Patent Publication Number: US-8543798-B2

Title: Electronic device board level security

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. application Ser. No. 12/037,141, filed Feb. 26, 2008, titled “Electronic Device Board Level Security,” now U.S. Pat. No. 8,266,415, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This description relates to electronic device board level security. 
     BACKGROUND 
     Printed circuit boards typically include one or more electronic components and are used in many different electronic devices such as, for example, personal computers, laptop computers, MP3 players, cellular phones and personal digital assistants (PDAs). Hackers may attempt to reverse engineer a board and its electronic components to gain information about the functioning and operation of the board and the electronic components. In some cases, the hacked information may be used to produce unauthorized copies of the boards and the electronic components for use in unauthorized and/or black market electronic devices. For example, the information may be used to create boards and devices where one or more electronic components on the boards have been illegally changed out with other components. 
     SUMMARY 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exemplary block diagram of a printed circuit board. 
         FIG. 2  is an exemplary block diagram of a printed circuit board. 
         FIGS. 3A and 3B  illustrate an exemplary flowchart of example operations of the system of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a printed circuit board (PCB)  100  may include a first component  102  located on the PCB  100 , a second component  104  located on the PCB  100 , and a processor  106  located on the PCB  100 . The components may be configured to communicate with each other using bus  110 . 
     The PCB  100  may be arranged and configured to operate and function in various type of devices. For example, the PCB  100  may be included in a personal computer (PC), a server, a cellular phone, an MP3 player, a personal digital assistant (PDA) and any other type of electronic device that may include a PCB. 
     The first component  102  may have at least one unique identifier that specifically identifies the first component. For example, the unique identifier may be a manufacturer&#39;s identification code, where the code may be in alphanumeric, binary, and/or hexadecimal form. In another exemplary implementation, the unique identifier may include a unique signature that is particular to that component on the PCB  100 . The first component  102  may have more than one unique identifier that specifically identifies the first component. For example, the first component  102  may have a unique manufacturer&#39;s identification code and a unique signature. In another exemplary implementation, the first component  102  may have multiple unique identification codes. The unique identifier for the first component  102  may be referred to below as the first unique identifier. 
     The second component  104  may have at least one unique identifier that specifically identifies the second component. For example, the unique identifier may be a manufacturer&#39;s identification code, where the code may be in alphanumeric, binary, and/or hexadecimal form. In another exemplary implementation, the unique identifier may include a unique signature that is particular to that component on the PCB  100 . The second component  104  may have more than one unique identifier that specifically identifies the second component. For example, the second component  104  may have a unique manufacturer&#39;s identification code and a unique signature. In another exemplary implementation, the second component  104  may have multiple unique identification codes. The unique identifier for the second component  104  may be referred to below as the second unique identifier. 
     The processor  106  may be arranged and configured to perform one or more processing functions. The processor  106  may include a section referred to as a one time programming (OTP) section  108 . The OTP section  108  may be programmed one time with information and then that information is bound to the processor  106  within the OTP section  108 . The OTP section  108  may be programmed with information that is to be kept permanently and not deleted or erased. Prior to being programmed, the OTP section  108  may be blank and may not include any information. During the manufacturing and assembly of the PCB  100 , the OTP section  108  of the processor  106  may be programmed as part of the manufacturing process. 
     In one exemplary implementation, the OTP section  108  may be programmed with the first unique identifier from the first component  102 . For example, upon a first time initialization (e.g., during a manufacturing process for the PCB  100 ), the processor  106  may acquire the first unique identifier from the first component  102  and store the first unique identifier in the OTP section  108 . Once the first unique identifier is stored in the OTP section  108  during this initial process, the OTP section  108  may not be programmed again. Thus, the storage of the first unique identifier is permanent in the OTP section  108 . 
