Enhancement. Fast mulmod method

[username1565]

Hello, Peter Olson! Can you add in your free time, fast multiply mod method, aka Montgomery trick: https://en.wikipedia.org/wiki/Montgomery_modular_multiplication

You can see source code here: https://github.com/indutny/bn.js/blob/master/lib/bn.js function BN.mont() and rewrite this for your bigInt-library.

[username1565]

Also, this is available, here, in the peercoin paperwallet: https://github.com/Elbandi/peercoin-walletgenerator/blob/master/src/biginteger.js

[gardhr]

You're overoptimizing.

Just need a faster machine!

[username1565]

What do you mean in picture? Mulmod is not multiple or square function. This is fast method for multiple and mod then. In many bigInteger libraries this function is named as mulmod ("x*x%n") As you can see by last link at line 1179, there is many functions:

//1. Montgomery reduction
function Montgomery(m){/*code*/}
//2. xR mod m
Montgomery.prototype.convert = function (x) {/*code*/}
//3. x/R mod m
Montgomery.prototype.revert = function (x) {/*code*/}
//4. x = x/R mod m (HAC 14.32)
Montgomery.prototype.reduce = function (x) {/*code*/}
//5. r = "xy/R mod m"; x,y != r
Montgomery.prototype.mulTo = function (x, y, r) {/*code*/}
//r = "x^2/R mod m"; x != r
Montgomery.prototype.sqrTo = function (x, r) {/*code*/}

Also, you can see there Barrett modular reduction, (at line 1241) and Modular reduction using "classic" algorithm, (at line 1164)

[peterolson]

BigInteger.js is not designed to be a fully-featured number theory library. A very small percentage of the users of this library would ever use a mulMod function, so I probably won't be adding this.