wxmp-rsa/dist/lib/jsbn/base64.js

兼容小程序环境的rsa加解密库，支持超长文本和中文字符

import { int2char } from "./util";
var b64map = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var b64pad = "=";
export function hex2b64(h) {
    var i;
    var c;
    var ret = "";
    for (i = 0; i + 3 <= h.length; i += 3) {
        c = parseInt(h.substring(i, i + 3), 16);
        ret += b64map.charAt(c >> 6) + b64map.charAt(c & 63);
    }
    if (i + 1 == h.length) {
        c = parseInt(h.substring(i, i + 1), 16);
        ret += b64map.charAt(c << 2);
    }
    else if (i + 2 == h.length) {
        c = parseInt(h.substring(i, i + 2), 16);
        ret += b64map.charAt(c >> 2) + b64map.charAt((c & 3) << 4);
    }
    while ((ret.length & 3) > 0) {
        ret += b64pad;
    }
    return ret;
}
// convert a base64 string to hex
export function b64tohex(s) {
    var ret = "";
    var i;
    var k = 0; // b64 state, 0-3
    var slop = 0;
    for (i = 0; i < s.length; ++i) {
        if (s.charAt(i) == b64pad) {
            break;
        }
        var v = b64map.indexOf(s.charAt(i));
        if (v < 0) {
            continue;
        }
        if (k == 0) {
            ret += int2char(v >> 2);
            slop = v & 3;
            k = 1;
        }
        else if (k == 1) {
            ret += int2char((slop << 2) | (v >> 4));
            slop = v & 0xf;
            k = 2;
        }
        else if (k == 2) {
            ret += int2char(slop);
            ret += int2char(v >> 2);
            slop = v & 3;
            k = 3;
        }
        else {
            ret += int2char((slop << 2) | (v >> 4));
            ret += int2char(v & 0xf);
            k = 0;
        }
    }
    if (k == 1) {
        ret += int2char(slop << 2);
    }
    return ret;
}
// convert a base64 string to a byte/number array
export function b64toBA(s) {
    // piggyback on b64tohex for now, optimize later
    var h = b64tohex(s);
    var i;
    var a = [];
    for (i = 0; 2 * i < h.length; ++i) {
        a[i] = parseInt(h.substring(2 * i, 2 * i + 2), 16);
    }
    return a;
}