The invention is directed to a data-
processing system comprising a processor and first encrypted information in a first persistent memory whose level of
information leakage is higher than that of a second persistent memory. In the second persistent memory is stored a first cryptographic key for decrypting the first encrypted information, thereby generating therefrom first unencrypted information that is
usable by the processor for executing an operation. The same cryptographic key may also be used for encrypting the first unencrypted information, thereby generating the first encrypted information. It is also directed to a method of
processing such a data-
processing system with an
operating system, comprising a writing step for writing first unencrypted information into the first persistent memory, an
encryption step for encrypting the first unencrypted information under use of the first cryptographic key, creating therefrom first encrypted information in the first persistent memory, and an access-limitation step for setting the data-processing
system to a state in which writing into the first persistent memory is controlled by the
operating system. It also relates to a method of executing an operation on such a data-processing system comprising a decryption step for decrypting the first encrypted information under use of the first cryptographic key, thereby generating therefrom first unencrypted information and an execution step for executing an operation by the processor, using the first unencrypted information.