How It WorksAssume you were going to send the draft of a contract to your lawyer in another town. You want to give your lawyer the assurance that it was unchanged from what you sent and that it is really from you.
- You copy-and-paste the contract (it's a short one!) into an e-mail note.
- Using special software, you obtain a message hash (mathematical summary) of the contract.
- You then use a private key that you have previously obtained from a public-private key authority to encrypt the hash.
- The encrypted hash becomes your digital signature of the message. (Note that it will be different each time you send a message.)
- To make sure it's intact and from you, your lawyer makes a hash of the received message.
- Your lawyer then uses your public key to decrypt the message hash or summary.
- If the hashes match, the received message is valid.