KANGAROO: function()

in src/mpin.js [882:932]
48 lines of code
9 McCabe index (conditional complexity)

        KANGAROO: function(E, F) {
            var ge = ctx.FP12.fromBytes(E),
                gf = ctx.FP12.fromBytes(F),
                distance = [],
                t = new ctx.FP12(gf),
                table = [],
                i, j, m, s, dn, dm, res, steps;

            s = 1;
            for (m = 0; m < this.TS; m++) {
                distance[m] = s;
                table[m] = new ctx.FP12(t);
                s *= 2;
                t.usqr();
            }
            t.one();
            dn = 0;
            for (j = 0; j < this.TRAP; j++) {
                i = t.geta().geta().getA().lastbits(20) % this.TS;
                t.mul(table[i]);
                dn += distance[i];
            }
            gf.copy(t);
            gf.conj();
            steps = 0;
            dm = 0;
            res = 0;
            while (dm - dn < this.MAXPIN) {
                steps++;
                if (steps > 4 * this.TRAP) {
                    break;
                }
                i = ge.geta().geta().getA().lastbits(20) % this.TS;
                ge.mul(table[i]);
                dm += distance[i];
                if (ge.equals(t)) {
                    res = dm - dn;
                    break;
                }
                if (ge.equals(gf)) {
                    res = dn - dm;
                    break;
                }

            }
            if (steps > 4 * this.TRAP || dm - dn >= this.MAXPIN) {
                res = 0;
            } // Trap Failed  - probable invalid token

            return res;
        },