feat(ext/node): embed std/node into the snapshot (#17724)

This commit moves "deno_std/node" in "ext/node" crate. The code is
transpiled and snapshotted during the build process.

During the first pass a minimal amount of work was done to create the
snapshot, a lot of code in "ext/node" depends on presence of "Deno"
global. This code will be gradually fixed in the follow up PRs to migrate
it to import relevant APIs from "internal:" modules.

Currently the code from snapshot is not used in any way, and all
Node/npm compatibility still uses code from 
"https://deno.land/std/node" (or from the location specified by 
"DENO_NODE_COMPAT_URL"). This will also be handled in a follow 
up PRs.

---------

Co-authored-by: crowlkats <crowlkats@toaxl.com>
Co-authored-by: Divy Srivastava <dj.srivastava23@gmail.com>
Co-authored-by: Yoshiya Hinosawa <stibium121@gmail.com>

1 files changed, 3605 insertions, 0 deletions

diff --git a/ext/node/polyfills/_crypto/crypto_browserify/bn.js/bn.js b/ext/node/polyfills/_crypto/crypto_browserify/bn.js/bn.js
new file mode 100644
index 000000000..4e9d1187e
--- /dev/null
+++ b/ext/node/polyfills/_crypto/crypto_browserify/bn.js/bn.js
@@ -0,0 +1,3605 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// Copyright 2015 Fedor Indutny. All rights reserved. MIT license.
+// deno-lint-ignore-file no-var no-inner-declarations no-this-alias no-unused-vars
+
+import { Buffer } from "internal:deno_node/polyfills/buffer.ts";
+
+// Utils
+function assert(val, msg) {
+  if (!val) throw new Error(msg || "Assertion failed");
+}
+
+// Could use `inherits` module, but don't want to move from single file
+// architecture yet.
+function inherits(ctor, superCtor) {
+  ctor.super_ = superCtor;
+  var TempCtor = function () {};
+  TempCtor.prototype = superCtor.prototype;
+  ctor.prototype = new TempCtor();
+  ctor.prototype.constructor = ctor;
+}
+
+// BN
+export function BN(number, base, endian) {
+  if (BN.isBN(number)) {
+    return number;
+  }
+
+  this.negative = 0;
+  this.words = null;
+  this.length = 0;
+
+  // Reduction context
+  this.red = null;
+
+  if (number !== null) {
+    if (base === "le" || base === "be") {
+      endian = base;
+      base = 10;
+    }
+
+    this._init(number || 0, base || 10, endian || "be");
+  }
+}
+export default BN;
+
+BN.BN = BN;
+BN.wordSize = 26;
+
+BN.isBN = function isBN(num) {
+  if (num instanceof BN) {
+    return true;
+  }
+
+  return num !== null && typeof num === "object" &&
+    num.constructor.wordSize === BN.wordSize && Array.isArray(num.words);
+};
+
+BN.max = function max(left, right) {
+  if (left.cmp(right) > 0) return left;
+  return right;
+};
+
+BN.min = function min(left, right) {
+  if (left.cmp(right) < 0) return left;
+  return right;
+};
+
+BN.prototype._init = function init(number, base, endian) {
+  if (typeof number === "number") {
+    return this._initNumber(number, base, endian);
+  }
+
+  if (typeof number === "object") {
+    return this._initArray(number, base, endian);
+  }
+
+  if (base === "hex") {
+    base = 16;
+  }
+  assert(base === (base | 0) && base >= 2 && base <= 36);
+
+  number = number.toString().replace(/\s+/g, "");
+  var start = 0;
+  if (number[0] === "-") {
+    start++;
+    this.negative = 1;
+  }
+
+  if (start < number.length) {
+    if (base === 16) {
+      this._parseHex(number, start, endian);
+    } else {
+      this._parseBase(number, base, start);
+      if (endian === "le") {
+        this._initArray(this.toArray(), base, endian);
+      }
+    }
+  }
+};
+
+BN.prototype._initNumber = function _initNumber(number, base, endian) {
+  if (number < 0) {
+    this.negative = 1;
+    number = -number;
+  }
+  if (number < 0x4000000) {
+    this.words = [number & 0x3ffffff];
+    this.length = 1;
+  } else if (number < 0x10000000000000) {
+    this.words = [
+      number & 0x3ffffff,
+      (number / 0x4000000) & 0x3ffffff,
+    ];
+    this.length = 2;
+  } else {
+    assert(number < 0x20000000000000); // 2 ^ 53 (unsafe)
+    this.words = [
+      number & 0x3ffffff,
+      (number / 0x4000000) & 0x3ffffff,
+      1,
+    ];
+    this.length = 3;
+  }
+
+  if (endian !== "le") return;
+
+  // Reverse the bytes
+  this._initArray(this.toArray(), base, endian);
+};
+
+BN.prototype._initArray = function _initArray(number, base, endian) {
+  // Perhaps a Uint8Array
+  assert(typeof number.length === "number");
+  if (number.length <= 0) {
+    this.words = [0];
+    this.length = 1;
+    return this;
+  }
+
+  this.length = Math.ceil(number.length / 3);
+  this.words = new Array(this.length);
+  for (var i = 0; i < this.length; i++) {
+    this.words[i] = 0;
+  }
+
+  var j, w;
+  var off = 0;
+  if (endian === "be") {
+    for (i = number.length - 1, j = 0; i >= 0; i -= 3) {
+      w = number[i] | (number[i - 1] << 8) | (number[i - 2] << 16);
+      this.words[j] |= (w << off) & 0x3ffffff;
+      this.words[j + 1] = (w >>> (26 - off)) & 0x3ffffff;
+      off += 24;
+      if (off >= 26) {
+        off -= 26;
+        j++;
+      }
+    }
+  } else if (endian === "le") {
+    for (i = 0, j = 0; i < number.length; i += 3) {
+      w = number[i] | (number[i + 1] << 8) | (number[i + 2] << 16);
+      this.words[j] |= (w << off) & 0x3ffffff;
+      this.words[j + 1] = (w >>> (26 - off)) & 0x3ffffff;
+      off += 24;
+      if (off >= 26) {
+        off -= 26;
+        j++;
+      }
+    }
+  }
+  return this._strip();
+};
+
+function parseHex4Bits(string, index) {
+  var c = string.charCodeAt(index);
+  // '0' - '9'
+  if (c >= 48 && c <= 57) {
+    return c - 48;
+    // 'A' - 'F'
+  } else if (c >= 65 && c <= 70) {
+    return c - 55;
+    // 'a' - 'f'
+  } else if (c >= 97 && c <= 102) {
+    return c - 87;
+  } else {
+    assert(false, "Invalid character in " + string);
+  }
+}
+
+function parseHexByte(string, lowerBound, index) {
+  var r = parseHex4Bits(string, index);
+  if (index - 1 >= lowerBound) {
+    r |= parseHex4Bits(string, index - 1) << 4;
+  }
+  return r;
+}
+
+BN.prototype._parseHex = function _parseHex(number, start, endian) {
+  // Create possibly bigger array to ensure that it fits the number
+  this.length = Math.ceil((number.length - start) / 6);
+  this.words = new Array(this.length);
+  for (var i = 0; i < this.length; i++) {
+    this.words[i] = 0;
+  }
+
+  // 24-bits chunks
+  var off = 0;
+  var j = 0;
+
+  var w;
+  if (endian === "be") {
+    for (i = number.length - 1; i >= start; i -= 2) {
+      w = parseHexByte(number, start, i) << off;
+      this.words[j] |= w & 0x3ffffff;
+      if (off >= 18) {
+        off -= 18;
+        j += 1;
+        this.words[j] |= w >>> 26;
+      } else {
+        off += 8;
+      }
+    }
+  } else {
+    var parseLength = number.length - start;
+    for (
+      i = parseLength % 2 === 0 ? start + 1 : start;
+      i < number.length;
+      i += 2
+    ) {
+      w = parseHexByte(number, start, i) << off;
+      this.words[j] |= w & 0x3ffffff;
+      if (off >= 18) {
+        off -= 18;
+        j += 1;
+        this.words[j] |= w >>> 26;
+      } else {
+        off += 8;
+      }
+    }
+  }
+
+  this._strip();
+};
+
+function parseBase(str, start, end, mul) {
+  var r = 0;
+  var b = 0;
+  var len = Math.min(str.length, end);
+  for (var i = start; i < len; i++) {
+    var c = str.charCodeAt(i) - 48;
+
+    r *= mul;
+
+    // 'a'
+    if (c >= 49) {
+      b = c - 49 + 0xa;
+
+      // 'A'
+    } else if (c >= 17) {
+      b = c - 17 + 0xa;
+
+      // '0' - '9'
+    } else {
+      b = c;
+    }
+    assert(c >= 0 && b < mul, "Invalid character");
+    r += b;
+  }
+  return r;
+}
+
+BN.prototype._parseBase = function _parseBase(number, base, start) {
+  // Initialize as zero
+  this.words = [0];
+  this.length = 1;
+
+  // Find length of limb in base
+  for (var limbLen = 0, limbPow = 1; limbPow <= 0x3ffffff; limbPow *= base) {
+    limbLen++;
+  }
+  limbLen--;
+  limbPow = (limbPow / base) | 0;
+
+  var total = number.length - start;
+  var mod = total % limbLen;
+  var end = Math.min(total, total - mod) + start;
+
+  var word = 0;
+  for (var i = start; i < end; i += limbLen) {
+    word = parseBase(number, i, i + limbLen, base);
+
+    this.imuln(limbPow);
+    if (this.words[0] + word < 0x4000000) {
+      this.words[0] += word;
+    } else {
+      this._iaddn(word);
+    }
+  }
+
+  if (mod !== 0) {
+    var pow = 1;
+    word = parseBase(number, i, number.length, base);
+
+    for (i = 0; i < mod; i++) {
+      pow *= base;
+    }
+
+    this.imuln(pow);
+    if (this.words[0] + word < 0x4000000) {
+      this.words[0] += word;
+    } else {
+      this._iaddn(word);
+    }
+  }
+
+  this._strip();
+};
+
+BN.prototype.copy = function copy(dest) {
+  dest.words = new Array(this.length);
+  for (var i = 0; i < this.length; i++) {
+    dest.words[i] = this.words[i];
+  }
+  dest.length = this.length;
+  dest.negative = this.negative;
+  dest.red = this.red;
+};
+
+function move(dest, src) {
+  dest.words = src.words;
+  dest.length = src.length;
+  dest.negative = src.negative;
+  dest.red = src.red;
+}
+
+BN.prototype._move = function _move(dest) {
+  move(dest, this);
+};
+
+BN.prototype.clone = function clone() {
+  var r = new BN(null);
+  this.copy(r);
+  return r;
+};
+
+BN.prototype._expand = function _expand(size) {
+  while (this.length < size) {
+    this.words[this.length++] = 0;
+  }
+  return this;
+};
+
+// Remove leading `0` from `this`
+BN.prototype._strip = function strip() {
+  while (this.length > 1 && this.words[this.length - 1] === 0) {
+    this.length--;
+  }
+  return this._normSign();
+};
+
+BN.prototype._normSign = function _normSign() {
+  // -0 = 0
+  if (this.length === 1 && this.words[0] === 0) {
+    this.negative = 0;
+  }
+  return this;
+};
+
+// Check Symbol.for because not everywhere where Symbol defined
+// See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol#Browser_compatibility
+if (typeof Symbol !== "undefined" && typeof Symbol.for === "function") {
+  try {
+    BN.prototype[Symbol.for("nodejs.util.inspect.custom")] = inspect;
+  } catch (e) {
+    BN.prototype.inspect = inspect;
+  }
+} else {
+  BN.prototype.inspect = inspect;
+}
+
+function inspect() {
+  return (this.red ? "<BN-R: " : "<BN: ") + this.toString(16) + ">";
+}
+
+/*
+
+    var zeros = [];
+    var groupSizes = [];
+    var groupBases = [];
+
+    var s = '';
+    var i = -1;
+    while (++i < BN.wordSize) {
+      zeros[i] = s;
+      s += '0';
+    }
+    groupSizes[0] = 0;
+    groupSizes[1] = 0;
+    groupBases[0] = 0;
+    groupBases[1] = 0;
+    var base = 2 - 1;
+    while (++base < 36 + 1) {
+      var groupSize = 0;
+      var groupBase = 1;
+      while (groupBase < (1 << BN.wordSize) / base) {
+        groupBase *= base;
+        groupSize += 1;
+      }
+      groupSizes[base] = groupSize;
+      groupBases[base] = groupBase;
+    }
+
+    */
+
+var zeros = [
+  "",
+  "0",
+  "00",
+  "000",
+  "0000",
+  "00000",
+  "000000",
+  "0000000",
+  "00000000",
+  "000000000",
+  "0000000000",
+  "00000000000",
+  "000000000000",
+  "0000000000000",
+  "00000000000000",
+  "000000000000000",
+  "0000000000000000",
+  "00000000000000000",
+  "000000000000000000",
+  "0000000000000000000",
+  "00000000000000000000",
+  "000000000000000000000",
+  "0000000000000000000000",
+  "00000000000000000000000",
+  "000000000000000000000000",
+  "0000000000000000000000000",
+];
+
+var groupSizes = [
+  0,
+  0,
+  25,
+  16,
+  12,
+  11,
+  10,
+  9,
+  8,
+  8,
+  7,
+  7,
+  7,
+  7,
+  6,
+  6,
+  6,
+  6,
+  6,
+  6,
+  6,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+  5,
+];
+
+var groupBases = [
+  0,
+  0,
+  33554432,
+  43046721,
+  16777216,
+  48828125,
+  60466176,
+  40353607,
+  16777216,
+  43046721,
+  10000000,
+  19487171,
+  35831808,
+  62748517,
+  7529536,
+  11390625,
+  16777216,
+  24137569,
+  34012224,
+  47045881,
+  64000000,
+  4084101,
+  5153632,
+  6436343,
+  7962624,
+  9765625,
+  11881376,
+  14348907,
+  17210368,
+  20511149,
+  24300000,
+  28629151,
+  33554432,
+  39135393,
+  45435424,
+  52521875,
+  60466176,
+];
+
+BN.prototype.toString = function toString(base, padding) {
+  base = base || 10;
+  padding = padding | 0 || 1;
+
+  var out;
+  if (base === 16 || base === "hex") {
+    out = "";
+    var off = 0;
+    var carry = 0;
+    for (var i = 0; i < this.length; i++) {
+      var w = this.words[i];
+      var word = (((w << off) | carry) & 0xffffff).toString(16);
+      carry = (w >>> (24 - off)) & 0xffffff;
+      if (carry !== 0 || i !== this.length - 1) {
+        out = zeros[6 - word.length] + word + out;
+      } else {
+        out = word + out;
+      }
+      off += 2;
+      if (off >= 26) {
+        off -= 26;
+        i--;
+      }
+    }
+    if (carry !== 0) {
+      out = carry.toString(16) + out;
+    }
+    while (out.length % padding !== 0) {
+      out = "0" + out;
+    }
+    if (this.negative !== 0) {
+      out = "-" + out;
+    }
+    return out;
+  }
+
+  if (base === (base | 0) && base >= 2 && base <= 36) {
+    // var groupSize = Math.floor(BN.wordSize * Math.LN2 / Math.log(base));
+    var groupSize = groupSizes[base];
+    // var groupBase = Math.pow(base, groupSize);
+    var groupBase = groupBases[base];
+    out = "";
+    var c = this.clone();
+    c.negative = 0;
+    while (!c.isZero()) {
+      var r = c.modrn(groupBase).toString(base);
+      c = c.idivn(groupBase);
+
+      if (!c.isZero()) {
+        out = zeros[groupSize - r.length] + r + out;
+      } else {
+        out = r + out;
+      }
+    }
+    if (this.isZero()) {
+      out = "0" + out;
+    }
+    while (out.length % padding !== 0) {
+      out = "0" + out;
+    }
