WO1997041666A1

WO1997041666A1 - Method and apparatus for securing programming information

Info

Publication number: WO1997041666A1
Application number: PCT/US1997/006729
Authority: WO
Inventors: Harry Hwa Chow; Jason William Robertson; Kenneth P. Greene
Original assignee: Motorola Inc.
Priority date: 1996-04-26
Filing date: 1997-04-14
Publication date: 1997-11-06
Also published as: ID16692A

Abstract

A method and apparatus is used for securing programming information in communication device (100). The apparatus comprises a read-only memory (116) containing a current serial number normally expected to be unchanged from an original serial number pre-programmed into the read-only memory (116), the original serial number being unique to the communication device (100). The apparatus further includes a non-volatile memory (114) having stored therein a current stored value normally expected to be unchanged from an original stored value derived from the original serial number. The processor (108) is programmed, in response to an occurrence of a predetermined event, to compare a first comparison value derived from the current serial number with a second comparison value derived from the current stored value, and allow an operation of the communication device (100) in response to the first comparison value matching the second comparison value.

Description

METHOD AND APPARATUS FOR SECURING PROGRAMMING INFORMATION

Field of the Invention

This invention relates in general to communication devices, and in particular to a method and apparatus in a communication device for securing programming information.

Background of the Invention

Current communication devices utilized in a radio communication system employ password protection methods for securing programming information in the communication device. The programming information includes information which if changed or if copied into another radio could allow theft of service. Examples of such information are frequency channel assignments for receiving selective call messages from the radio communication system, selective call addresses for identifying when selective call messages are intended for the communication device, and service provider identification.

The password protection methods generally provide an effective means for preventing unauthorized access to the programming information in the communication device. This method, however, does not prevent an unscrupulous user from reading the programming information in a communication device in which the passwords are known, duplicating the programming information into a second communication device, and then reprogramming selected parts of the information, e.g., the selective call address, in the second communication device. Commercial non-volatile memory devices are especially vulnerable to pirating of the programming information. To bypass password protection, an unscrupulous user can simply read the programming information by way of a commercial memory reader. Once this information is attained, mass duplication as described above can be done that is virtually undetectable. Such a weakness to protecting proprietary programming information is undesirable and can result in significant losses to a manufacturer or a service provider. Thus, what is needed is a method and apparatus in a communication device for securing programming information. Preferably, the method and apparatus in the communication device should be inexpensive and provide a secure protection mechanism for the programming information.

Summary of the Invention

An aspect of the present invention is a method for controlling an operation of a communication device. The method comprises the steps of pre-programming a read-only memory of the communication device with an original serial number that is unique to the communication device, and storing an original stored value derived from the original serial number in a non- volatile memory of the communication device. The method further comprises the steps of, in response to an occurrence of a predetermined event, comparing a first comparison value derived from a current serial number stored in the read-only memory with a second comparison value derived from a current stored value stored in the non¬ volatile memory, and allowing the operation of the communication device in response to the first comparison value matching the second comparison value.

Another aspect of the present invention is an apparatus for controlling an operation of a communication device. The apparatus comprising a read-only memory containing a current serial number normally expected to be unchanged from an original serial number pre¬ programmed into the read-only memory, the original serial number being unique to the communication device, and a non-volatile memory coupled to the read-only memory and having stored therein a current stored value normally expected to be unchanged from an original stored value derived from the original serial number. The apparatus is programmed, in response to an occurrence of a predetermined event, to compare a first comparison value derived from the current serial number with a second comparison value derived from the current stored value, and allow the operation of the communication device in response to the first comparison value matching the second comparison value. Another aspect of the present invention is a communication device comprising an antenna for intercepting a radio signal including information, a receiver coupled to the antenna for demodulating the radio signal to derive the information, a processor coupled to the receiver for processing the information, and a user interface coupled to the processor for conveying the information to a user. The communication device further comprises a read-only memory coupled to the processor and containing a current serial number normally expected to be unchanged from an original serial number pre-programmed into the read-only memory, the original serial number being unique to the communication device, and a non-volatile memory coupled to the processor and having stored therein a current stored value normally expected to be unchanged from an original stored value derived from the original serial number. The processor is programmed, in response to an occurrence of a predetermined event, to compare a first comparison value derived from the current serial number with a second comparison value derived from the current stored value, and allow an operation of the communication device in response to the first comparison value matching the second comparison value.

