Coded data generation or conversion – Analog to or from digital conversion – Digital to analog conversion
Reexamination Certificate
1999-12-10
2004-03-09
JeanPierre, Peguy (Department: 2819)
Coded data generation or conversion
Analog to or from digital conversion
Digital to analog conversion
C257S532000
Reexamination Certificate
active
06703953
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device suitably applicable to a user terminal such as a portable telephone and a method of manufacturing the same as well as a communication method suitable for utilizing the semiconductor device.
2. Description of the Background Art
It is said that illegal use of a user terminal such as a portable telephone, i.e., a criminal act of pretending that one's user terminal belongs to another person in a communication network by changing the identification number or the like to evade paying the communication charges is recently on the increase. While such illegal use must be socially controlled through legal action similarly to other crimes as a matter of course, it is recognized as one of particularly important countermeasures for preventing such a crime to make illegal use technically difficult, i.e., to improve a technical barrier (security) against the illegal use.
FIG. 93
is an explanatory diagram quoted from a report in “Nikkei Electronics” No. 736 dated Feb. 8, 1999, pp. 155 to 162 (hereinafter referred to as literature 1), showing an exemplary countermeasure against illegal use currently carried out in relation to a portable telephone. As described in literature 1, the method shown in
FIG. 93
is regarded as providing the highest security among the current countermeasures against illegal use, and utilizes a procedure of “authentication”.
In this method, each portable telephone
903
is provided with a serial number (ESN: Electronic Serial Number) for the portable telephone
903
, shared secrete data (SSD) shared by the portable telephone
903
and an authentication center
901
of a communications common carrier and a mobile identification number (MIN). The identification number is encoded to a cipher referred to as AUTHREQ on the basis of a CAVE (Cellular Authentication and Voice Encryption) algorithm
904
. In this encryption, a random number referred to as RAND output from a mobile exchange center
902
of the communications common carrier is employed.
The communications common carrier decodes the cipher AUTHREQ transmitted from the portable telephone
903
on the basis of the CAVE algorithm
905
. The decoded identification number is compared with an identification number including the shared secret data SSD held only by the authentication center
901
so that a determination on authorization or unauthorization of communication is made in response to the result of the comparison. Thus, whether or not the user of the portable telephone
903
is legal is checked, i.e., authenticated on the basis of the shared secret data SSD shared only by the portable telephone
903
and the communications common carrier.
Also for the authentication system shown in
FIG. 93
regarded as the strongest countermeasure against illegal use at present, however, it is said that illegal use is now spreading while avoiding the authentication. It is said that the main technical factor resides in that the identification number supplied to the portable telephone
903
is written in a reloadable flash memory (flash ROM), as described in literature 1.
FIG. 94
is a block diagram briefly showing the internal structure of a conventional portable telephone
903
. The conventional portable telephone
903
comprises a communication circuit
907
and a flash memory
908
. The communication circuit
907
operates in accordance with a program written in the flash memory
908
. The flash memory
908
also holds an identification ID, and the communication circuit
907
performs encoding on the basis of the identification number ID read from the flash memory
908
for transmitting a cipher AUTHREQ generated by encoding to the communications common carrier.
The reloadable flash memory
908
is employed as a storage medium since it is necessary to cope with program change by the communications common carrier such as change to a program corresponding to a new communication system, for example. If an unreloadable mask ROM is employed, it is impossible to cope with program change, and the identification number must be recorded with a mask pattern responsive to the identification number varying with each individual in the process of manufacturing the mask ROM, to result in reduction in the manufacturing efficiency and increase in the manufacturing cost.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, a semiconductor device comprises a semiconductor element having a polycrystal and an encoder circuit converting an electric characteristic of the semiconductor element to a digital signal so that the value is dispersed in derivation from dispersion of the crystal structure of the polycrystal thereby generating and outputting a code.
According to the first aspect, the value of the code is dispersed among individuals, whereby the code can be utilized as an identification code for a system or the like assembled with the device of the present invention. Further, the code is generated by utilizing dispersion of crystal structures of polycrystals manufactured through the same step among the individuals, whereby manufacturing of the device is simplified. In addition, the characteristic of the semiconductor element forming the basis of the code cannot be externally changed and hence the semiconductor device implements a high barrier against illegal change of the code.
According to a second aspect of the present invention, the semiconductor device further comprises a comparator circuit regarding the code output from the encoder circuit as a first code, comparing an externally input second code with the first code, determining agreement or approximation between the codes and outputting a prescribed signal indicating the result of determination.
According to the second aspect, the comparator circuit determines agreement or approximation between the codes, whereby the codes can be utilized for authentication.
According to a third aspect of the present invention, the semiconductor device further comprises a prescribed circuit including a circuit part selectively entering an operating or non-operating state in response to the prescribed signal.
According to the third aspect, the semiconductor device comprises the prescribed circuit including the circuit part selectively entering an operating or non-operating state on the basis of the determination of the comparator circuit, whereby a prescribed operation of a system can be authorized and unauthorized in response to the result of determination of a password or authentication of the code by forming part of a circuit implementing functions of the system by the prescribed circuit and utilizing the code as the password or a code for authentication.
According to a fourth aspect of the present invention, the semiconductor element and the encoder circuit are formed on a single semiconductor substrate.
According to the fourth aspect, the semiconductor element and the encoder circuit are formed on the single semiconductor substrate, whereby not only characteristic data of the semiconductor element is unchangeable but also output of the encoder circuit can be prevented from being changed by external input of a signal in the encoder and hence the barrier against illegal use of the system assembled with the inventive device is further improved.
According to a fifth aspect of the present invention, the encoder circuit includes a conversion circuit converting an electric characteristic of the semiconductor element to a digital signal so that the value is dispersed in derivation from dispersion of the crystal structure of the polycrystal thereby generating a code, and a code memory formed on the single semiconductor substrate for storing the code generated by the conversion circuit in a nonvolatile manner and reading the code thereby outputting the same as the code output from the encoder circuit.
According to the fifth aspect, the semiconductor device comprises the code memory, whereby the code does not fluctuate even if the temperature or the power supply volta
Honda Hiroki
Ipposhi Takashi
Kuriyama Hirotada
Maeda Shigenobu
Jean-Pierre Peguy
McDermott & Will & Emery
Renesas Technology Corp.
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