snarkjs/src/futils.js

/*
    Copyright 2018 0kims association

    This file is part of zksnark javascript library.

    zksnark javascript library is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    zksnark javascript library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with zksnark javascript library.  If not, see <https://www.gnu.org/licenses/>.
*/
const bigInt = require("./bigint.js");

exports.mulScalar = (F, base, e) =>{
    let res = F.zero;
    let rem = bigInt(e);
    let exp = base;

    while (! rem.isZero()) {
        if (rem.isOdd()) {
            res = F.add(res, exp);
        }
        exp = F.double(exp);
        rem = rem.shr(1);
    }

    return res;
};


exports.exp = (F, base, e) =>{
    let res = F.one;
    let rem = bigInt(e);
    let exp = base;

    while (! rem.isZero()) {
        if (rem.isOdd()) {
            res = F.mul(res, exp);
        }
        exp = F.square(exp);
        rem = rem.shr(1);
    }

    return res;
};