How can i decrypt file in ios that was encrypted in c# using Rijndael

I have an application in C# that encrypt my files with AES algorithm with this method:

private static void encryptFile(string inputFile, string outputFile, string strKey)
{
  try
  {
    using (RijndaelManaged aes = new RijndaelManaged())
    {
      byte[] key = Encoding.UTF8.GetBytes(strKey);
      byte[] IV = Encoding.UTF8.GetBytes(strKey);

      using (FileStream fsCrypt = new FileStream(outputFile, FileMode.Create))
      {
        using (ICryptoTransform encryptor = aes.CreateEncryptor(key, IV))
        {
          using (CryptoStream cs = new CryptoStream(fsCrypt, encryptor, CryptoStreamMode.Write))
          {
            using (FileStream fsIn = new FileStream(inputFile, FileMode.Open))
            {
              int data;
              while ((data = fsIn.ReadByte()) != -1)
              {
                cs.WriteByte((byte)data);
              }
            }
          }
        }
      }
    }
  }
  catch (Exception ex)
  {
    Debug.WriteLine(ex.Message);
  }
}

The file is encrypted without an issue.

Then I want to decrypt the encrypted file with my Android (2.2) application. So I do this:

private void decriptFile() throws NoSuchPaddingException, NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException, InvalidAlgorithmParameterException, InvalidKeyException, IOException {
        //byte[] docBytes = serialize(myDoc);
        byte[] b = new byte[0];
        try {
            Resources res = getResources();
            InputStream in_s = res.openRawResource(R.raw.output27);

            b = new byte[in_s.available()];
            in_s.read(b);
            //txtHelp.setText(new String(b));
        } catch (Exception e) {
            // e.printStackTrace();
            //txtHelp.setText("Error: can't show help.");
        }

        //byte[] dataBytes = FileUtils.readFileToByteArray(File file);
        byte[] key = new byte[0];
        try {
           // key = ("HR$2pIjHR$2pIj12").getBytes("UTF-8");
            key = ("HR$2pIjHR$2pIj12").getBytes("UTF-8");
            Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");
            SecretKeySpec k = new SecretKeySpec(key, "AES");
            IvParameterSpec iv = new IvParameterSpec(key);
            c.init(Cipher.DECRYPT_MODE, k, iv);

            // IllegalBlockSizeException Occurred

            //File folder = new File(Environment.getExternalStorageDirectory(),
                    //"test");
            File folder = new File("/sdcard",
                    "test");
            if (!folder.exists()) {
                folder.mkdir();
            }

            byte[] decryptedDocBytes = c.doFinal(b);
            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(folder.getPath()+"/test.epub"));
            bos.write(decryptedDocBytes);
            bos.flush();
            bos.close();
            //DocumentsContract.Document decryptedDoc = (DocumentsContract.Document)deserialize(decryptedDocBytes);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        //IvParameterSpec iv = new IvParameterSpec(key);



        //And my serialize/deserialize methods:
    }

This time decryption works fine.For decrypting same file in Objective C I am using the following method:

- (NSData *)decrypt:(NSData *)plainText key:(NSData *)aSymmetricKey padding:(CCOptions *)pkcs7
{
    //return [self doCipher:plainText key:aSymmetricKey context:kCCDecrypt padding:pkcs7];
    return [self doCipher2:plainText iv:[self generateRandomIV:128] key:aSymmetricKey context:kCCDecrypt error:nil];
}

- (NSData *)doCipher2:(NSData *)dataIn
                  iv:(NSData *)iv
                 key:(NSData *)symmetricKey
             context:(CCOperation)encryptOrDecrypt // kCCEncrypt or kCCDecrypt
               error:(NSError **)error
{
    CCCryptorStatus ccStatus   = kCCSuccess;
    size_t          cryptBytes = 0;
    NSMutableData  *dataOut    = [NSMutableData dataWithLength:dataIn.length + kCCBlockSizeAES128];

    ccStatus = CCCrypt( encryptOrDecrypt,
                       kCCAlgorithmAES128,
                       0, //kCCOptionPKCS7Padding,
                       symmetricKey.bytes,
                       kCCKeySizeAES128,
                       iv.bytes,
                       dataIn.bytes,
                       dataIn.length,
                       dataOut.mutableBytes,
                       dataOut.length,
                       &cryptBytes);

    if (ccStatus == kCCSuccess) {
        dataOut.length = cryptBytes;
    }
    else {
        if (error) {
            *error = [NSError errorWithDomain:@"kEncryptionError"
                                         code:ccStatus
                                     userInfo:nil];
        }
        dataOut = nil;
    }

    return dataOut;
}

This time no luck.What might be the problem?? Any help would be appreciated.

Solution

In the Android version you specify PKCS5Padding but no padding it the iOS version. Note that PKCS5Padding andPKCS7Padding amount to the same thing, there is just a definition difference.

Change:

0, //kCCOptionPKCS7Padding,

kCCOptionPKCS7Padding,