     Upon each subsequent initialization of the PCB  100 , the processor  106  may acquire the first unique identifier from the first component  102  and compare the acquired identifier to the first unique identifier that was previously stored in the OTP section  108 . If the acquired identifier from the first component  102  matches the first unique identifier previously stored in the OTP section  108 , then the processor  106  may allow the initialization of the processor  106  and the PCB  100  to proceed. The initialization may be the boot up process for the processor  106  and the overall PCB  100 , including all of the PCB components. However, if the acquired identifier from the first component  102  does not match the first unique identifier stored in the OTP section  108 , then the processor  106  may disallow the initialization of the processor  106  and the PCB  100  from proceeding. When the identifiers do not match, the processor  106  may take action by shutting down itself so that the PCB  100  does not function and/or the processor  106  may cause one or more of the components on the PCB  100 , including the entire PCB, to cease functioning and/or to shut down. 
     In this manner, the processor  106  is performing a check upon each initialization to make sure that the first component  102  is the exact same first component as when the PCB  100  was first assembled and first initialized. If the first component  102  has been removed, such that the processor  106  cannot acquire the first unique identifier during a subsequent initialization, then the processor  106  may disallow the initialization from proceeding. Similarly, if the first component  102  has been replaced, even with a same or similar component, then the identifier from the replaced component will not match the stored first unique identifier and the processor  106  may disallow the initialization from proceeding. In this manner, board level security is provided because a check is being performed each time the PCB  100  may be booted up. If the PCB  100  has been tampered with, for example, by removing the first component  102  or by replacing the first component  102 , then the processor  106  may prevent the PCB  100  from functioning. 
     In one exemplary implementation, the OTP section  108  may be programmed with the second unique identifier from the second component  104 . For example, upon a first time initialization (e.g., during a manufacturing process for the PCB  100 ), the processor  106  may acquire the second unique identifier from the second component  104  and store the second unique identifier in the OTP section  108 . Once the second unique identifier is stored in the OTP section  108  during this initial process, the OTP section  108  may not be programmed again. Thus, the storage of the second unique identifier is permanent in the OTP section  108 . 
     Upon each subsequent initialization of the PCB  100 , the processor  106  may acquire the second unique identifier from the second component  104  and compare the acquired identifier to the second unique identifier that was previously stored in the OTP section  108 . If the acquired identifier from the second component  104  matches the second unique identifier previously stored in the OTP section  108 , then the processor  106  may allow the initialization of the processor  106  and the PCB  100  to proceed. The initialization may be the boot up process for the processor  106  and the overall PCB  100 , including all of the PCB components. However, if the acquired identifier from the second component  104  does not match the second unique identifier stored in the OTP section  108 , then the processor  106  may disallow the initialization of the processor  106  and the PCB  100  from proceeding. When the identifiers do not match, the processor  106  may take action by shutting down itself so that the PCB  100  does not function and/or the processor  106  may cause one or more of the components on the PCB  100 , including the entire PCB, to cease functioning and/or to shut down. 
     In this manner, the processor  106  is performing a check upon each initialization to make sure that the second component  104  is the exact same second component as when the PCB  100  was first assembled and first initialized. If the second component  104  has been removed, such that the processor  106  cannot acquire the second unique identifier during a subsequent initialization, then the processor  106  may disallow the initialization from proceeding. Similarly, if the second component  104  has been replaced, even with a same or similar component, then the identifier from the replaced component will not match the stored second unique identifier and the processor  106  may disallow the initialization from proceeding. In this manner, board level security is provided because a check is being performed each time the PCB  100  may be booted up. If the PCB  100  has been tampered with, for example, by removing the second component  104  or by replacing the second component  104 , then the processor  106  may prevent the PCB  100  from functioning. 
     In one exemplary implementation, the OTP section  108  may be programmed with more than one unique identifier from more than one component. For example, the OTP section  108  may be programmed with the first unique identifier from the first component  102  and the second unique identifier from the second component  104 . For example, upon a first time initialization (e.g., during a manufacturing process for the PCB  100 ), the processor  106  may acquire the first unique identifier from the first component  102  and may acquire the second unique identifier from the second component  104 . The first unique identifier and the second unique identifier may be stored in the OTP section  108 . Once the first unique identifier and the second unique identifier are stored in the OTP section  108  during this initial process, the OTP section  108  may not be programmed again. Thus, the storage of the first unique identifier and the second unique identifier is permanent in the OTP section  108 . 
