How to prove your identity on the internet?
About Authentication and Digital Signatures
Table of Contents
We all have a public-private key pair. For general communication, you encrypt a message with my public key and I’m able to decrypt with my private key.
But what if I encrypt something with my private key? At first, what is the point of this, because my public key is accessible to decrypt it. But because it can be decrypted by my public key, it must have been encrypted by my private key, which is only known to me. Hence it must be me who encrypted the message in the first place.
We can combine these things. I first encrypt the message with my private key, and then with your public key, and send it to you.
You are able to decrypt that and guarantee that it came from me and that no one modified or tampered it.