I\'m building an application with NFC which is a wireless communication protocol

Question

I'm building an application with NFC which is a wireless communication protocol. An attacker can modify bits in a wireless communication protocol. I want to prevent this. I know we can't prevent an attacker from changing the wireless signal, but it's possible to detect the modified information.

My question is: is this possible by encrypting your data with e.g. AES? I'm not 100% sure but in my thoughts AES can only be decrypted one way. So if the attacker modifies one or several bits, won't the receiving client be able to decrypt the information?

Explanation / Answer

At least the block where the attacker does the modification, its information will not be recoverable (you'll recover senseless info, be careful on that also because it may have sense even!), but depending on the block cipher mode it could disturb your decryption in a longer set. No information is released on that, but how you react to this issue may release information (thinking on side channels about your time response).

What you seems to want is integrity, and you may like to think on authenticated encryption. You can apply an error handler, not only to detect but also to correct certain level of noise, there are many correct options there. But I insists sooner or later your attacker will force you to resend and it's a big weakness point to be careful for.

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