Brief Description of the Drawings

FIG. 1 is an electrical block diagram of a communication device according to the present invention. FIG. 2 is an example block diagram of the elements of the non¬ volatile memory according to the present invention.

FIG. 3 is a flow chart showing the operation of the communication device according to a first embodiment of the present invention.

FIG. 4 is a flow chart showing the operation of the communication device according to a second embodiment of the present invention.

Description of the Preferred Embodiment

FIG. 1 is an electrical block diagram of a communication device 100 according to the present invention. The communication device 100 receives selective call signals, composed of selective call messages, transmitted by a radio communication system (not shown) using techniques well known in the art. The selective call messages are originated by a caller who communicates with the radio communication system in a conventional manner to send messages intended for the user of the communication device 100.

The communication device 100 comprises a receiver antenna 102, a receiver 104, a power switch 106, a processor 108, a non-volatile memory 114, a read-only memory 116, user controls 118, an alerting device 120, and a user interface 122. The receiver antenna 102 is coupled to the receiver 104 for receiving a selective call signal transmitted by the radio communication system. The receiver antenna 102 and the receiver 104 utilize conventional hardware for demodulating the selective call signal, which is modulated by the radio communication system with, for example, frequency shift keying techniques.

The receiver 104 is also coupled to the power switch 106 and the processor 108. The power switch 106 utilizes a conventional circuit element such as, for example, a MOS switch for shutting down power to the receiver 104. Operation of the power switch 106 is controlled by the processor 108, which determines at particular moments during the decoding process of the selective call signal when shutdown of the receiver 104 is appropriate. A shutdown of the receiver 104 prior to the completion of a portion of the selective call signal provides a battery saving function. The processor 108 controls the overall operations of the communication device 100. One such operation is the decoding of the demodulated signal generated by the receiver 104. This operation is accomplished by the elements of the processor 108, which include a microprocessor 110, and a memory 112. The microprocessor 110 preferably is conventional and available off the shelf.

The memory 112 includes, for example, a random access memory (RAM), and a read-only memory (ROM). The RAM is used for storage and processing of selective call messages, and the ROM section is used for storage of the instructions that control the operation of the processor 108. It will be appreciated that other types of memory may be used such as, for example, FLASH memory. It will be further appreciated that the memory 112, singly or in combination, can be an integral portion of the microprocessor 110.

The processor 108 is further coupled to the read-only memory 116, and non- volatile memory 114. The read-only memory 116 contains a current serial number normally expected to be unchanged from an original serial number pre-programmed, for example, during the manufacturing process, into the read-only memory 116. The original serial number is a unique number associated with the communication device 100. Thus, the read-only memory 116 is used for storing a unique serial number that is not shared by any other of the communication devices 100 in the radio communication system. That is, each communication device 100 has a unique serial number associated with it. The serial number, as will be shown below, is one element utilized in a method for securing programming information in the non-volatile memory 114, thereby substantially preventing duplication.

It will be appreciated that other secure conventional circuit devices can be used for the storage of the serial number of the communication device 100. It will be further appreciated that, alternatively, the storage of the serial number can be in a secure portion of the memory 112 that cannot be duplicated by unauthorized personnel. It will also be appreciated that when storing the serial number in a secure portion of the memory 112, the serial number does not necessarily have to be encrypted. In addition it will be appreciated that the present invention can be applied to a two-way selective call radio, e.g., an acknowledge-back pager, as well. The non- volatile memory 114 stores a current stored value normally expected to be unchanged from an original stored value derived from the original serial number stored in the read-only memory 116. The non¬ volatile memory 114 is implemented with, for example, an electrically erasable programmable read-only memory (EEPROM), which is used for the storage of programming parameters of the communication device 100.

FIG. 2 is an example block diagram of the elements of the non¬ volatile memory 114 according to the present invention. The non- volatile memory 114 includes, for example, one or more encrypted selective call addresses 124, an encrypted serial number 126, a plurality of encrypted encryption keys 128, and a plurality of encrypted programming options 130 for the communication device 100.

