GB2285159A - Device for preventing unauthorised use of e.g. a selective calling receiver - Google Patents

Abstract

In a radio selective calling receiver, a hard protect code is permanently set in a protect code selling portion 28, and a ROM protect code corresponding to the hard protect code is set in an EEPROM 16. A microprocessor (MPU) 14 does not allow the receiver to operate, even if the power source switch 26 is depressed, unless the two codes coincide, thereby providing a degree of security against unauthorized use. When a ROM writer 30 is used to load the EEPROM 16, the MPU 14 derives the ROM protect code from the hard protect code and loads it into the EEPROM 16. <IMAGE>

Description

Device Por Preventing Unauthorized Use of a Selective Calling Receiver BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a device which prohibits unauthorized use of a radio selective calling receiver.

Description of the Related Art In devices such as a paging receiver, portable telephone or cellular phone, it is important to protect against illegal or unauthorized use of the device.

Such devices have an EEPROM; for example, a conventional radio selective calling receiver includes an electrically erasable programmable read only memory (EEPROM) in which is stored a pre-assigned selective calling identification (ID) number. Also stored in the EEPROM is system setting information for setting its own system condition. Since such an EEPROM is usually inexpensive and commercially available, it is easily obtained by anyone. In addition, since the interface is also publicly known and available, the information stored in the EEPROM can be easily copied. Further, as the radio selective calling receiver can be purchased at any electric and electronic product shop, non-registered receivers, each receiver having no system setting information in the EEPROM, can be easily obtained.

Under such situations, it is possible to provide any number of identical radio selective calling receivers if one of them is legally registered. It is illegal to copy the system setting information from the legally registered radio selective calling receiver, and to use such copied radio selective calling receivers. Consequently, it is necessary for the manager of the paging system to prevent use of such illegally-copied radio selective calling receivers as completely as possible.

SUMMARY OF THE INVENTION The invention in its various aspects is defined in the independent claims below, to which reference should now be made. Advantageous features of the invention are set forth in the appendant claims.

Preferred embodiments of the invention are described below with reference to the drawings, which take the form of a radio selective calling receiver, in which a hard protect (or protection) code is permanently set in a protect code setting portion of the receiver, and a ROM protect code corresponding in any convenient way to the hard protect code is set in an EEPROM. The receiver has a microprocessor which does not allow the receiver to operate, even if the power switch is depressed, unless the two codes coincide.

In this way unauthorised use in the manner described above is more or less prevented.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail, by way of example with reference to the accompanying drawings, in which: FIG. 1 is a block diagram of a radio selective calling receiver according to a preferred embodiment of the present invention; FIG. 2 illustrates a preferred embodiment of a memory map in the EEPROM shown in FIG. 1; FIG. 3 illustrates the correspondence between hard protect codes set by the protect code setting portion shown in FIG. 1 and ROM protect codes set in the EEPROM shown in FIG. 1; FIG. 4 is a flow-chart showing a preferred operation according to the present invention; FIG. 5 is a flow-chart showing a preferred operation during a registration in the ROM writer mode according to the present invention; and FIG. 6 is a block diagram of a radio selective calling receiver according to another preferred embodiment of the present invention.

In the drawings, the same reference numerals denote the same structural elements.

DESCRIPTION OF THE PREPERRED EMBODIMENT Now a preferred embodiment of the present invention will be described in detail with reference to FIGs. 1 to 6. FIG. 1 is a block diagram of a radio selective calling receiver according to a first preferred embodiment of the present invention.

First, the basic construction, function and operation of this embodiment will be described. A radio selective calling receiver of a preferred embodiment receives a selective calling signal at a radio section 10, including an antenna, from a base station (not shown). The selective calling signal contains an identification (ID) number and a message. The radio section 10 demodulates the selective calling signal to a base-band signal.

A decoder 12 decodes the base-band signal to a decoded signal and supplies the decoded signal to a microprocessor (MPU) 14 through a bus. The MPU 14 includes a read only memory (ROM) 32 for storing a program for operating the MPU 14 and a random access memory (RAM) 34 for temporarily storing the message and control data necessary for operating the MPU 14.

The MPU 14 compares the ID number contained in the decoded signal with a pre-assigned ID number stored in an EEPROM 16. The EEPROM 16 also stores system setting information other than the pre-assigned ID number. When both of the ID numbers coincide, the MPU 14 activates an alert driver 18. A loudspeaker 20 or a light emissive diode (LED) 22 driven by the alert driver 18 informs the user of the reception of the selective calling signal.

In addition, a liquid crystal display (LCD) 24 displays the message.

Next, the construction, function and operation of the device for preventing unauthorized use of the selective calling receiver will be described.

