Patent ID: 7330979

Claim:
A method for protecting the processing of sensitive information in a security module having a monolithic structure comprising at least an information processing device, a storage device for storing information capable of being processed by said processing device and at least a data bus, the security module further comprising means for checking the integrity of information, said means for checking the integrity being either a table contained in the processing device or a plurality of software program instructions of the storage device or a specific hardware circuit, the method comprising at least the following steps: selecting a piece of sensitive information stored in the storage device addressed by the processing means; determining, by the means for checking the integrity, a specific condition for establishing the integrity of said sensitive information to be transmitted on said data bus; transferring a datum of said sensitive information from the storage device to the processing device, on said data bus; verifying said datum transferred on said data bus, by said means for checking the integrity for verifying that said specific condition is satisfied; and disabling the processing of said sensitive information by the processing device if the specific condition is not satisfied, wherein said datum of said sensitive information is an operation code datum read in the storage device, said operation code datum being recognized in said table contained in the processing device, said specific condition being satisfied if said operation code datum is equal to a valid operation code datum of the table and said specific condition is not satisfied at least if bits of the operation code datum are all equal to a same binary value.