高校教务系统登录页面JS分析——华南理工大学

高校教务系统密码加密逻辑及JS逆向

本文将介绍高校教务系统的密码加密逻辑以及使用JavaScript进行逆向分析的过程。通过本文，你将了解到密码加密的基本概念、常用加密算法以及如何通过逆向分析来破解密码。

本文仅供交流学习，勿用于非法用途。

一、密码加密基本概念

密码加密是一种保护信息安全的技术手段，它通过将明文（原始信息）转换为密文（加密后的信息），以防止未经授权的访问和篡改。常见的密码加密算法有MD5、SHA-1、SHA-256等。

1.1 加密过程

加密过程通常包括以下步骤：

1. 密钥扩展：将密钥扩展为多个轮值，每个轮值都与明文的一部分有关。
2. 初始轮值生成：将扩展后的密钥与轮常数进行某种运算，生成第一轮加密的密文。
3. 多轮迭代：对密文进行多轮迭代操作，每轮操作都包括非线性函数、模运算和轮常数的变换。
4. 最终密文：经过多轮迭代后，得到最终的密文。

1.2 解密过程

解密过程与加密过程相反，通过反向操作来恢复原始明文。通常需要知道加密时使用的密钥和算法。

二、高校教务系统密码加密逻辑分析

2.1 抓包

我们首先打开教务系统的登录页面，我们可以看到，只有学号和密码，有的高校会有验证码，或者有的高校是错误一次密码，会验证验证码。

我们打开开发者工具，尝试登录抓包，网页会返回这样的数据接口。我们用户名和密码都是默认输入1234，你也可以输入其他的。

2.2 分析加密参数

我们接下来，就是来分析这个密码是怎么加密的。我们全局搜索rsa。定位到加密的位置。我们这里只有这个参数被加密了。我们猜想密码相关信息都包含在这个里面。

我们可以看到这里，定义了rsa是怎么生成的，是把u+p+lt拼接了在一起，这个还是第一次遇到。

三、JS逆向分析方法

逆向分析是指从已知的加密文本或程序中还原出原始信息的过程。在本例中，我们将使用JavaScript编写一个简单的逆向分析工具，用于逆向高校教务系统的密码。

环境使用

• python 3.9
• pycharm
• node

我们全局搜索strEnc，我们就很容易定位到一个函数，我们不难发现其加密原理。

function strEnc(data,firstKey,secondKey,thirdKey){  var leng = data.length;  var encData = "";  var firstKeyBt,secondKeyBt,thirdKeyBt,firstLength,secondLength,thirdLength;  if(firstKey != null && firstKey != ""){      firstKeyBt = getKeyBytes(firstKey);  firstLength = firstKeyBt.length;  }  if(secondKey != null && secondKey != ""){  secondKeyBt = getKeyBytes(secondKey);  secondLength = secondKeyBt.length;  }  if(thirdKey != null && thirdKey != ""){  thirdKeyBt = getKeyBytes(thirdKey);  thirdLength = thirdKeyBt.length;  }    

1. 首先，函数会接受两个参数：数据字符串data和密钥key。
2. 然后，通过CryptoJS.enc.Utf8.parse(key)将密钥从普通的字符串转换为CryptoJS可以处理的二进制格式。
3. 接着，使用CryptoJS.AES.encrypt(data, key, {mode: CryptoJS.mode.ECB, padding: CryptoJS.pad.Pkcs7})对数据进行加密。这里使用了ECB模式和PKCS7填充方式。
4. 最后，通过调用.toString()将加密后的数据对象转换为字符串形式并返回。 

