JS实现Base64加密解密

2019-10-23 阅读：3368 类型：前端分类：jQuery 标签： jQuery

JavaScript实现Base64加密解密。Base64与其说是加密算法不如说是方便数据传输而生的数据转换手段。

测试代码：

<!DOCTYPE html>
<html>
<head>
    <title>test</title>
    <meta charset="utf-8">
    <script type="text/javascript" src="js/base64.js"></script>
    <style>
        .resource_enc, .resource_dec{
            width: 500px;
        }

        .p1, .p2{
            min-height: 100px;
            background-color: #dcffe1;
        }
    </style>
</head>
<body>

<input type="text" class="resource_enc"><input type="button" onclick="encoding()" value="编码"><br/>
<p class="p1"></p>
<input type="text" class="resource_dec"><input type="button" onclick="decoding()" value="解码"><br/>
<p class="p2"></p>

<script type="text/javascript">

    var base = new Base64();

    function encoding() {
        var text = document.getElementsByClassName("resource_enc")[0].value;
        document.getElementsByClassName("p1")[0].innerText = base.encode(text);
    }

    function decoding() {
        var text = document.getElementsByClassName("resource_dec")[0].value;
        document.getElementsByClassName("p2")[0].innerText = base.decode(text);
    }

</script>


</body>
</html>

Base64.js

function Base64() {

    var _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

    this.encode = function (input) {
        var output = "";
        var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
        var i = 0;
        input = utf8Encode(input);
        while (i < input.length) {
            chr1 = input.charCodeAt(i++);
            chr2 = input.charCodeAt(i++);
            chr3 = input.charCodeAt(i++);
            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;
            if (isNaN(chr2)) {
                enc3 = enc4 = 64;
            } else if (isNaN(chr3)) {
                enc4 = 64;
            }
            output = output +
                _keyStr.charAt(enc1) + _keyStr.charAt(enc2) +
                _keyStr.charAt(enc3) + _keyStr.charAt(enc4);
        }
        return output;
    };

    this.decode = function (input) {
        var output = "";
        var chr1, chr2, chr3;
        var enc1, enc2, enc3, enc4;
        var i = 0;
        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
        while (i < input.length) {
            enc1 = _keyStr.indexOf(input.charAt(i++));
            enc2 = _keyStr.indexOf(input.charAt(i++));
            enc3 = _keyStr.indexOf(input.charAt(i++));
            enc4 = _keyStr.indexOf(input.charAt(i++));
            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;
            output = output + String.fromCharCode(chr1);
            if (enc3 !== 64) {
                output = output + String.fromCharCode(chr2);
            }
            if (enc4 !== 64) {
                output = output + String.fromCharCode(chr3);
            }
        }
        output = utf8Decode(output);
        return output;
    };

    utf8Encode = function (string) {
        string = string.replace(/\r\n/g,"\n");
        var utfText = "";
        for (var n = 0; n < string.length; n++) {
            var c = string.charCodeAt(n);
            if (c < 128) {
                utfText += String.fromCharCode(c);
            } else if((c > 127) && (c < 2048)) {
                utfText += String.fromCharCode((c >> 6) | 192);
                utfText += String.fromCharCode((c & 63) | 128);
            } else {
                utfText += String.fromCharCode((c >> 12) | 224);
                utfText += String.fromCharCode(((c >> 6) & 63) | 128);
                utfText += String.fromCharCode((c & 63) | 128);
            }
        }
        return utfText;
    };

    utf8Decode = function (utfText) {
        var string = "";
        var i = 0;
        var c = 0;
        var c1 = 0;
        var c2 = 0;
        while ( i < utfText.length ) {
            c = utfText.charCodeAt(i);
            if (c < 128) {
                string += String.fromCharCode(c);
                i++;
            } else if((c > 191) && (c < 224)) {
                c1 = utfText.charCodeAt(i+1);
                string += String.fromCharCode(((c & 31) << 6) | (c1 & 63));
                i += 2;
            } else {
                c1 = utfText.charCodeAt(i+1);
                c2 = utfText.charCodeAt(i+2);
                string += String.fromCharCode(((c & 15) << 12) | ((c1 & 63) << 6) | (c2 & 63));
                i += 3;
            }
        }
        return string;
    }
}