+    if (this.negative !== 0) {
+      out = "-" + out;
+    }
+    return out;
+  }
+
+  assert(false, "Base should be between 2 and 36");
+};
+
+BN.prototype.toNumber = function toNumber() {
+  var ret = this.words[0];
+  if (this.length === 2) {
+    ret += this.words[1] * 0x4000000;
+  } else if (this.length === 3 && this.words[2] === 0x01) {
+    // NOTE: at this stage it is known that the top bit is set
+    ret += 0x10000000000000 + (this.words[1] * 0x4000000);
+  } else if (this.length > 2) {
+    assert(false, "Number can only safely store up to 53 bits");
+  }
+  return (this.negative !== 0) ? -ret : ret;
+};
+
+BN.prototype.toJSON = function toJSON() {
+  return this.toString(16, 2);
+};
+
+if (Buffer) {
+  BN.prototype.toBuffer = function toBuffer(endian, length) {
+    return this.toArrayLike(Buffer, endian, length);
+  };
+}
+
+BN.prototype.toArray = function toArray(endian, length) {
+  return this.toArrayLike(Array, endian, length);
+};
+
+var allocate = function allocate(ArrayType, size) {
+  if (ArrayType.allocUnsafe) {
+    return ArrayType.allocUnsafe(size);
+  }
+  return new ArrayType(size);
+};
+
+BN.prototype.toArrayLike = function toArrayLike(ArrayType, endian, length) {
+  this._strip();
+
+  var byteLength = this.byteLength();
+  var reqLength = length || Math.max(1, byteLength);
+  assert(byteLength <= reqLength, "byte array longer than desired length");
+  assert(reqLength > 0, "Requested array length <= 0");
+
+  var res = allocate(ArrayType, reqLength);
+  var postfix = endian === "le" ? "LE" : "BE";
+  this["_toArrayLike" + postfix](res, byteLength);
+  return res;
+};
+
+BN.prototype._toArrayLikeLE = function _toArrayLikeLE(res, byteLength) {
+  var position = 0;
+  var carry = 0;
+
+  for (var i = 0, shift = 0; i < this.length; i++) {
+    var word = (this.words[i] << shift) | carry;
+
+    res[position++] = word & 0xff;
+    if (position < res.length) {
+      res[position++] = (word >> 8) & 0xff;
+    }
+    if (position < res.length) {
+      res[position++] = (word >> 16) & 0xff;
+    }
+
+    if (shift === 6) {
+      if (position < res.length) {
+        res[position++] = (word >> 24) & 0xff;
+      }
+      carry = 0;
+      shift = 0;
+    } else {
+      carry = word >>> 24;
+      shift += 2;
+    }
+  }
+
+  if (position < res.length) {
+    res[position++] = carry;
+
+    while (position < res.length) {
+      res[position++] = 0;
+    }
+  }
+};
+
+BN.prototype._toArrayLikeBE = function _toArrayLikeBE(res, byteLength) {
+  var position = res.length - 1;
+  var carry = 0;
+
+  for (var i = 0, shift = 0; i < this.length; i++) {
+    var word = (this.words[i] << shift) | carry;
+
+    res[position--] = word & 0xff;
+    if (position >= 0) {
+      res[position--] = (word >> 8) & 0xff;
+    }
+    if (position >= 0) {
+      res[position--] = (word >> 16) & 0xff;
+    }
+
+    if (shift === 6) {
+      if (position >= 0) {
+        res[position--] = (word >> 24) & 0xff;
+      }
+      carry = 0;
+      shift = 0;
+    } else {
+      carry = word >>> 24;
+      shift += 2;
+    }
+  }
+
+  if (position >= 0) {
+    res[position--] = carry;
+
+    while (position >= 0) {
+      res[position--] = 0;
+    }
+  }
+};
+
+if (Math.clz32) {
+  BN.prototype._countBits = function _countBits(w) {
+    return 32 - Math.clz32(w);
+  };
+} else {
+  BN.prototype._countBits = function _countBits(w) {
+    var t = w;
+    var r = 0;
+    if (t >= 0x1000) {
+      r += 13;
+      t >>>= 13;
+    }
+    if (t >= 0x40) {
+      r += 7;
+      t >>>= 7;
+    }
+    if (t >= 0x8) {
+      r += 4;
+      t >>>= 4;
+    }
+    if (t >= 0x02) {
+      r += 2;
+      t >>>= 2;
+    }
+    return r + t;
+  };
+}
+
+BN.prototype._zeroBits = function _zeroBits(w) {
+  // Short-cut
+  if (w === 0) return 26;
+
+  var t = w;
+  var r = 0;
+  if ((t & 0x1fff) === 0) {
+    r += 13;
+    t >>>= 13;
+  }
+  if ((t & 0x7f) === 0) {
+    r += 7;
+    t >>>= 7;
+  }
+  if ((t & 0xf) === 0) {
+    r += 4;
+    t >>>= 4;
+  }
+  if ((t & 0x3) === 0) {
+    r += 2;
+    t >>>= 2;
+  }
+  if ((t & 0x1) === 0) {
+    r++;
+  }
+  return r;
+};
+
+// Return number of used bits in a BN
+BN.prototype.bitLength = function bitLength() {
+  var w = this.words[this.length - 1];
+  var hi = this._countBits(w);
+  return (this.length - 1) * 26 + hi;
+};
+
+function toBitArray(num) {
+  var w = new Array(num.bitLength());
+
+  for (var bit = 0; bit < w.length; bit++) {
+    var off = (bit / 26) | 0;
+    var wbit = bit % 26;
+
+    w[bit] = (num.words[off] >>> wbit) & 0x01;
+  }
+
+  return w;
+}
+
+// Number of trailing zero bits
+BN.prototype.zeroBits = function zeroBits() {
+  if (this.isZero()) return 0;
+
+  var r = 0;
+  for (var i = 0; i < this.length; i++) {
+    var b = this._zeroBits(this.words[i]);
+    r += b;
+    if (b !== 26) break;
+  }
+  return r;
+};
+
+BN.prototype.byteLength = function byteLength() {
+  return Math.ceil(this.bitLength() / 8);
+};
+
+BN.prototype.toTwos = function toTwos(width) {
+  if (this.negative !== 0) {
+    return this.abs().inotn(width).iaddn(1);
+  }
+  return this.clone();
+};
+
+BN.prototype.fromTwos = function fromTwos(width) {
+  if (this.testn(width - 1)) {
+    return this.notn(width).iaddn(1).ineg();
+  }
+  return this.clone();
+};
+
+BN.prototype.isNeg = function isNeg() {
+  return this.negative !== 0;
+};
+
+// Return negative clone of `this`
+BN.prototype.neg = function neg() {
+  return this.clone().ineg();
+};
+
+BN.prototype.ineg = function ineg() {
+  if (!this.isZero()) {
+    this.negative ^= 1;
+  }
+
+  return this;
+};
+
+// Or `num` with `this` in-place
+BN.prototype.iuor = function iuor(num) {
+  while (this.length < num.length) {
+    this.words[this.length++] = 0;
+  }
+
+  for (var i = 0; i < num.length; i++) {
+    this.words[i] = this.words[i] | num.words[i];
+  }
+
+  return this._strip();
+};
+
+BN.prototype.ior = function ior(num) {
+  assert((this.negative | num.negative) === 0);
+  return this.iuor(num);
+};
+
+// Or `num` with `this`
+BN.prototype.or = function or(num) {
+  if (this.length > num.length) return this.clone().ior(num);
+  return num.clone().ior(this);
+};
+
+BN.prototype.uor = function uor(num) {
+  if (this.length > num.length) return this.clone().iuor(num);
+  return num.clone().iuor(this);
+};
+
+// And `num` with `this` in-place
+BN.prototype.iuand = function iuand(num) {
+  // b = min-length(num, this)
+  var b;
+  if (this.length > num.length) {
+    b = num;
+  } else {
+    b = this;
+  }
+
+  for (var i = 0; i < b.length; i++) {
+    this.words[i] = this.words[i] & num.words[i];
+  }
+
+  this.length = b.length;
+
+  return this._strip();
+};
+
+BN.prototype.iand = function iand(num) {
+  assert((this.negative | num.negative) === 0);
+  return this.iuand(num);
+};
+
+// And `num` with `this`
+BN.prototype.and = function and(num) {
+  if (this.length > num.length) return this.clone().iand(num);
+  return num.clone().iand(this);
+};
+
+BN.prototype.uand = function uand(num) {
+  if (this.length > num.length) return this.clone().iuand(num);
+  return num.clone().iuand(this);
+};
+
+// Xor `num` with `this` in-place
+BN.prototype.iuxor = function iuxor(num) {
+  // a.length > b.length
+  var a;
+  var b;
+  if (this.length > num.length) {
+    a = this;
+    b = num;
+  } else {
+    a = num;
+    b = this;
+  }
+
+  for (var i = 0; i < b.length; i++) {
+    this.words[i] = a.words[i] ^ b.words[i];
+  }
+
+  if (this !== a) {
+    for (; i < a.length; i++) {
+      this.words[i] = a.words[i];
+    }
+  }
+
+  this.length = a.length;
+
+  return this._strip();
+};
+
+BN.prototype.ixor = function ixor(num) {
+  assert((this.negative | num.negative) === 0);
+  return this.iuxor(num);
+};
+
+// Xor `num` with `this`
+BN.prototype.xor = function xor(num) {
+  if (this.length > num.length) return this.clone().ixor(num);
+  return num.clone().ixor(this);
+};
+
+BN.prototype.uxor = function uxor(num) {
+  if (this.length > num.length) return this.clone().iuxor(num);
+  return num.clone().iuxor(this);
+};
+
+// Not ``this`` with ``width`` bitwidth
+BN.prototype.inotn = function inotn(width) {
+  assert(typeof width === "number" && width >= 0);
+
+  var bytesNeeded = Math.ceil(width / 26) | 0;
+  var bitsLeft = width % 26;
+
+  // Extend the buffer with leading zeroes
+  this._expand(bytesNeeded);
+
+  if (bitsLeft > 0) {
+    bytesNeeded--;
+  }
+
+  // Handle complete words
+  for (var i = 0; i < bytesNeeded; i++) {
+    this.words[i] = ~this.words[i] & 0x3ffffff;
+  }
+
+  // Handle the residue
+  if (bitsLeft > 0) {
+    this.words[i] = ~this.words[i] & (0x3ffffff >> (26 - bitsLeft));
+  }
+
+  // And remove leading zeroes
+  return this._strip();
+};
+
+BN.prototype.notn = function notn(width) {
+  return this.clone().inotn(width);
+};
+
+// Set `bit` of `this`
+BN.prototype.setn = function setn(bit, val) {
+  assert(typeof bit === "number" && bit >= 0);
+
+  var off = (bit / 26) | 0;
+  var wbit = bit % 26;
+
+  this._expand(off + 1);
+
+  if (val) {
+    this.words[off] = this.words[off] | (1 << wbit);
+  } else {
+    this.words[off] = this.words[off] & ~(1 << wbit);
+  }
+
+  return this._strip();
+};
+
+// Add `num` to `this` in-place
+BN.prototype.iadd = function iadd(num) {
+  var r;
+
+  // negative + positive
+  if (this.negative !== 0 && num.negative === 0) {
+    this.negative = 0;
+    r = this.isub(num);
+    this.negative ^= 1;
+    return this._normSign();
+
+    // positive + negative
+  } else if (this.negative === 0 && num.negative !== 0) {
+    num.negative = 0;
+    r = this.isub(num);
+    num.negative = 1;
+    return r._normSign();
+  }
+
+  // a.length > b.length
+  var a, b;
+  if (this.length > num.length) {
+    a = this;
+    b = num;
+  } else {
+    a = num;
+    b = this;
+  }
+
+  var carry = 0;
+  for (var i = 0; i < b.length; i++) {
+    r = (a.words[i] | 0) + (b.words[i] | 0) + carry;
+    this.words[i] = r & 0x3ffffff;
+    carry = r >>> 26;
+  }
+  for (; carry !== 0 && i < a.length; i++) {
+    r = (a.words[i] | 0) + carry;
+    this.words[i] = r & 0x3ffffff;
+    carry = r >>> 26;
+  }
+
+  this.length = a.length;
+  if (carry !== 0) {
+    this.words[this.length] = carry;
+    this.length++;
+    // Copy the rest of the words
+  } else if (a !== this) {
+    for (; i < a.length; i++) {
+      this.words[i] = a.words[i];
+    }
+  }
+
+  return this;
+};
+
+// Add `num` to `this`
+BN.prototype.add = function add(num) {
+  var res;
+  if (num.negative !== 0 && this.negative === 0) {
+    num.negative = 0;
+    res = this.sub(num);
+    num.negative ^= 1;
+    return res;
+  } else if (num.negative === 0 && this.negative !== 0) {
+    this.negative = 0;
+    res = num.sub(this);
+    this.negative = 1;
+    return res;
+  }
+
+  if (this.length > num.length) return this.clone().iadd(num);
+
+  return num.clone().iadd(this);
+};
+
+// Subtract `num` from `this` in-place
+BN.prototype.isub = function isub(num) {
+  // this - (-num) = this + num
+  if (num.negative !== 0) {
+    num.negative = 0;
+    var r = this.iadd(num);
+    num.negative = 1;
+    return r._normSign();
+
+    // -this - num = -(this + num)
+  } else if (this.negative !== 0) {
+    this.negative = 0;
+    this.iadd(num);
+    this.negative = 1;
+    return this._normSign();
+  }
+
+  // At this point both numbers are positive
+  var cmp = this.cmp(num);
+
+  // Optimization - zeroify
+  if (cmp === 0) {
+    this.negative = 0;
+    this.length = 1;
+    this.words[0] = 0;
+    return this;
+  }
+
+  // a > b
+  var a, b;
+  if (cmp > 0) {
+    a = this;
+    b = num;
+  } else {
+    a = num;
+    b = this;
+  }
+
+  var carry = 0;
+  for (var i = 0; i < b.length; i++) {
+    r = (a.words[i] | 0) - (b.words[i] | 0) + carry;
+    carry = r >> 26;
+    this.words[i] = r & 0x3ffffff;
+  }
+  for (; carry !== 0 && i < a.length; i++) {
+    r = (a.words[i] | 0) + carry;
+    carry = r >> 26;
+    this.words[i] = r & 0x3ffffff;
+  }
+
+  // Copy rest of the words
+  if (carry === 0 && i < a.length && a !== this) {
+    for (; i < a.length; i++) {
+      this.words[i] = a.words[i];
+    }
+  }
+
+  this.length = Math.max(this.length, i);
+
+  if (a !== this) {
+    this.negative = 1;
+  }
+
+  return this._strip();
+};
+
+// Subtract `num` from `this`
+BN.prototype.sub = function sub(num) {
+  return this.clone().isub(num);
+};
+
+function smallMulTo(self, num, out) {
+  out.negative = num.negative ^ self.negative;
+  var len = (self.length + num.length) | 0;
+  out.length = len;
+  len = (len - 1) | 0;
+
+  // Peel one iteration (compiler can't do it, because of code complexity)
+  var a = self.words[0] | 0;
+  var b = num.words[0] | 0;
+  var r = a * b;
+
+  var lo = r & 0x3ffffff;
+  var carry = (r / 0x4000000) | 0;
+  out.words[0] = lo;
+
+  for (var k = 1; k < len; k++) {
+    // Sum all words with the same `i + j = k` and accumulate `ncarry`,
+    // note that ncarry could be >= 0x3ffffff
+    var ncarry = carry >>> 26;
+    var rword = carry & 0x3ffffff;
+    var maxJ = Math.min(k, num.length - 1);
+    for (var j = Math.max(0, k - self.length + 1); j <= maxJ; j++) {
+      var i = (k - j) | 0;
+      a = self.words[i] | 0;
+      b = num.words[j] | 0;
+      r = a * b + rword;
+      ncarry += (r / 0x4000000) | 0;
+      rword = r & 0x3ffffff;
+    }
+    out.words[k] = rword | 0;
+    carry = ncarry | 0;
+  }
+  if (carry !== 0) {
+    out.words[k] = carry | 0;
+  } else {
+    out.length--;
+  }
+
+  return out._strip();
+}
+
+// TODO(indutny): it may be reasonable to omit it for users who don't need
+// to work with 256-bit numbers, otherwise it gives 20% improvement for 256-bit
+// multiplication (like elliptic secp256k1).
