I have a rather particular classmate who wholeheartedly believes that there isn't such a thing as reasonably secure cryptography and that most people can steal encrypted data. I have attempted to explain (with must frustration) the security of AES. I often attempt to make points about how certain implementations and stream ciphers can result in data leaks, but AES in practice with proper implementations is feasibly unbreakable.
I am trying to find a way to present that AES is secure when everything is done correctly by developers. Any help to explain this to someone who is not cryptographically inclined would be a great help.
I have attempted to explain the math and just how large the keyspace is; the amount of energy required to bruteforce a key; econmical impacts of cracking the cipher, and with no avail.