RSA Decryption Error BadPaddingException

Question

I am encrypting file with symmetric key(AES), and then encrypting key with rsa key. Encrption is working fine but in decryption it gives error: Here is the stacktrace: http://pastebin.com/37AB7EPH

I have tried everything please help me thanks.

@RequestMapping(value= "/{userId}/uploadresource/{userEmail:.*}", method = RequestMethod.POST )
@ResponseBody
public void GetResourcesByUser(@PathVariable("userId") int UserId, @PathVariable("userEmail") String userEmail,  HttpServletRequest request, @RequestParam MultipartFile file ) throws InvalidKeySpecException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException, IOException{
    Users recieverUser =userService.GetUserByEmail(userEmail);
    Users senderUser= userService.getUserById(UserId);
    int receiverUserId = recieverUser.getUser_id();
    Profile receiverProfile = userService.getUserProfile(receiverUserId);
    byte[] receiverPublicKey=receiverProfile.getPublicKey();
    PublicKey testPubKey=X509CertificateGenerator.encodedByteToPublicKey(receiverPublicKey);            

    KeyGenerator keyGen = KeyGenerator.getInstance("AES");
    keyGen.init(192); // for example
    SecretKey secretKey = keyGen.generateKey();

    byte[] secretKeyEncoded= secretKey.getEncoded();

    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.ENCRYPT_MODE, secretKey);
    byte[] cipherData = cipher.doFinal(file.getBytes());

    Cipher cipher1 = Cipher.getInstance("RSA/ECB/PKCS1Padding");
    cipher1.init(Cipher.ENCRYPT_MODE, testPubKey);
    byte[] aesKeyEncryptedBytes = cipher.doFinal(secretKeyEncoded); 


    String senderUserName= senderUser.getUser_email();          
    AsymetricSharing sharing= new AsymetricSharing();

    sharing.setReceiverId(receiverUserId);
    sharing.setResourceFile(cipherData);
    sharing.setResourceName(file.getOriginalFilename());
    sharing.setSenderId(senderUser.getUser_id());
    sharing.setSenderName(senderUserName);
    sharing.setSymetricKey(aesKeyEncryptedBytes);

    resourseService.uploadAsymmetricResource(sharing);      
    //resources=this.resourseService.GetResourcesInGroup(group_id);     
}

Decrypt Asmmetric File...

@RequestMapping(value="/{userId}/downloadfile/{sharingId}", method = RequestMethod.GET, produces="application/json")
    public ResponseEntity<?> downloadAsymmetricFile(@PathVariable("sharingId") int sharingId, @PathVariable("userId") int userId, HttpServletResponse response) throws IOException, SQLException, InvalidKeyException, InvalidAlgorithmParameterException, NoSuchAlgorithmException, NoSuchProviderException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException, InvalidKeySpecException {     

    AsymetricSharing file= resourseService.getFile(sharingId);

    if(file!=null){ 
        Profile receiverProfile=  userService.getUserProfile(userId);

        byte [] receiverPrivateKey=receiverProfile.getPrivateKey();         

        PrivateKey testPvtKey=Converter.encodedByteToKey(receiverPrivateKey);

        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, testPvtKey);

        byte[] symetricKeyBytes = cipher.doFinal(file.getSymetricKey());    

        SecretKey symetricKey = new SecretKeySpec(symetricKeyBytes, "AES");

        Cipher cipher1 = Cipher.getInstance("AES");
        cipher1.init(Cipher.DECRYPT_MODE, symetricKey);
        byte[] plainText = cipher.doFinal(file.getResourceFile());

        response.setContentLength(plainText.length);
        response.setHeader("Content-Disposition","attachment; filename=\"" + file.getResourceName() +"\"");
        FileCopyUtils.copy(plainText, response.getOutputStream());
        return new ResponseEntity<>(file, HttpStatus.OK);
    }
    else
    {
        //if no entity present against id, return not found and bad request Http status.
        return new ResponseEntity<>("Not found", HttpStatus.BAD_REQUEST);
    }
}

What did you check? Symmetric key values? Input / output of your cipher? Note that SO is not a community debugger. — Maarten Bodewes
– Maarten Bodewes, Commented May 17, 2015 at 19:43

Juris Lacis · Accepted Answer · 2015-05-31 04:27:14Z

2

Cipher cipher = Cipher.getInstance("RSA");

It is no padded RSA in decryption (like RSA/ECB/NoPadding). Try to change it to the same value as in encryption ("RSA/ECB/PKCS1Padding"). RSA encrypted values can be also unpadded, sorry for my english if I am unclear :/

answered May 31, 2015 at 4:27

Juris Lacis

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