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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6. import javax.crypto.Cipher;
  7. import javax.crypto.SecretKey;
  8. import javax.crypto.SecretKeyFactory;
  9. import javax.crypto.spec.IvParameterSpec;
  10. import javax.crypto.spec.PBEKeySpec;
  11. import javax.crypto.spec.SecretKeySpec;
  12. import java.nio.charset.StandardCharsets;
  13.  
  14. /* Name of the class has to be "Main" only if the class is public. */
  15. class Ideone
  16. {
  17. private static SecretKey secretKey;
  18.  
  19. private static void generateSecretKey() {
  20. try {
  21. secretKey = new SecretKeySpec(SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256").generateSecret(new PBEKeySpec(new String(Base64.getDecoder().decode("VHJpYW5nbGUgb2YgQW5kcm9pZA=="), StandardCharsets.UTF_8).toCharArray(), new byte[32], 65536, 256)).getEncoded(), "AES");
  22. } catch (Exception e) {
  23. }
  24. }
  25.  
  26. public static void main (String[] args) throws java.lang.Exception
  27. {
  28. generateSecretKey();
  29. Cipher instance = Cipher.getInstance("AES/CBC/PKCS5PADDING");
  30. instance.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(new byte[16]));
  31. System.out.println(new String(instance.doFinal(Base64.getDecoder().decode("Fd60z2/WC/boWFPcZ1pbJW5v3eOjGcR3vajE7rPNN67pxtzYfNRYCE2XoTeOlw1uGYO24cqV/QnvD2rykyXzxQ=="))));
  32. }
  33. }
Success #stdin #stdout 0.41s 61744KB
stdin
Standard input is empty
stdout
CTF{the_triangle_of_android_f62eb802e6aca13743e9}