+var comb10MulTo = function comb10MulTo(self, num, out) {
+  var a = self.words;
+  var b = num.words;
+  var o = out.words;
+  var c = 0;
+  var lo;
+  var mid;
+  var hi;
+  var a0 = a[0] | 0;
+  var al0 = a0 & 0x1fff;
+  var ah0 = a0 >>> 13;
+  var a1 = a[1] | 0;
+  var al1 = a1 & 0x1fff;
+  var ah1 = a1 >>> 13;
+  var a2 = a[2] | 0;
+  var al2 = a2 & 0x1fff;
+  var ah2 = a2 >>> 13;
+  var a3 = a[3] | 0;
+  var al3 = a3 & 0x1fff;
+  var ah3 = a3 >>> 13;
+  var a4 = a[4] | 0;
+  var al4 = a4 & 0x1fff;
+  var ah4 = a4 >>> 13;
+  var a5 = a[5] | 0;
+  var al5 = a5 & 0x1fff;
+  var ah5 = a5 >>> 13;
+  var a6 = a[6] | 0;
+  var al6 = a6 & 0x1fff;
+  var ah6 = a6 >>> 13;
+  var a7 = a[7] | 0;
+  var al7 = a7 & 0x1fff;
+  var ah7 = a7 >>> 13;
+  var a8 = a[8] | 0;
+  var al8 = a8 & 0x1fff;
+  var ah8 = a8 >>> 13;
+  var a9 = a[9] | 0;
+  var al9 = a9 & 0x1fff;
+  var ah9 = a9 >>> 13;
+  var b0 = b[0] | 0;
+  var bl0 = b0 & 0x1fff;
+  var bh0 = b0 >>> 13;
+  var b1 = b[1] | 0;
+  var bl1 = b1 & 0x1fff;
+  var bh1 = b1 >>> 13;
+  var b2 = b[2] | 0;
+  var bl2 = b2 & 0x1fff;
+  var bh2 = b2 >>> 13;
+  var b3 = b[3] | 0;
+  var bl3 = b3 & 0x1fff;
+  var bh3 = b3 >>> 13;
+  var b4 = b[4] | 0;
+  var bl4 = b4 & 0x1fff;
+  var bh4 = b4 >>> 13;
+  var b5 = b[5] | 0;
+  var bl5 = b5 & 0x1fff;
+  var bh5 = b5 >>> 13;
+  var b6 = b[6] | 0;
+  var bl6 = b6 & 0x1fff;
+  var bh6 = b6 >>> 13;
+  var b7 = b[7] | 0;
+  var bl7 = b7 & 0x1fff;
+  var bh7 = b7 >>> 13;
+  var b8 = b[8] | 0;
+  var bl8 = b8 & 0x1fff;
+  var bh8 = b8 >>> 13;
+  var b9 = b[9] | 0;
+  var bl9 = b9 & 0x1fff;
+  var bh9 = b9 >>> 13;
+
+  out.negative = self.negative ^ num.negative;
+  out.length = 19;
+  /* k = 0 */
+  lo = Math.imul(al0, bl0);
+  mid = Math.imul(al0, bh0);
+  mid = (mid + Math.imul(ah0, bl0)) | 0;
+  hi = Math.imul(ah0, bh0);
+  var w0 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w0 >>> 26)) | 0;
+  w0 &= 0x3ffffff;
+  /* k = 1 */
+  lo = Math.imul(al1, bl0);
+  mid = Math.imul(al1, bh0);
+  mid = (mid + Math.imul(ah1, bl0)) | 0;
+  hi = Math.imul(ah1, bh0);
+  lo = (lo + Math.imul(al0, bl1)) | 0;
+  mid = (mid + Math.imul(al0, bh1)) | 0;
+  mid = (mid + Math.imul(ah0, bl1)) | 0;
+  hi = (hi + Math.imul(ah0, bh1)) | 0;
+  var w1 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w1 >>> 26)) | 0;
+  w1 &= 0x3ffffff;
+  /* k = 2 */
+  lo = Math.imul(al2, bl0);
+  mid = Math.imul(al2, bh0);
+  mid = (mid + Math.imul(ah2, bl0)) | 0;
+  hi = Math.imul(ah2, bh0);
+  lo = (lo + Math.imul(al1, bl1)) | 0;
+  mid = (mid + Math.imul(al1, bh1)) | 0;
+  mid = (mid + Math.imul(ah1, bl1)) | 0;
+  hi = (hi + Math.imul(ah1, bh1)) | 0;
+  lo = (lo + Math.imul(al0, bl2)) | 0;
+  mid = (mid + Math.imul(al0, bh2)) | 0;
+  mid = (mid + Math.imul(ah0, bl2)) | 0;
+  hi = (hi + Math.imul(ah0, bh2)) | 0;
+  var w2 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w2 >>> 26)) | 0;
+  w2 &= 0x3ffffff;
+  /* k = 3 */
+  lo = Math.imul(al3, bl0);
+  mid = Math.imul(al3, bh0);
+  mid = (mid + Math.imul(ah3, bl0)) | 0;
+  hi = Math.imul(ah3, bh0);
+  lo = (lo + Math.imul(al2, bl1)) | 0;
+  mid = (mid + Math.imul(al2, bh1)) | 0;
+  mid = (mid + Math.imul(ah2, bl1)) | 0;
+  hi = (hi + Math.imul(ah2, bh1)) | 0;
+  lo = (lo + Math.imul(al1, bl2)) | 0;
+  mid = (mid + Math.imul(al1, bh2)) | 0;
+  mid = (mid + Math.imul(ah1, bl2)) | 0;
+  hi = (hi + Math.imul(ah1, bh2)) | 0;
+  lo = (lo + Math.imul(al0, bl3)) | 0;
+  mid = (mid + Math.imul(al0, bh3)) | 0;
+  mid = (mid + Math.imul(ah0, bl3)) | 0;
+  hi = (hi + Math.imul(ah0, bh3)) | 0;
+  var w3 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w3 >>> 26)) | 0;
+  w3 &= 0x3ffffff;
+  /* k = 4 */
+  lo = Math.imul(al4, bl0);
+  mid = Math.imul(al4, bh0);
+  mid = (mid + Math.imul(ah4, bl0)) | 0;
+  hi = Math.imul(ah4, bh0);
+  lo = (lo + Math.imul(al3, bl1)) | 0;
+  mid = (mid + Math.imul(al3, bh1)) | 0;
+  mid = (mid + Math.imul(ah3, bl1)) | 0;
+  hi = (hi + Math.imul(ah3, bh1)) | 0;
+  lo = (lo + Math.imul(al2, bl2)) | 0;
+  mid = (mid + Math.imul(al2, bh2)) | 0;
+  mid = (mid + Math.imul(ah2, bl2)) | 0;
+  hi = (hi + Math.imul(ah2, bh2)) | 0;
+  lo = (lo + Math.imul(al1, bl3)) | 0;
+  mid = (mid + Math.imul(al1, bh3)) | 0;
+  mid = (mid + Math.imul(ah1, bl3)) | 0;
+  hi = (hi + Math.imul(ah1, bh3)) | 0;
+  lo = (lo + Math.imul(al0, bl4)) | 0;
+  mid = (mid + Math.imul(al0, bh4)) | 0;
+  mid = (mid + Math.imul(ah0, bl4)) | 0;
+  hi = (hi + Math.imul(ah0, bh4)) | 0;
+  var w4 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w4 >>> 26)) | 0;
+  w4 &= 0x3ffffff;
+  /* k = 5 */
+  lo = Math.imul(al5, bl0);
+  mid = Math.imul(al5, bh0);
+  mid = (mid + Math.imul(ah5, bl0)) | 0;
+  hi = Math.imul(ah5, bh0);
+  lo = (lo + Math.imul(al4, bl1)) | 0;
+  mid = (mid + Math.imul(al4, bh1)) | 0;
+  mid = (mid + Math.imul(ah4, bl1)) | 0;
+  hi = (hi + Math.imul(ah4, bh1)) | 0;
+  lo = (lo + Math.imul(al3, bl2)) | 0;
+  mid = (mid + Math.imul(al3, bh2)) | 0;
+  mid = (mid + Math.imul(ah3, bl2)) | 0;
+  hi = (hi + Math.imul(ah3, bh2)) | 0;
+  lo = (lo + Math.imul(al2, bl3)) | 0;
+  mid = (mid + Math.imul(al2, bh3)) | 0;
+  mid = (mid + Math.imul(ah2, bl3)) | 0;
+  hi = (hi + Math.imul(ah2, bh3)) | 0;
+  lo = (lo + Math.imul(al1, bl4)) | 0;
+  mid = (mid + Math.imul(al1, bh4)) | 0;
+  mid = (mid + Math.imul(ah1, bl4)) | 0;
+  hi = (hi + Math.imul(ah1, bh4)) | 0;
+  lo = (lo + Math.imul(al0, bl5)) | 0;
+  mid = (mid + Math.imul(al0, bh5)) | 0;
+  mid = (mid + Math.imul(ah0, bl5)) | 0;
+  hi = (hi + Math.imul(ah0, bh5)) | 0;
+  var w5 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w5 >>> 26)) | 0;
+  w5 &= 0x3ffffff;
+  /* k = 6 */
+  lo = Math.imul(al6, bl0);
+  mid = Math.imul(al6, bh0);
+  mid = (mid + Math.imul(ah6, bl0)) | 0;
+  hi = Math.imul(ah6, bh0);
+  lo = (lo + Math.imul(al5, bl1)) | 0;
+  mid = (mid + Math.imul(al5, bh1)) | 0;
+  mid = (mid + Math.imul(ah5, bl1)) | 0;
+  hi = (hi + Math.imul(ah5, bh1)) | 0;
+  lo = (lo + Math.imul(al4, bl2)) | 0;
+  mid = (mid + Math.imul(al4, bh2)) | 0;
+  mid = (mid + Math.imul(ah4, bl2)) | 0;
+  hi = (hi + Math.imul(ah4, bh2)) | 0;
+  lo = (lo + Math.imul(al3, bl3)) | 0;
+  mid = (mid + Math.imul(al3, bh3)) | 0;
+  mid = (mid + Math.imul(ah3, bl3)) | 0;
+  hi = (hi + Math.imul(ah3, bh3)) | 0;
+  lo = (lo + Math.imul(al2, bl4)) | 0;
+  mid = (mid + Math.imul(al2, bh4)) | 0;
+  mid = (mid + Math.imul(ah2, bl4)) | 0;
+  hi = (hi + Math.imul(ah2, bh4)) | 0;
+  lo = (lo + Math.imul(al1, bl5)) | 0;
+  mid = (mid + Math.imul(al1, bh5)) | 0;
+  mid = (mid + Math.imul(ah1, bl5)) | 0;
+  hi = (hi + Math.imul(ah1, bh5)) | 0;
+  lo = (lo + Math.imul(al0, bl6)) | 0;
+  mid = (mid + Math.imul(al0, bh6)) | 0;
+  mid = (mid + Math.imul(ah0, bl6)) | 0;
+  hi = (hi + Math.imul(ah0, bh6)) | 0;
+  var w6 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w6 >>> 26)) | 0;
+  w6 &= 0x3ffffff;
+  /* k = 7 */
+  lo = Math.imul(al7, bl0);
+  mid = Math.imul(al7, bh0);
+  mid = (mid + Math.imul(ah7, bl0)) | 0;
+  hi = Math.imul(ah7, bh0);
+  lo = (lo + Math.imul(al6, bl1)) | 0;
+  mid = (mid + Math.imul(al6, bh1)) | 0;
+  mid = (mid + Math.imul(ah6, bl1)) | 0;
+  hi = (hi + Math.imul(ah6, bh1)) | 0;
+  lo = (lo + Math.imul(al5, bl2)) | 0;
+  mid = (mid + Math.imul(al5, bh2)) | 0;
+  mid = (mid + Math.imul(ah5, bl2)) | 0;
+  hi = (hi + Math.imul(ah5, bh2)) | 0;
+  lo = (lo + Math.imul(al4, bl3)) | 0;
+  mid = (mid + Math.imul(al4, bh3)) | 0;
+  mid = (mid + Math.imul(ah4, bl3)) | 0;
+  hi = (hi + Math.imul(ah4, bh3)) | 0;
+  lo = (lo + Math.imul(al3, bl4)) | 0;
+  mid = (mid + Math.imul(al3, bh4)) | 0;
+  mid = (mid + Math.imul(ah3, bl4)) | 0;
+  hi = (hi + Math.imul(ah3, bh4)) | 0;
+  lo = (lo + Math.imul(al2, bl5)) | 0;
+  mid = (mid + Math.imul(al2, bh5)) | 0;
+  mid = (mid + Math.imul(ah2, bl5)) | 0;
+  hi = (hi + Math.imul(ah2, bh5)) | 0;
+  lo = (lo + Math.imul(al1, bl6)) | 0;
+  mid = (mid + Math.imul(al1, bh6)) | 0;
+  mid = (mid + Math.imul(ah1, bl6)) | 0;
+  hi = (hi + Math.imul(ah1, bh6)) | 0;
+  lo = (lo + Math.imul(al0, bl7)) | 0;
+  mid = (mid + Math.imul(al0, bh7)) | 0;
+  mid = (mid + Math.imul(ah0, bl7)) | 0;
+  hi = (hi + Math.imul(ah0, bh7)) | 0;
+  var w7 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w7 >>> 26)) | 0;
+  w7 &= 0x3ffffff;
+  /* k = 8 */
+  lo = Math.imul(al8, bl0);
+  mid = Math.imul(al8, bh0);
+  mid = (mid + Math.imul(ah8, bl0)) | 0;
+  hi = Math.imul(ah8, bh0);
+  lo = (lo + Math.imul(al7, bl1)) | 0;
+  mid = (mid + Math.imul(al7, bh1)) | 0;
+  mid = (mid + Math.imul(ah7, bl1)) | 0;
+  hi = (hi + Math.imul(ah7, bh1)) | 0;
+  lo = (lo + Math.imul(al6, bl2)) | 0;
+  mid = (mid + Math.imul(al6, bh2)) | 0;
+  mid = (mid + Math.imul(ah6, bl2)) | 0;
+  hi = (hi + Math.imul(ah6, bh2)) | 0;
+  lo = (lo + Math.imul(al5, bl3)) | 0;
+  mid = (mid + Math.imul(al5, bh3)) | 0;
+  mid = (mid + Math.imul(ah5, bl3)) | 0;
+  hi = (hi + Math.imul(ah5, bh3)) | 0;
+  lo = (lo + Math.imul(al4, bl4)) | 0;
+  mid = (mid + Math.imul(al4, bh4)) | 0;
+  mid = (mid + Math.imul(ah4, bl4)) | 0;
+  hi = (hi + Math.imul(ah4, bh4)) | 0;
+  lo = (lo + Math.imul(al3, bl5)) | 0;
+  mid = (mid + Math.imul(al3, bh5)) | 0;
+  mid = (mid + Math.imul(ah3, bl5)) | 0;
+  hi = (hi + Math.imul(ah3, bh5)) | 0;
+  lo = (lo + Math.imul(al2, bl6)) | 0;
+  mid = (mid + Math.imul(al2, bh6)) | 0;
+  mid = (mid + Math.imul(ah2, bl6)) | 0;
+  hi = (hi + Math.imul(ah2, bh6)) | 0;
+  lo = (lo + Math.imul(al1, bl7)) | 0;