代码实现

/**
* DES加密解密
* @Copyright Copyright (c) 2006
* @author Guapo
* @see DESCore
*//*
* encrypt the string to string made up of hex
* return the encrypted string
*/
function strEnc(data,firstKey,secondKey,thirdKey){var leng = data.length;var encData = "";var firstKeyBt,secondKeyBt,thirdKeyBt,firstLength,secondLength,thirdLength;if(firstKey != null && firstKey != ""){firstKeyBt = getKeyBytes(firstKey);firstLength = firstKeyBt.length;}if(secondKey != null && secondKey != ""){secondKeyBt = getKeyBytes(secondKey);secondLength = secondKeyBt.length;}if(thirdKey != null && thirdKey != ""){thirdKeyBt = getKeyBytes(thirdKey);thirdLength = thirdKeyBt.length;}if(leng > 0){if(leng < 4){var bt = strToBt(data);var encByte ;if(firstKey != null && firstKey !="" && secondKey != null && secondKey != "" && thirdKey != null && thirdKey != ""){var tempBt;var x,y,z;tempBt = bt;for(x = 0;x < firstLength ;x ++){tempBt = enc(tempBt,firstKeyBt[x]);}for(y = 0;y < secondLength ;y ++){tempBt = enc(tempBt,secondKeyBt[y]);}for(z = 0;z < thirdLength ;z ++){tempBt = enc(tempBt,thirdKeyBt[z]);}encByte = tempBt;}else{if(firstKey != null && firstKey !="" && secondKey != null && secondKey != ""){var tempBt;var x,y;tempBt = bt;for(x = 0;x < firstLength ;x ++){tempBt = enc(tempBt,firstKeyBt[x]);}for(y = 0;y < secondLength ;y ++){tempBt = enc(tempBt,secondKeyBt[y]);}encByte = tempBt;}else{if(firstKey != null && firstKey !=""){var tempBt;var x = 0;tempBt = bt;for(x = 0;x < firstLength ;x ++){tempBt = enc(tempBt,firstKeyBt[x]);}encByte = tempBt;}}}encData = bt64ToHex(encByte);}else{var iterator = parseInt(leng/4);var remainder = leng%4;var i=0;for(i = 0;i < iterator;i++){var tempData = data.substring(i*4+0,i*4+4);var tempByte = strToBt(tempData);var encByte ;if(firstKey != null && firstKey !="" && secondKey != null && secondKey != "" && thirdKey != null && thirdKey != ""){var tempBt;var x,y,z;tempBt = tempByte;for(x = 0;x < firstLength ;x ++){tempBt = enc(tempBt,firstKeyBt[x]);}for(y = 0;y < secondLength ;y ++){tempBt = enc(tempBt,secondKeyBt[y]);}for(z = 0;z < thirdLength ;z ++){tempBt = enc(tempBt,thirdKeyBt[z]);}encByte = tempBt;}else{if(firstKey != null && firstKey !="" && secondKey != null && secondKey != ""){var tempBt;var x,y;tempBt = tempByte;for(x = 0;x < firstLength ;x ++){tempBt = enc(tempBt,firstKeyBt[x]);}for(y = 0;y < secondLength ;y ++){tempBt = enc(tempBt,secondKeyBt[y]);}encByte = tempBt;}else{if(firstKey != null && firstKey !=""){var tempBt;var x;tempBt = tempByte;for(x = 0;x < firstLength ;x ++){tempBt = enc(tempBt,firstKeyBt[x]);}encByte = tempBt;}}}encData += bt64ToHex(encByte);}if(remainder > 0){var remainderData = data.substring(iterator*4+0,leng);var tempByte = strToBt(remainderData);var encByte ;if(firstKey != null && firstKey !="" && secondKey != null && secondKey != "" && thirdKey != null && thirdKey != ""){var tempBt;var x,y,z;tempBt = tempByte;for(x = 0;x < firstLength ;x ++){tempBt = enc(tempBt,firstKeyBt[x]);}for(y = 0;y < secondLength ;y ++){tempBt = enc(tempBt,secondKeyBt[y]);}for(z = 0;z < thirdLength ;z ++){tempBt = enc(tempBt,thirdKeyBt[z]);}encByte = tempBt;}else{if(firstKey != null && firstKey !="" && secondKey != null && secondKey != ""){var tempBt;var x,y;tempBt = tempByte;for(x = 0;x < firstLength ;x ++){tempBt = enc(tempBt,firstKeyBt[x]);}for(y = 0;y < secondLength ;y ++){tempBt = enc(tempBt,secondKeyBt[y]);}encByte = tempBt;}else{if(firstKey != null && firstKey !=""){var tempBt;var x;tempBt = tempByte;for(x = 0;x < firstLength ;x ++){tempBt = enc(tempBt,firstKeyBt[x]);}encByte = tempBt;}}}encData += bt64ToHex(encByte);}}}return encData;