     Upon each subsequent initialization of the PCB  100 , the processor  106  may acquire the first unique identifier from the first component  102  and the second unique identifier from the second component  104  and compare the acquired first identifier to the first unique identifier and the acquired second identifier to the second unique identifier that were previously stored in the OTP section  108 . If the acquired first identifier from the first component  102  matches the first unique identifier previously stored in the OTP section  108  and the acquired second identifier from the second component  104  matches the second unique identifier previously stored in the OTP section  108 , then the processor  106  may allow the initialization of the processor  106  and the PCB  100  to proceed. The initialization may be the boot up process for the processor  106  and the overall PCB  100 , including all of the PCB components. However, if the acquired identifier from the first component  102  does not match the first unique identifier stored in the OTP section  108  or the acquired identifier from the second component  104  does not match the second unique identifier stored in the OTP section  108 , then the processor  106  may disallow the initialization of the processor  106  and the PCB  100  from proceeding. When either of the identifiers do not match, the processor  106  may take action by shutting down itself so that the PCB  100  does not function and/or the processor  106  may cause one or more of the components on the PCB  100 , including the entire PCB, to cease functioning and/or to shut down. 
     In this manner, the processor  106  is performing a check upon each initialization to make sure that the first component  102  and the second component  104  are the exact same components as when the PCB  100  was first assembled and first initialized. If the first component  102  or the second component  104  has been removed, such that the processor  106  cannot acquire the first unique identifier or the second unique identifier during a subsequent initialization, then the processor  106  may disallow the initialization from proceeding. Similarly, if the first component  102  or the second component  104  has been replaced, even with a same or similar component, then the identifier from the replaced component will not match the stored first unique identifier or the stored second unique identifier and the processor  106  may disallow the initialization from proceeding. In this manner, board level security is provided because a check is being performed each time the PCB  100  may be booted up. If the PCB  100  has been tampered with, for example, by removing the first component  102  or the second component  104  or by replacing the first component  102  or the second component  104 , then the processor  106  may prevent the PCB  100  from functioning. 
     Thus, the processor  106  and the OTP section  108  of the processor may be configured to store one or more unique identifiers and to perform a check of the one or more unique identifiers upon each initialization or boot up of the PCB  100 . The PCB  100  may include other additional components (not shown). The processor  106  may be configured to store all or less than all of the unique identifiers for the components of the PCB  100  and to perform a check of all or less than all of the unique identifiers upon each initialization or boot up of the PCB  100 . 
     The PCB  100  also may include a sensor  112  that is located on the PCB  100 . The sensor  112  may be arranged and configured to sense at least one characteristic of the PCB  100 . The characteristic that is being sensed by the sensor  112  may be a board level characteristic or a component level characteristic. 
     The sensor  112  may be configured to sense a single characteristic or multiple characteristics. In one exemplary implementation, the sensor  112  may include a voltage sensor, a current sensor, and/or a temperature sensor. The sensor  112  may be positioned on the PCB  100  such that the sensor  112  senses a characteristic related to the first component  102  and/or the second component  104 . Thus, the sensor  112  may be configured to sense a characteristic that is related to one or more of the components located on the PCB  100 . 
     Upon a first time initialization (e.g., during a manufacturing process for the PCB  100 ), the processor  106  may be arranged and configured to acquire a value of the characteristic of the PCB  100  from the sensor  112  and store the value of the characteristic as a range of values in the OTP section  108  of the processor  106 . Once the range of values is stored in the OTP section  108  during this initial process, the OTP section  108  may not be programmed again. Thus, the storage of the range of values is permanent in the OTP section  108 . 
