Riskless/static/js/modules/crypto/math.js

export function mod_exp(a, b, n) {
    let res = 1n;

    while (b > 0n) {
        if (b % 2n === 1n) {
            res = (res * a) % n;
        }

        b >>= 1n;
        a = (a * a) % n;
    }

    return res;
}

export function mod_inv(a, n) {
    let t = 0n;
    let new_t = 1n;
    let r = n;
    let new_r = a;

    while (new_r !== 0n) {
        let quotient = r / new_r;
        t = new_t;
        new_t = t - quotient * new_t;
        r = new_r;
        new_r = r - quotient * new_r;
    }

    if (t < 0) {
        t = t + n;
    }

    return t;
}