}/*
* decrypt the encrypted string to the original string
*
* return  the original string
*/
function strDec(data,firstKey,secondKey,thirdKey){var leng = data.length;var decStr = "";var firstKeyBt,secondKeyBt,thirdKeyBt,firstLength,secondLength,thirdLength;if(firstKey != null && firstKey != ""){firstKeyBt = getKeyBytes(firstKey);firstLength = firstKeyBt.length;}if(secondKey != null && secondKey != ""){secondKeyBt = getKeyBytes(secondKey);secondLength = secondKeyBt.length;}if(thirdKey != null && thirdKey != ""){thirdKeyBt = getKeyBytes(thirdKey);thirdLength = thirdKeyBt.length;}var iterator = parseInt(leng/16);var i=0;for(i = 0;i < iterator;i++){var tempData = data.substring(i*16+0,i*16+16);var strByte = hexToBt64(tempData);var intByte = new Array(64);var j = 0;for(j = 0;j < 64; j++){intByte[j] = parseInt(strByte.substring(j,j+1));}var decByte;if(firstKey != null && firstKey !="" && secondKey != null && secondKey != "" && thirdKey != null && thirdKey != ""){var tempBt;var x,y,z;tempBt = intByte;for(x = thirdLength - 1;x >= 0;x --){tempBt = dec(tempBt,thirdKeyBt[x]);}for(y = secondLength - 1;y >= 0;y --){tempBt = dec(tempBt,secondKeyBt[y]);}for(z = firstLength - 1;z >= 0 ;z --){tempBt = dec(tempBt,firstKeyBt[z]);}decByte = tempBt;}else{if(firstKey != null && firstKey !="" && secondKey != null && secondKey != ""){var tempBt;var x,y,z;tempBt = intByte;for(x = secondLength - 1;x >= 0 ;x --){tempBt = dec(tempBt,secondKeyBt[x]);}for(y = firstLength - 1;y >= 0 ;y --){tempBt = dec(tempBt,firstKeyBt[y]);}decByte = tempBt;}else{if(firstKey != null && firstKey !=""){var tempBt;var x,y,z;tempBt = intByte;for(x = firstLength - 1;x >= 0 ;x --){tempBt = dec(tempBt,firstKeyBt[x]);}decByte = tempBt;}}}decStr += byteToString(decByte);}return decStr;
}
/*
* chang the string into the bit array
*
* return bit array(it's length % 64 = 0)
*/
function getKeyBytes(key){var keyBytes = new Array();var leng = key.length;var iterator = parseInt(leng/4);var remainder = leng%4;var i = 0;for(i = 0;i < iterator; i ++){keyBytes[i] = strToBt(key.substring(i*4+0,i*4+4));}if(remainder > 0){keyBytes[i] = strToBt(key.substring(i*4+0,leng));}return keyBytes;
}/*
* chang the string(it's length <= 4) into the bit array
*
* return bit array(it's length = 64)
*/
function strToBt(str){var leng = str.length;var bt = new Array(64);if(leng < 4){var i=0,j=0,p=0,q=0;for(i = 0;i<leng;i++){var k = str.charCodeAt(i);for(j=0;j<16;j++){var pow=1,m=0;for(m=15;m>j;m--){pow *= 2;}bt[16*i+j]=parseInt(k/pow)%2;}}for(p = leng;p<4;p++){var k = 0;for(q=0;q<16;q++){var pow=1,m=0;for(m=15;m>q;m--){pow *= 2;}bt[16*p+q]=parseInt(k/pow)%2;}}}else{for(i = 0;i<4;i++){var k = str.charCodeAt(i);for(j=0;j<16;j++){var pow=1;for(m=15;m>j;m--){pow *= 2;}bt[16*i+j]=parseInt(k/pow)%2;}}}return bt;
}/*
* chang the bit(it's length = 4) into the hex
*
* return hex
*/
function bt4ToHex(binary) {var hex;switch (binary) {case "0000" : hex = "0"; break;case "0001" : hex = "1"; break;case "0010" : hex = "2"; break;case "0011" : hex = "3"; break;case "0100" : hex = "4"; break;case "0101" : hex = "5"; break;case "0110" : hex = "6"; break;case "0111" : hex = "7"; break;case "1000" : hex = "8"; break;case "1001" : hex = "9"; break;case "1010" : hex = "A"; break;case "1011" : hex = "B"; break;case "1100" : hex = "C"; break;case "1101" : hex = "D"; break;case "1110" : hex = "E"; break;case "1111" : hex = "F"; break;}return hex;
