Method for access to all the cells of a memory area for purposes of writing or reading data blocks in said cells

An access method to access to cells in a memory area of a card for purposes of writing or reading data blocks in said cells,

• the memory area comprising N+1 separately addressable, physically contiguous cells, where N is an integer greater than or equal to 0;
• the address of each cell being between 0 and N sequentially;
• wherein said method comprises:
• for each access time to said cells in said memory area to be accessed, the total number of access times being N+1 per memory area, performing a process of determining an address of a cell of the memory area to be accessed at said access time, the address determined for an access time not being once again determined for another access time;
• and determining the value of a random number;
• wherein said address determination process comprises:
• pseudorandomly determining a pseudorandom bit which can thus take either a first value or a second value;
• and calculating a mask value and applying to said value of the pseudorandom number a bitwise logic AND operation with said mask, and applying to an index determined for the access time in question a bitwise exclusive OR logic operation with a result of said logic AND operation, the value resulting from the exclusive OR operation being the value of the address for access to the cell of the memory area to be accessed at said access time.

An access method to access to cells in a memory area of a card for purposes of writing or reading data blocks in said cells,

• the memory area comprising N+1 separately addressable, physically contiguous cells, where N is an integer greater than or equal to 0;
• the address of each cell being between 0 and N sequentially;
• wherein said method comprises:
• for each access time to said cells in said memory area to be accessed, the total number of access times being N+1 per memory area, performing a process of address determining an address of a cell of the memory area to be accessed at said access time, the address determined for an access time not being once again determined for another access time, the address determination process comprising:
• pseudorandomly determining a pseudorandom bit which can thus take either a first value or a second value;
• testing the value taken by said random bit that switches said process either to:
• (1) in the event of the first value, determining a value index as being equal to the value of a first index, followed by incrementing a unit of said first index modulo N+1, or (2) in the event of the second value, determining said value index as being equal to the value of a second index, followed by decrementing a unit of said second index modulo N+1, the value of said value index being the value of said address of the cell of the memory area to be accessed at said access time;
• and applying to the value index a bitwise exclusive OR operation with another pseudorandom number before the address determination process.