An information processor includes a data storage portion that stores a first capability list indicating capabilities regarding an encryption. The information processor also includes a communication portion that receives a second capability list indicating capabilities, regarding the encryption, of a device. Further, the information processor includes a processing unit that determines an algorithm, by which communications are performed with the device, by referring to the first capability list and the second capability list. The communication portion sends identification information for identifying the algorithm determined by the processing unit and a public key relying on the algorithm to the device.