1. A speech recognition system, comprising: a first information processing device comprising a speech recognition processing unit for receiving data to be used for speech recognition transmitted via a network, carrying out speech recognition processing, and returning resultant data; and a second information processing device which is connected to the first information processing device via the network, which transmits the data to be used for the speech recognition by the speech recognition processing unit after performing mapping thereof by using a mapping function unknown to the first information processing device, and constructing a speech recognition result by modifying the resultant data returned from the first information processing device into the same result as a result of performing the speech recognition without using the mapping function.