.decNew.update(payload);
  }
  /* public encode(payload: Uint8Array) {
    let res = this.encNew.encrypt(payload);
    let bytes = new Uint8Array(bytesFromWordss(res));
    
    return bytes;
  }

  public decode(payload: Uint8Array) {
    let res = this.decNew.decrypt(payload);
    let bytes = new Uint8Array(bytesFromWordss(res));
    
    return bytes;
  } */
}