     Upon each subsequent initialization of the PCB  100 , the processor  106  may acquire the value of the characteristic from the sensor  112  and compare the acquired value to the range of values that are stored in the OTP section  108 . If the acquired value from the sensor  112  is within the range of values stored in the OTP section  108 , then the processor  106  may allow the initialization of the processor  106  and the PCB  100  to proceed. The initialization may be the boot up process for the processor  106  and the overall PCB  100 , including all of the PCB components. However, if the acquired value does not fall within the ranges of values, then the processor  106  may disallow the initialization of the processor  106  and the PCB  100  from proceeding. When the acquired value does not fall within the range of stored values, the processor  106  may take action by shutting down itself so that the PCB  100  does not function and/or the processor  106  may cause one or more of the component on the PCB  100 , including the entire PCB, to cease functioning and/or to shut down. 
     In this manner, the processor  106  is performing a check upon each initialization to make sure that the characteristics of the PCB  100  have not changed such as, for example, by removing or replacing one or more of the components of the PCB  100 . If a component has been removed and/or replaced, then the value of the characteristic of the PCB  100  may no longer fall within the ranges of values stored in the OTP section  108  and the processor  106  may take action to shut down and/or prevent the PCB  100  from being used. In this manner, board level security is provided because a check is being performed each time the PCB  100  may be booted up. If the PCB  100  has been tampered with, for example, by removing one or more of the components (e.g., first component  102  and/or second component  104 ) or by replacing one or more of the components (e.g., first component  102  and/or second component  104 ), then the processor  106  may take action to prevent the PCB  100  from functioning. 
     Similarly, if an additional component or a probe or other node is introduced to the PCB  100 , the value of the characteristic of the PCB  100  may change and fall outside of the range of values stored in the OTP section  108  of the processor  106 . For example, a probe may be introduced to the PCB  100  in order to reverse engineer and decode the functioning and features of the components and processor on the PCB  100 . By providing a check of the value of the characteristic of the PCB  100  upon each initialization, then the processor  106  may detect an attempt at an unauthorized access to the PCB  100  and take action to shut down the PCB  100 . These actions by the processor  106  may prevent someone from hacking into the PCB  100  and its components. 
     In one exemplary implementation, the OTP section  108  may be programmed with one or more unique identifiers from one or more components, respectively, and a value or range of values for a characteristic of the PCB  100 . For example, upon a first time initialization (e.g., during a manufacturing process for the PCB  100 ), the processor may acquire a first unique identifier from the first component  102 , a second unique identifier from the second component  104 , and a value of the characteristic of the PCB  100  from the sensor  112 . The first unique identifier and the second unique identifier may be stored in the OTP section  108 . The value of the characteristic may be stored in the OTP section  108  as a range of values. Once the first unique identifier, the second unique identifier and the range of values have been stored in the OTP section  108 , they are permanently programmed in the OTP section  108 . 
     Upon each subsequent initialization of the PCB  100 , the processor  106  may acquire the first unique identifier from the first component  102 , the second unique identifier from the second component  104 , and the value of the characteristic from the sensor  112 . The processor  106  may compare the acquired identifiers and value to the respective stored unique identifiers and the range of values stored in the OTP section  108 . If the acquired identifiers match the respective stored unique identifiers and the acquired value falls within the stored range of values, then the processor  106  may allow the initialization of the processor  106  and the PCB  100  to proceed. However, if one of the acquired identifiers does not match its respective stored identifier or the acquired value does not fall within the range of the stored values, then the processor  106  may disallow the initialization of the processor  106  and the PCB  100  from proceeding. The processor  106  may take action by shutting itself so that the PCB  100  does not function and/or the processor  106  may cause one or more of the components on the PCB  100 , including the entire PCB  100 , to cease functioning and/or to shut down. 
     In this manner, board level security is provided because a check is being performed each time the PCB  100  may be booted up. If the PCB  100  has been tampered with, then the processor  106  may prevent the PCB  100  from functioning. 