In FIG. 1, when the power source (not shown) of the selective calling receiver is off and a switch 26 is depressed, the decoder 12 detects the state change of the switch 26 and sends an interrupt signal IS to the MPU 14. Upon the interrupt signal IS, the MPU 14 turns the power source on and reads a ROM protect code stored in the EEPROM 16 and a hard protect code in a protect code setting portion 28. The hard and ROM protect codes may be called first and second protect codes, respectively.

The MPU 14 compares the ROM protect code with the hard protect code. Only when there is a predetermined correspondence between these codes, e.g., both codes coincide, the MPU 14 performs a system set-up of the selective calling receiver in response to the system setting information stored in the EEPROM 16 causing the receiver to enter a stand-by mode.

The protect code setting portion 28 consists of four (4) resistors and can set four (4) bits, that is, sixteen (16) hard protect codes by setting these resistors at different potentials.

When the potential across each resistor is set to +Vdd, it becomes logical "1" and when it is set to ground potential, it becomes logical "O". In this embodiment as shown in FIG. 1, the logical value set at terminals PRO and PR1 of the MPU 14 is "1" and at terminals PR2 and PR3 is "O". The hard protect codes are set such that they are distributed as randomly as possible with respect to the serial number of the receivers even if they are of the same type. It is, of course, possible to change the number of bits of the hard protect code.

FIG. 2 illustrates a preferred embodiment of the memory map of the EEPROM 16 shown in FIG. 1. The system setting information is stored in address numbers OOH to 23H and the ROM protect code is stored in an address number 24H. Address numbers 25H to 7FH are unused memory area. In each of the addresses, an eight-bit memory area is provided. In the address number 24H of the EEPROM 16, a ROM protect code equal to any one of the sixteen (16) hard protect codes is stored.

FIG. 3 illustrates the correspondence between the hard protect code set by the protect code setting portion 28 shown in FIG. 1 and the ROM protect code set in the EEPROM 16 shown in FIG. 1.

For example, if the PRO to PR3 set in the MPU 14 are logical "0", a protect code OH is stored in the EEPROM 16, and, if the PRO to PR3 in the MPU 14 are logical "1", a protect code FH is stored.

In this embodiment, since the PRO and PR1 are logical "0" and the PR2 and PR3 are logical "1", i.e., hard protect codes are "0011", the ROM protect code stored in the EEPROM 16 is 3H. This ROM protect code can use eight bits and it may be possible to make other codes determined by, for example, preliminarily coding corresponding to the respective hard protect codes.

The system setting information and the ROM protect code are written by a ROM writer 30, shown in FIG. 1, which is managed by a system managing company when the selective calling receiver is registered.

The operation of the present invention will be described in detail in reference with FIGs. 1 and 4.

FIG. 4 is a flow-chart showing a preferred operation for preventing unauthorized use according to the present invention.

When the power source of the receiver is turned on by depressing the switch 26 (Step 101), the MPU 14 checks whether the ROM writer 30 is connected to the MPU 14 (Step 102). If the ROM writer 30 is connected to the MPU 14, the selective calling receiver enters a ROM writer mode (Step 110) as described later.

If the ROM writer 30 is not connected to the MPU 14, the receiver is in a use mode (Step 103) and the MPU 14 reads the system setting information and the ROM protect code from the EEPROM 16 (Step 104), and the hard protect code set in the protect code setting portion 28 (Step 105). In response, the MPU 14 compares the ROM protect code with the hard protect code (Step 106). If there is the correspondence shown in FIG. 3 between the ROM protect code and the hard protect code, the MPU 14 sets-up the system of this receiver (Step 107) and controls the alert driver 18 to operate the loudspeaker 20 to thereby generate the power-on sound which indicates power-on (Step 108). When the power-on sound terminates, the MPU 14 allows the receiving operation of the receiver to start, so that the receiver goes to a stand-by mode where it waits for a selective calling signal (Step 109).In Step 106, if the ROM protect code is not in correspondence with the hard protect code, the operation of the system set-up is not executed.

FIG. 5 is a flow-chart showing the operation of the present embodiment during a registration in the ROM writer mode. The ROM writer mode is a registration mode for writing the system setting information and the ROM protect code into the EEPROM 16 by means of the ROM writer 30.

In FIG. 5, the MPU 14 controls the alert driver 18 to operate the loudspeaker 20 to thereby generate a ROM writer mode sound indicating that the receiver is in the ROM writer mode (Step 110). The ROM writer mode sound is different from the power-on sound for the stand-by mode.