+  mid = (mid + Math.imul(al1, bh7)) | 0;
+  mid = (mid + Math.imul(ah1, bl7)) | 0;
+  hi = (hi + Math.imul(ah1, bh7)) | 0;
+  lo = (lo + Math.imul(al0, bl8)) | 0;
+  mid = (mid + Math.imul(al0, bh8)) | 0;
+  mid = (mid + Math.imul(ah0, bl8)) | 0;
+  hi = (hi + Math.imul(ah0, bh8)) | 0;
+  var w8 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w8 >>> 26)) | 0;
+  w8 &= 0x3ffffff;
+  /* k = 9 */
+  lo = Math.imul(al9, bl0);
+  mid = Math.imul(al9, bh0);
+  mid = (mid + Math.imul(ah9, bl0)) | 0;
+  hi = Math.imul(ah9, bh0);
+  lo = (lo + Math.imul(al8, bl1)) | 0;
+  mid = (mid + Math.imul(al8, bh1)) | 0;
+  mid = (mid + Math.imul(ah8, bl1)) | 0;
+  hi = (hi + Math.imul(ah8, bh1)) | 0;
+  lo = (lo + Math.imul(al7, bl2)) | 0;
+  mid = (mid + Math.imul(al7, bh2)) | 0;
+  mid = (mid + Math.imul(ah7, bl2)) | 0;
+  hi = (hi + Math.imul(ah7, bh2)) | 0;
+  lo = (lo + Math.imul(al6, bl3)) | 0;
+  mid = (mid + Math.imul(al6, bh3)) | 0;
+  mid = (mid + Math.imul(ah6, bl3)) | 0;
+  hi = (hi + Math.imul(ah6, bh3)) | 0;
+  lo = (lo + Math.imul(al5, bl4)) | 0;
+  mid = (mid + Math.imul(al5, bh4)) | 0;
+  mid = (mid + Math.imul(ah5, bl4)) | 0;
+  hi = (hi + Math.imul(ah5, bh4)) | 0;
+  lo = (lo + Math.imul(al4, bl5)) | 0;
+  mid = (mid + Math.imul(al4, bh5)) | 0;
+  mid = (mid + Math.imul(ah4, bl5)) | 0;
+  hi = (hi + Math.imul(ah4, bh5)) | 0;
+  lo = (lo + Math.imul(al3, bl6)) | 0;
+  mid = (mid + Math.imul(al3, bh6)) | 0;
+  mid = (mid + Math.imul(ah3, bl6)) | 0;
+  hi = (hi + Math.imul(ah3, bh6)) | 0;
+  lo = (lo + Math.imul(al2, bl7)) | 0;
+  mid = (mid + Math.imul(al2, bh7)) | 0;
+  mid = (mid + Math.imul(ah2, bl7)) | 0;
+  hi = (hi + Math.imul(ah2, bh7)) | 0;
+  lo = (lo + Math.imul(al1, bl8)) | 0;
+  mid = (mid + Math.imul(al1, bh8)) | 0;
+  mid = (mid + Math.imul(ah1, bl8)) | 0;
+  hi = (hi + Math.imul(ah1, bh8)) | 0;
+  lo = (lo + Math.imul(al0, bl9)) | 0;
+  mid = (mid + Math.imul(al0, bh9)) | 0;
+  mid = (mid + Math.imul(ah0, bl9)) | 0;
+  hi = (hi + Math.imul(ah0, bh9)) | 0;
+  var w9 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w9 >>> 26)) | 0;
+  w9 &= 0x3ffffff;
+  /* k = 10 */
+  lo = Math.imul(al9, bl1);
+  mid = Math.imul(al9, bh1);
+  mid = (mid + Math.imul(ah9, bl1)) | 0;
+  hi = Math.imul(ah9, bh1);
+  lo = (lo + Math.imul(al8, bl2)) | 0;
+  mid = (mid + Math.imul(al8, bh2)) | 0;
+  mid = (mid + Math.imul(ah8, bl2)) | 0;
+  hi = (hi + Math.imul(ah8, bh2)) | 0;
+  lo = (lo + Math.imul(al7, bl3)) | 0;
+  mid = (mid + Math.imul(al7, bh3)) | 0;
+  mid = (mid + Math.imul(ah7, bl3)) | 0;
+  hi = (hi + Math.imul(ah7, bh3)) | 0;
+  lo = (lo + Math.imul(al6, bl4)) | 0;
+  mid = (mid + Math.imul(al6, bh4)) | 0;
+  mid = (mid + Math.imul(ah6, bl4)) | 0;
+  hi = (hi + Math.imul(ah6, bh4)) | 0;
+  lo = (lo + Math.imul(al5, bl5)) | 0;
+  mid = (mid + Math.imul(al5, bh5)) | 0;
+  mid = (mid + Math.imul(ah5, bl5)) | 0;
+  hi = (hi + Math.imul(ah5, bh5)) | 0;
+  lo = (lo + Math.imul(al4, bl6)) | 0;
+  mid = (mid + Math.imul(al4, bh6)) | 0;
+  mid = (mid + Math.imul(ah4, bl6)) | 0;
+  hi = (hi + Math.imul(ah4, bh6)) | 0;
+  lo = (lo + Math.imul(al3, bl7)) | 0;
+  mid = (mid + Math.imul(al3, bh7)) | 0;
+  mid = (mid + Math.imul(ah3, bl7)) | 0;
+  hi = (hi + Math.imul(ah3, bh7)) | 0;
+  lo = (lo + Math.imul(al2, bl8)) | 0;
+  mid = (mid + Math.imul(al2, bh8)) | 0;
+  mid = (mid + Math.imul(ah2, bl8)) | 0;
+  hi = (hi + Math.imul(ah2, bh8)) | 0;
+  lo = (lo + Math.imul(al1, bl9)) | 0;
+  mid = (mid + Math.imul(al1, bh9)) | 0;
+  mid = (mid + Math.imul(ah1, bl9)) | 0;
+  hi = (hi + Math.imul(ah1, bh9)) | 0;
+  var w10 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w10 >>> 26)) | 0;
+  w10 &= 0x3ffffff;
+  /* k = 11 */
+  lo = Math.imul(al9, bl2);
+  mid = Math.imul(al9, bh2);
+  mid = (mid + Math.imul(ah9, bl2)) | 0;
+  hi = Math.imul(ah9, bh2);
+  lo = (lo + Math.imul(al8, bl3)) | 0;
+  mid = (mid + Math.imul(al8, bh3)) | 0;
+  mid = (mid + Math.imul(ah8, bl3)) | 0;
+  hi = (hi + Math.imul(ah8, bh3)) | 0;
+  lo = (lo + Math.imul(al7, bl4)) | 0;
+  mid = (mid + Math.imul(al7, bh4)) | 0;
+  mid = (mid + Math.imul(ah7, bl4)) | 0;
+  hi = (hi + Math.imul(ah7, bh4)) | 0;
+  lo = (lo + Math.imul(al6, bl5)) | 0;
+  mid = (mid + Math.imul(al6, bh5)) | 0;
+  mid = (mid + Math.imul(ah6, bl5)) | 0;
+  hi = (hi + Math.imul(ah6, bh5)) | 0;
+  lo = (lo + Math.imul(al5, bl6)) | 0;
+  mid = (mid + Math.imul(al5, bh6)) | 0;
+  mid = (mid + Math.imul(ah5, bl6)) | 0;
+  hi = (hi + Math.imul(ah5, bh6)) | 0;
+  lo = (lo + Math.imul(al4, bl7)) | 0;
+  mid = (mid + Math.imul(al4, bh7)) | 0;
+  mid = (mid + Math.imul(ah4, bl7)) | 0;
+  hi = (hi + Math.imul(ah4, bh7)) | 0;
+  lo = (lo + Math.imul(al3, bl8)) | 0;
+  mid = (mid + Math.imul(al3, bh8)) | 0;
+  mid = (mid + Math.imul(ah3, bl8)) | 0;
+  hi = (hi + Math.imul(ah3, bh8)) | 0;
+  lo = (lo + Math.imul(al2, bl9)) | 0;
+  mid = (mid + Math.imul(al2, bh9)) | 0;
+  mid = (mid + Math.imul(ah2, bl9)) | 0;
+  hi = (hi + Math.imul(ah2, bh9)) | 0;
+  var w11 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w11 >>> 26)) | 0;
+  w11 &= 0x3ffffff;
+  /* k = 12 */
+  lo = Math.imul(al9, bl3);
+  mid = Math.imul(al9, bh3);
+  mid = (mid + Math.imul(ah9, bl3)) | 0;
+  hi = Math.imul(ah9, bh3);
+  lo = (lo + Math.imul(al8, bl4)) | 0;
+  mid = (mid + Math.imul(al8, bh4)) | 0;
+  mid = (mid + Math.imul(ah8, bl4)) | 0;
+  hi = (hi + Math.imul(ah8, bh4)) | 0;
+  lo = (lo + Math.imul(al7, bl5)) | 0;
+  mid = (mid + Math.imul(al7, bh5)) | 0;
+  mid = (mid + Math.imul(ah7, bl5)) | 0;
+  hi = (hi + Math.imul(ah7, bh5)) | 0;
+  lo = (lo + Math.imul(al6, bl6)) | 0;
+  mid = (mid + Math.imul(al6, bh6)) | 0;
+  mid = (mid + Math.imul(ah6, bl6)) | 0;
+  hi = (hi + Math.imul(ah6, bh6)) | 0;
+  lo = (lo + Math.imul(al5, bl7)) | 0;
+  mid = (mid + Math.imul(al5, bh7)) | 0;
+  mid = (mid + Math.imul(ah5, bl7)) | 0;
+  hi = (hi + Math.imul(ah5, bh7)) | 0;
+  lo = (lo + Math.imul(al4, bl8)) | 0;
+  mid = (mid + Math.imul(al4, bh8)) | 0;
+  mid = (mid + Math.imul(ah4, bl8)) | 0;
+  hi = (hi + Math.imul(ah4, bh8)) | 0;
+  lo = (lo + Math.imul(al3, bl9)) | 0;
+  mid = (mid + Math.imul(al3, bh9)) | 0;
+  mid = (mid + Math.imul(ah3, bl9)) | 0;
+  hi = (hi + Math.imul(ah3, bh9)) | 0;
+  var w12 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w12 >>> 26)) | 0;
+  w12 &= 0x3ffffff;
+  /* k = 13 */
+  lo = Math.imul(al9, bl4);
+  mid = Math.imul(al9, bh4);
+  mid = (mid + Math.imul(ah9, bl4)) | 0;
+  hi = Math.imul(ah9, bh4);
+  lo = (lo + Math.imul(al8, bl5)) | 0;
+  mid = (mid + Math.imul(al8, bh5)) | 0;
+  mid = (mid + Math.imul(ah8, bl5)) | 0;
+  hi = (hi + Math.imul(ah8, bh5)) | 0;
+  lo = (lo + Math.imul(al7, bl6)) | 0;
+  mid = (mid + Math.imul(al7, bh6)) | 0;
+  mid = (mid + Math.imul(ah7, bl6)) | 0;
+  hi = (hi + Math.imul(ah7, bh6)) | 0;
+  lo = (lo + Math.imul(al6, bl7)) | 0;
+  mid = (mid + Math.imul(al6, bh7)) | 0;
+  mid = (mid + Math.imul(ah6, bl7)) | 0;
+  hi = (hi + Math.imul(ah6, bh7)) | 0;
+  lo = (lo + Math.imul(al5, bl8)) | 0;
+  mid = (mid + Math.imul(al5, bh8)) | 0;
+  mid = (mid + Math.imul(ah5, bl8)) | 0;
+  hi = (hi + Math.imul(ah5, bh8)) | 0;
+  lo = (lo + Math.imul(al4, bl9)) | 0;
+  mid = (mid + Math.imul(al4, bh9)) | 0;
+  mid = (mid + Math.imul(ah4, bl9)) | 0;
+  hi = (hi + Math.imul(ah4, bh9)) | 0;
+  var w13 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w13 >>> 26)) | 0;
+  w13 &= 0x3ffffff;
+  /* k = 14 */
+  lo = Math.imul(al9, bl5);
+  mid = Math.imul(al9, bh5);
+  mid = (mid + Math.imul(ah9, bl5)) | 0;
+  hi = Math.imul(ah9, bh5);
+  lo = (lo + Math.imul(al8, bl6)) | 0;
+  mid = (mid + Math.imul(al8, bh6)) | 0;
+  mid = (mid + Math.imul(ah8, bl6)) | 0;
+  hi = (hi + Math.imul(ah8, bh6)) | 0;
+  lo = (lo + Math.imul(al7, bl7)) | 0;
+  mid = (mid + Math.imul(al7, bh7)) | 0;
+  mid = (mid + Math.imul(ah7, bl7)) | 0;
+  hi = (hi + Math.imul(ah7, bh7)) | 0;
+  lo = (lo + Math.imul(al6, bl8)) | 0;
+  mid = (mid + Math.imul(al6, bh8)) | 0;
+  mid = (mid + Math.imul(ah6, bl8)) | 0;
+  hi = (hi + Math.imul(ah6, bh8)) | 0;
+  lo = (lo + Math.imul(al5, bl9)) | 0;
+  mid = (mid + Math.imul(al5, bh9)) | 0;
+  mid = (mid + Math.imul(ah5, bl9)) | 0;
+  hi = (hi + Math.imul(ah5, bh9)) | 0;
+  var w14 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w14 >>> 26)) | 0;
+  w14 &= 0x3ffffff;
+  /* k = 15 */
+  lo = Math.imul(al9, bl6);
+  mid = Math.imul(al9, bh6);
+  mid = (mid + Math.imul(ah9, bl6)) | 0;
+  hi = Math.imul(ah9, bh6);
+  lo = (lo + Math.imul(al8, bl7)) | 0;
+  mid = (mid + Math.imul(al8, bh7)) | 0;
+  mid = (mid + Math.imul(ah8, bl7)) | 0;
+  hi = (hi + Math.imul(ah8, bh7)) | 0;
+  lo = (lo + Math.imul(al7, bl8)) | 0;
+  mid = (mid + Math.imul(al7, bh8)) | 0;
+  mid = (mid + Math.imul(ah7, bl8)) | 0;
+  hi = (hi + Math.imul(ah7, bh8)) | 0;
+  lo = (lo + Math.imul(al6, bl9)) | 0;
+  mid = (mid + Math.imul(al6, bh9)) | 0;
+  mid = (mid + Math.imul(ah6, bl9)) | 0;
+  hi = (hi + Math.imul(ah6, bh9)) | 0;
+  var w15 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w15 >>> 26)) | 0;
+  w15 &= 0x3ffffff;
+  /* k = 16 */
+  lo = Math.imul(al9, bl7);
+  mid = Math.imul(al9, bh7);
+  mid = (mid + Math.imul(ah9, bl7)) | 0;
+  hi = Math.imul(ah9, bh7);
+  lo = (lo + Math.imul(al8, bl8)) | 0;
+  mid = (mid + Math.imul(al8, bh8)) | 0;
+  mid = (mid + Math.imul(ah8, bl8)) | 0;
+  hi = (hi + Math.imul(ah8, bh8)) | 0;
+  lo = (lo + Math.imul(al7, bl9)) | 0;
+  mid = (mid + Math.imul(al7, bh9)) | 0;
