Microcontroller and authentication method between the controllers

1. A microcontroller, comprising:

a program memory configured to store a program group and a first encryption key;

a CPU; and

an identification (ID) storage section configured to store an identification data peculiar to a user of said microcontroller,

wherein said CPU executes said program group to generate a second encryption key based on said identification data and said first encryption key and to encrypt a random number with said second encryption key.

2. The microcontroller according to claim 1 , wherein said CPU executes a random number generating program of said program group to generate said random number.

3. The microcontroller according to claim 1 , further comprising:

a random number generating circuit configured to generate said random number.

4. The microcontroller according to claim 1 , further comprising:

a port configured to receive said random number.

5. The microcontroller according to claim 1 , wherein said CPU executes said program group to compare said random number encrypted with said second encryption key and an encrypted random number received from an external device and to output the comparison result.

6. The microcontroller according to claim 1 , wherein said program memory and said ID storage section are constituted by a nonvolatile memory.

7. The microcontroller according to claim 6 , further comprising:

a control section configured to carry out an erasing operation and a writing operation to said program memory in response to a write request of a program into said program memory, and

wherein said control section erases said identification data from said ID storage section when said erasing operation is carried out to said program memory.

8. The microcontroller according to claim 1 , wherein said program group comprises:

a first encryption key supplying program adapted to supply said first encryption key;

a second encryption key generating program adaptive to acquire said first encryption key and said identification data and to generate said second encryption key based on said first encryption key and said identification data; and

an encrypting program adapted to encrypt said random number with said second encryption key.

9. The microcontroller according to claim 8 , wherein said program group further comprises:

a comparing program adapted to compare said random number encrypted using said second encryption key and an encrypted random number received from an external device and to output the comparison result.

10. An authentication method between first and second microcontrollers, said method comprising:

supplying a first encryption key through execution of a first encryption key supplying program stored in a first program memory of said first microcontroller;

holding a first identification data peculiar to said first microcontroller in a first identification (ID) storage section of said first microcontroller;

generating a second encryption key in said first microcontroller based on said first identification data and said first encryption key;

encrypting a random number with said second encryption key in said first microcontroller to generate a first encrypted random number;

receiving a second encrypted random number from said second microcontroller; and

comparing said first encrypted random number and said second encrypted random number to output the comparing result.

11. The authentication method according to claim 10 , further comprising:

reading said random number from said first program memory.

12. The authentication method according to claim 11 further comprising:

generating said random number to store in said first program memory.

13. The authentication method according to claim 12 , wherein said generating said random number comprises:

executing a random number generating program stored in said first program memory to generate said random number.

14. The authentication method according to claim 10 , wherein said program memory and said ID storage section are constituted by a nonvolatile memory, and

said microcontroller further comprises:

carrying out an erasing operation and a writing operation to said first program memory in response to a write request of a program into said first program memory; and

carrying out said erasing operation to said ID storage section in response to the write request.

15. The authentication method according to claim 10 , further comprising:

supplying a third encryption key through execution of a second encryption key supplying program stored in a second program memory of said second microcontroller;

holding a second identification data peculiar to said second microcontroller in a second identification (ID) storage section of said second microcontroller;

generating a fourth encryption key in said second microcontroller based on said second identification data and said third encryption key;

encrypting said random number from said first microcontroller with said fourth encryption key in said second microcontroller to generate said second encrypted random number; and

transmitting said second encrypted random number to said first microcontroller.

16. The authentication method according to claim 15 , further comprising:

supplying power to said second microcontroller when a unit containing said second microcontroller is installed to a unit containing said first microcontroller,

wherein said supplying a third encryption key is performed after the power is supplied to said second microcontroller.

17. The authentication method according to claim 10 , further comprising:

supplying a third encryption key through execution of a second encryption key supplying program stored in a second program memory of said second microcontroller;

holding a second identification data peculiar to said second microcontroller in a second identification (ID) storage section of said second microcontroller;

generating a fourth encryption key in said second microcontroller based on said second identification data and said third encryption key;

encrypting said random number from said first microcontroller with said fourth encryption key in said second microcontroller to generate said second encrypted random number; and

transmitting said second encrypted random number to said first microcontroller.

18. The authentication method according to claim 17 , further comprising:

supplying power to said first microcontroller when a unit containing said second microcontroller is installed to a unit containing said first microcontroller,

wherein said supplying a first encryption key is performed after the power is supplied to said first microcontroller.

19. The authentication method according to claim 10 , wherein said first identification data comprises a predetermined customer identifier.

20. The authentication method according to claim 10 , wherein, when said first identification data is readable but unrewriteable from a user memory program.