Encryption of data for sending, how easy?

Question

Information Security

There is a small task - to make a wifi rfid reader so that it sends the card code to the server. We are going to use an ESP8266, but it's not very good to run numbers in plain text over the network. But I also don’t want to write SSL support on ESP.
Is it possible to somehow simply encrypt (and at the same time safely) the data? After all, we only send one line. And you don’t need to accept anything ... Or is it impossible to do this and be sure to raise SSL?

Answer 1

You can drive or not, this is a more philosophical question.
The traffic itself from the reader to the Wi-Fi AP is encrypted (as I understand it, this WPA2-PSK module can do it for example), then your network goes on and then it becomes a question of trusting your own network and its own topology.
Give an example of the attack vector that you are afraid of, and then we'll talk :)
Well, you can encrypt as you like, the same string, but even XOR is normal or something more interesting, if it is possible to send data wrapping in SSL, then of course it will be good, but I'm not familiar with ESP8266 from the inside.

Answer 2

I don’t know which option you will end up with, but let me remind you about lightweight SSL implementations specifically designed for use in MK with very limited resources:
Perhaps some of this will be able to compile under the ESP8266.

Answer 3

I'm certainly not an expert. safe, but maybe try to make SHA-1 with salt, and on the server already compare it with hashes according to the list of cards? Seems cheap and cheerful :)

Answer 4

How many bytes will be transferred data? In principle, AES is enough for protection if the key is not known to the attacker.