+  mid = (mid + Math.imul(ah7, bl9)) | 0;
+  hi = (hi + Math.imul(ah7, bh9)) | 0;
+  var w16 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w16 >>> 26)) | 0;
+  w16 &= 0x3ffffff;
+  /* k = 17 */
+  lo = Math.imul(al9, bl8);
+  mid = Math.imul(al9, bh8);
+  mid = (mid + Math.imul(ah9, bl8)) | 0;
+  hi = Math.imul(ah9, bh8);
+  lo = (lo + Math.imul(al8, bl9)) | 0;
+  mid = (mid + Math.imul(al8, bh9)) | 0;
+  mid = (mid + Math.imul(ah8, bl9)) | 0;
+  hi = (hi + Math.imul(ah8, bh9)) | 0;
+  var w17 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w17 >>> 26)) | 0;
+  w17 &= 0x3ffffff;
+  /* k = 18 */
+  lo = Math.imul(al9, bl9);
+  mid = Math.imul(al9, bh9);
+  mid = (mid + Math.imul(ah9, bl9)) | 0;
+  hi = Math.imul(ah9, bh9);
+  var w18 = (((c + lo) | 0) + ((mid & 0x1fff) << 13)) | 0;
+  c = (((hi + (mid >>> 13)) | 0) + (w18 >>> 26)) | 0;
+  w18 &= 0x3ffffff;
+  o[0] = w0;
+  o[1] = w1;
+  o[2] = w2;
+  o[3] = w3;
+  o[4] = w4;
+  o[5] = w5;
+  o[6] = w6;
+  o[7] = w7;
+  o[8] = w8;
+  o[9] = w9;
+  o[10] = w10;
+  o[11] = w11;
+  o[12] = w12;
+  o[13] = w13;
+  o[14] = w14;
+  o[15] = w15;
+  o[16] = w16;
+  o[17] = w17;
+  o[18] = w18;
+  if (c !== 0) {
+    o[19] = c;
+    out.length++;
+  }
+  return out;
+};
+
+// Polyfill comb
+if (!Math.imul) {
+  comb10MulTo = smallMulTo;
+}
+
+function bigMulTo(self, num, out) {
+  out.negative = num.negative ^ self.negative;
+  out.length = self.length + num.length;
+
+  var carry = 0;
+  var hncarry = 0;
+  for (var k = 0; k < out.length - 1; k++) {
+    // Sum all words with the same `i + j = k` and accumulate `ncarry`,
+    // note that ncarry could be >= 0x3ffffff
+    var ncarry = hncarry;
+    hncarry = 0;
+    var rword = carry & 0x3ffffff;
+    var maxJ = Math.min(k, num.length - 1);
+    for (var j = Math.max(0, k - self.length + 1); j <= maxJ; j++) {
+      var i = k - j;
+      var a = self.words[i] | 0;
+      var b = num.words[j] | 0;
+      var r = a * b;
+
+      var lo = r & 0x3ffffff;
+      ncarry = (ncarry + ((r / 0x4000000) | 0)) | 0;
+      lo = (lo + rword) | 0;
+      rword = lo & 0x3ffffff;
+      ncarry = (ncarry + (lo >>> 26)) | 0;
+
+      hncarry += ncarry >>> 26;
+      ncarry &= 0x3ffffff;
+    }
+    out.words[k] = rword;
+    carry = ncarry;
+    ncarry = hncarry;
+  }
+  if (carry !== 0) {
+    out.words[k] = carry;
+  } else {
+    out.length--;
+  }
+
+  return out._strip();
+}
+
+function jumboMulTo(self, num, out) {
+  // Temporary disable, see https://github.com/indutny/bn.js/issues/211
+  // var fftm = new FFTM();
+  // return fftm.mulp(self, num, out);
+  return bigMulTo(self, num, out);
+}
+
+BN.prototype.mulTo = function mulTo(num, out) {
+  var res;
+  var len = this.length + num.length;
+  if (this.length === 10 && num.length === 10) {
+    res = comb10MulTo(this, num, out);
+  } else if (len < 63) {
+    res = smallMulTo(this, num, out);
+  } else if (len < 1024) {
+    res = bigMulTo(this, num, out);
+  } else {
+    res = jumboMulTo(this, num, out);
+  }
+
+  return res;
+};
+
+// Cooley-Tukey algorithm for FFT
+// slightly revisited to rely on looping instead of recursion
+
+function FFTM(x, y) {
+  this.x = x;
+  this.y = y;
+}
+
+FFTM.prototype.makeRBT = function makeRBT(N) {
+  var t = new Array(N);
+  var l = BN.prototype._countBits(N) - 1;
+  for (var i = 0; i < N; i++) {
+    t[i] = this.revBin(i, l, N);
+  }
+
+  return t;
+};
+
+// Returns binary-reversed representation of `x`
+FFTM.prototype.revBin = function revBin(x, l, N) {
+  if (x === 0 || x === N - 1) return x;
+
+  var rb = 0;
+  for (var i = 0; i < l; i++) {
+    rb |= (x & 1) << (l - i - 1);
+    x >>= 1;
+  }
+
+  return rb;
+};
+
+// Performs "tweedling" phase, therefore 'emulating'
+// behaviour of the recursive algorithm
+FFTM.prototype.permute = function permute(rbt, rws, iws, rtws, itws, N) {
+  for (var i = 0; i < N; i++) {
+    rtws[i] = rws[rbt[i]];
+    itws[i] = iws[rbt[i]];
+  }
+};
+
+FFTM.prototype.transform = function transform(rws, iws, rtws, itws, N, rbt) {
+  this.permute(rbt, rws, iws, rtws, itws, N);
+
+  for (var s = 1; s < N; s <<= 1) {
+    var l = s << 1;
+
+    var rtwdf = Math.cos(2 * Math.PI / l);
+    var itwdf = Math.sin(2 * Math.PI / l);
+
+    for (var p = 0; p < N; p += l) {
+      var rtwdf_ = rtwdf;
+      var itwdf_ = itwdf;
+
+      for (var j = 0; j < s; j++) {
+        var re = rtws[p + j];
+        var ie = itws[p + j];
+
+        var ro = rtws[p + j + s];
+        var io = itws[p + j + s];
+
+        var rx = rtwdf_ * ro - itwdf_ * io;
+
+        io = rtwdf_ * io + itwdf_ * ro;
+        ro = rx;
+
+        rtws[p + j] = re + ro;
+        itws[p + j] = ie + io;
+
+        rtws[p + j + s] = re - ro;
+        itws[p + j + s] = ie - io;
+
+        /* jshint maxdepth : false */
+        if (j !== l) {
+          rx = rtwdf * rtwdf_ - itwdf * itwdf_;
+
+          itwdf_ = rtwdf * itwdf_ + itwdf * rtwdf_;
+          rtwdf_ = rx;
+        }
+      }
+    }
+  }
+};
+
+FFTM.prototype.guessLen13b = function guessLen13b(n, m) {
+  var N = Math.max(m, n) | 1;
+  var odd = N & 1;
+  var i = 0;
+  for (N = N / 2 | 0; N; N = N >>> 1) {
+    i++;
+  }
+
+  return 1 << i + 1 + odd;
+};
+
+FFTM.prototype.conjugate = function conjugate(rws, iws, N) {
+  if (N <= 1) return;
+
+  for (var i = 0; i < N / 2; i++) {
+    var t = rws[i];
+
+    rws[i] = rws[N - i - 1];
+    rws[N - i - 1] = t;
+
+    t = iws[i];
+
+    iws[i] = -iws[N - i - 1];
+    iws[N - i - 1] = -t;
+  }
+};
+
+FFTM.prototype.normalize13b = function normalize13b(ws, N) {
+  var carry = 0;
+  for (var i = 0; i < N / 2; i++) {
+    var w = Math.round(ws[2 * i + 1] / N) * 0x2000 +
+      Math.round(ws[2 * i] / N) +
+      carry;
+
+    ws[i] = w & 0x3ffffff;
+
+    if (w < 0x4000000) {
+      carry = 0;
+    } else {
+      carry = w / 0x4000000 | 0;
+    }
+  }
+
+  return ws;
+};
+
+FFTM.prototype.convert13b = function convert13b(ws, len, rws, N) {
+  var carry = 0;
+  for (var i = 0; i < len; i++) {
+    carry = carry + (ws[i] | 0);
+
+    rws[2 * i] = carry & 0x1fff;
+    carry = carry >>> 13;
+    rws[2 * i + 1] = carry & 0x1fff;
+    carry = carry >>> 13;
+  }
+
+  // Pad with zeroes
+  for (i = 2 * len; i < N; ++i) {
+    rws[i] = 0;
+  }
+
+  assert(carry === 0);
+  assert((carry & ~0x1fff) === 0);
+};
+
+FFTM.prototype.stub = function stub(N) {
+  var ph = new Array(N);
+  for (var i = 0; i < N; i++) {
+    ph[i] = 0;
+  }
+
+  return ph;
+};
+
+FFTM.prototype.mulp = function mulp(x, y, out) {
+  var N = 2 * this.guessLen13b(x.length, y.length);
+
+  var rbt = this.makeRBT(N);
+
+  var _ = this.stub(N);
+
+  var rws = new Array(N);
+  var rwst = new Array(N);
+  var iwst = new Array(N);
+
+  var nrws = new Array(N);
+  var nrwst = new Array(N);
+  var niwst = new Array(N);
+
+  var rmws = out.words;
+  rmws.length = N;
+
+  this.convert13b(x.words, x.length, rws, N);
+  this.convert13b(y.words, y.length, nrws, N);
+
+  this.transform(rws, _, rwst, iwst, N, rbt);
+  this.transform(nrws, _, nrwst, niwst, N, rbt);
+
+  for (var i = 0; i < N; i++) {
+    var rx = rwst[i] * nrwst[i] - iwst[i] * niwst[i];
+    iwst[i] = rwst[i] * niwst[i] + iwst[i] * nrwst[i];
+    rwst[i] = rx;
+  }
+
+  this.conjugate(rwst, iwst, N);
+  this.transform(rwst, iwst, rmws, _, N, rbt);
+  this.conjugate(rmws, _, N);
+  this.normalize13b(rmws, N);
+
+  out.negative = x.negative ^ y.negative;
+  out.length = x.length + y.length;
+  return out._strip();
+};
+
+// Multiply `this` by `num`
+BN.prototype.mul = function mul(num) {
+  var out = new BN(null);
+  out.words = new Array(this.length + num.length);
+  return this.mulTo(num, out);
+};
+
+// Multiply employing FFT
+BN.prototype.mulf = function mulf(num) {
+  var out = new BN(null);
+  out.words = new Array(this.length + num.length);
+  return jumboMulTo(this, num, out);
+};
+
+// In-place Multiplication
+BN.prototype.imul = function imul(num) {
+  return this.clone().mulTo(num, this);
+};
+
+BN.prototype.imuln = function imuln(num) {
+  var isNegNum = num < 0;
+  if (isNegNum) num = -num;
+
+  assert(typeof num === "number");
+  assert(num < 0x4000000);
+
+  // Carry
+  var carry = 0;
+  for (var i = 0; i < this.length; i++) {
+    var w = (this.words[i] | 0) * num;
+    var lo = (w & 0x3ffffff) + (carry & 0x3ffffff);
+    carry >>= 26;
+    carry += (w / 0x4000000) | 0;
+    // NOTE: lo is 27bit maximum
+    carry += lo >>> 26;
+    this.words[i] = lo & 0x3ffffff;
+  }
+
+  if (carry !== 0) {
+    this.words[i] = carry;
+    this.length++;
+  }
+
+  return isNegNum ? this.ineg() : this;
+};
+
+BN.prototype.muln = function muln(num) {
+  return this.clone().imuln(num);
+};
+
+// `this` * `this`
+BN.prototype.sqr = function sqr() {
+  return this.mul(this);
+};
+
+// `this` * `this` in-place
+BN.prototype.isqr = function isqr() {
+  return this.imul(this.clone());
+};
+
+// Math.pow(`this`, `num`)
+BN.prototype.pow = function pow(num) {
+  var w = toBitArray(num);
+  if (w.length === 0) return new BN(1);
+
+  // Skip leading zeroes
+  var res = this;
+  for (var i = 0; i < w.length; i++, res = res.sqr()) {
+    if (w[i] !== 0) break;
+  }
+
+  if (++i < w.length) {
+    for (var q = res.sqr(); i < w.length; i++, q = q.sqr()) {
+      if (w[i] === 0) continue;
+
+      res = res.mul(q);
+    }
+  }
+
+  return res;
+};
+
+// Shift-left in-place
+BN.prototype.iushln = function iushln(bits) {
+  assert(typeof bits === "number" && bits >= 0);
+  var r = bits % 26;