The encrypted selective call addresses 124 are used for identifying selective call messages intended for the communication device 100. The encrypted serial number 126 is an encrypted version of the original serial number stored in the read-only memory 116. The plurality of encryption keys 128 are used by the processor 108 to decrypt the data elements included in the non- volatile memory 114. Details of the use of the encrypted serial number 126 and the encrypted encryption keys 128 are described below. The encrypted programming options 130 include information such as, for example, the service provider identification, selective call addresses utilized by the communication device 100, the default frequency channels for receiving messages, etc. The encryption used on the elements of the non- volatile memory 114 is a conventional encryption method such as, for example, the Data Encryption Standard (DES).

It will be appreciated that other encryption methods may be used that are suitable for this invention. It will be further appreciated that the non¬ volatile memory 114 can be an integral portion of the memory 112. During selective call message processing, the microprocessor 110 samples the demodulated signal generated by the receiver 104. The microprocessor 110 then decodes a selective call address in the demodulated data of the selective call message, compares the decoded selective call address with one or more of the selective call addresses having been decrypted from the non-volatile memory 114, and when a match is detected, proceeds to process the remaining portion of the selective call message.

Once the processor 108 has processed the selective call message, the selective call message is stored in the memory 112, and a call alerting signal is generated to alert a user that the selective call message has been received. The call alerting signal is directed to a conventional audible or tactile alerting device 120 for generating an audible or tactile call alerting signal. Alternatively, a visual alert can be utilized. The selective call message can be accessed by the user through user controls 118, which provide functions such as lock, unlock, delete, read, etc. More specifically, by the use of appropriate functions provided by the user controls 118, the message is recovered from the memory 112, and then presented on the user interface 122. The user interface 122 is a conventional display or loudspeaker used for conveying the information included in the selective call message to the user visibly or audibly. FIG. 3 is a flow chart 200 showing the operation of the communication device 100 according to a first embodiment of the present invention. The flow chart 200 begins with step 202 where the communication device 100 is triggered by a predetermined event to verify the integrity of the non- volatile memory 114 and the read-only memory 116 as a matched pair. The predetermined event that triggers the communication device 100 to perform the verification step can be, for example, the event of inserting a battery, or switching the communication device 100 on, or a periodic time-out that occurs once an hour, etc.

In step 204 the communication device 100 reads the current serial number normally expected to be unchanged from the original serial number that was pre-programmed in the read-only memory 116, and the current stored value in the non-volatile memory 114 normally expected to be unchanged from the original stored value derived from the original serial number. In step 206 the communication device 100 reads the plurality of encryption keys 128 stored in the non- volatile memory 114. In step 208 the processor 108 utilizes the encryption keys in a predetermined decryption algorithm, such as DES, to derive the decrypted value of the original serial number for comparison with the current serial number.

In step 210 the processor 108 compares the current serial number with the decrypted original serial number derived from the current stored value. The original stored value comprises the encrypted value of the original serial number. The processor 108 allows the operation of the communication device 100 in response to the current serial number matching the decrypted original serial number, i.e., if the first and second comparison values are equal.

The processor 108 disallows, in step 212, the operation of the communication device 100 in response to the first comparison value not matching the second comparison value, i.e., if the first and second comparison values are not equal. In step 214 the processor 108 preferably is programmed to generate an audible or visible alert through the user interface 122 to indicate that an error condition has occurred. FIG. 4 is a flow chart 300 showing the operation of the communication device 100 according to a second embodiment of the present invention. The flow chart 300 is similar to the flow chart 200, the essential difference being that steps 208 and 210 of the flow chart 200 have been replaced with steps 302 and 304, respectively. In step 302 the processor 108 utilizes the encryption keys to encrypt the current serial number stored in the read-only memory 116 to create an encrypted current serial number. In step 304 the processor 108 reads the encrypted serial number 126 stored in the non- volatile memory 114, and compares it with the encrypted current serial number. If both are equal, the processor 108 allows the operation of the communication device 100 to continue. Otherwise, the processor 108 disallows processing of the communication device 100 in steps 212 and 214 in the manner described for the flow chart 200. Thus, it should be apparent by now that the present invention provides a novel method and apparatus for securing programming information. In particular, by utilizing a secure read-only memory 116 that cannot be easily duplicated, the present invention advantageously deters an unscrupulous user from copying the original serial number of the communication device 100. Moreover, by encrypting the data in the non- volatile memory 114, the present invention advantageously adds an additional layer of security to prevent the changing of programming information included therein. Thus, without access to the encryption keys 128 and without the capability of readily duplicating the read-only memory 116, the programming information remains secure.

