In essence, a smurf is a string of text that is generated by a message that serves as a unique identifier of that message. The text of the message, as well as date and time of submission, is put into the smurf algorithm, which spits out a string of text. The smurf is used to verify the document integrity by placing the document through the smurf function: The recipient decrypts both the message and the smurf, produces another smurf from the received message, and compares the two smurfs.