In the ROM writer mode, if the MPU 14 receives a start command from the ROM writer 30 (Step 202), the MPU 14 sends an acknowledge (ACK) signal to the ROM writer 30 (Step 203). In addition, the MPU 14 checks whether the ROM writer 30 is an authorized ROM writer (Step 204). For example, the MPU 14 sends a special command signal to check the ROM writer 30 and awaits a response signal to the special command signal from the ROM writer 30. If the ROM writer 30 is not authorized, the MPU 14 turns off the power source (Step 218). If the ROM writer 30 is authorized, the MPU 14 receives several kinds of command signal from the ROM writer 30 (Step 205).

When the MPU 14 receives a read command signal from the ROM writer 30, the MPU 14 sends an ACK signal to the ROM writer 30 (Step 206). Next, the MPU 14 transmits the system setting information of the EEPROM 16 to the ROM writer 30, for example, an Intel HEX1 record unit (Step 207). If the EEPROM 16 is unused, no system setting information is stored therein. On the other hand, if the EEPROM 16 is of a receiver which had been registered already, some system setting information may be read out. The system setting information thus read out can be utilized for managing the paging system by the manager of the ROM writer 30. After the sending of all system setting information has been completed (Step 208), the MPU 14 sends an end record signal to the ROM writer 30 (Step 209) and returns to Step 204.

Then, when the MPU 14 receives a write command from the ROM writer 30, the MPU 14 sends an ACK signal to the ROM writer 30 (Step 210). In response, the MPU 14 receives system setting information, in for example HEX format, from the ROM writer 30 (Step 211). This system setting information may be information to be newly set in the EEPROM 16, overwrite information of system information already set in the EEPROM 16, or additional system setting information. If the MPU 14 receives an end code indicating completion of reception of the system setting information (Step 212), the MPU 14 writes the received system setting information in the EEPROM 16 (Step 213). Next, the MPU 14 reads the hard protect code (Step 214) and writes the correspondence to the hard protect code in the EEPROM 16 as a ROM protect code ;Step 215).When this write is completed, the MPU 14 sends an ACK signal to the ROM writer 30 (Step 216) and the flow of the receiver returns to Step 205.

In Step 205, when the MPU 14 receives commands other than the read command and write command, the MPU 14 sends a nonacknowledge (NACK) signal to the ROM writer 30 (Step 217) and the flow of the receiver returns to Step 205.

As described with reference to the flow-charts shown in FIGs. 4 and 5, in the radio selective calling receiver of the preferred embodiment according to the present invention, the hard protect code of four-bits is set in the protect code setting portion 28 which is constituted by the hardware circuit and the ROM protect code corresponding to the hard protect code is stored in the EEPROM 16. The MPU 14 compares both of the protect codes and does not set-up the system of this receiver unless it is recognized that both of the protect codes are identical.

Therefore, even if system setting information is copied and stored in an EEPROM which is not authorized as the EEPROM 16 of this receiver, it is difficult to store the ROM protect code corresponding to one of various hard protect codes in this unauthorized EEPROM, unless the ROM writer 30 which is severely managed is used. Thus, it is possible to prevent the selective calling receiver embodying the present invention from being used illegally as previously described.

FIG. 6 is a block diagram of a selective calling receiver according to a second preferred embodiment of the present invention.

In FIG. 6, the selective calling receiver includes a radio section 10, a decoder 36, a MPU 38, an EEPROM 16, an alert driver 18, a loudspeaker 20, a LED 22, a switch 26 and a LCD 40. A ROM writer 30 is connected to the MPU 38. These circuits have substantially the same functions as those of the constitutional components indicated by the same reference numerals used in the first embodiment shown in FIG. 1. The decoder 36 and the MPU 38 are integrated together with a one-time programmable ROM (OP-ROM) 42, which is written in only once, to a single chip integrated circuit 44 and these circuits are connected to each other through a data bus 46 and an address/control bus 48. An electrical serial number of this receiver is stored in the OP-ROM 42. The LCD 40, a RAM 50 and a ROM 52 are connected to the MPU 38 through the data bus 46 and the address/control bus 48.The LCD 40 includes a driver for driving the display screen. The RAM 50 and the ROM 52 correspond to the RAM 34 and the ROM 32 shown in FIG.

1, respectively.

The electrical serial number stored in the OP-ROM 42 corresponds to the hard protect code set by the protect code setting portion 28 of the first embodiment. Therefore, in the selective calling receiver according to this embodiment, the flowcharts shown in FIGs. 4 and 5 can be used as they are by using the electrical serial number stored in the OP-ROM 42 instead of the hard protect code set in the protect code setting portion 28.

Since, in the second embodiment, the MPU 38, the decoder 36 and the OP-ROM 42 are mounted on the single chip integrated circuit 44, it is almost impossible even for those having knowledge of circuit design of this kind of selective calling receiver to illegally read out the electrical serial number stored in the OP-ROM 42.

