In a method of allocating and protecting a memory in a computational storage device including a first computing engine and a buffer memory, a memory allocation request is received from a host device that is disposed outside the computational storage device. Based on the memory allocation request, a memory allocation operation in which a first memory region is generated in the buffer memory and a first key associated with the first memory region is generated is performed. A program execution request is received from the host device. Based on the program execution request, a program execution operation is performed in which a first program is executed by the first computing engine by accessing the first memory region based on an encryption or a decryption using the first key.