covid-certificate/lib/parse/base45.js

Parse and verify a european digital covid certificate (dcc)

"use strict";
// https://github.com/irony/base45/blob/main/lib/base45.js
Object.defineProperty(exports, "__esModule", { value: true });
exports.decode = void 0;
const buffer_1 = require("buffer");
const CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";
const divmod = (x, y) => [Math.floor(x / y), x % y];
/**
 * Decode a base45 encoded string
 *
 * @param input
 */
const decode = (input) => {
    const buffer = Array.from(input).map((c) => CHARSET.indexOf(c));
    const res = [];
    for (let i = 0; i < buffer.length; i = i + 3) {
        if (buffer.length - i >= 3) {
            const x = buffer[i] + buffer[i + 1] * 45 + buffer[i + 2] * 45 * 45;
            if (x > 0xffff) {
                throw new Error("Invalid base45 string");
            }
            res.push(...divmod(x, 256));
        }
        else {
            const x = buffer[i] + buffer[i + 1] * 45;
            if (x > 0xff) {
                throw new Error("Invalid base45 string");
            }
            res.push(x);
        }
    }
    return buffer_1.Buffer.from(res);
};
exports.decode = decode;