re :Knight Bank Robbery
这是一道简单的Java逆向
源码已经放出
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| import java.util.Scanner;
public class KS_Encryption
{
public static void main(String args[ ]
{
String str, Newstring=" ";
System.out.print("Enter your password: ");
try {//测试模块
Scanner in=new Scanner(System.in);//接受键盘数据
str=in.nextLine();//输入赋值给str
char [] strArr = str.trim().toCharArray();//去除空格和将字符串转化成char数组
for (int i = 0; i < strArr.length; i++)//遍历数组
{
if(strArr[i] >= 'a' && strArr[i] <= 'z')//如果是小写条件一
{
if(strArr[i] <= 'm')//<=109 条件二
{
strArr[i] += 13//本身加13;
}else if(strArr[i] <= 'z')//如果<=122
{
strArr[i] -= 13;
}
}else if(strArr[i] >= 'A' && strArr[i] <= 'Z')//如果是大写
{
if(strArr[i] <= 'M')//如果他小于等于大写M
{
strArr[i] += 13;
}else{
strArr[i] -= 13;
}
}
}
str = new String(strArr)//将 new String 转换成字符串数组赋值给str;
for (int i=0;i
{
char ch=Character.toLowerCase(str.charAt(i));//选定str的指定位置并转换成小写然后把字母赋值给ch
switch (ch)
{
case 'a':
Newstring=Newstring+"}";
break;
case 'b':
Newstring=Newstring+"{";
break;
case 'c':
Newstring=Newstring+"#";
break;
case 'd':
Newstring=Newstring+"~";
break;
case 'e':
Newstring=Newstring+"+";
break;
case 'f':
Newstring=Newstring+"-";
break;
case 'g':
Newstring=Newstring+"*";
break;
case 'h':
Newstring=Newstring+"@";
break;
case 'i':
Newstring=Newstring+"/";
break;
case 'j':
Newstring=Newstring+"%";
break;
case 'k':
Newstring=Newstring+"?";
break;
case 'l':
Newstring=Newstring+"$";
break;
case 'm':
Newstring=Newstring+"!";
break;
case 'n':
Newstring=Newstring+"^";
break;
case 'o':
Newstring=Newstring+"(";
break;
case 'p':
Newstring=Newstring+")";
break;
case 'q':
Newstring=Newstring+"<";
break;
case 'r':
Newstring=Newstring+">";
break;
case 's' :
Newstring=Newstring+"=";
break;
case 't':
Newstring=Newstring+";";
break;
case 'u':
Newstring=Newstring+",";
break;
case 'v' :
Newstring=Newstring+"_";
break;
case 'w':
Newstring=Newstring+"[";
break;
case 'x' :
Newstring=Newstring+"]";
break;
case 'y':
Newstring=Newstring+":";
break;
case 'z' :
Newstring=Newstring+""";
break;
case '{':
Newstring=Newstring+"A";
break;
case '}':
Newstring=Newstring+"B";
break;
case ''':
Newstring=Newstring+"C";
break;
case '_':
Newstring=Newstring+"D";
break;
case '@':
Newstring=Newstring+"E";
break;
case '-':
Newstring=Newstring+"F";
break;
case '1':
Newstring=Newstring+"H";
break;
case '2':
Newstring=Newstring+"I";
break;
case '3':
Newstring=Newstring+"J";
break;
case '4':
Newstring = Newstring+"K";
break;
case '5':
Newstring = Newstring+"L";
break;
case '6':
Newstring = Newstring+"M";
