Because of the algorithm that is used to produce a digital signature, it is possible to create a signature that can readily be verified by both the sender and the receiver. The typically digital signature system actually uses three separate algorithms to ensure that no one can intercept it or create a fake signature. These are the key generation algorithm that chooses one private key from a specific set at random and then sends out both the private and public key.
The Other Two Digital Signature Algorithms Create and Verify
Once the signing algorithm receives both the message and the private key it will produce the required signature. At the other end of the process, there is a signature verification algorithm that will take the message, the public key and the signature itself, will examine what is has received and either accept it or reject it as being invalid. If the sender does not have a valid private key, it is virtually impossible to generate an authentic digital signature.