}/*
* chang the hex into the bit(it's length = 4)
*
* return the bit(it's length = 4)
*/
function hexToBt4(hex) {var binary;switch (hex) {case "0" : binary = "0000"; break;case "1" : binary = "0001"; break;case "2" : binary = "0010"; break;case "3" : binary = "0011"; break;case "4" : binary = "0100"; break;case "5" : binary = "0101"; break;case "6" : binary = "0110"; break;case "7" : binary = "0111"; break;case "8" : binary = "1000"; break;case "9" : binary = "1001"; break;case "A" : binary = "1010"; break;case "B" : binary = "1011"; break;case "C" : binary = "1100"; break;case "D" : binary = "1101"; break;case "E" : binary = "1110"; break;case "F" : binary = "1111"; break;}return binary;
}/*
* chang the bit(it's length = 64) into the string
*
* return string
*/
function byteToString(byteData){var str="";for(i = 0;i<4;i++){var count=0;for(j=0;j<16;j++){var pow=1;for(m=15;m>j;m--){pow*=2;}count+=byteData[16*i+j]*pow;}if(count != 0){str+=String.fromCharCode(count);}}return str;
}function bt64ToHex(byteData){var hex = "";for(i = 0;i<16;i++){var bt = "";for(j=0;j<4;j++){bt += byteData[i*4+j];}hex+=bt4ToHex(bt);}return hex;
}function hexToBt64(hex){var binary = "";for(i = 0;i<16;i++){binary+=hexToBt4(hex.substring(i,i+1));}return binary;
}/*
* the 64 bit des core arithmetic
*/function enc(dataByte,keyByte){var keys = generateKeys(keyByte);var ipByte   = initPermute(dataByte);var ipLeft   = new Array(32);var ipRight  = new Array(32);var tempLeft = new Array(32);var i = 0,j = 0,k = 0,m = 0, n = 0;for(k = 0;k < 32;k ++){ipLeft[k] = ipByte[k];ipRight[k] = ipByte[32+k];}for(i = 0;i < 16;i ++){for(j = 0;j < 32;j ++){tempLeft[j] = ipLeft[j];ipLeft[j] = ipRight[j];}var key = new Array(48);for(m = 0;m < 48;m ++){key[m] = keys[i][m];}var  tempRight = xor(pPermute(sBoxPermute(xor(expandPermute(ipRight),key))), tempLeft);for(n = 0;n < 32;n ++){ipRight[n] = tempRight[n];}}var finalData =new Array(64);for(i = 0;i < 32;i ++){finalData[i] = ipRight[i];finalData[32+i] = ipLeft[i];}return finallyPermute(finalData);
}function dec(dataByte,keyByte){var keys = generateKeys(keyByte);var ipByte   = initPermute(dataByte);var ipLeft   = new Array(32);var ipRight  = new Array(32);var tempLeft = new Array(32);var i = 0,j = 0,k = 0,m = 0, n = 0;for(k = 0;k < 32;k ++){ipLeft[k] = ipByte[k];ipRight[k] = ipByte[32+k];}for(i = 15;i >= 0;i --){for(j = 0;j < 32;j ++){tempLeft[j] = ipLeft[j];ipLeft[j] = ipRight[j];}var key = new Array(48);for(m = 0;m < 48;m ++){key[m] = keys[i][m];}var  tempRight = xor(pPermute(sBoxPermute(xor(expandPermute(ipRight),key))), tempLeft);for(n = 0;n < 32;n ++){ipRight[n] = tempRight[n];}}var finalData =new Array(64);for(i = 0;i < 32;i ++){finalData[i] = ipRight[i];finalData[32+i] = ipLeft[i];}return finallyPermute(finalData);
}function initPermute(originalData){var ipByte = new Array(64);for (i = 0, m = 1, n = 0; i < 4; i++, m += 2, n += 2) {for (j = 7, k = 0; j >= 0; j--, k++) {ipByte[i * 8 + k] = originalData[j * 8 + m];ipByte[i * 8 + k + 32] = originalData[j * 8 + n];}}return ipByte;
}function expandPermute(rightData){var epByte = new Array(48);for (i = 0; i < 8; i++) {if (i == 0) {epByte[i * 6 + 0] = rightData[31];} else {epByte[i * 6 + 0] = rightData[i * 4 - 1];}epByte[i * 6 + 1] = rightData[i * 4 + 0];epByte[i * 6 + 2] = rightData[i * 4 + 1];epByte[i * 6 + 3] = rightData[i * 4 + 2];epByte[i * 6 + 4] = rightData[i * 4 + 3];if (i == 7) {epByte[i * 6 + 5] = rightData[0];} else {epByte[i * 6 + 5] = rightData[i * 4 + 4];}}return epByte;