+  var s = (bits - r) / 26;
+  var carryMask = (0x3ffffff >>> (26 - r)) << (26 - r);
+  var i;
+
+  if (r !== 0) {
+    var carry = 0;
+
+    for (i = 0; i < this.length; i++) {
+      var newCarry = this.words[i] & carryMask;
+      var c = ((this.words[i] | 0) - newCarry) << r;
+      this.words[i] = c | carry;
+      carry = newCarry >>> (26 - r);
+    }
+
+    if (carry) {
+      this.words[i] = carry;
+      this.length++;
+    }
+  }
+
+  if (s !== 0) {
+    for (i = this.length - 1; i >= 0; i--) {
+      this.words[i + s] = this.words[i];
+    }
+
+    for (i = 0; i < s; i++) {
+      this.words[i] = 0;
+    }
+
+    this.length += s;
+  }
+
+  return this._strip();
+};
+
+BN.prototype.ishln = function ishln(bits) {
+  // TODO(indutny): implement me
+  assert(this.negative === 0);
+  return this.iushln(bits);
+};
+
+// Shift-right in-place
+// NOTE: `hint` is a lowest bit before trailing zeroes
+// NOTE: if `extended` is present - it will be filled with destroyed bits
+BN.prototype.iushrn = function iushrn(bits, hint, extended) {
+  assert(typeof bits === "number" && bits >= 0);
+  var h;
+  if (hint) {
+    h = (hint - (hint % 26)) / 26;
+  } else {
+    h = 0;
+  }
+
+  var r = bits % 26;
+  var s = Math.min((bits - r) / 26, this.length);
+  var mask = 0x3ffffff ^ ((0x3ffffff >>> r) << r);
+  var maskedWords = extended;
+
+  h -= s;
+  h = Math.max(0, h);
+
+  // Extended mode, copy masked part
+  if (maskedWords) {
+    for (var i = 0; i < s; i++) {
+      maskedWords.words[i] = this.words[i];
+    }
+    maskedWords.length = s;
+  }
+
+  if (s === 0) {
+    // No-op, we should not move anything at all
+  } else if (this.length > s) {
+    this.length -= s;
+    for (i = 0; i < this.length; i++) {
+      this.words[i] = this.words[i + s];
+    }
+  } else {
+    this.words[0] = 0;
+    this.length = 1;
+  }
+
+  var carry = 0;
+  for (i = this.length - 1; i >= 0 && (carry !== 0 || i >= h); i--) {
+    var word = this.words[i] | 0;
+    this.words[i] = (carry << (26 - r)) | (word >>> r);
+    carry = word & mask;
+  }
+
+  // Push carried bits as a mask
+  if (maskedWords && carry !== 0) {
+    maskedWords.words[maskedWords.length++] = carry;
+  }
+
+  if (this.length === 0) {
+    this.words[0] = 0;
+    this.length = 1;
+  }
+
+  return this._strip();
+};
+
+BN.prototype.ishrn = function ishrn(bits, hint, extended) {
+  // TODO(indutny): implement me
+  assert(this.negative === 0);
+  return this.iushrn(bits, hint, extended);
+};
+
+// Shift-left
+BN.prototype.shln = function shln(bits) {
+  return this.clone().ishln(bits);
+};
+
+BN.prototype.ushln = function ushln(bits) {
+  return this.clone().iushln(bits);
+};
+
+// Shift-right
+BN.prototype.shrn = function shrn(bits) {
+  return this.clone().ishrn(bits);
+};
+
+BN.prototype.ushrn = function ushrn(bits) {
+  return this.clone().iushrn(bits);
+};
+
+// Test if n bit is set
+BN.prototype.testn = function testn(bit) {
+  assert(typeof bit === "number" && bit >= 0);
+  var r = bit % 26;
+  var s = (bit - r) / 26;
+  var q = 1 << r;
+
+  // Fast case: bit is much higher than all existing words
+  if (this.length <= s) return false;
+
+  // Check bit and return
+  var w = this.words[s];
+
+  return !!(w & q);
+};
+
+// Return only lowers bits of number (in-place)
+BN.prototype.imaskn = function imaskn(bits) {
+  assert(typeof bits === "number" && bits >= 0);
+  var r = bits % 26;
+  var s = (bits - r) / 26;
+
+  assert(this.negative === 0, "imaskn works only with positive numbers");
+
+  if (this.length <= s) {
+    return this;
+  }
+
+  if (r !== 0) {
+    s++;
+  }
+  this.length = Math.min(s, this.length);
+
+  if (r !== 0) {
+    var mask = 0x3ffffff ^ ((0x3ffffff >>> r) << r);
+    this.words[this.length - 1] &= mask;
+  }
+
+  return this._strip();
+};
+
+// Return only lowers bits of number
+BN.prototype.maskn = function maskn(bits) {
+  return this.clone().imaskn(bits);
+};
+
+// Add plain number `num` to `this`
+BN.prototype.iaddn = function iaddn(num) {
+  assert(typeof num === "number");
+  assert(num < 0x4000000);
+  if (num < 0) return this.isubn(-num);
+
+  // Possible sign change
+  if (this.negative !== 0) {
+    if (this.length === 1 && (this.words[0] | 0) <= num) {
+      this.words[0] = num - (this.words[0] | 0);
+      this.negative = 0;
+      return this;
+    }
+
+    this.negative = 0;
+    this.isubn(num);
+    this.negative = 1;
+    return this;
+  }
+
+  // Add without checks
+  return this._iaddn(num);
+};
+
+BN.prototype._iaddn = function _iaddn(num) {
+  this.words[0] += num;
+
+  // Carry
+  for (var i = 0; i < this.length && this.words[i] >= 0x4000000; i++) {
+    this.words[i] -= 0x4000000;
+    if (i === this.length - 1) {
+      this.words[i + 1] = 1;
+    } else {
+      this.words[i + 1]++;
+    }
+  }
+  this.length = Math.max(this.length, i + 1);
+
+  return this;
+};
+
+// Subtract plain number `num` from `this`
+BN.prototype.isubn = function isubn(num) {
+  assert(typeof num === "number");
+  assert(num < 0x4000000);
+  if (num < 0) return this.iaddn(-num);
+
+  if (this.negative !== 0) {
+    this.negative = 0;
+    this.iaddn(num);
+    this.negative = 1;
+    return this;
+  }
+
+  this.words[0] -= num;
+
+  if (this.length === 1 && this.words[0] < 0) {
+    this.words[0] = -this.words[0];
+    this.negative = 1;
+  } else {
+    // Carry
+    for (var i = 0; i < this.length && this.words[i] < 0; i++) {
+      this.words[i] += 0x4000000;
+      this.words[i + 1] -= 1;
+    }
+  }
+
+  return this._strip();
+};
+
+BN.prototype.addn = function addn(num) {
+  return this.clone().iaddn(num);
+};
+
+BN.prototype.subn = function subn(num) {
+  return this.clone().isubn(num);
+};
+
+BN.prototype.iabs = function iabs() {
+  this.negative = 0;
+
+  return this;
+};
+
+BN.prototype.abs = function abs() {
+  return this.clone().iabs();
+};
+
+BN.prototype._ishlnsubmul = function _ishlnsubmul(num, mul, shift) {
+  var len = num.length + shift;
+  var i;
+
+  this._expand(len);
+
+  var w;
+  var carry = 0;
+  for (i = 0; i < num.length; i++) {
+    w = (this.words[i + shift] | 0) + carry;
+    var right = (num.words[i] | 0) * mul;
+    w -= right & 0x3ffffff;
+    carry = (w >> 26) - ((right / 0x4000000) | 0);
+    this.words[i + shift] = w & 0x3ffffff;
+  }
+  for (; i < this.length - shift; i++) {
+    w = (this.words[i + shift] | 0) + carry;
+    carry = w >> 26;
+    this.words[i + shift] = w & 0x3ffffff;
+  }
+
+  if (carry === 0) return this._strip();
+
+  // Subtraction overflow
+  assert(carry === -1);
+  carry = 0;
+  for (i = 0; i < this.length; i++) {
+    w = -(this.words[i] | 0) + carry;
+    carry = w >> 26;
+    this.words[i] = w & 0x3ffffff;
+  }
+  this.negative = 1;
+
+  return this._strip();
+};
+
+BN.prototype._wordDiv = function _wordDiv(num, mode) {
+  var shift = this.length - num.length;
+
+  var a = this.clone();
+  var b = num;
+
+  // Normalize
+  var bhi = b.words[b.length - 1] | 0;
+  var bhiBits = this._countBits(bhi);
+  shift = 26 - bhiBits;
+  if (shift !== 0) {
+    b = b.ushln(shift);
+    a.iushln(shift);
+    bhi = b.words[b.length - 1] | 0;
+  }
+
+  // Initialize quotient
+  var m = a.length - b.length;
+  var q;
+
+  if (mode !== "mod") {
+    q = new BN(null);
+    q.length = m + 1;
+    q.words = new Array(q.length);
+    for (var i = 0; i < q.length; i++) {
+      q.words[i] = 0;
+    }
+  }
+
+  var diff = a.clone()._ishlnsubmul(b, 1, m);
+  if (diff.negative === 0) {
+    a = diff;
+    if (q) {
+      q.words[m] = 1;
+    }
+  }
+
+  for (var j = m - 1; j >= 0; j--) {
+    var qj = (a.words[b.length + j] | 0) * 0x4000000 +
+      (a.words[b.length + j - 1] | 0);
+
+    // NOTE: (qj / bhi) is (0x3ffffff * 0x4000000 + 0x3ffffff) / 0x2000000 max
+    // (0x7ffffff)
+    qj = Math.min((qj / bhi) | 0, 0x3ffffff);
+
+    a._ishlnsubmul(b, qj, j);
+    while (a.negative !== 0) {
+      qj--;
+      a.negative = 0;
+      a._ishlnsubmul(b, 1, j);
+      if (!a.isZero()) {
+        a.negative ^= 1;
+      }
+    }
+    if (q) {
+      q.words[j] = qj;
+    }
+  }
+  if (q) {
+    q._strip();
+  }
+  a._strip();
+
+  // Denormalize
+  if (mode !== "div" && shift !== 0) {
+    a.iushrn(shift);
+  }
+
+  return {
+    div: q || null,
+    mod: a,
+  };
+};
+
+// NOTE: 1) `mode` can be set to `mod` to request mod only,
+//       to `div` to request div only, or be absent to
+//       request both div & mod
+//       2) `positive` is true if unsigned mod is requested
+BN.prototype.divmod = function divmod(num, mode, positive) {
+  assert(!num.isZero());
+
+  if (this.isZero()) {
+    return {
+      div: new BN(0),
+      mod: new BN(0),
+    };
+  }
+
+  var div, mod, res;
+  if (this.negative !== 0 && num.negative === 0) {
+    res = this.neg().divmod(num, mode);
+
+    if (mode !== "mod") {
+      div = res.div.neg();
+    }
+
+    if (mode !== "div") {
+      mod = res.mod.neg();
+      if (positive && mod.negative !== 0) {
+        mod.iadd(num);
+      }
+    }
+
+    return {
+      div: div,
+      mod: mod,
+    };
+  }
+
+  if (this.negative === 0 && num.negative !== 0) {
+    res = this.divmod(num.neg(), mode);
+
+    if (mode !== "mod") {
+      div = res.div.neg();
+    }
+
+    return {
+      div: div,
+      mod: res.mod,
+    };
+  }
+
+  if ((this.negative & num.negative) !== 0) {
+    res = this.neg().divmod(num.neg(), mode);
+
+    if (mode !== "div") {
+      mod = res.mod.neg();
