title: iOS encryption AES128/CBC/nopadding why is not working?
body: <p>I have an app that needs to encode some data using AES/CBC/no padding. The app is ported also on android. There the encoding is done like this:</p>
  
  <pre><code>byte[] encodedKey = getKey();
      SecretKeySpec skeySpec = new SecretKeySpec(encodedKey, "AES");
      AlgorithmParameterSpec paramSpec = new IvParameterSpec(initializationVector);
  
      Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
      cipher.init(Cipher.ENCRYPT_MODE, skeySpec, paramSpec);
  
      int blockSize = cipher.getBlockSize();
      int diffSize = decrypted.length % blockSize;
      System.out.println("Cipher size: " + blockSize);
      System.out.println("Current size: " + decrypted.length);
      if (diffSize != 0) {
        diffSize = blockSize - diffSize;
        byte[] oldDecrypted = decrypted;
        decrypted = new byte[decrypted.length + diffSize];
        System.arraycopy(oldDecrypted, 0, decrypted, 0, oldDecrypted.length);
        for (int i = 0; i &lt; diffSize; i++) {
          decrypted[i + oldDecrypted.length] = " ".getBytes()[0];
        }
        System.out.println("New size: " + decrypted.length);
  
      }
      return cipher.doFinal(decrypted);
  </code></pre>
  
  <p>the initializationVector looks like this:</p>
  
  <pre><code>private byte[] initializationVector = new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
  </code></pre>
  
  <p>on iOS i have something like this for encryption:</p>
  
  <pre><code>- (NSData *)AES128EncryptWithKey:(NSString *)key 
  {
      // 'key' should be 16 bytes for AES128, will be null-padded otherwise
      char keyPtr[kCCKeySizeAES128+1]; // room for terminator (unused)
      bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
  
  
      // fetch key data
      [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
  
      NSUInteger dataLength = [self length];
  
      //See the doc: For block ciphers, the output size will always be less than or 
      //equal to the input size plus the size of one block.
      //That's why we need to add the size of one block here
      size_t bufferSize = dataLength + kCCBlockSizeAES128;
      void *buffer = malloc(bufferSize);
  
      size_t numBytesEncrypted = 0;
      CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, 
                                            kCCAlgorithmAES128, 
                                            0x0000,
                                            keyPtr, 
                                            kCCKeySizeAES128,
                                            NULL /* initialization vector (optional) */,
                                            [self bytes], dataLength, /* input */
                                            buffer, bufferSize, /* output */
                                            &amp;numBytesEncrypted);
      if (cryptStatus == kCCSuccess) {
          //the returned NSData takes ownership of the buffer and will free it on deallocation
          return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
      }
  
      free(buffer); //free the buffer;
      return nil;
  }
  </code></pre>
  
  <p>the method described above is part of a category over NSData.
  the method is called like this:</p>
  
  <pre><code>NSData *data = [@"4915200456727" dataUsingEncoding:NSUTF8StringEncoding];
      NSData *cipher  = [data AES128EncryptWithKey:@"@x#zddXekZerBBw6"];
      NSString *ecriptedString = [NSString stringWithFormat:@"%.*s", [cipher length], [cipher bytes]];
  </code></pre>
  
  <p>the problem that i have is that i don't receive the same encrypted data on iOS and android. On iOS the encrypted data has 0 bytes in length. </p>
  
  <p>Could you give any pointers on how to encrypt a string using AES128 with CBC and no padding and perhaps an example?</p>
  
  <p>Thank you</p>