From 19aa9ad6a3842962178b71b7af685c8c4edd20eb Mon Sep 17 00:00:00 2001
From: pdlan <pengdinglan@gmail.com>
Date: Tue, 5 Apr 2022 02:40:47 -0400
Subject: [PATCH] Remove bigint-mod-arith.js

---
 core/rfb.js                   |  15 +-
 core/util/bigint-mod-arith.js | 283 ----------------------------------
 2 files changed, 13 insertions(+), 285 deletions(-)
 delete mode 100644 core/util/bigint-mod-arith.js

diff --git a/core/rfb.js b/core/rfb.js
index 83cfce77..121d9e5e 100644
--- a/core/rfb.js
+++ b/core/rfb.js
@@ -27,7 +27,6 @@ import XtScancode from "./input/xtscancodes.js";
 import { encodings } from "./encodings.js";
 import RSAAESAuthenticationState from "./ra2.js";
 import { MD5 } from "./util/md5.js";
-import { modPow } from "./util/bigint-mod-arith.js";
 
 import RawDecoder from "./decoders/raw.js";
 import CopyRectDecoder from "./decoders/copyrect.js";
@@ -1595,7 +1594,19 @@ export default class RFB extends EventTargetMixin {
         let exponentHex = "0x"+Array.from(exponent, byte => ('0' + (byte & 0xFF).toString(16)).slice(-2)).join('');
         let modulusHex = "0x"+Array.from(modulus, byte => ('0' + (byte & 0xFF).toString(16)).slice(-2)).join('');
 
-        let hexResult = modPow(BigInt(baseHex), BigInt(exponentHex), BigInt(modulusHex)).toString(16);
+        let b = BigInt(baseHex);
+        let e = BigInt(exponentHex);
+        let m = BigInt(modulusHex);
+        let r = 1n;
+        b = b % m;
+        while (e > 0) {
+            if (e % 2n === 1n) {
+                r = (r * b) % m;
+            }
+            e = e / 2n;
+            b = (b * b) % m;
+        }
+        let hexResult = r.toString(16);
 
