<P> In a public key signature system , a person can combine a message with a private key to create a short digital signature on the message . Anyone with the corresponding public key can combine a message , a putative digital signature on it , and the known public key to verify whether the signature was valid , i.e. made by the owner of the corresponding private key . Changing the message , even replacing a single letter , will cause verification to fail . In a secure signature system , it is computationally infeasible for anyone who does not know the private key to deduce it from the public key or any number of signatures , or to find a valid signature on any message for which a signature has not hitherto been seen . Thus the authenticity of a message can be demonstrated by the signature , provided the owner of the private key keeps the private key secret . </P>
<P> In a public key signature system , a person can combine a message with a private key to create a short digital signature on the message . Anyone with the corresponding public key can combine a message , a putative digital signature on it , and the known public key to verify whether the signature was valid , i.e. made by the owner of the corresponding private key . Changing the message , even replacing a single letter , will cause verification to fail . In a secure signature system , it is computationally infeasible for anyone who does not know the private key to deduce it from the public key or any number of signatures , or to find a valid signature on any message for which a signature has not hitherto been seen . Thus the authenticity of a message can be demonstrated by the signature , provided the owner of the private key keeps the private key secret . </P>
the combination of a public key and a private key is known as a
the combination of a public key and a private key is known as a
digital signature
digital signature