+      if (positive && mod.negative !== 0) {
+        mod.isub(num);
+      }
+    }
+
+    return {
+      div: res.div,
+      mod: mod,
+    };
+  }
+
+  // Both numbers are positive at this point
+
+  // Strip both numbers to approximate shift value
+  if (num.length > this.length || this.cmp(num) < 0) {
+    return {
+      div: new BN(0),
+      mod: this,
+    };
+  }
+
+  // Very short reduction
+  if (num.length === 1) {
+    if (mode === "div") {
+      return {
+        div: this.divn(num.words[0]),
+        mod: null,
+      };
+    }
+
+    if (mode === "mod") {
+      return {
+        div: null,
+        mod: new BN(this.modrn(num.words[0])),
+      };
+    }
+
+    return {
+      div: this.divn(num.words[0]),
+      mod: new BN(this.modrn(num.words[0])),
+    };
+  }
+
+  return this._wordDiv(num, mode);
+};
+
+// Find `this` / `num`
+BN.prototype.div = function div(num) {
+  return this.divmod(num, "div", false).div;
+};
+
+// Find `this` % `num`
+BN.prototype.mod = function mod(num) {
+  return this.divmod(num, "mod", false).mod;
+};
+
+BN.prototype.umod = function umod(num) {
+  return this.divmod(num, "mod", true).mod;
+};
+
+// Find Round(`this` / `num`)
+BN.prototype.divRound = function divRound(num) {
+  var dm = this.divmod(num);
+
+  // Fast case - exact division
+  if (dm.mod.isZero()) return dm.div;
+
+  var mod = dm.div.negative !== 0 ? dm.mod.isub(num) : dm.mod;
+
+  var half = num.ushrn(1);
+  var r2 = num.andln(1);
+  var cmp = mod.cmp(half);
+
+  // Round down
+  if (cmp < 0 || (r2 === 1 && cmp === 0)) return dm.div;
+
+  // Round up
+  return dm.div.negative !== 0 ? dm.div.isubn(1) : dm.div.iaddn(1);
+};
+
+BN.prototype.modrn = function modrn(num) {
+  var isNegNum = num < 0;
+  if (isNegNum) num = -num;
+
+  assert(num <= 0x3ffffff);
+  var p = (1 << 26) % num;
+
+  var acc = 0;
+  for (var i = this.length - 1; i >= 0; i--) {
+    acc = (p * acc + (this.words[i] | 0)) % num;
+  }
+
+  return isNegNum ? -acc : acc;
+};
+
+// WARNING: DEPRECATED
+BN.prototype.modn = function modn(num) {
+  return this.modrn(num);
+};
+
+// In-place division by number
+BN.prototype.idivn = function idivn(num) {
+  var isNegNum = num < 0;
+  if (isNegNum) num = -num;
+
+  assert(num <= 0x3ffffff);
+
+  var carry = 0;
+  for (var i = this.length - 1; i >= 0; i--) {
+    var w = (this.words[i] | 0) + carry * 0x4000000;
+    this.words[i] = (w / num) | 0;
+    carry = w % num;
+  }
+
+  this._strip();
+  return isNegNum ? this.ineg() : this;
+};
+
+BN.prototype.divn = function divn(num) {
+  return this.clone().idivn(num);
+};
+
+BN.prototype.egcd = function egcd(p) {
+  assert(p.negative === 0);
+  assert(!p.isZero());
+
+  var x = this;
+  var y = p.clone();
+
+  if (x.negative !== 0) {
+    x = x.umod(p);
+  } else {
+    x = x.clone();
+  }
+
+  // A * x + B * y = x
+  var A = new BN(1);
+  var B = new BN(0);
+
+  // C * x + D * y = y
+  var C = new BN(0);
+  var D = new BN(1);
+
+  var g = 0;
+
+  while (x.isEven() && y.isEven()) {
+    x.iushrn(1);
+    y.iushrn(1);
+    ++g;
+  }
+
+  var yp = y.clone();
+  var xp = x.clone();
+
+  while (!x.isZero()) {
+    for (var i = 0, im = 1; (x.words[0] & im) === 0 && i < 26; ++i, im <<= 1);
+    if (i > 0) {
+      x.iushrn(i);
+      while (i-- > 0) {
+        if (A.isOdd() || B.isOdd()) {
+          A.iadd(yp);
+          B.isub(xp);
+        }
+
+        A.iushrn(1);
+        B.iushrn(1);
+      }
+    }
+
+    for (var j = 0, jm = 1; (y.words[0] & jm) === 0 && j < 26; ++j, jm <<= 1);
+    if (j > 0) {
+      y.iushrn(j);
+      while (j-- > 0) {
+        if (C.isOdd() || D.isOdd()) {
+          C.iadd(yp);
+          D.isub(xp);
+        }
+
+        C.iushrn(1);
+        D.iushrn(1);
+      }
+    }
+
+    if (x.cmp(y) >= 0) {
+      x.isub(y);
+      A.isub(C);
+      B.isub(D);
+    } else {
+      y.isub(x);
+      C.isub(A);
+      D.isub(B);
+    }
+  }
+
+  return {
+    a: C,
+    b: D,
+    gcd: y.iushln(g),
+  };
+};
+
+// This is reduced incarnation of the binary EEA
+// above, designated to invert members of the
+// _prime_ fields F(p) at a maximal speed
+BN.prototype._invmp = function _invmp(p) {
+  assert(p.negative === 0);
+  assert(!p.isZero());
+
+  var a = this;
+  var b = p.clone();
+
+  if (a.negative !== 0) {
+    a = a.umod(p);
+  } else {
+    a = a.clone();
+  }
+
+  var x1 = new BN(1);
+  var x2 = new BN(0);
+
+  var delta = b.clone();
+
+  while (a.cmpn(1) > 0 && b.cmpn(1) > 0) {
+    for (var i = 0, im = 1; (a.words[0] & im) === 0 && i < 26; ++i, im <<= 1);
+    if (i > 0) {
+      a.iushrn(i);
+      while (i-- > 0) {
+        if (x1.isOdd()) {
+          x1.iadd(delta);
+        }
+
+        x1.iushrn(1);
+      }
+    }
+
+    for (var j = 0, jm = 1; (b.words[0] & jm) === 0 && j < 26; ++j, jm <<= 1);
+    if (j > 0) {
+      b.iushrn(j);
+      while (j-- > 0) {
+        if (x2.isOdd()) {
+          x2.iadd(delta);
+        }
+
+        x2.iushrn(1);
+      }
+    }
+
+    if (a.cmp(b) >= 0) {
+      a.isub(b);
+      x1.isub(x2);
+    } else {
+      b.isub(a);
+      x2.isub(x1);
+    }
+  }
+
+  var res;
+  if (a.cmpn(1) === 0) {
+    res = x1;
+  } else {
+    res = x2;
+  }
+
+  if (res.cmpn(0) < 0) {
+    res.iadd(p);
+  }
+
+  return res;
+};
+
+BN.prototype.gcd = function gcd(num) {
+  if (this.isZero()) return num.abs();
+  if (num.isZero()) return this.abs();
+
+  var a = this.clone();
+  var b = num.clone();
+  a.negative = 0;
+  b.negative = 0;
+
+  // Remove common factor of two
+  for (var shift = 0; a.isEven() && b.isEven(); shift++) {
+    a.iushrn(1);
+    b.iushrn(1);
+  }
+
+  do {
+    while (a.isEven()) {
+      a.iushrn(1);
+    }
+    while (b.isEven()) {
+      b.iushrn(1);
+    }
+
+    var r = a.cmp(b);
+    if (r < 0) {
+      // Swap `a` and `b` to make `a` always bigger than `b`
+      var t = a;
+      a = b;
+      b = t;
+    } else if (r === 0 || b.cmpn(1) === 0) {
+      break;
+    }
+
+    a.isub(b);
+  } while (true);
+
+  return b.iushln(shift);
+};
+
+// Invert number in the field F(num)
+BN.prototype.invm = function invm(num) {
+  return this.egcd(num).a.umod(num);
+};
+
+BN.prototype.isEven = function isEven() {
+  return (this.words[0] & 1) === 0;
+};
+
+BN.prototype.isOdd = function isOdd() {
+  return (this.words[0] & 1) === 1;
+};
+
+// And first word and num
+BN.prototype.andln = function andln(num) {
+  return this.words[0] & num;
+};
+
+// Increment at the bit position in-line
+BN.prototype.bincn = function bincn(bit) {
+  assert(typeof bit === "number");
+  var r = bit % 26;
+  var s = (bit - r) / 26;
+  var q = 1 << r;
+
+  // Fast case: bit is much higher than all existing words
+  if (this.length <= s) {
+    this._expand(s + 1);
+    this.words[s] |= q;
+    return this;
+  }
+
+  // Add bit and propagate, if needed
+  var carry = q;
+  for (var i = s; carry !== 0 && i < this.length; i++) {
+    var w = this.words[i] | 0;
+    w += carry;
+    carry = w >>> 26;
+    w &= 0x3ffffff;
+    this.words[i] = w;
+  }
+  if (carry !== 0) {
+    this.words[i] = carry;
+    this.length++;
+  }
+  return this;
+};
+
+BN.prototype.isZero = function isZero() {
+  return this.length === 1 && this.words[0] === 0;
+};
+
+BN.prototype.cmpn = function cmpn(num) {
+  var negative = num < 0;
+
+  if (this.negative !== 0 && !negative) return -1;
+  if (this.negative === 0 && negative) return 1;
+
+  this._strip();
+
+  var res;
+  if (this.length > 1) {
+    res = 1;
+  } else {
+    if (negative) {
+      num = -num;
+    }
+
+    assert(num <= 0x3ffffff, "Number is too big");
+
+    var w = this.words[0] | 0;
+    res = w === num ? 0 : w < num ? -1 : 1;
+  }
+  if (this.negative !== 0) return -res | 0;
+  return res;
+};
+
+// Compare two numbers and return:
+// 1 - if `this` > `num`
+// 0 - if `this` == `num`
+// -1 - if `this` < `num`
+BN.prototype.cmp = function cmp(num) {
+  if (this.negative !== 0 && num.negative === 0) return -1;
+  if (this.negative === 0 && num.negative !== 0) return 1;
+
+  var res = this.ucmp(num);
+  if (this.negative !== 0) return -res | 0;
+  return res;
+};
+
+// Unsigned comparison
+BN.prototype.ucmp = function ucmp(num) {
+  // At this point both numbers have the same sign
+  if (this.length > num.length) return 1;
+  if (this.length < num.length) return -1;
+
+  var res = 0;
+  for (var i = this.length - 1; i >= 0; i--) {
+    var a = this.words[i] | 0;
+    var b = num.words[i] | 0;
+
+    if (a === b) continue;
+    if (a < b) {
+      res = -1;
+    } else if (a > b) {
+      res = 1;
+    }
+    break;
+  }
+  return res;
+};
+
+BN.prototype.gtn = function gtn(num) {
+  return this.cmpn(num) === 1;
+};
+
+BN.prototype.gt = function gt(num) {
+  return this.cmp(num) === 1;
+};
+
+BN.prototype.gten = function gten(num) {
+  return this.cmpn(num) >= 0;
+};
+
+BN.prototype.gte = function gte(num) {
+  return this.cmp(num) >= 0;
+};
+
+BN.prototype.ltn = function ltn(num) {
+  return this.cmpn(num) === -1;
+};
+
+BN.prototype.lt = function lt(num) {
+  return this.cmp(num) === -1;
+};
+
+BN.prototype.lten = function lten(num) {
+  return this.cmpn(num) <= 0;
+};
+
+BN.prototype.lte = function lte(num) {
+  return this.cmp(num) <= 0;
+};
+
+BN.prototype.eqn = function eqn(num) {
+  return this.cmpn(num) === 0;
+};
+
+BN.prototype.eq = function eq(num) {
+  return this.cmp(num) === 0;
+};
+
+//
+// A reduce context, could be using montgomery or something better, depending
+// on the `m` itself.
