为什么要使用javascript加密呢？
服务端加密远远不够，客户端或者浏览器端也需要加密，以此保证传输信息过程的安全。
今天就我工作中说说这么几种加密算法及其对应的应用场景，如下所示:
base64
md5
des
一、Base64Base64通常可以用于Cookie加密，比如每个用户通过相关操作，对应的用户和数据库信息会有对应的更新，为了保证对应的用户在web端看到的信息一致，我们使用Cookie，而Cookie如果是明文的话，不是特别安全，因此我们采用Base64对其进行加密。
示例代码如下:
<!DOCTYPE html> <html> <head> <meta charset=http://www.likecs.com/"utf-8" /> <title>base64加密解密</title> </head> <body> <script> // 创建Base64对象 var Base64 =http://www.likecs.com/ { _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=", encode: function(e) { var t = ""; var n, r, i, s, o, u, a; var f = 0; e =http://www.likecs.com/ Base64._utf8_encode(e); while (f < e.length) { n = e.charCodeAt(f++); r = e.charCodeAt(f++); i = e.charCodeAt(f++); s = n >> 2; o = (n & 3) << 4 | r >> 4; u = (r & 15) << 2 | i >> 6; a = i & 63; if (isNaN(r)) { u = a = 64 } else if (isNaN(i)) { a = 64 } t = t + this._keyStr.charAt(s) + this._keyStr.charAt(o) + this._keyStr.charAt(u) + this._keyStr.charAt(a) } return t }, decode: function(e) { var t = ""; var n, r, i; var s, o, u, a; var f = 0; e=e.replace(/[^A-Za-z0-9+/=]/g,""); while (f < e.length) { s = this._keyStr.indexOf(e.charAt(f++)); o = this._keyStr.indexOf(e.charAt(f++)); u = this._keyStr.indexOf(e.charAt(f++)); a = this._keyStr.indexOf(e.charAt(f++)); n = s << 2 | o >> 4; r = (o & 15) << 4 | u >> 2; i = (u & 3) << 6 | a; t = t + String.fromCharCode(n); if (u != 64) { t = t + String.fromCharCode(r) } if (a != 64) { t = t + String.fromCharCode(i) } } t =http://www.likecs.com/ Base64._utf8_decode(t); return t }, _utf8_encode: function(e) { e = e.replace(/rn/g, "n"); var t = ""; for (var n = 0; n < e.length; n++) { var r =http://www.likecs.com/ e.charCodeAt(n); if (r < 128) { t +=http://www.likecs.com/ String.fromCharCode(r) } else if (r > 127 && r < 2048) { t += String.fromCharCode(r >> 6 | 192); t += String.fromCharCode(r & 63 | 128) } else { t += String.fromCharCode(r >> 12 | 224); t += String.fromCharCode(r >> 6 & 63 | 128); t += String.fromCharCode(r & 63 | 128) } } return t }, _utf8_decode: function(e) { var t = ""; var n = 0; var r = c1 = c2 = 0; while (n < e.length) { r =http://www.likecs.com/ e.charCodeAt(n); if (r < 128) { t +=http://www.likecs.com/ String.fromCharCode(r); n++ } else if (r > 191 && r < 224) { c2 = e.charCodeAt(n + 1); t += String.fromCharCode((r & 31) << 6 | c2 & 63); n += 2 } else { c2 = e.charCodeAt(n + 1); c3 = e.charCodeAt(n + 2); t += String.fromCharCode((r & 15) << 12 | (c2 & 63) << 6 | c3 & 63); n += 3 } } return t } } // 定义字符串 var string = '!'; // 加密 var encodedString = Base64.encode(string); console.log(encodedString); // 解密 var decodedString =http://www.likecs.com/ Base64.decode(encodedString); console.log(decodedString); </script> </body> </html>