Abstract:
A security system involving a user includes a token attachable to the user. The token is associated with the user while attached to the user. The association is automatically discontinued when the token is detached from the user.

Description:
BACKGROUND 
     Security systems such as access control systems are used to control access to buildings and areas within buildings. The magnetic strip found on the back of a work badge may be used for access control. The work badge is scanned across a reader, which reads the information encoded in the magnetic strip, and sends that information to a computer. The computer consults a database to make an access decision. The access decision might be to unlock a door-locking mechanism. 
     This type of security system, and security systems in general, are not fool proof because security situations are dynamic. Security situations can change at any time granularity, location, or identity. For example, a work badge may be exchanged between individuals. The access control system might be able to authenticate access for a particular work badge, but it might not be able to verify that the work badge is actually possessed by the authorized person. 
     SUMMARY 
     According to one aspect of the present invention, a security system involving a user includes a token attachable to the user. The token is associated with the user while attached to the user. The association is automatically discontinued when the token is detached from the user. 
     Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of a security system according to an embodiment of the present invention. 
         FIG. 2  is an illustration of a token for the security system. 
         FIG. 3  is another illustration of a security system according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     As shown in the drawings for the purpose of illustration, the present invention is embodied in a security system for controlling access to one or more “assets.” Examples of assets include a location, a room, a car, an Internet appliance, a safe, a computer, etc. 
     Reference is made to  FIG. 1 , which shows a security system  100  for controlling a user&#39;s  10  access to an asset  12 . The system  100  includes a token  102 , which is attachable to the user  10 . For example, the token  102  may be a watch that is worn on the wrist, a badge that is clipped onto an article of clothing, a box that is clipped onto a belt, etc. The token  102  includes a processor and data storage device for storing security information. The security information may include identification information about the user  10 . The identification information might include the name of the person, a password, code, PIN, etc. The security information may include security parameters. The security parameters specify privileges and conditions upon which the user  10  may use the asset  12 . Security parameters might specify a security clearance, a location, a time stamp, a maximum number of uses, etc. The token  102  would not be able to access the asset  12  after the time stamp (e.g., after midnight) or it would not be able to access the asset  12  more than the maximum number of times. The security parameters might specify the computer files that a person is allowed to access (e.g., a visitor is allowed to run application X, but not application Y), a requirement to be accompanied by another authorized party (e.g., a patient cannot enter a room unless accompanied by an attendant), etc. 
     The security parameters can also specify how security information is sent to the asset  12 . For example, the security parameters might specify whether the security information should be sent encrypted. 
     The security parameters can specify conditions for which the security information is expunged from the token  102 . The security information might be expunged if the token  102  detects a security violation, (e.g., the token  102  has been removed from a user  10 ) or if an attempt is made to physically alter the token  102 . 
     The token  102  further includes a communication device (e.g., a transceiver) for sending and receiving the security information. The token  102  also includes a sensor for detecting when the token  102  is removed from the user  10 . 
     A security control mechanism  110  is responsible for maintaining security information for different users, authenticating the identity of the user  10  to whom (or which) the token  102  is attached, and sending the security information to the attached token  102 . There is no limitation on how the security control mechanism  110  performs its functions. The security control mechanism  110  may use a combination of humans and machines to perform its functions. 
     After the token  102  is attached to the user  10 , the token  102  receives the security information, and stores the security information. At this point, an association is created between the token  102  and the user  10 . This association may be regarded as a first leg  106  of a security path between the token  102  and the user  10 . The first leg  106  of the security path stays intact as long as the token  102  remains attached to the user  10  and no other security violations are detected. 
     The system  100  may also include an agent  104  for the asset  12 . If the asset  12  cannot communicate with the token  102 , an agent  104  would be provided for the asset  12 . As a first example, the token  102  might not be able to communicate with an asset  12  such as a building. However, the token  102  could communicate with an agent  104  such as a security gate, which controls access to the building. As a second example, the token  102  might not be able to communicate with an asset such as currency. However, the token  102  could communicate with an agent  104  such as a smart safe lock, which controls access to the currency. 