What is claimed is:

Claims

1. A method for controlling an operation of a communication device, comprising the steps of: pre-programming a read-only memory of the communication device with an original serial number that is unique to the communication device; storing an original stored value derived from the original serial number in a non-volatile memory of the communication device; and in response to an occurrence of a predetermined event: comparing a first comparison value derived from a current serial number stored in the read-only memory with a second comparison value derived from a current stored value stored in the non- volatile memory; and allowing the operation of the communication device in response to the first comparison value matching the second comparison value.

2. The method of claim 1, wherein the pre-programming step occurs during a process of manufacturing the read-only memory.

3. The method of claim 1, wherein the storing step occurs during a process of manufacturing the communication device.

4. The method of claim 1, wherein the storing step comprises the step of encrypting the original serial number to derive the original stored value, and wherein the comparing step comprises one of the steps of:

(a) deriving the first comparison value by decrypting the current stored value, and deriving the second comparison value by utilizing the current serial number without modification; and

(b) deriving the first comparison value by utilizing the current stored value without modification, and deriving the second comparison value by encrypting the current serial number.

5. The method of claim 1, further comprising the step of disallowing the operation of the communication device in response to the first comparison value not matching the second comparison value.

6. The method of claim 5, wherein the disallowing step includes the step of generating an audible or visible alert to indicate that an error condition has occurred.

7. An apparatus for controlling an operation of a communication device, comprising: a read-only memory containing a current serial number normally expected to be unchanged from an original serial number pre¬ programmed into the read-only memory, the original serial number being unique to the communication device; and a non-volatile memory coupled to the read-only memory and having stored therein a current stored value normally expected to be unchanged from an original stored value derived from the original serial number, wherein the apparatus is programmed, in response to an occurrence of a predetermined event, to: compare a first comparison value derived from the current serial number with a second comparison value derived from the current stored value; and allow the operation of the communication device in response to the first comparison value matching the second comparison value.

8. The apparatus of claim 7, wherein the original stored value comprises an encrypted value of the original serial number, and wherein the first and second comparison values comprise, respectively, one of: (a) a decrypted value of the current stored value, and the current serial number without modification; and

(b) the current stored value without modification, and an encrypted value of the current serial number.

9. The apparatus of claim 7, wherein the apparatus is further programmed to disallow the operation of the communication device in response to the first comparison value not matching the second comparison value.

10. The apparatus of claim 9, wherein in disallowing the operation of the communication device the apparatus is further programmed to generate an audible or visible alert to indicate that an error condition has occurred.

11. A communication device comprising: an antenna for intercepting a radio signal including information; a receiver coupled to the antenna for demodulating the radio signal to derive the information; a processor coupled to the receiver for processing the information; a user interface coupled to the processor for conveying the information to a user; a read-only memory coupled to the processor and containing a current serial number normally expected to be unchanged from an original serial number pre-programmed into the read-only memory, the original serial number being unique to the communication device; and a non-volatile memory coupled to the processor and having stored therein a current stored value normally expected to be unchanged from an original stored value derived from the original serial number, wherein the processor is programmed, in response to an occurrence of a predetermined event, to: compare a first comparison value derived from the current serial number with a second comparison value derived from the current stored value; and allow an operation of the communication device in response to the first comparison value matching the second comparison value.

12. The communication device of claim 11, wherein the original stored value comprises an encrypted value of the original serial number, and wherein the first and second comparison values comprise, respectively, one of: (a) a decrypted value of the current stored value, and the current serial number without modification; and

13. The communication device of claim 11, wherein the processor is further programmed to disallow the operation of the communication device in response to the first comparison value not matching the second comparison value.

14. The communication device of claim 13, wherein in disallowing the operation of the communication device the processor is further programmed to generate an audible or visible alert through the user interface to indicate that an error condition has occurred.