Secure memory management method
AssigneeGemplus
InventorsPhilippe Brun, Charles Coulier
Life of this patent
Estimating the term…
Abstract
The invention provides a method for reducing occupancy of descriptors used for protecting files in storage. The method includes separating the functions files are going to be subjected to from the protection modes to which said functions subscribe. The descriptors comprise a number of octets equal to the number of protection modes proposed. The bits of these octets, depending on whether they are active or inactive, refer to function memory words whose number is directly equal to the number of active bits in the mode memory words. The function memory words comprise references to secret codes to be used for implementing the desired security functions.
Claims8
Secure method of managing a memory (13-15) in which:
- files (44) in the memory are allocated file descriptors (41),
- said file descriptors include information (47-49) on security modes needed to apply processing functions (50) to data stored in the files, and
- the security of the files in the memory is managed (40) in accordance with the content of said file descriptors, characterised in that:
- the security modes are divided into M different types (19-21) and the functions are divided into N different types (22-28),
- a first group (47-49) of M mode memory words is created in the descriptor of each file, the length in bits of the mode memory words being at least equal to the number N of different types of functions,
- the functions are stored in a particular order (G1-G7), the positions (52-54) of the bits in the mode memory words conforming to that order, and
- the bits of the mode memory words are rendered active or inactive according to whether a security mode (47) must or must not be applied on application of a function (G1) to a file to which a descriptor relates.
Dependencies are inferred from the claim text.