Abstract: A device is provided that combines data protection for stored data with ease of use in cases where data encrypted using a public key is received and stored.

Abstract: A system which allows each server in a network to verify the signature of a party issuing a service instruction in a system for providing a cooperative service by allowing servers to send and receive instruction data indicating instructions to each server and to execute the instruction written in the instruction data. An instruction input device receiving an instruction from a service requestor attaches an electronic signature (initiator signature (74)) of the requestor or the instruction input device to an instruction which indicates process content of each server, to create a signed individual instruction (72). The instruction input device further attaches an initiator signature (76) to data in which the signed individual instructions (72) for all servers involved in the service are merged, to create a collective instruction (70). The collective instruction (70) is transmitted to a flow controller controlling the servers.

Abstract: A printing device that comprises a receiver for receiving print data from a host computer, a transmitter for transmitting to the host computer a reception process completion signal indicating that the receiver completes the receiving of print data, a recognizing device for recognizing that the host computer requests the receiver and transmitter to change a communication protocol to another, and an altering device for altering the timing of transmitting a reception process completion signal sent by the transmitter when the recognizer recognizes the change of the communication protocol to another.

Abstract: An image processing system 1 (information processing system) includes a plurality of input interfaces 11, 12, and 13 for inputting image data output from a plurality of host systems C, PC1, and PC2, an input buffer 41 for storing the image data input through the input interfaces, determination mechanism for determining the upper limit value of the storage amount of the image data stored in the input buffer 41 for at least one of the input interfaces 11-13, and mechanism for storing image data in the input buffer in a scattering manner so as not to exceed the upper limit value determined by the determination mechanism.