     In one exemplary implementation, the sensor  112  may include a voltage sensor. The characteristic of the PCB  100  that may be sensed may be a voltage on the PCB  100 . The voltage may be related to one or more of the components. For instance, the voltage sensed may be a voltage between the first component  102  and the second component  104  on the PCB  100 . Upon a first time initialization, the processor  106  may acquire the voltage from the sensor  112  and store the voltage as a range of voltages in the OTP section  108 , such that the range of voltages becomes permanently programmed in the OTP section  108 . Upon subsequent initialization, the processor  106  may acquire the voltage from the sensor  112  and compare the acquired voltage to the stored range of voltages. If the acquired voltage falls within the stored range of voltages, then the processor  106  may allow the initialization of the processor  106  and the PCB  100  to proceed. If the acquired voltage does not fall within the stored range of voltages, then the processor  106  may disallow the initialization of the processor  106  and the PCB  100  from proceeding. 
     In one exemplary implementation, the sensor  112  may include a current sensor. The characteristic of the PCB  100  that may be sensed may be a current on the PCB  100 . The current may be related to one or more of the components. For instance, the current sensed may be a current between the first component  102  and the second component  104  on the PCB  100 . Upon a first time initialization, the processor  106  may acquire the current from the sensor  112  and store the current as a range of currents in the OTP section  108 , such that the range of currents becomes permanently programmed in the OTP section  108 . Upon subsequent initialization, the processor  106  may acquire the current from the sensor  112  and compare the acquired current to the stored range of currents. If the acquired current falls within the stored range of currents, then the processor  106  may allow the initialization of the processor  106  and the PCB  100  to proceed. If the acquired current does not fall within the stored range of currents, then the processor  106  may disallow the initialization of the processor  106  and the PCB  100  from proceeding. 
     In one exemplary implementation, the sensor  112  may include a temperature sensor. The characteristic of the PCB  100  that may be sensed may be a temperature on the PCB  100 . The temperature may be related to one or more of the components. For instance, the temperature sensed may be a temperature between the first component  102  and the second component  104  on the PCB  100 . Upon a first time initialization, the processor  106  may acquire the temperature from the sensor  112  and store the temperature as a range of temperatures in the OTP section  108 , such that the range of temperatures becomes permanently programmed in the OTP section  108 . Upon subsequent initialization, the processor  106  may acquire the temperature from the sensor  112  and compare the acquired temperature to the stored range of temperatures. If the acquired temperature falls within the stored range of temperatures, then the processor  106  may allow the initialization of the processor  106  and the PCB  100  to proceed. If the acquired temperature does not fall within the stored range of temperatures, then the processor  106  may disallow the initialization of the processor  106  and the PCB  100  from proceeding. 
     Referring to  FIG. 2 , a PCB  200  is illustrated. In this exemplary implementation, the PCB  200  may be used in a cellular phone or in any device that may include cellular phone features and functionality. The PCB  200  may include a flash memory  202 , a random access memory (RAM)  204 , a baseband processor  206  having an OTP section  108 , and a sensor  112 . The PCB  200  also may include a bus  110  to enable the components to communicate with one another and to function together as a unit. It is understood that the PCB  200  may include other components (not shown) for the functioning of the board in a cellular phone-type device. 
     In this exemplary implementation, the flash memory  202  may include a unique identifier that uniquely identifies the flash memory  202  and may be referred to as the flash memory identifier below. The flash memory  202  may be configured to store one or more application programs, which may be accessed by one or more components of the PCB  200 , including the baseband processor  206 , to cause the PCB  200  to perform properly. The application programs may control the features and functionality of the PCB  200  and may be run by the baseband processor  206 . 
     The RAM  204  may include a unique identifier that uniquely identifies the RAM  204  and may be referred to as the RAM identifier below. The sensor  112  may include the features and functionality of the sensor  112  of  FIG. 1 , as described above. 
     The OTP section  108  of the baseband processor  206  may function as described above with respect to the OTP section  108  of  FIG. 1 , as described above. 