}function xor(byteOne,byteTwo){var xorByte = new Array(byteOne.length);for(i = 0;i < byteOne.length; i ++){xorByte[i] = byteOne[i] ^ byteTwo[i];}return xorByte;
}function sBoxPermute(expandByte){var sBoxByte = new Array(32);var binary = "";var s1 = [[14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7],[0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8],[4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0],[15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13 ]];/* Table - s2 */var s2 = [[15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10],[3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5],[0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15],[13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9 ]];/* Table - s3 */var s3= [[10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8],[13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1],[13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7],[1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12 ]];/* Table - s4 */var s4 = [[7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15],[13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9],[10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4],[3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14 ]];/* Table - s5 */var s5 = [[2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9],[14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6],[4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14],[11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3 ]];/* Table - s6 */var s6 = [[12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11],[10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8],[9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6],[4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13 ]];/* Table - s7 */var s7 = [[4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1],[13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6],[1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2],[6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12]];/* Table - s8 */var s8 = [[13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7],[1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2],[7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8],[2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11]];for(m=0;m<8;m++){var i=0,j=0;i = expandByte[m*6+0]*2+expandByte[m*6+5];j = expandByte[m * 6 + 1] * 2 * 2 * 2+ expandByte[m * 6 + 2] * 2* 2+ expandByte[m * 6 + 3] * 2+ expandByte[m * 6 + 4];switch (m) {case 0 :binary = getBoxBinary(s1[i][j]);break;case 1 :binary = getBoxBinary(s2[i][j]);break;case 2 :binary = getBoxBinary(s3[i][j]);break;case 3 :binary = getBoxBinary(s4[i][j]);break;case 4 :binary = getBoxBinary(s5[i][j]);break;case 5 :binary = getBoxBinary(s6[i][j]);break;case 6 :binary = getBoxBinary(s7[i][j]);break;case 7 :binary = getBoxBinary(s8[i][j]);break;}sBoxByte[m*4+0] = parseInt(binary.substring(0,1));sBoxByte[m*4+1] = parseInt(binary.substring(1,2));sBoxByte[m*4+2] = parseInt(binary.substring(2,3));sBoxByte[m*4+3] = parseInt(binary.substring(3,4));}return sBoxByte;