break;
case '7':
Newstring = Newstring+"N";
break;
case '8' :
Newstring= Newstring+"O";
break;
case '9':
Newstring = Newstring+"P";
break;
case '0':
Newstring = Newstring+"Q";
break;
default:
Newstring=Newstring+"0";
break;
}
}
}
catch(Exception ioe)
{
ioe.printStackTrace();
}
System.out.println("Your encrypted password is: " +Newstring);//加密代码就是Newstring
}
}
|
虽然我没有系统学习过java script 但是只是猜测逻辑的话应该不算太难
这是网站上给的密文：]-AQ@+D]}H;,ND(E}]C-D(+E}),D}@”(J+DKMOPDE*D-H:_)Q}JD/^::J$DHLD}Q%D-J)@+J<D%HN,D%,+H:C-D]LFJ})+$#NHQ}B
解密脚本
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| s=list("]-AQ@+D]}H;,ND(E}]C-D(+E}),D}@\"(J+DKMOPDE*D-H:_)Q}JD/^::J$DHLD}Q%D-J)@+J<D%HN,D%,+H:C-D]LFJ})+$#NHQ}B")
for i in range(len(s)):
if s[i]== '}':
s[i]='a'
elif s[i]=="{":
s[i]="b"
elif s[i]=="#":
s[i]="c"
elif s[i]== "~":
s[i]= "d"
elif s[i]=="+":
s[i]="e"
elif s[i]=="-":
s[i]="f"
elif s[i]== "*":
s[i]= "g"
elif s[i]=="@":
s[i]="h"
elif s[i]=="/":
s[i]="i"
elif s[i]== "%":
s[i]= "j"
elif s[i]=="?":
s[i]="k"
elif s[i]=="$":
s[i]="l"
elif s[i]== "!":
s[i]= "m"
elif s[i]== "^":
s[i]= "n"
elif s[i]== "(":
s[i]= "o"
elif s[i]== ")":
s[i]= "p"
elif s[i]== "<":
s[i]= "q"
elif s[i]== ">":
s[i]= "r"
elif s[i]== "=":
s[i]= "s"
elif s[i]== ";":
s[i]= "t"
elif s[i]== ",":
s[i]= "u"
elif s[i]== "_":
s[i]= "v"
elif s[i]== "[":
s[i]= "w"
elif s[i]== "]":
s[i]= "x"
elif s[i]== ":":
s[i]= "y"
elif s[i]== "\"":
s[i]= "z"
elif s[i] == "A":
s[i] = "{"
elif s[i] == "B":
s[i] = "}"
elif s[i] == "\'":
s[i] = "C"
elif s[i] == "D":
s[i] = "_"
elif s[i] == "E":
s[i] = "@"
elif s[i] == "F":
s[i] = "-"
elif s[i] == "H":
s[i] = "1"
elif s[i] == "I":
s[i] = "2"
elif s[i] == "J":
s[i] = "3"
elif s[i] == "K":
s[i] = "4"
elif s[i] == "L":
s[i] = "5"
elif s[i] == "M":
s[i] = "6"
elif s[i] == "N":
s[i] = "7"
elif s[i] == "O":
s[i] = "8"
elif s[i] == "p":
s[i] = "9"
elif s[i] == "Q":
s[i] = "0"
s=''.join(s)
print(s)
shuru = s
shuru1 = list(shuru)
for i in range(len(shuru1)):
shuru1[i]=ord(shuru1[i])
for i in range(len(shuru1)):
if shuru1[i] >= ord('a') and shuru1[i] <= ord('z'):
if shuru1[i] <= ord('m'):
shuru1[i] += 13
elif shuru1[i] <= ord('z'):
shuru1[i] -= 13
elif shuru1[i] >= ord('A') and shuru1[i] <= ord('Z'):
if shuru1[i] <= ord('M'):
shuru1[i] += 13
else:
shuru1[i] -= 13
for i in range(len(shuru1)):
shuru1[i]=chr(shuru1[i])
shuru1=''.join(shuru1)
print(shuru1.upper())
|
解码出来的flag是全小写的，不过源代码里面有lowercase
不得不反思一下是否flag区分大小写
查看一下lowercase 的代码检查是哪些位降了小写
还有这个for循环的初始化值很奇怪，没有递增
这个for 是有问题
不过从逻辑上推测，应该是把所有位都lowercase了，这样就没法反推哪些位置是大写了，shit
不然只能用穷举法了
尼玛全大写
