An information processing system includes: a service system, a plurality of agent machines, and a plurality of encryption machines. The plurality of agent machines and the plurality of encryption machines are divided into a plurality of groups, and each group includes at least two encryption machines and a plurality of agent machines communicatively connected to the at least two encryption machines. The encryption machine is configured to encrypt and decrypt data from the service system and to perform signature verification on the data when the service system performs a security call on the encryption machine via the agent machine in the group containing the encryption machine. The service system is configured to perform service processing and to perform the security call on the encryption machine via the agent machine in the group containing the encryption machine.