}function pPermute(sBoxByte){var pBoxPermute = new Array(32);pBoxPermute[ 0] = sBoxByte[15];pBoxPermute[ 1] = sBoxByte[ 6];pBoxPermute[ 2] = sBoxByte[19];pBoxPermute[ 3] = sBoxByte[20];pBoxPermute[ 4] = sBoxByte[28];pBoxPermute[ 5] = sBoxByte[11];pBoxPermute[ 6] = sBoxByte[27];pBoxPermute[ 7] = sBoxByte[16];pBoxPermute[ 8] = sBoxByte[ 0];pBoxPermute[ 9] = sBoxByte[14];pBoxPermute[10] = sBoxByte[22];pBoxPermute[11] = sBoxByte[25];pBoxPermute[12] = sBoxByte[ 4];pBoxPermute[13] = sBoxByte[17];pBoxPermute[14] = sBoxByte[30];pBoxPermute[15] = sBoxByte[ 9];pBoxPermute[16] = sBoxByte[ 1];pBoxPermute[17] = sBoxByte[ 7];pBoxPermute[18] = sBoxByte[23];pBoxPermute[19] = sBoxByte[13];pBoxPermute[20] = sBoxByte[31];pBoxPermute[21] = sBoxByte[26];pBoxPermute[22] = sBoxByte[ 2];pBoxPermute[23] = sBoxByte[ 8];pBoxPermute[24] = sBoxByte[18];pBoxPermute[25] = sBoxByte[12];pBoxPermute[26] = sBoxByte[29];pBoxPermute[27] = sBoxByte[ 5];pBoxPermute[28] = sBoxByte[21];pBoxPermute[29] = sBoxByte[10];pBoxPermute[30] = sBoxByte[ 3];pBoxPermute[31] = sBoxByte[24];return pBoxPermute;
}function finallyPermute(endByte){var fpByte = new Array(64);fpByte[ 0] = endByte[39];fpByte[ 1] = endByte[ 7];fpByte[ 2] = endByte[47];fpByte[ 3] = endByte[15];fpByte[ 4] = endByte[55];fpByte[ 5] = endByte[23];fpByte[ 6] = endByte[63];fpByte[ 7] = endByte[31];fpByte[ 8] = endByte[38];fpByte[ 9] = endByte[ 6];fpByte[10] = endByte[46];fpByte[11] = endByte[14];fpByte[12] = endByte[54];fpByte[13] = endByte[22];fpByte[14] = endByte[62];fpByte[15] = endByte[30];fpByte[16] = endByte[37];fpByte[17] = endByte[ 5];fpByte[18] = endByte[45];fpByte[19] = endByte[13];fpByte[20] = endByte[53];fpByte[21] = endByte[21];fpByte[22] = endByte[61];fpByte[23] = endByte[29];fpByte[24] = endByte[36];fpByte[25] = endByte[ 4];fpByte[26] = endByte[44];fpByte[27] = endByte[12];fpByte[28] = endByte[52];fpByte[29] = endByte[20];fpByte[30] = endByte[60];fpByte[31] = endByte[28];fpByte[32] = endByte[35];fpByte[33] = endByte[ 3];fpByte[34] = endByte[43];fpByte[35] = endByte[11];fpByte[36] = endByte[51];fpByte[37] = endByte[19];fpByte[38] = endByte[59];fpByte[39] = endByte[27];fpByte[40] = endByte[34];fpByte[41] = endByte[ 2];fpByte[42] = endByte[42];fpByte[43] = endByte[10];fpByte[44] = endByte[50];fpByte[45] = endByte[18];fpByte[46] = endByte[58];fpByte[47] = endByte[26];fpByte[48] = endByte[33];fpByte[49] = endByte[ 1];fpByte[50] = endByte[41];fpByte[51] = endByte[ 9];fpByte[52] = endByte[49];fpByte[53] = endByte[17];fpByte[54] = endByte[57];fpByte[55] = endByte[25];fpByte[56] = endByte[32];fpByte[57] = endByte[ 0];fpByte[58] = endByte[40];fpByte[59] = endByte[ 8];fpByte[60] = endByte[48];fpByte[61] = endByte[16];fpByte[62] = endByte[56];fpByte[63] = endByte[24];return fpByte;
}function getBoxBinary(i) {var binary = "";switch (i) {case 0 :binary = "0000";break;case 1 :binary = "0001";break;case 2 :binary = "0010";break;case 3 :binary = "0011";break;case 4 :binary = "0100";break;case 5 :binary = "0101";break;case 6 :binary = "0110";break;case 7 :binary = "0111";break;case 8 :binary = "1000";break;case 9 :binary = "1001";break;case 10 :binary = "1010";break;case 11 :binary = "1011";break;case 12 :binary = "1100";break;case 13 :binary = "1101";break;case 14 :binary = "1110";break;case 15 :binary = "1111";break;}return binary;
}
/*
* generate 16 keys for xor
*
*/
