JavaScript Base64 解密方法

最新推荐文章于 2024-09-12 16:29:05 发布

diaoquan4385

最新推荐文章于 2024-09-12 16:29:05 发布

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文章标签： javascript ViewUI

原文链接：http://www.cnblogs.com/hanf/archive/2012/02/25/2367928.html

版权

    var END_OF_INPUT = -1;
var base64Chars = new Array("A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "+", "/");
var reverseBase64Chars = new Array();
for (var i = 0; i < base64Chars.length; i++) {
        reverseBase64Chars[base64Chars[i]] = i
    }
var base64Str;
var base64Count;
function setBase64Str(a) {
        base64Str = a;
        base64Count = 0
    }
function readReverseBase64() {
if (!base64Str) {
return END_OF_INPUT
        }
while (true) {
if (base64Count >= base64Str.length) {
return END_OF_INPUT
            }
var a = base64Str.charAt(base64Count);
            base64Count++;
if (reverseBase64Chars[a]) {
return reverseBase64Chars[a]
            }
if (a == "A") {
return 0
            }
        }
return END_OF_INPUT
    }
function ntos(a) {
        a = a.toString(16);
if (a.length == 1) {
            a = "0" + a
        }
        a = "%" + a;
return unescape(a)
    }
function decodeBase64(d) {
        setBase64Str(d);
var a = "";
var c = new Array(4);
var b = false;
while (!b && (c[0] = readReverseBase64()) != END_OF_INPUT && (c[1] = readReverseBase64()) != END_OF_INPUT) {
            c[2] = readReverseBase64();
            c[3] = readReverseBase64();
            a += ntos((((c[0] << 2) & 255) | c[1] >> 4));
if (c[2] != END_OF_INPUT) {
                a += ntos((((c[1] << 4) & 255) | c[2] >> 2));
if (c[3] != END_OF_INPUT) {
                    a += ntos((((c[2] << 6) & 255) | c[3]))
                } else {
                    b = true
                }
            } else {
                b = true
            }
        }
return a
    }