The process of creating a digital signature allows someone to send a message and prove they sent it. The process is:
- The message is encrypted with the private key of the person sending the message.
- Anyone receiving the message can decrypt and read the message with the public key.
- If the public key can be used to successfully decrypt the message, it is proof that the message was really sent by the person who claimed to send it.
The author of the message cannot deny having created or sent the message. Most digital signature processes use the hash or CRC value of the message which is the only part encrypted to verify the sender of the message. Then when the encrypted hash or CRC is decrypted and recalculated from the contents of the message, if the two values are equal, the sender of the message has been verified.