     In one exemplary implementation, the OTP section  108  may be programmed with the flash memory identifier, the RAM identifier, and/or a range of values for a characteristic of the PCB  200 . For example, during a first time initialization (e.g., during a manufacturing process for the PCB  200 ), the baseband processor  206  may acquire the flash identifier from the flash memory  202 , the RAM identifier from the RAM  204  and/or a value for a characteristic for the PCB  200  from the sensor  112 . The baseband processor  206  may store the flash identifier and the RAM identifier in the OTP section  108 . The baseband processor  206  may store the value for the characteristic for the PCB  200  as a range of values in the OTP section  108 . The flash identifier, the RAM identifier and the range of values may be permanently programmed in the OTP section  108  during the first time initialization of the PCB  200 . 
     Upon each subsequent initialization, the baseband processor  206  may acquire the flash memory identifier from the flash memory  202 , the RAM identifier from the RAM  204  and/or the value of the characteristic from the sensor  112 . The baseband processor  206  may compare the acquired identifiers to the respective stored identifiers and the value to the stored range of values. If the acquired identifiers match the stored identifiers and the acquired value is within the stored range of values, then the baseband processor  206  may allow the initialization of the baseband processor  206  and the PCB  200  to proceed. If either of the acquired identifiers does not match their respective stored identifiers or the acquired value is not within the stored range of values, then the baseband processor  206  may disallow the itself and the PCB  200  from proceeding with the initialization. When one of the identifiers do not match or the value is not within the range of values, the baseband processor  206  may take action by shutting down itself so that the PCB  200  does not function and/or the baseband processor  206  may cause one or more of the components on the PCB  200 , including the entire PCB, to cease functioning and/or to shut down. 
     In this manner, the baseband processor  206  is performing a check upon each initialization to make sure that the flash memory  202  and the RAM  204  have not been removed, replaced and/or tampered with in some way. Thus, board level security is being provided. 
     Referring to  FIGS. 3A and 3B , an exemplary process  300  illustrates an example process of the functioning of the processor  106  of  FIG. 1 . Process  300  may include acquiring a first unique identifier from a first component located on a PCB upon a first time initialization ( 310 ) and storing the first unique identifier in an OTP section ( 320 ). Upon subsequent initializations, the process  300  may include acquiring the first unique identifier from the first component ( 330 ) and comparing the first unique identifier to the first unique identifier stored in the OTP section ( 340 ). If the first unique identifier matches the stored first unique identifier, then the subsequent initializations may be allowed to proceed ( 350 ). If the first unique identifier does not match the stored first unique identifier, then the subsequent initializations may be disallowed from proceeding ( 360 ). 
     In one exemplary implementation, the processor  106  may acquire the first unique identifier from the first component  102  located on a PCB  100  upon a first time initialization ( 310 ). Acquiring the first unique identifier ( 310 ) may further include acquiring the first unique identifier from the first component and a second unique identifier from a second component located on the PCB upon the first time initialization ( 314 ). For example, the processor  106  may acquire the first unique identifier from the first component  102  located on a PCB  100  and the second identifier from the second component  104  located on the PCB  100  upon the first time initialization ( 314 ). 
     Process  300  may further include acquiring a value of a characteristic of the PCB from a sensor located on the PCB during the first time initialization ( 316 ). For example, the processor  106  may acquire the value of a characteristic of the PCB  100  from the sensor  112  during the first time initialization ( 316 ). 
     In one exemplary implementation, the processor  106  may store the first unique identifier in an OTP section  108  ( 320 ). Storing the first unique identifier ( 320 ) may further include storing the first unique identifier and the second unique identifier in the OTP section ( 322 ). For example, the processor  106  may store the first unique identifier and the second unique identifier in the OTP section  108  ( 322 ). 
     Process  300  may further include storing the value of the characteristic of the PCB as a range of values in the OTP section during the first initialization ( 324 ). For example, the processor  106  may store the value of the characteristic of the PCB  100  as a range of values in the OTP section  108  ( 324 ). 
