Is this public key encryption?

[DaveC426913]

TL;DR Summary

I mean, sure, it only uses a key that has 365 combinations...

I've tried to intuit public key encryption but never quite managed.
But this seems to wrap it up in a bow.

This seems to be a very elegant way of transmitting a message publicly that only the sender and receiver can decipher.

Is this how PKE works?

No, it cant be. In the above case, the requester knows the target's "secret" key - because they have his ID, and therefore knows his birthdate.

 

[Ibix]

No, that's something like a one-time pad. There's a single secret that can be used for encryption and decryption.

The thing about public key encryption is that I can share the encryption key with you and you still can't decrypt a message. Or (more precisely) you need a very large computer and a lot of time to deduce the decryption key from the encryption key. Here, anybody who knows the birthdate (which is the secret key) can both encrypt and decrypt.

It's clever, though.