Need specific cipher transformation that isn't available for some reason.

[strange crane]

I need to use Cipher class (https://docs.oracle.com/javase%2F7%2Fdocs%2Fapi%2F%2F/javax/crypto/Cipher.html) with exact transformation "AES/CBC/PKCS5Padding". But I get an error NoSuchAlgorithmException.

I found a function online that shows all available transformations and apparently I don't have it (https://imgur.com/zDPmdPw).

I thought these are tied to java version, so I tried java 21, java 11 java 8, java 7, different versions of Eclipse Adoptium, but no luck.

Please help with enabling "AES/CBC/PKCS5Padding"

[still arrow]

<@&987246399047479336> please have a look, thanks.

[still arrow]

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rmation "AES/CBC/PKCS5Padding".

[agile kernel]

hey there!

[strange crane]

Helloooo 👋

[agile kernel]

would you like to share your code please

i need to see

• SecretKey
• IvParameterSpec
• Algorithm Name

how you declare those

[strange crane]

import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Security;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;
import java.io.File;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.charset.Charset;

public class ByteDecrypter {
   public static String DecryptFromByte(byte[] Src, String Key, String Mode) {

      Cipher cipher = Cipher.getInstance(Mode);
      byte[] key = Key.getBytes(Charset.forName("ASCII"));
      SecretKeySpec keySpec = new SecretKeySpec(key, "AES");

      cipher.init(Cipher.DECRYPT_MODE, keySpec);
      byte[] encrypted1 = Src;
      byte[] original = cipher.doFinal(encrypted1);
      String originalString = new String(original);
      return originalString;
   }

   public static void main(String[] args) {
      byte[] fileContent = Files.readAllBytes(Paths.get("file.byte"));
      String output = DecryptFromByte(fileContent, "PASSWORD_HERE", "AES/CBC/PKCS5Padding");
      System.out.println(output);
   }
}

[still arrow]

Detected code, here are some useful tools:

[strange crane]

Tried to import everything I could find

It the first time i'm working with Java

[agile kernel]

ah i see

yeah but that's not all

[strange crane]

I'm getting NoSuchAlgorithmException

I'll add try catch and show what it return in an hour

[agile kernel]

I think the problem is: you need to use SecretKey

not SecretKeySpec

KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
keyGenerator.init(128);
SecretKey key = keyGenerator.generateKey();

then you do

cipher.init(Cipher.DECRYPT_MODE, key);

[strange crane]

That generates key? I have the key already

[agile kernel]

the object must be of type SecretKey

the current one you using is SecretKeySpec

[strange crane]

Ok, I'll try this too

[agile kernel]

i think you must set IV

initialization vector

you can create one easily like this

byte[] iv = new byte[16];

your new method would be like this

public static String DecryptFromByte(byte[] Src, String Key, String Mode, byte[] iv) throws Exception {

      Cipher cipher = Cipher.getInstance(Mode);
      byte[] key = Key.getBytes(Charset.forName("ASCII"));
      SecretKeySpec keySpec = new SecretKeySpec(key, "AES");

      IvParameterSpec ivSpec = new IvParameterSpec(iv); // Initialization Vector

      cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
      byte[] original = cipher.doFinal(Src);
      String originalString = new String(original);
      return originalString;
   }

[strange crane]

added try-catch to my code

public static String DecryptFromByte(byte[] Src, String Key, String Mode) {
      try {
         Cipher cipher = Cipher.getInstance(Mode);
         byte[] key = Key.getBytes(Charset.forName("ASCII"));
         SecretKeySpec keySpec = new SecretKeySpec(key, "AES");

         cipher.init(Cipher.DECRYPT_MODE, keySpec);
         byte[] encrypted1 = Src;
         byte[] original = cipher.doFinal(encrypted1);
         String originalString = new String(original);
         return originalString;
      } catch(Exception e) {
         System.out.println(e);
      }

      return "forced to add return";
   }

   public static void main(String[] args) {
      try {
         byte[] fileContent = Files.readAllBytes(Paths.get("./file.byte"));
         String output = DecryptFromByte(fileContent, "PASSWORD_HERE", "AES/CBC/PKCS5Padding");
         System.out.println(output);
      } catch(Exception e) {
         System.out.println(e);
      }
   }

the result is Missing Parameter https://imgur.com/bth8usb
before that it was throwing IOExceptions on Paths.get("./file.byte") so I silenced it too xd

I went back to the version of code without try-catch
and tried to change SecretKeySpec to SecretKey
now it shows error

and if I change back SecretKey to SecretKeySpec, leaving iv, I get this:

[agile kernel]

you can just add throws Exception

to your method declaration

[agile kernel]

btw are you using an IDE ?

im not sure, what's this

[strange crane]

no I just found on some website that java can be compiled with javac and then run with java

via command line

i am sure that this function should work on a very old version of java

[agile kernel]

where are you exploring your java files?

[strange crane]

in VSCode

[agile kernel]

are you using the java extension ?

[strange crane]

no, but highlighting works

[agile kernel]

it's not enough, it seems you have compiler errors

you need to see them up

[strange crane]

let's stop for now
I'll bash my head against this decryption for a bit and later tell if i manage to make it work
i am sure this function worked "as is" at some time

[still arrow]

Closed the thread due to inactivity.

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