     In one exemplary implementation, upon subsequent initializations, the processor  106  may acquire the first unique identifier from the first component  102  ( 330 ). Acquiring the first unique identifier from the first component ( 330 ) may further include, upon subsequent initializations, acquiring the first unique identifier from the first component and the second unique identifier from the second component ( 332 ). For example, upon subsequent initializations, the processor  106  may acquire the first unique identifier from the first component  102  and the second unique identifier from the second component  104  ( 332 ). 
     Process  300  may further include, upon subsequent initializations, acquiring the value of the characteristic of the PCB from the sensor ( 334 ). For example, the processor  106 , upon subsequent initializations, may acquire the value of the characteristic of the PCB  100  from the sensor  112  ( 334 ). 
     In one exemplary implementation, the processor  106  may compare the first unique identifier to the first unique identifier stored in the OTP section  108  ( 340 ). Comparing the first unique identifier ( 340 ) may further include comparing the first unique identifier to the stored first unique identifier and the second unique identifier to the stored second unique identifier ( 342 ). For example, the processor  106  may compare the first unique identifier to the stored first unique identifier and the second unique identifier to the stored second unique identifier. 
     Process  300  may further include comparing the value to the range of values stored in the OTP section ( 344 ). For example, the processor  106  may compare the value to the range of values stored in the OTP section  108  ( 344 ). 
     In one exemplary implementation, the processor  106  may allow the subsequent initializations to proceed if the first unique identifier matches the stored unique identifier ( 350 ). Allowing the subsequent initializations to proceed ( 350 ) may further include allowing the subsequent initializations to proceed if the first unique identifier matches the stored first unique identifier and the second unique identifier matches the stored second unique identifier ( 352 ). For example, the processor  106  may allow the subsequent initializations to proceed if the first unique identifier matches the stored first unique identifier and the second unique identifier matches the stored second unique identifier ( 352 ). 
     Allowing the subsequent initializations to proceed ( 350 ) may further include allowing the subsequent initializations to proceed if the first unique identifier matches the stored first unique identifier and the value acquired from the sensor is within the stored range of values ( 354 ). For example, the processor  106  may allow the subsequent initializations to proceed if the first unique identifier matches the stored first unique identifier and the value acquired from the sensor  112  is within the stored range of values ( 354 ). 
     In one exemplary implementation, the processor  106  may disallow the subsequent initializations from proceeding if the first unique identifier does not match the stored first unique identifier ( 360 ). Disallowing the subsequent initializations from proceeding ( 360 ) may further include disallowing the subsequent initializations from proceeding if the first unique identifier does not match the stored first unique identifier or the second unique identifier does not match the stored second unique identifier ( 362 ). For example, the processor  106  may disallow the subsequent initializations from proceeding if the first unique identifier does not match the stored first unique identifier or the second unique identifier does not match the stored second unique identifier ( 362 ). 
     Disallowing the subsequent initializations from proceeding ( 360 ) may further include disallowing the subsequent initializations from proceeding if the first unique identifier does not match the stored first unique identifier or value acquired from the sensor is not within the stored range of values ( 364 ). For example, the processor  106  may disallow the subsequent initializations from proceeding if the first unique identifier does not match the stored first unique identifier or value acquired from the sensor  112  is not within the stored range of values ( 364 ). 
     Implementations of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Implementations may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. A computer program, such as the computer program(s) described above, can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. 
     Method steps may be performed by one or more programmable processors executing a computer program to perform functions by operating on input data and generating output. Method steps also may be performed by, and an apparatus may be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). 
     Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Elements of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also may include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in special purpose logic circuitry. 
     To provide for interaction with a user, implementations may be implemented on a computer having a display device, e.g., a cathode ray tube (CRT) or liquid crystal display (LCD) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. 
     Implementations may be implemented in a computing system that includes a back-end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front-end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation, or any combination of such back-end, middleware, or front-end components. Components may be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (LAN) and a wide area network (WAN), e.g., the Internet. 
     While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the scope of the implementations.