Although the preferred embodiments have been described, the present invention is not restricted to a radio selective calling receiver.

As hitherto described, according to the present invention a first protect code and a second protect code, which is in correspondence with the first protect code, are set separately, and normal operation is prohibited unless a correspondence between the first and second protect codes can be recognized.

Therefore, even if unauthorized use is attempted by a person by copying normal system setting information to an illegal EEPROM and/or even if the person has knowledge of circuit design, it is very difficult to make the two protect codes coincident and, thus, it is possible virtually to prevent a device according to the Preser invention from being used illegally.

Further, since the above-mentioned circuit of the present invention can reduce the possibility of unauthorized, illegal copying of the system setting information, losses to the system manager can be reduced.

Although the embodiment has been described with respect to a case in which the modification was based on a specific arrangement, it goes without saying that the present invention is not restricted to this case.

Claims (20)

1. A device for preventing unauthorized use of an apparatus containing said device, comprising: means for permanently setting in said apparatus a first protect code; means for storing in said apparatus a second protect code; and means for comparing said first protect code with said second protect code; whereby said apparatus is rendered non-operational when said first and second protect codes do not correspond.

2. The device as claimed in claim 1, further including means for storing said second protect code on the basis of said first protect code at a registration of said apparatus.

3. The device as claimed in claim 2, wherein said apparatus is a radio selective calling receiver.

4. A device for preventing unauthorized use of an apparatus containing said device, comprising: a protect code setting circuit for permanently setting a first protect code in said apparatus; a memory for storing a second protect code; and a controller for comparing said first protect code with said second protect code and for rendering said apparatus operational only when said first protect code is in correspondence with said second protect code.

5. The device as claimed in claim 4, further including means for storing said second on a basis of said first protect code at a registration of said apparatus.

6. The device as claimed in claim 5, wherein said protect code setting circuit comprises hardware circuit of discrete passive components and said memory comprises an EEPROM.

7. The device as claimed in claim 5, wherein said first protect code is a serial number of said apparatus.

8. An apparatus including the device as claimed in claim 5, said apparatus comprising: a decoder for decoding a received selecting calling signal into a decoded signal; a display; and a microprocessor, included in said controller, for comparing an identification number contained in said received signal with a pre-assigned identification number and for displaying a message on said display when said received identification number coincides with said pre-assigned identification number.

9. The device as claimed in claim 8, wherein said decoder, said controller including said microprocessor and said protect code setting circuit are contained in a single integrated circuit.

10. The device as claimed in claim 9, wherein said protect code setting circuit comprises a one-time programmable ROM.

11. Apparatus as claimed in claim 8, further comprising: alerting means, connected to said microprocessor through a driver, for informing a user that said selective calling signal has been received.

12. A device for preventing unauthorized use of an apparatus including said device, comprising: means for fixedly setting a first protect code; means for detecting said first protect code; means for storing a second protect code corresponding to said first protect code in said apparatus; and means for comparing said first protect code with said second protect code; whereby said apparatus is operational only when said first protect code corresponds to said second protect code, thereby preventing unauthorized use of said apparatus.

13. The device as claimed in claim 12, wherein said apparatus is a radio selective calling receiver.

14. The device as claimed in claim 12, wherein said means for storing a second protect code includes a ROM writer.

15. A method for preventing unauthorized use of an apparatus, the method comprising the steps of: detecting a first protect code permanently resident in said apparatus; detecting a second protect code stored in said apparatus; comparing said first protect code with said second protect code; and rendering said apparatus operational only when there is correspondence between said first and second protect codes.

16. A method for preventing unauthorized used of an apparatus, the method comprising the steps of: detecting a first protect code fixedly maintained in said apparatus; storing a second protect code corresponding to said first protect code in a memory; comparing said first protect code with said second protect code when said apparatus is used; and operating said apparatus when said first protect code is in correspondence with said second protect code.

17. A method for preventing unauthorized use of an apparatus, the method comprising the steps of: detecting whether a writer, which stores information into said apparatus, is connected to said apparatus; detecting a first protect code when said writer is not connected to said apparatus; detecting a second protect code; and turning on said apparatus when correspondence between said first and second protect codes is identified.

18. A radio selective calling receiver comprising a radio receiver section, a programmable memory for containing a first protection code, protection code setting means for defining a second protection code, and a microprocessor connected to the radio receiver section, the programmable memory, and the protection code setting means; the microprocessor being arranged to compare the first protection code and the second protection code and, in the absence of a predetermined correspondence between them, to inhibit operation of the receiver.

19. A device for preventing unauthorized use substantially as herein described with reference to Figures 1 to 5 or Figure 6 of the drawings.

20. A method for preventing unauthorized use substantially as herein described with reference to the drawings.