jsencrypt.min.js通过JSEncrypt分段加密解密

雨点打透心脏的1/2处 2022-05-24 06:27 427阅读 0赞

最近捣鼓了一下js RSA前端加解密。是通过用jsencrypt.min.js来实现的，这个js本身自带了RSA公钥加密和RSA私钥解密。对一些短字符串加解密足够。但如果加密的和解密的内容比较长的时候，就会有问题。所以要进行分段加解密，参考了网上的一些例子。多少有点问题。所以自己捣鼓了一下。直接看看代码吧

需要注意一个问题：如果与JAVA后台数据交互。某些中文字符可能因为编码原因会乱码，可以加密前先进行  encodeURIComponent(s)。然后解密后在decode回来，就完美了。

先看看添加的方法吧。后面给下载链接：

1、添加两个转换函数

// Convert a hex string to a byte array
        function hexToBytes(hex) {
            for (var bytes = [], c = 0; c < hex.length; c += 2)
                bytes.push(parseInt(hex.substr(c, 2), 16));
            return bytes;
        }
    
    // Convert a byte array to a hex string
        function bytesToHex(bytes) {
            for (var hex = [], i = 0; i < bytes.length; i++) {
                hex.push((bytes[i] >>> 4).toString(16));
                hex.push((bytes[i] & 0xF).toString(16));
            }
            return hex.join("");
        }

2、添加分段加解密函数（分段解密有两个方法，建议用第二个）

JSEncrypt.prototype.encryptLong=function (d){
      var k = this.key;
      var maxLength = (((k.n.bitLength() + 7) >> 3) - 11);
    
      try {
        var lt = "";
        var ct = "";
    
        if (d.length > maxLength) {
          lt = d.match(/.{1,117}/g);
          lt.forEach(function (entry) {
            var t1 = k.encrypt(entry);
            ct += t1;
          });
          return hex2b64(ct);
        }
        var t = k.encrypt(d);
        var y = hex2b64(t);
        return y;
      } catch (ex) {
        return false;
      }
    } 
    
    
    
    JSEncrypt.prototype.encryptLong2 = function (string) {
                var k = this.getKey();
                try {
                    var lt = "";
                    var ct = "";
                    //RSA每次加密117bytes，需要辅助方法判断字符串截取位置
                    //1.获取字符串截取点
                    var bytes = new Array();
                    bytes.push(0);
                    var byteNo = 0;
                    var len, c;
                    len = string.length;
                    var temp = 0;
                    for (var i = 0; i < len; i++) {
                        c = string.charCodeAt(i);
                        if (c >= 0x010000 && c <= 0x10FFFF) {
                            byteNo += 4;
                        } else if (c >= 0x000800 && c <= 0x00FFFF) {
                            byteNo += 3;
                        } else if (c >= 0x000080 && c <= 0x0007FF) {
                            byteNo += 2;
                        } else {
                            byteNo += 1;
                        }
                        if ((byteNo % 117) >= 114 || (byteNo % 117) == 0) {
                            if (byteNo - temp >= 114) {
                                bytes.push(i);
                                temp = byteNo;
                            }
                        }
                    }
                    //2.截取字符串并分段加密
                    if (bytes.length > 1) {
                        for (var i = 0; i < bytes.length - 1; i++) {
                            var str;
                            if (i == 0) {
                                str = string.substring(0, bytes[i + 1] + 1);
                            } else {
                                str = string.substring(bytes[i] + 1, bytes[i + 1] + 1);
                            }
                            var t1 = k.encrypt(str);
                            ct += t1;
                        }
                        ;
                        if (bytes[bytes.length - 1] != string.length - 1) {
                            var lastStr = string.substring(bytes[bytes.length - 1] + 1);
                            ct += k.encrypt(lastStr);
                        }
                        return hex2b64(ct);
                    }
                    var t = k.encrypt(string);
                    var y = hex2b64(t);
                    return y;
                } catch (ex) {
                    return false;
                }
            };
    
    
            JSEncrypt.prototype.decryptLong = function (string) {
                var k = this.getKey();
                var maxLength = ((k.n.bitLength() + 7) >> 3);
                //var maxLength = 128;
                try {
    
                    var str = b64tohex(string);
                    //var b=hex2Bytes(str);
    
                    var inputLen = str.length;
    
                    var ct = "";
                    if (str.length > maxLength) {
    
                        var lt = str.match(/.{1,256}/g);
                        lt.forEach(function (entry) {
                            var t1 = k.decrypt(entry);
                            ct += t1;
                        });
                        return ct;
                    }
                    var y = k.decrypt(b64tohex(string));
                    return y;
                } catch (ex) {
                    return false;
                }
            };
    
    
            JSEncrypt.prototype.decryptLong2 = function (string) {
                var k = this.getKey();
                // var maxLength = ((k.n.bitLength()+7)>>3);
                var MAX_DECRYPT_BLOCK = 128;
                try {
                    var ct = "";
                    var t1;
                    var bufTmp;
                    var hexTmp;
                    var str = b64tohex(string);
                    var buf = hexToBytes(str);
                    var inputLen = buf.length;
                    //开始长度
                    var offSet = 0;
                    //结束长度
                    var endOffSet = MAX_DECRYPT_BLOCK;
    
                    //分段加密
                    while (inputLen - offSet > 0) {
                        if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                            bufTmp = buf.slice(offSet, endOffSet);
                            hexTmp = bytesToHex(bufTmp);
                            t1 = k.decrypt(hexTmp);
                            ct += t1;
                            
                        } else {
                            bufTmp = buf.slice(offSet, inputLen);
                            hexTmp = bytesToHex(bufTmp);
                            t1 = k.decrypt(hexTmp);
                            ct += t1;
                         
                        }
                        offSet += MAX_DECRYPT_BLOCK;
                        endOffSet += MAX_DECRYPT_BLOCK;
                    }
                    return ct;
                } catch (ex) {
                    return false;
                }
            };

3用法：

//实例化加密对象
            var encrypt = new JSEncrypt();
            //设置加密公钥
            encrypt.setPublicKey("......");
    
            //分段加密
            var sss=encrypt.encryptLong("这几天心里颇不宁静。今晚在院子里坐着乘凉，忽然想起日日走过的荷塘，");
            alert(sss);
            //密文
           var ttt="..........................";
            //设置解密私钥
            encrypt.setPrivateKey(".......")
            //分段解密
            var sss= encrypt.decryptLong(sss);

js下载链接：[点击打开链接][Link 1]

[Link 1]: https://download.csdn.net/download/kokjuis/10429753