First commit

META-INF/MANIFEST.MF

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+Manifest-Version: 1.0
+Main-Class: com.developerfromjokela.opdecoder.Main
+

src/com/developerfromjokela/opdecoder/Main.java

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+package com.developerfromjokela.opdecoder;
+
+import javax.crypto.*;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.PBEKeySpec;
+import javax.crypto.spec.SecretKeySpec;
+import java.io.*;
+import java.nio.ByteBuffer;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.security.spec.InvalidKeySpecException;
+
+public class Main {
+
+    public static final String PBKDF2_ALGORITHM = "PBKDF2WithHmacSHA1";
+
+    public static void main(String[] args) {
+        if (args.length < 3) {
+            System.out.println("Arguments missing!");
+            return;
+        }
+        String pass = args[0];
+
+        pass = pass.trim();
+
+
+        try {
+            System.out.println("Reading file");
+
+            byte[] fileToDecrypt = Files.readAllBytes(new File(args[1]).toPath());
+
+            byte[] generated_pbkdf2 = rawPbkdf2(pass.toCharArray(), pass.getBytes(), 2000, 32+16);
+            System.out.println("Calculating keys");
+
+            DataInputStream inputStream = new DataInputStream(new ByteArrayInputStream(generated_pbkdf2));
+            byte[] encKey = new byte[32];
+            byte[] ivArray = new byte[16];
+
+
+            inputStream.read(encKey, 0, 32);
+            inputStream.read(ivArray, 0, 16);
+            System.out.println("Done!");
+
+            System.out.println("Decrypting");
+
+            Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
+            cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(encKey, "AES"), new IvParameterSpec(ivArray));
+            byte[] decryptedResult = cipher.doFinal(fileToDecrypt);
+            System.out.println("File decrypted!");
+            System.out.println("Writing to file");
+
+            FileOutputStream fileOutputStream = new FileOutputStream(new File(args[2]));
+            fileOutputStream.write(decryptedResult);
+            fileOutputStream.close();
+            System.out.println("Done!");
+
+        } catch (InvalidKeySpecException e) {
+            e.printStackTrace();
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+        } catch (IOException e) {
+            e.printStackTrace();
+        } catch (NoSuchPaddingException e) {
+            e.printStackTrace();
+        } catch (BadPaddingException e) {
+            e.printStackTrace();
+        } catch (IllegalBlockSizeException e) {
+            e.printStackTrace();
+        } catch (InvalidAlgorithmParameterException e) {
+            e.printStackTrace();
+        } catch (InvalidKeyException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    /**
+     *  Computes the PBKDF2 hash of a password.
+     *
+     * @param   password    the password to hash.
+     * @param   salt        the salt
+     * @param   iterations  the iteration count (slowness factor)
+     * @param   bytes       the length of the hash to compute in bytes
+     * @return              the PBDKF2 hash of the password
+     */
+    private static byte[] pbkdf2(char[] password, byte[] salt, int iterations, int bytes)
+            throws InvalidKeySpecException, NoSuchAlgorithmException {
+        PBEKeySpec spec = new PBEKeySpec(password, salt, iterations, bytes * 8);
+        SecretKeyFactory skf = SecretKeyFactory.getInstance(PBKDF2_ALGORITHM);
+        return skf.generateSecret(spec).getEncoded();
+    }
+
+    /**
+     *  Computes the PBKDF2 hash of a password.
+     *
+     * @param   password    the password to hash.
+     * @param   salt        the salt
+     * @param   iterations  the iteration count (slowness factor)
+     * @param   bytes       the length of the hash to compute in bytes
+     * @return              the PBDKF2 hash of the password
+     */
+    private static byte[] rawPbkdf2(char[] password, byte[] salt, int iterations, int bytes)
+            throws InvalidKeySpecException, NoSuchAlgorithmException {
+        PBEKeySpec spec = new PBEKeySpec(password, salt, iterations, bytes * 8);
+        SecretKeyFactory skf = SecretKeyFactory.getInstance(PBKDF2_ALGORITHM);
+        return skf.generateSecret(spec).getEncoded();
+    }
+
+}