1.  Field of the Invention
This invention relates to an information processing method and an information processing system capable of tracing distribution information of an information distribution route, distribution range, distribution amount, etc. 
2.  Description of the Related Art
By the digital information technology development and the information highway initiative and the like, it will be soon accomplished that all information is digitalized and distributed through networks.  Distribution of various pieces of information such as images, moving pictures, voice, and programs as well as text information has already begun through network media such as internets and personal computer communication.  Although information originators or issuers and receivers are distinguished clearly from each other with information media like conventional broadcasting, in such a system, all users may be both information originators (issuers) and receivers.  Therefore, anyone can readily distribute various pieces of information in various forms.  Digitalized information, which has a feature of easy copying, is distributed via a number of persons; it is distributed among the users who copy and redistribute the information, and the information distribution range and speed will be accelerated. 
Under such circumstances, a situation in which once information is left from a person, how it is passed to and used by what person is unknown occurs.  Each person may want to know whether or not once distributed information has been passed to his or her intended person, what point the information has been distributed to on the distribution route, what route the information has been distributed through, etc.  Further, recently, programs into which computer viruses are mixed, information containing a violation of privacy, and the like have often been distributed illegally without recognition.  When such illegal information is distributed, a demand for specifying the originator or issuer and the distribution route of the information also occurs.  However, in the conventional art, such demands cannot fully be solved and some demands are only solved. 
For example, in an electronic mail communication network described in Unexamined Japanese Patent Publication (kokai) No.  Hei 4-268849, at the node receiving electronic mail, information concerning the originator name and passed-through node added to the received electronic mail can be compared with information concerning the network configuration held in the node to see if the electronic mail originator name is false.  Further, in transfer of electronic mail, the transmitter prepares transmission and reception logs together with information to be sent to the receiver and transfers both as a unit to the receiver. 
However, in the electronic mail communication network, the passed-through node route when information is transmitted from one user A to another B is only recorded and when the information is further transmitted from user B to user C, user A information is not left.  Thus, the function cannot be used for tracing across the users.  Since the electronic mail communication network depends on a specific feature of electronic mail, for example, if information is simply copied from a storage of one person to a storage of another person, the route of distribution (in this case, copy) of the information is not recorded and the distribution route of the information cannot be known later.  Further, for example, when the transmitter wants to know what point his or her transmitted information reaches at present, he or she cannot trace it. 
In an office information processing system described in Unexamined Japanese Patent Publication (kokai) No.  Hei 5-63728, control information indicating what processing can be performed after reception is added to electronic mail and history information on operation performed on received mail is stored.  By referencing the history information, the transmitter can know whether or not transmitted electronic mail has been processed, for example.  However, in the system, what route the information has been distributed through cannot be known although the originator of received electronic mail can be known.  Like the above-mentioned electronic mail system, the office information processing system does not consider any distribution route other than the electronic mail system.  Thus, in the office information processing system, the distribution route of received information cannot be known. 
Further, in an electronic document preparation/approval system with an electronic certification function described in Unexamined Japanese Patent Publication No.  Hei 2-297288, certification data created by a certification process at approval is registered in a certification logging file, thereby enabling a document approval state to be traced.  Since the electronic document preparation/approval system enables the approval requester to know the current approval state, even if a document is distributed to a person who does not perform an approval process, the fact cannot be known.  As with the electronic mail communication network, if information not related to approval is simply copied from a storage of one person to a storage of another person, the route of distribution (in this case, copy) of the information is not recorded and the distribution route of the information cannot be known later. 
As we have discussed, without using a special system such as the electronic mail or approval system, when various kinds of information are distributed by various methods through various persons, once distributed information cannot be traced to its distribution route and when illegal information is distributed, the originator (issuer) and distribution route of the information cannot be located either.