         while (hexResult.length/2<exponent.length || (hexResult.length%2 != 0)) {
             hexResult = "0"+hexResult;
diff --git a/core/util/bigint-mod-arith.js b/core/util/bigint-mod-arith.js
deleted file mode 100644
index beffd430..00000000
--- a/core/util/bigint-mod-arith.js
+++ /dev/null
@@ -1,283 +0,0 @@
-/*
- * bigint-mod-arith implementation:
- *    https://github.com/juanelas/bigint-mod-arith
- *
- * Full attribution follows:
- *
- * -------------------------------------------------------------------------
- *
- * MIT License
- *
- * Copyright (c) 2018 Juan Hernández Serrano
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all
- * copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
- *
-*/
-
-/**
- * Absolute value. abs(a)==a if a>=0. abs(a)==-a if a<0
- *
- * @param a
- *
- * @returns The absolute value of a
- */
-function abs(a) {
-    return (a >= 0) ? a : -a;
-}
-
-/**
- * Returns the bitlength of a number
- *
- * @param a
- * @returns The bit length
- */
-function bitLength(a) {
-    if (typeof a === 'number') {
-        a = BigInt(a);
-    }
-    if (a === 1n) {
-        return 1;
-    }
-    let bits = 1;
-    do {
-        bits++;
-    } while ((a >>= 1n) > 1n);
-    return bits;
-}
-
-/**
- * An iterative implementation of the extended euclidean algorithm or extended greatest common divisor algorithm.
- * Take positive integers a, b as input, and return a triple (g, x, y), such that ax + by = g = gcd(a, b).
- *
- * @param a
- * @param b
- *
- * @throws {RangeError}
- * This excepction is thrown if a or b are less than 0
- *
- * @returns A triple (g, x, y), such that ax + by = g = gcd(a, b).
- */
-function eGcd(a, b) {
-    if (typeof a === 'number') {
-        a = BigInt(a);
-    }
-    if (typeof b === 'number') {
-        b = BigInt(b);
-    }
-    if (a <= 0n || b <= 0n) {
-        throw new RangeError('a and b MUST be > 0'); // a and b MUST be positive
-    }
-    let x = 0n;
-    let y = 1n;
-    let u = 1n;
-    let v = 0n;
-    while (a !== 0n) {
-        const q = b / a;
-        const r = b % a;
-        const m = x - (u * q);
-        const n = y - (v * q);
-        b = a;
-        a = r;
-        x = u;
-        y = v;
-        u = m;
-        v = n;
-    }
-    return {
-        g: b,
-        x: x,
-        y: y
-    };
-}
-
-/**
- * Greatest-common divisor of two integers based on the iterative binary algorithm.
- *
- * @param a
- * @param b
- *
- * @returns The greatest common divisor of a and b
- */
-function gcd(a, b) {
-    let aAbs = (typeof a === 'number') ? BigInt(abs(a)) : abs(a);
-    let bAbs = (typeof b === 'number') ? BigInt(abs(b)) : abs(b);
-    if (aAbs === 0n) {
-        return bAbs;
-    } else if (bAbs === 0n) {
-        return aAbs;
-    }
-    let shift = 0n;
-    while (((aAbs | bAbs) & 1n) === 0n) {
-        aAbs >>= 1n;
-        bAbs >>= 1n;
-        shift++;
-    }
-    while ((aAbs & 1n) === 0n) {
-        aAbs >>= 1n;
-    }
-    do {
-        while ((bAbs & 1n) === 0n) {
-            bAbs >>= 1n;
-        }
-        if (aAbs > bAbs) {
-            const x = aAbs;
-            aAbs = bAbs;
-            bAbs = x;
-        }
-        bAbs -= aAbs;
-    } while (bAbs !== 0n);
-    // rescale
-    return aAbs << shift;
-}
-
-/**
- * The least common multiple computed as abs(a*b)/gcd(a,b)
- * @param a
- * @param b
- *
- * @returns The least common multiple of a and b
- */
-function lcm(a, b) {
-    if (typeof a === 'number') {
-        a = BigInt(a);
-    }
-    if (typeof b === 'number') {
-        b = BigInt(b);
-    }
-    if (a === 0n && b === 0n) {
-        return BigInt(0);
-    }
-    return abs(a * b) / gcd(a, b);
-}
-
-/**
- * Maximum. max(a,b)==a if a>=b. max(a,b)==b if a<=b
- *
- * @param a
- * @param b
- *
- * @returns Maximum of numbers a and b
- */
-function max(a, b) {
-    return (a >= b) ? a : b;
-}
-
-/**
- * Minimum. min(a,b)==b if a>=b. min(a,b)==a if a<=b
- *
- * @param a
- * @param b
- *
- * @returns Minimum of numbers a and b
- */
-function min(a, b) {
-    return (a >= b) ? b : a;
-}
-
-/**
- * Finds the smallest positive element that is congruent to a in modulo n
- *
- * @remarks
- * a and b must be the same type, either number or bigint
- *
- * @param a - An integer
- * @param n - The modulo
- *
- * @throws {RangeError}
- * Excpeption thrown when n is not > 0
- *
- * @returns A bigint with the smallest positive representation of a modulo n
- */
-function toZn(a, n) {
-    if (typeof a === 'number') {
-        a = BigInt(a);
-    }
-    if (typeof n === 'number') {
-        n = BigInt(n);
-    }
-    if (n <= 0n) {
-        throw new RangeError('n must be > 0');
-    }
-    const aZn = a % n;
-    return (aZn < 0n) ? aZn + n : aZn;
-}
-
-/**
- * Modular inverse.
- *
- * @param a The number to find an inverse for
- * @param n The modulo
- *
- * @throws {RangeError}
- * Excpeption thorwn when a does not have inverse modulo n
- *
- * @returns The inverse modulo n
- */
-function modInv(a, n) {
-    const egcd = eGcd(toZn(a, n), n);
-    if (egcd.g !== 1n) {
-        throw new RangeError(`${a.toString()} does not have inverse modulo ${n.toString()}`); // modular inverse does not exist
-    } else {
-        return toZn(egcd.x, n);
-    }
-}
-
-/**
- * Modular exponentiation b**e mod n. Currently using the right-to-left binary method
- *
- * @param b base
- * @param e exponent
- * @param n modulo
- *
- * @throws {RangeError}
- * Excpeption thrown when n is not > 0
- *
- * @returns b**e mod n
- */
-function modPow(b, e, n) {
-    if (typeof b === 'number') {
-        b = BigInt(b);
-    }
-    if (typeof e === 'number') {
-        e = BigInt(e);
-    }
-    if (typeof n === 'number') {
-        n = BigInt(n);
-    }
-    if (n <= 0n) {
-        throw new RangeError('n must be > 0');
-    } else if (n === 1n) {
-        return 0n;
-    }
-    b = toZn(b, n);
-    if (e < 0n) {
-        return modInv(modPow(b, abs(e), n), n);
-    }
-    let r = 1n;
-    while (e > 0) {
-        if ((e % 2n) === 1n) {
-            r = r * b % n;
-        }
-        e = e / 2n;
-        b = b ** 2n % n;
-    }
-    return r;
-}
-
-export { abs, bitLength, eGcd, gcd, lcm, max, min, modInv, modPow, toZn };
\ No newline at end of file