A processing unit comprising: a processor; and a memory, coupled to the processor and adapted to provide a plurality of enclaves isolated from each other, where the plurality of enclaves include a plurality of application enclaves, each of the application enclaves is used for running a respective application program, and the plurality of enclaves further include at least one of the following: a runtime enclave adapted to provide a storage space required for an invokable program; and a crypto enclave adapted to provide a storage space required for a crypto related program, wherein the runtime enclave and the crypto enclave have read/write permission for the plurality of application enclaves, and each of the application enclaves has no read/write permission for the runtime enclave and the crypto enclave.