Cryptography – secret messages? No. These are the messages that everybody can see but nobody knows what they mean, unless of course you have the key to decipher the message.
But, is that very different from talking?
When people talk to each other, they never say what they actually mean, what they actually want to say. They say something else, they mean something else. You are left to decipher the hidden meanings of the talking. And the key here is gracefully named as “understanding”. If you are unable to interpret the hidden and actual message, you’ll be accused as “you do not understand me”.
Everybody knows cryptography, we always use cryptography.