Many years ago, we lived and worked in the same town. Everyone knew you and business was conducted because of your reputation. As time went by, people were able to do business across longer distances and, today, we conduct business with people from all around the world.
We don’t personally know the people we are working with and they do not know us. We rely on public key encryption to verify from whom we are receiving information and to whom we are sending information.
Public key encryption is used to secure our transactions on the Web and many of the digital verifications used today. The green lock that you see in your browser when you go to a website uses public key encryption to secure your information sent back and forth.
Public key encryption means that there are two keys for the encryption. When something is encrypted with one of these keys it can only be decrypted using the other key and encrypting it again. It is very difficult if not impossible to defeat this if it is properly set up. This means I can sign things and you can use my public key to verify that it is really from me.
You can encrypt a message with a person’s public key and they will be the only one that is able to read the message. The magic in public key encryption is that only by encrypting with both the public and private keys you get the original message back. If you have one of the keys, you are no closer to seeing the message encrypted with the key you have than anyone else.
This means you can give everyone your (public) key and they can send you messages that only you can read. You can create a signature that anyone with your public key can verify, but only you with your private key can create the signature. Public key encryption is the lynch pin of much of our online security. It is used to verify that we are who we claim to be and make sure messages are not altered in transit. It can prevent others from reading messages that we want to remain confidential. Much of what we do online is dependent on public key encryption and it being set up properly.