Coded data generation or conversion – Digital code to digital code converters
Reexamination Certificate
2001-08-31
2003-09-16
Jeanpierre, Peguy (Department: 2819)
Coded data generation or conversion
Digital code to digital code converters
C341S106000, C713S182000
Reexamination Certificate
active
06621425
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device, a terminal device and a communication method.
2. Description of the Background Art
It is said that a fraudulent use of a terminal device such as a cellular phone, i.e., an illegal action of evading the duty of payment on the pretence that a user's own terminal device is some other's one in a communication network has recently increased. Though, naturally, the fraudulent use should be socially controlled by inflicting some legal punishment, it is recognized at the same time that a technical difficulty of fraudulent use, in other words, a higher technical barrier (security) against the fraudulent use is one of especially important countermeasures for preventing the crime.
FIG. 64
is an illustration cited from an article of “NIKKEI ELECTRONICS”, on Feb. 8, 1999 (No. 736), pp. 155-162 (document 1), showing an example of the current countermeasures for fraud prevention on the cellular phone. As described in the document 1, the method of
FIG. 64
is one with the highest level of security among the current countermeasures for fraud prevention, utilizing a procedure of “authentication”.
In this method, an electronic serial number (ESN) of a cellular phone, shared secret data (SSD) which are shared by the cellular phone and an authentication center of a communication common carrier and a mobile identification number (MIN) are given to each cellular phone. These identification numbers are encoded into cipher referred to as AUTHREQ on the basis of the CAVE (Cellular Authentication and Voice Encryption) algorithm. In the encryption, a random number referred to as RAND outputted from a mobile exchange center of the communication common carrier is used.
The communication common carrier decodes the cipher AUTHREQ transmitted from the cellular phone on the basis of the CAVE algorithm. The identification number obtained by decoding is compared with an identification number including the shared secret data (SSD) known only by the authentication center and a judgment on whether the communication should be permitted or not is made in accordance with the comparison result. Thus, a check on whether the user of the cellular phone is authorized or not, i.e., an authentication is performed on the basis of the shared secret data (SSD) shared only between the cellular phone and the communication common carrier.
It is said, however, that the illegal action through the fraudulent use eluding this authentication system of
FIG. 64
, which is considered as the current countermeasure for fraud prevention with the highest level of security, is prevailing. Further, it is said that one of the technical causes is that the identification number given to the cellular phone is written in a flash memory (flash ROM) which is rewritable, as described in the document 1.
FIG. 65
is a block diagram briefly showing an internal constitution of a cellular phone. A cellular phone
903
in the background art comprises a flash memory
908
as well as a communication circuit
907
. The communication circuit
907
operates in accordance with a program written in the flash memory
908
. The identification number ID is also stored in the flash memory
908
, and the communication circuit
907
performs encoding of the identification number ID read out from the flash memory
908
and transmits a cipher AUTHREQ obtained by encoding to the communication common carrier.
The reason why the rewritable flash memory
908
is used as a storage medium is that it is necessary to respond to a program change made by the communication common carrier, e.g., a change into a program for a new communication system. Further, the use of a non-rewritable mask ROM not only disables the program change but also needs to use different mask patterns corresponding to the identification numbers which are different from one device to another in the manufacturing process of the mask ROM to record the identification numbers, causing deterioration of manufacturing efficiency and an increase in manufacturing cost.
The application (Japanese Patent Application Laid Open Gazette 2001-007290: document 2) by the present applicant discloses a technique to solve the above cause, in which a semiconductor element having a polycrystalline substance is formed in a semiconductor substrate and variation in electric properties caused by variation in crystal structures of the polycrystalline substances is used for generation of an identification number.
On the other hand, as well as the above type of fraudulent use by rewriting of an identification number, known is another type of fraudulent use of terminal device by replacing a semiconductor substrate (semiconductor chip) mounted in a terminal device. Specifically, the fraudulent use through replacement of a semiconductor substrate in which an identification number is recorded with a semiconductor substrate in which another identification number is recorded so as to evade the duty of payment on the pretense that a user's own terminal device is some other's one has appeared. Further known is a crime to make an illegal gain through the fraudulent use through replacement of the semiconductor substrate in a general appliance of semiconductor device including a game machine for gamble (“pachinko machine” in Japan as a good example) and the like.
Furthermore known is still another type of fraudulent use of a terminal device which is capable of performing radio communication through a communication common carrier (i.e., a cellular phone) to evade the duty of payment on the pretense that the terminal device has been lost while being used.
SUMMARY OF THE INVENTION
The present invention is directed to a semiconductor device. According to a first aspect of the present invention, the semiconductor device comprises: N (1≦N) code generation unit formed in N semiconductor substrate in one to one correspondence, each of the N code generation unit being configured to generate an identification code inherent in a corresponding semiconductor substrate; and N memory formed in one-to-one correspondence to the N identification code, each of the N memory storing a code which coincides with a corresponding identification code as a memory code, and each of the N memory being formed in other semiconductor substrate than a corresponding semiconductor substrate.
According to a second aspect of the present invention, in the semiconductor device of the first aspect, each of the N memory comprises an OTPROM storing the memory code.
According to a third aspect of the present invention, in the semiconductor device of the first or second aspect, each of the N code generation unit comprises a semiconductor element; and a coding circuit configured to convert an electric property of the semiconductor element into a digital signal so that a value of the digital signal varies with variation in the electric property of the semiconductor element to generate the identification code and outputting the identification code.
According to a fourth aspect of the present invention, in the semiconductor device of the third aspect, the semiconductor element has a polycrystalline substance, and the variation in the electric property of the semiconductor element is caused by variation in crystal structure of the polycrystalline substance.
According to a fifth aspect of the present invention, in the semiconductor device of the first or second aspect, each of the N code generation unit comprises an OTPROM storing the identification code.
According to a sixth aspect of the present invention, the semiconductor device of any one of the first to fifth aspects further comprises: N comparator circuit formed in one-to-one correspondence to the N identification code, each of the N comparator circuit being configured to compare a corresponding identification code and a corresponding memory code to thereby judge whether these codes coincide with each other or not and outputting an enable signal representing the judgment result.
According to a seventh aspec
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