CSICTF-Writeups/Crypto/The Climb/theclimb.java

100 lines
2.4 KiB
Java

public class Main
{
int kmatrix[][];
int tmatrix[];
int rmatrix[];
public void div(String temp, int size)
{
while (temp.length() > size)
{
String substr = temp.substring(0, size);
temp = temp.substring(size, temp.length());
perf(substr);
}
if (temp.length() == size)
perf(temp);
else if (temp.length() < size)
{
for (int i = temp.length(); i < size; i++)
temp = temp + 'x';
perf(temp);
}
}
public void perf(String text)
{
textconv(text);
multiply(text.length());
res(text.length());
}
public void keyconv(String key, int len)
{
kmatrix = new int[len][len];
int c = 0;
for (int i = 0; i < len; i++)
{
for (int j = 0; j < len; j++)
{
kmatrix[i][j] = ((int) key.charAt(c)) - 97;
c++;
}
}
}
public void textconv(String text)
{
tmatrix = new int[text.length()];
for (int i = 0; i < text.length(); i++)
{
tmatrix[i] = ((int) text.charAt(i)) - 97;
}
}
public void multiply(int len)
{
rmatrix = new int[len];
for (int i = 0; i < len; i++)
{
for (int j = 0; j < len; j++)
{
rmatrix[i] += kmatrix[i][j] * tmatrix[j];
}
rmatrix[i] %= 26;
}
}
public void res(int len)
{
String res = "";
for (int i = 0; i < len; i++)
{
res += (char) (rmatrix[i] + 97);
}
System.out.print(res);
}
public static void main(String[] args)
{
Main obj = new Main();
System.out.println("Enter the plain text: ");
String text = "fakeflag";
System.out.println(text);
System.out.println("Enter the key: ");
String key = "gybnqkurp";
System.out.println(key);
double root = Math.sqrt(key.length());
if (root != (long) root)
System.out.println("Invalid key length.");
else
{
int size = (int) root;
System.out.println("Encrypted text = ");
obj.keyconv(key, size);
obj.div(text, size);
}
}
}