function generateKeys(keyByte){var key   = new Array(56);var keys = new Array();keys[ 0] = new Array();keys[ 1] = new Array();keys[ 2] = new Array();keys[ 3] = new Array();keys[ 4] = new Array();keys[ 5] = new Array();keys[ 6] = new Array();keys[ 7] = new Array();keys[ 8] = new Array();keys[ 9] = new Array();keys[10] = new Array();keys[11] = new Array();keys[12] = new Array();keys[13] = new Array();keys[14] = new Array();keys[15] = new Array();var loop = [1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1];for(i=0;i<7;i++){for(j=0,k=7;j<8;j++,k--){key[i*8+j]=keyByte[8*k+i];}}var i = 0;for(i = 0;i < 16;i ++){var tempLeft=0;var tempRight=0;for(j = 0; j < loop[i];j ++){tempLeft = key[0];tempRight = key[28];for(k = 0;k < 27 ;k ++){key[k] = key[k+1];key[28+k] = key[29+k];}key[27]=tempLeft;key[55]=tempRight;}var tempKey = new Array(48);tempKey[ 0] = key[13];tempKey[ 1] = key[16];tempKey[ 2] = key[10];tempKey[ 3] = key[23];tempKey[ 4] = key[ 0];tempKey[ 5] = key[ 4];tempKey[ 6] = key[ 2];tempKey[ 7] = key[27];tempKey[ 8] = key[14];tempKey[ 9] = key[ 5];tempKey[10] = key[20];tempKey[11] = key[ 9];tempKey[12] = key[22];tempKey[13] = key[18];tempKey[14] = key[11];tempKey[15] = key[ 3];tempKey[16] = key[25];tempKey[17] = key[ 7];tempKey[18] = key[15];tempKey[19] = key[ 6];tempKey[20] = key[26];tempKey[21] = key[19];tempKey[22] = key[12];tempKey[23] = key[ 1];tempKey[24] = key[40];tempKey[25] = key[51];tempKey[26] = key[30];tempKey[27] = key[36];tempKey[28] = key[46];tempKey[29] = key[54];tempKey[30] = key[29];tempKey[31] = key[39];tempKey[32] = key[50];tempKey[33] = key[44];tempKey[34] = key[32];tempKey[35] = key[47];tempKey[36] = key[43];tempKey[37] = key[48];tempKey[38] = key[38];tempKey[39] = key[55];tempKey[40] = key[33];tempKey[41] = key[52];tempKey[42] = key[45];tempKey[43] = key[41];tempKey[44] = key[49];tempKey[45] = key[35];tempKey[46] = key[28];tempKey[47] = key[31];switch(i){case 0: for(m=0;m < 48 ;m++){ keys[ 0][m] = tempKey[m]; } break;case 1: for(m=0;m < 48 ;m++){ keys[ 1][m] = tempKey[m]; } break;case 2: for(m=0;m < 48 ;m++){ keys[ 2][m] = tempKey[m]; } break;case 3: for(m=0;m < 48 ;m++){ keys[ 3][m] = tempKey[m]; } break;case 4: for(m=0;m < 48 ;m++){ keys[ 4][m] = tempKey[m]; } break;case 5: for(m=0;m < 48 ;m++){ keys[ 5][m] = tempKey[m]; } break;case 6: for(m=0;m < 48 ;m++){ keys[ 6][m] = tempKey[m]; } break;case 7: for(m=0;m < 48 ;m++){ keys[ 7][m] = tempKey[m]; } break;case 8: for(m=0;m < 48 ;m++){ keys[ 8][m] = tempKey[m]; } break;case 9: for(m=0;m < 48 ;m++){ keys[ 9][m] = tempKey[m]; } break;case 10: for(m=0;m < 48 ;m++){ keys[10][m] = tempKey[m]; } break;case 11: for(m=0;m < 48 ;m++){ keys[11][m] = tempKey[m]; } break;case 12: for(m=0;m < 48 ;m++){ keys[12][m] = tempKey[m]; } break;case 13: for(m=0;m < 48 ;m++){ keys[13][m] = tempKey[m]; } break;case 14: for(m=0;m < 48 ;m++){ keys[14][m] = tempKey[m]; } break;case 15: for(m=0;m < 48 ;m++){ keys[15][m] = tempKey[m]; } break;}}return keys;
}
var u = '1234'
var p = '1234'
var lt = ' LT-318507-wymVTnxdHIivdYhDVasTwXTNEKnqTI-cas'
var rsa =strEnc(u+p+lt , '1' , '2' , '3')console.log(rsa)

我这里直接把代码给大家，大家感兴趣可以先尝试直接去写，可以和我写的做比较。 

实现效果

C1BB5938DF9F2190C1BB5938DF9F21906C47B718205114E97CBA49C9BE760421885CBED73DBA20760A8CE596669EA996ECAE08DFB1001AFC0C53B6B482DC1A450D45FA2BFB9C2F07AEF9D3E23DE6C7061D6814B8F1D6CEBC279B336B204A11587914575B59A84A0FB2DA8880EA270330

 我们可以发现，这个结果和网页的结果一样的，说明我们逆向成功了。

四、总结

本文介绍了高校教务系统的密码加密逻辑以及使用JavaScript进行逆向分析的方法。通过学习这些知识，你可以更好地理解密码加密技术的原理，并掌握一定的逆向分析技巧。请注意，逆向分析可能涉及到法律问题，请在合法范围内进行研究和实践。

五、累计更新

争取到到底早日更新30所高校，大家可以在评论区留言。前期更的可能会多一点，有的学校教务系统都没有加密，我这里就不写了，还有，部分学校的教务系统已经和我之前写的是一样的，我也不重复赘述了。

往期作品可以查看专栏👇👇👇

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