Random number processing device generating random numbers by using data read from non-volatile memory cells, and integrated circuit card

1. A random number processing device generating random number data by using data read from memory cells, the random number processing device comprising:

a random number processing circuit that, in operation, generates first random number data from a combination of first resistance value information and second resistance value information, the first resistance value information being information about a resistance value of a first memory cell among the memory cells, the resistance value of the first memory cell falling within at least one resistance value range, the second resistance value information being information about a resistance value of a second memory cell that is different from the first memory cell among the memory cells, the resistance value of the second memory cell falling within the at least one resistance value range, wherein:

in a variable state, in response to application of different electrical signals to the memory cells, a resistance value of each of the memory cells reversibly transitions between resistance value ranges including the at least one resistance value range; and

in a case where the resistance value of each of the memory cells falls within the at least one resistance value range, the resistance value of each of the memory cells changes as time passes.

2. The random number processing device according to claim 1 , wherein

the random number processing circuit includes

a first random number data generation circuit that, in operation, generates the first random number data in accordance with a difference or a magnitude relationship between the first resistance value information and the second resistance value information.

3. The random number processing device according to claim 2 , wherein

the random number processing circuit further includes

a second random number data generation circuit that, in operation, generates second random number data in accordance with a difference or a magnitude relationship between third resistance value information and fourth resistance value information, the third resistance value information and the fourth resistance value information being information about the resistance value of a third memory cell among the memory cells, the resistance value of the third memory cell falling within the at least one resistance value range, the third resistance value information being obtained at a first time point, the fourth resistance value information being obtained at a second time point.

4. The random number processing device according to claim 3 , wherein

the third resistance value information and the fourth resistance value information are each represented by a digital value, and, in operation,

the second random number data generation circuit generates the second random number data in accordance with whether the difference has a value of an even number or an odd number.

5. The random number processing device according to claim 3 , wherein

the random number processing circuit further includes

a third random number data generation circuit that, in operation, generates third random number data by performing an exclusive OR operation on the first random number data and the second random number data.

6. The random number processing device according to claim 2 , wherein

the first resistance value information and the second resistance value information are each represented by a digital value, and, in operation,

the first random number data generation circuit generates the first random number data in accordance with whether the difference has a value of an even number or an odd number.

7. A non-volatile memory device comprising:

a memory array that includes memory cells each having a resistance value and having a property that, in a variable state, in response to application of different electrical signals to the memory cells, the resistance value reversibly transitions between resistance value ranges and, in a case where the resistance value falls within at least one resistance value range among the resistance value ranges, the resistance value changes as time passes;

a read circuit that, in operation, obtains first resistance value information and second resistance value information, the first resistance value information being information about the resistance value of a first memory cell among the memory cells, the resistance value of the first memory cell falling within the at least one resistance value range, the second resistance value information being information about the resistance value of a second memory cell that is different from the first memory cell among the memory cells, the resistance value of the second memory cell falling within the at least one resistance value range; and

a random number processing circuit that, in operation, generates first random number data from a combination of the first resistance value information and the second resistance value information.

8. The non-volatile memory device according to claim 7 , wherein

each of the memory cells includes a variable resistance element including

a first electrode,

a second electrode, and

a variable resistance layer interposed between the first electrode and the second electrode.

9. The non-volatile memory device according to claim 8 , wherein

the variable resistance layer includes a layer of an insulator.

10. The non-volatile memory device according to claim 9 , wherein

the variable resistance layer includes a local region that passes through the layer of the insulator.

11. The non-volatile memory device according to claim 10 , wherein

the insulator contains a metal oxide, and

the local region contains a metal oxide of an oxygen deficient type having a lower percentage of oxygen content than a percentage of oxygen content of the insulator.

12. The non-volatile memory device according to claim 8 , wherein

the variable resistance layer contains a metal oxide.

13. The non-volatile memory device according to claim 12 , wherein

the metal oxide is of an oxygen deficient type.

14. The non-volatile memory device according to claim 12 , wherein

the metal oxide is at least one selected from the group consisting of a transition metal oxide and an aluminum oxide.

15. The non-volatile memory device according to claim 12 , wherein

the metal oxide is at least one selected from the group consisting of a tantalum oxide, a hafnium oxide, and a zirconium oxide.

16. An integrated circuit card comprising:

a memory array that includes memory cells each having a resistance value and having a property that, in a variable state, in response to application of different electrical signals to the memory cells, the resistance value of the memory cells reversibly transitions between a resistance value ranges and, in a case where the resistance value falls within at least one resistance value range among the resistance value ranges, the resistance value changes as time passes;

a read circuit that, in operation, obtains first resistance value information and second resistance value information, the first resistance value information being information about the resistance value of a first memory cell among the memory cells, the resistance value of the first memory cell falling within the at least one resistance value range, the second resistance value information being information about the resistance value of a second memory cell that is different from the first memory cell among the memory cells, the resistance value of the second memory cell falling within the at least one resistance value range;

a random number processing circuit that, in operation, generates first random number data from a combination of the first resistance value information and the second resistance value information; and

an input/output interface unit from which individual identification information generated by using the first random number data is output.