How to use the bcrypto/lib/bn.js function in bcrypto

if (i === j)
      continue;

    const p = BN.decode(primes[i]);
    const q = BN.decode(primes[j]);
    const n = p.mul(q);
    const pm1 = p.subn(1);
    const qm1 = q.subn(1);
    const phi = pm1.mul(qm1);

    let e = null;
    let d = null;

    for (let i = 1; i < smallPrimes.length; i++) {
      try {
        e = new BN(smallPrimes[i]);
        d = e.invert(phi);
      } catch (e) {
        continue;
      }
      break;
    }

    if (e == null || d == null)
      throw new Error('Could not find a suitable exponent!');

    const key = new rsa.RSAPrivateKey(
      n.encode(),
      e.encode(),
      d.encode(),
      p.encode(),
      q.encode()

this.chal = new BN(0);
    this.ell = new BN(0);
    this.Aq = new BN(0);
    this.Bq = new BN(0);
    this.Cq = new BN(0);
    this.Dq = new BN(0);
    this.Eq = new BN(0);

    this.z_w = new BN(0);
    this.z_w2 = new BN(0);
    this.z_s1 = new BN(0);
    this.z_a = new BN(0);
    this.z_an = new BN(0);
    this.z_s1w = new BN(0);
    this.z_sa = new BN(0);
    this.z_s2 = new BN(0);

    if (options != null)
      this.init(options);
  }

this.chal = new BN(0);
    this.ell = new BN(0);
    this.Aq = new BN(0);
    this.Bq = new BN(0);
    this.Cq = new BN(0);
    this.Dq = new BN(0);
    this.Eq = new BN(0);

    this.z_w = new BN(0);
    this.z_w2 = new BN(0);
    this.z_s1 = new BN(0);
    this.z_a = new BN(0);
    this.z_an = new BN(0);
    this.z_s1w = new BN(0);
    this.z_sa = new BN(0);
    this.z_s2 = new BN(0);

    if (options != null)
      this.init(options);
  }

init(key, nonce) {
    assert(Buffer.isBuffer(key));
    assert(Buffer.isBuffer(nonce));
    assert(key.length === 32);
    assert(nonce.length >= 24);

    this.ctx.init(key, nonce.slice(0, 24));
    this.save = new BN(0);
    this.total = 0;

    return this;
  }

constructor(options) {
    this.C2 = new BN(0);
    this.C3 = new BN(0);
    this.t = new BN(0);

    this.chal = new BN(0);
    this.ell = new BN(0);
    this.Aq = new BN(0);
    this.Bq = new BN(0);
    this.Cq = new BN(0);
    this.Dq = new BN(0);
    this.Eq = new BN(0);

    this.z_w = new BN(0);
    this.z_w2 = new BN(0);
    this.z_s1 = new BN(0);
    this.z_a = new BN(0);
    this.z_an = new BN(0);
    this.z_s1w = new BN(0);
    this.z_sa = new BN(0);
    this.z_s2 = new BN(0);

    if (options != null)
      this.init(options);
  }

'use strict';

const assert = require('bsert');
const bio = require('bufio');
const BN = require('bcrypto/lib/bn.js');
const consensus = require('../protocol/consensus');
const Headers = require('../primitives/headers');
const InvItem = require('../primitives/invitem');
const util = require('../utils/util');

/*
 * Constants
 */

const ZERO = new BN(0);

/**
 * Chain Entry
 * Represents an entry in the chain.
 * @alias module:blockchain.ChainEntry
 * @property {Hash} hash
 * @property {Number} version
 * @property {Hash} prevBlock
 * @property {Hash} merkleRoot
 * @property {Hash} witnessRoot
 * @property {Hash} treeRoot
 * @property {Hash} filterRoot
 * @property {Hash} reservedRoot
 * @property {Number} time
 * @property {Number} bits
 * @property {Buffer} nonce

constructor(n, g, h, bits) {
    if (bits == null)
      bits = 0;

    assert(Buffer.isBuffer(n));
    assert((g >>> 0) === g);
    assert((h >>> 0) === h);
    assert((bits >>> 0) === bits);

    this.n = BN.decode(n);
    this.red = BN.red(this.n);
    this.g = new BN(g).toRed(this.red);
    this.h = new BN(h).toRed(this.red);
    this.nh = this.n.ushrn(1);

    this.bits = this.n.bitLength();
    this.size = (this.bits + 7) >>> 3;
    this.randBits = this.bits - 1;

    this.groupHash = SHA256.multi(this.g.fromRed().encode('be', 4),
                                  this.h.fromRed().encode('be', 4),
                                  this.n.encode('be'));

    this.zero = new BN(0).toRed(this.red);
    this.one = new BN(1).toRed(this.red);

    this.wnaf0 = new Int32Array(constants.MAX_RSA_BITS + 1);
    this.wnaf1 = new Int32Array(constants.ELL_BITS + 1);

constructor(options) {
    this.C2 = new BN(0);
    this.C3 = new BN(0);
    this.t = new BN(0);

    this.chal = new BN(0);
    this.ell = new BN(0);
    this.Aq = new BN(0);
    this.Bq = new BN(0);
    this.Cq = new BN(0);
    this.Dq = new BN(0);
    this.Eq = new BN(0);

    this.z_w = new BN(0);
    this.z_w2 = new BN(0);
    this.z_s1 = new BN(0);
    this.z_a = new BN(0);
    this.z_an = new BN(0);
    this.z_s1w = new BN(0);
    this.z_sa = new BN(0);

constructor(options) {
    this.C2 = new BN(0);
    this.C3 = new BN(0);
    this.t = new BN(0);

    this.chal = new BN(0);
    this.ell = new BN(0);
    this.Aq = new BN(0);
    this.Bq = new BN(0);
    this.Cq = new BN(0);
    this.Dq = new BN(0);
    this.Eq = new BN(0);

    this.z_w = new BN(0);
    this.z_w2 = new BN(0);
    this.z_s1 = new BN(0);
    this.z_a = new BN(0);
    this.z_an = new BN(0);
    this.z_s1w = new BN(0);

if (p.isEven()) {
    inc += 1;
    p.iaddn(1);
  }

  while (!isPrime(p, key)) {
    if (max != null && inc > max)
      break;

    p.iaddn(2);
    inc += 2;
  }

  if (max != null && inc > max)
    return new BN(0);

  return p;
}