+//
+BN.red = function red(num) {
+  return new Red(num);
+};
+
+BN.prototype.toRed = function toRed(ctx) {
+  assert(!this.red, "Already a number in reduction context");
+  assert(this.negative === 0, "red works only with positives");
+  return ctx.convertTo(this)._forceRed(ctx);
+};
+
+BN.prototype.fromRed = function fromRed() {
+  assert(this.red, "fromRed works only with numbers in reduction context");
+  return this.red.convertFrom(this);
+};
+
+BN.prototype._forceRed = function _forceRed(ctx) {
+  this.red = ctx;
+  return this;
+};
+
+BN.prototype.forceRed = function forceRed(ctx) {
+  assert(!this.red, "Already a number in reduction context");
+  return this._forceRed(ctx);
+};
+
+BN.prototype.redAdd = function redAdd(num) {
+  assert(this.red, "redAdd works only with red numbers");
+  return this.red.add(this, num);
+};
+
+BN.prototype.redIAdd = function redIAdd(num) {
+  assert(this.red, "redIAdd works only with red numbers");
+  return this.red.iadd(this, num);
+};
+
+BN.prototype.redSub = function redSub(num) {
+  assert(this.red, "redSub works only with red numbers");
+  return this.red.sub(this, num);
+};
+
+BN.prototype.redISub = function redISub(num) {
+  assert(this.red, "redISub works only with red numbers");
+  return this.red.isub(this, num);
+};
+
+BN.prototype.redShl = function redShl(num) {
+  assert(this.red, "redShl works only with red numbers");
+  return this.red.shl(this, num);
+};
+
+BN.prototype.redMul = function redMul(num) {
+  assert(this.red, "redMul works only with red numbers");
+  this.red._verify2(this, num);
+  return this.red.mul(this, num);
+};
+
+BN.prototype.redIMul = function redIMul(num) {
+  assert(this.red, "redMul works only with red numbers");
+  this.red._verify2(this, num);
+  return this.red.imul(this, num);
+};
+
+BN.prototype.redSqr = function redSqr() {
+  assert(this.red, "redSqr works only with red numbers");
+  this.red._verify1(this);
+  return this.red.sqr(this);
+};
+
+BN.prototype.redISqr = function redISqr() {
+  assert(this.red, "redISqr works only with red numbers");
+  this.red._verify1(this);
+  return this.red.isqr(this);
+};
+
+// Square root over p
+BN.prototype.redSqrt = function redSqrt() {
+  assert(this.red, "redSqrt works only with red numbers");
+  this.red._verify1(this);
+  return this.red.sqrt(this);
+};
+
+BN.prototype.redInvm = function redInvm() {
+  assert(this.red, "redInvm works only with red numbers");
+  this.red._verify1(this);
+  return this.red.invm(this);
+};
+
+// Return negative clone of `this` % `red modulo`
+BN.prototype.redNeg = function redNeg() {
+  assert(this.red, "redNeg works only with red numbers");
+  this.red._verify1(this);
+  return this.red.neg(this);
+};
+
+BN.prototype.redPow = function redPow(num) {
+  assert(this.red && !num.red, "redPow(normalNum)");
+  this.red._verify1(this);
+  return this.red.pow(this, num);
+};
+
+// Prime numbers with efficient reduction
+var primes = {
+  k256: null,
+  p224: null,
+  p192: null,
+  p25519: null,
+};
+
+// Pseudo-Mersenne prime
+function MPrime(name, p) {
+  // P = 2 ^ N - K
+  this.name = name;
+  this.p = new BN(p, 16);
+  this.n = this.p.bitLength();
+  this.k = new BN(1).iushln(this.n).isub(this.p);
+
+  this.tmp = this._tmp();
+}
+
+MPrime.prototype._tmp = function _tmp() {
+  var tmp = new BN(null);
+  tmp.words = new Array(Math.ceil(this.n / 13));
+  return tmp;
+};
+
+MPrime.prototype.ireduce = function ireduce(num) {
+  // Assumes that `num` is less than `P^2`
+  // num = HI * (2 ^ N - K) + HI * K + LO = HI * K + LO (mod P)
+  var r = num;
+  var rlen;
+
+  do {
+    this.split(r, this.tmp);
+    r = this.imulK(r);
+    r = r.iadd(this.tmp);
+    rlen = r.bitLength();
+  } while (rlen > this.n);
+
+  var cmp = rlen < this.n ? -1 : r.ucmp(this.p);
+  if (cmp === 0) {
+    r.words[0] = 0;
+    r.length = 1;
+  } else if (cmp > 0) {
+    r.isub(this.p);
+  } else {
+    if (r.strip !== undefined) {
+      // r is a BN v4 instance
+      r.strip();
+    } else {
+      // r is a BN v5 instance
+      r._strip();
+    }
+  }
+
+  return r;
+};
+
+MPrime.prototype.split = function split(input, out) {
+  input.iushrn(this.n, 0, out);
+};
+
+MPrime.prototype.imulK = function imulK(num) {
+  return num.imul(this.k);
+};
+
+function K256() {
+  MPrime.call(
+    this,
+    "k256",
+    "ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff fffffffe fffffc2f",
+  );
+}
+inherits(K256, MPrime);
+
+K256.prototype.split = function split(input, output) {
+  // 256 = 9 * 26 + 22
+  var mask = 0x3fffff;
+
+  var outLen = Math.min(input.length, 9);
+  for (var i = 0; i < outLen; i++) {
+    output.words[i] = input.words[i];
+  }
+  output.length = outLen;
+
+  if (input.length <= 9) {
+    input.words[0] = 0;
+    input.length = 1;
+    return;
+  }
+
+  // Shift by 9 limbs
+  var prev = input.words[9];
+  output.words[output.length++] = prev & mask;
+
+  for (i = 10; i < input.length; i++) {
+    var next = input.words[i] | 0;
+    input.words[i - 10] = ((next & mask) << 4) | (prev >>> 22);
+    prev = next;
+  }
+  prev >>>= 22;
+  input.words[i - 10] = prev;
+  if (prev === 0 && input.length > 10) {
+    input.length -= 10;
+  } else {
+    input.length -= 9;
+  }
+};
+
+K256.prototype.imulK = function imulK(num) {
+  // K = 0x1000003d1 = [ 0x40, 0x3d1 ]
+  num.words[num.length] = 0;
+  num.words[num.length + 1] = 0;
+  num.length += 2;
+
+  // bounded at: 0x40 * 0x3ffffff + 0x3d0 = 0x100000390
+  var lo = 0;
+  for (var i = 0; i < num.length; i++) {
+    var w = num.words[i] | 0;
+    lo += w * 0x3d1;
+    num.words[i] = lo & 0x3ffffff;
+    lo = w * 0x40 + ((lo / 0x4000000) | 0);
+  }
+
+  // Fast length reduction
+  if (num.words[num.length - 1] === 0) {
+    num.length--;
+    if (num.words[num.length - 1] === 0) {
+      num.length--;
+    }
+  }
+  return num;
+};
+
+function P224() {
+  MPrime.call(
+    this,
+    "p224",
+    "ffffffff ffffffff ffffffff ffffffff 00000000 00000000 00000001",
+  );
+}
+inherits(P224, MPrime);
+
+function P192() {
+  MPrime.call(
+    this,
+    "p192",
+    "ffffffff ffffffff ffffffff fffffffe ffffffff ffffffff",
+  );
+}
+inherits(P192, MPrime);
+
+function P25519() {
+  // 2 ^ 255 - 19
+  MPrime.call(
+    this,
+    "25519",
+    "7fffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffed",
+  );
+}
+inherits(P25519, MPrime);
+
+P25519.prototype.imulK = function imulK(num) {
+  // K = 0x13
+  var carry = 0;
+  for (var i = 0; i < num.length; i++) {
+    var hi = (num.words[i] | 0) * 0x13 + carry;
+    var lo = hi & 0x3ffffff;
+    hi >>>= 26;
+
+    num.words[i] = lo;
+    carry = hi;
+  }
+  if (carry !== 0) {
+    num.words[num.length++] = carry;
+  }
+  return num;
+};
+
+// Exported mostly for testing purposes, use plain name instead
+BN._prime = function prime(name) {
+  // Cached version of prime
+  if (primes[name]) return primes[name];
+
+  var prime;
+  if (name === "k256") {
+    prime = new K256();
+  } else if (name === "p224") {
+    prime = new P224();
+  } else if (name === "p192") {
+    prime = new P192();
+  } else if (name === "p25519") {
+    prime = new P25519();
+  } else {
+    throw new Error("Unknown prime " + name);
+  }
+  primes[name] = prime;
+
+  return prime;
+};
+
+//
+// Base reduction engine
+//
+function Red(m) {
+  if (typeof m === "string") {
+    var prime = BN._prime(m);
+    this.m = prime.p;
+    this.prime = prime;
+  } else {
+    assert(m.gtn(1), "modulus must be greater than 1");
+    this.m = m;
+    this.prime = null;
+  }
+}
+
+Red.prototype._verify1 = function _verify1(a) {
+  assert(a.negative === 0, "red works only with positives");
+  assert(a.red, "red works only with red numbers");
+};
+
+Red.prototype._verify2 = function _verify2(a, b) {
+  assert((a.negative | b.negative) === 0, "red works only with positives");
+  assert(a.red && a.red === b.red, "red works only with red numbers");
+};
+
+Red.prototype.imod = function imod(a) {
+  if (this.prime) return this.prime.ireduce(a)._forceRed(this);
+
+  move(a, a.umod(this.m)._forceRed(this));
+  return a;
+};
+
+Red.prototype.neg = function neg(a) {
+  if (a.isZero()) {
+    return a.clone();
+  }
+
+  return this.m.sub(a)._forceRed(this);
+};
+
+Red.prototype.add = function add(a, b) {
+  this._verify2(a, b);
+
+  var res = a.add(b);
+  if (res.cmp(this.m) >= 0) {
+    res.isub(this.m);
+  }
+  return res._forceRed(this);
+};
+
+Red.prototype.iadd = function iadd(a, b) {
+  this._verify2(a, b);
+
+  var res = a.iadd(b);
+  if (res.cmp(this.m) >= 0) {
+    res.isub(this.m);
+  }
+  return res;
+};
+
+Red.prototype.sub = function sub(a, b) {
+  this._verify2(a, b);
+
+  var res = a.sub(b);
+  if (res.cmpn(0) < 0) {
+    res.iadd(this.m);
+  }
+  return res._forceRed(this);
+};
+
+Red.prototype.isub = function isub(a, b) {
+  this._verify2(a, b);
+
+  var res = a.isub(b);
+  if (res.cmpn(0) < 0) {
+    res.iadd(this.m);
+  }
+  return res;
+};
+
+Red.prototype.shl = function shl(a, num) {
+  this._verify1(a);
+  return this.imod(a.ushln(num));
+};
+
+Red.prototype.imul = function imul(a, b) {
+  this._verify2(a, b);
+  return this.imod(a.imul(b));
+};
+
+Red.prototype.mul = function mul(a, b) {
+  this._verify2(a, b);
+  return this.imod(a.mul(b));
+};
+
+Red.prototype.isqr = function isqr(a) {
+  return this.imul(a, a.clone());
+};
+
+Red.prototype.sqr = function sqr(a) {
+  return this.mul(a, a);
+};
+
+Red.prototype.sqrt = function sqrt(a) {
+  if (a.isZero()) return a.clone();
+
+  var mod3 = this.m.andln(3);
+  assert(mod3 % 2 === 1);
+
+  // Fast case
+  if (mod3 === 3) {
+    var pow = this.m.add(new BN(1)).iushrn(2);
+    return this.pow(a, pow);
+  }
+
+  // Tonelli-Shanks algorithm (Totally unoptimized and slow)
+  //
+  // Find Q and S, that Q * 2 ^ S = (P - 1)
+  var q = this.m.subn(1);
+  var s = 0;
+  while (!q.isZero() && q.andln(1) === 0) {
+    s++;
+    q.iushrn(1);
+  }
+  assert(!q.isZero());
+
+  var one = new BN(1).toRed(this);
+  var nOne = one.redNeg();
+
+  // Find quadratic non-residue
+  // NOTE: Max is such because of generalized Riemann hypothesis.
+  var lpow = this.m.subn(1).iushrn(1);
+  var z = this.m.bitLength();
+  z = new BN(2 * z * z).toRed(this);
+
+  while (this.pow(z, lpow).cmp(nOne) !== 0) {
+    z.redIAdd(nOne);
+  }
+
+  var c = this.pow(z, q);
+  var r = this.pow(a, q.addn(1).iushrn(1));
+  var t = this.pow(a, q);
+  var m = s;
+  while (t.cmp(one) !== 0) {
+    var tmp = t;
+    for (var i = 0; tmp.cmp(one) !== 0; i++) {
+      tmp = tmp.redSqr();
+    }
+    assert(i < m);
+    var b = this.pow(c, new BN(1).iushln(m - i - 1));
+
+    r = r.redMul(b);
+    c = b.redSqr();
+    t = t.redMul(c);
+    m = i;
+  }
+
+  return r;
+};
+
+Red.prototype.invm = function invm(a) {
+  var inv = a._invmp(this.m);
+  if (inv.negative !== 0) {
+    inv.negative = 0;
+    return this.imod(inv).redNeg();
+  } else {
+    return this.imod(inv);
+  }
+};
+
+Red.prototype.pow = function pow(a, num) {
+  if (num.isZero()) return new BN(1).toRed(this);
+  if (num.cmpn(1) === 0) return a.clone();
+
+  var windowSize = 4;
+  var wnd = new Array(1 << windowSize);
+  wnd[0] = new BN(1).toRed(this);
+  wnd[1] = a;
+  for (var i = 2; i < wnd.length; i++) {
+    wnd[i] = this.mul(wnd[i - 1], a);
+  }
+
+  var res = wnd[0];
+  var current = 0;
+  var currentLen = 0;
+  var start = num.bitLength() % 26;
+  if (start === 0) {
+    start = 26;
+  }
+
+  for (i = num.length - 1; i >= 0; i--) {
+    var word = num.words[i];
+    for (var j = start - 1; j >= 0; j--) {
+      var bit = (word >> j) & 1;
+      if (res !== wnd[0]) {
+        res = this.sqr(res);
+      }
+
+      if (bit === 0 && current === 0) {
+        currentLen = 0;
+        continue;
+      }
+
+      current <<= 1;
+      current |= bit;
+      currentLen++;
+      if (currentLen !== windowSize && (i !== 0 || j !== 0)) continue;
+
+      res = this.mul(res, wnd[current]);
+      currentLen = 0;
+      current = 0;
+    }
+    start = 26;
+  }
+
+  return res;
+};
+
+Red.prototype.convertTo = function convertTo(num) {
+  var r = num.umod(this.m);
+
+  return r === num ? r.clone() : r;
+};
+
+Red.prototype.convertFrom = function convertFrom(num) {
+  var res = num.clone();
+  res.red = null;
+  return res;
+};
+
+//
+// Montgomery method engine
+//
+
+BN.mont = function mont(num) {
+  return new Mont(num);
+};
+
+function Mont(m) {
+  Red.call(this, m);
+
+  this.shift = this.m.bitLength();
+  if (this.shift % 26 !== 0) {
+    this.shift += 26 - (this.shift % 26);
+  }
+
+  this.r = new BN(1).iushln(this.shift);
+  this.r2 = this.imod(this.r.sqr());
+  this.rinv = this.r._invmp(this.m);
+
+  this.minv = this.rinv.mul(this.r).isubn(1).div(this.m);
+  this.minv = this.minv.umod(this.r);
+  this.minv = this.r.sub(this.minv);
+}
+inherits(Mont, Red);
+
+Mont.prototype.convertTo = function convertTo(num) {
+  return this.imod(num.ushln(this.shift));
+};
+
+Mont.prototype.convertFrom = function convertFrom(num) {
+  var r = this.imod(num.mul(this.rinv));
+  r.red = null;
+  return r;
+};
+
+Mont.prototype.imul = function imul(a, b) {
+  if (a.isZero() || b.isZero()) {
+    a.words[0] = 0;
+    a.length = 1;
+    return a;
+  }
+
+  var t = a.imul(b);
+  var c = t.maskn(this.shift).mul(this.minv).imaskn(this.shift).mul(this.m);
+  var u = t.isub(c).iushrn(this.shift);
+  var res = u;
+
+  if (u.cmp(this.m) >= 0) {
+    res = u.isub(this.m);
+  } else if (u.cmpn(0) < 0) {
+    res = u.iadd(this.m);
+  }
+
+  return res._forceRed(this);
+};
+
+Mont.prototype.mul = function mul(a, b) {
+  if (a.isZero() || b.isZero()) return new BN(0)._forceRed(this);
+
+  var t = a.mul(b);
+  var c = t.maskn(this.shift).mul(this.minv).imaskn(this.shift).mul(this.m);
+  var u = t.isub(c).iushrn(this.shift);
+  var res = u;
+  if (u.cmp(this.m) >= 0) {
+    res = u.isub(this.m);
+  } else if (u.cmpn(0) < 0) {
+    res = u.iadd(this.m);
+  }
+
+  return res._forceRed(this);
+};
+
+Mont.prototype.invm = function invm(a) {
+  // (AR)^-1 * R^2 = (A^-1 * R^-1) * R^2 = A^-1 * R
+  var res = this.imod(a._invmp(this.m).mul(this.r2));
+  return res._forceRed(this);
+};