code: public static InputStream decrypt(InputStream inputStream, byte[] key, byte[] iv) {
          checkNotNull(inputStream);
          checkNotNull(key);
          checkNotNull(iv);
          checkArgument(key.length == iv.length);
          AESFastEngine aesEngine = new AESFastEngine();
          PaddedBufferedBlockCipher cipher =
                  new PaddedBufferedBlockCipher(new CBCBlockCipher(aesEngine), new PKCS7Padding());
          cipher.init(false, new ParametersWithIV(new KeyParameter(key), iv));
          return new CipherInputStream(inputStream, cipher);
      }
docs: AES/CBC/PKCS5Padding Decryption
  
  @param inputStream input stream to be decrypted
  @param key         valid AES key sizes are 128, 192, or 256 bits (16, 24, or 32 bytes).
  @param iv          AES initialization vector. Must be the same size as the key.
  @return decrypted input stream