     If the asset  12  has processing capability and can communicate with the token  102 , then an agent  104  might not be necessary. For example, an asset such as a computer or Internet appliance might not need an agent  104 . 
     The asset  12  shown in  FIG. 1  lacks the communication/processing capability. Therefore, an agent  104  is provided for it. 
     A second leg  108  of the security path is formed while the token  102  is communicating with the agent  104 . The second leg  108  completes the security path. 
     The security path represents an association between the user  10 , the token  102  and the agent  104 /asset  12 . Once any one of these elements breaks the association, the security path is broken and the user  10  is denied access to the asset  12 . 
     When the token  102  detects that it has been removed from the user  10 , the token processor expunges all of the security information from the token data storage, thus making the token  102  a “clean slate.” Consequently, the first leg  106  of the security path is broken, and the user  10  is denied access to the asset  12 . The first leg  106  is not re-established until the user  10  re-attaches the token  102  and receives the security information again. 
     The second leg  108  may be broken if the token  102  stops communicating with the agent  104 . As a first example, the communication is stopped because the token  102  is outside the communication range of the agent  104 . In this example, the second leg  108  can be reestablished when the token  12  is moved within communication range of the asset  12 . As a second example, the token  102  stops communicating with the agent  104  because the first leg  106  has been broken. 
     While both security path legs  106  and  108  are established, a decision is made as to whether the user  10  should be denied or granted access to the asset  12 . The decision may be made by the asset  12 /agent  104 , or by another entity. For example, the agent  104  receives a security code from the token  102 , and decides to grant or deny access according to that security code. If the agent  104  does not have decision-making capability, it might send the security code to the security control mechanism  110 , which makes the decision and instructs the agent  104  to deny or grant access. 
     Reference is now made to  FIG. 2 , which shows an exemplary token  102 . The token  102  includes a body (e.g., a housing, a substrate)  202 , and the following components attached to the body  202 : a processor  204 , data storage  206 , an attachment sensor  208 , a transceiver  210 , and an attachment device  212 . The type of attachment device  212  depends upon the type of user  10  to which the token  102  is attached. If the user  10  is a person, the attachment device  212  might be a clip, a wristband, or other device that attaches directly to the person or article of clothing. 
     The type of attachment sensor  208  depends upon how the token  102  is attached to the user  10 . For example, a galvanic or heat sensor can be used to determine when a wristband is removed from a wrist, or a proximity sensor may be used to determine when a housing is unclipped from a belt. 
     The data storage  206  includes non-volatile and/or volatile memory (e.g., Flash memory, RAM) for storing the security information. The data storage  206  may include non-volatile memory (e.g., ROM) for storing a control program for the processor  204 . 
     The program instructs the processor  204  to control the various functions performed by the token  102 . These function include, but are not limited to, storing security information in the data storage  206 , sending security information (to be transmitted) to the transceiver  210 , receiving data from the transceiver  210 , encrypting and decrypting information for secure transmission, analyzing sensor data to determine when the token  102  has been removed from the user  10 , and expunging the security information from data storage  206  when token removal has been detected. 
     The transceiver  210  may also be used to transmit a tracking signal. The tracking signal could be used (by examining signal strength, time of flight) to determine the location of the token  102  and the user  10 . In the alternative or in addition, the token  102  may include a tracking device such as an IR beacon or a GPS device. 
     The token  102  may also include a biometric sensor  214  for capturing biometric information about the user  10 . The biometric information may be transmitted by the transceiver  210  to the security control mechanism  110 , thus providing information that would help the security control mechanism  110  authenticate the user  10 . 
     The data storage  206  could be programmed with a database containing security information, the same type of security information used by the security control mechanism  110 . For example, the database might include the identities and privileges for a group of people. Interaction with the security control mechanism  110  can be eliminated or reduced if the token  102  is equipped with the biometric sensor  214  and programmed the security information. 
     The token  102  may include one or more context sensors  216  for obtaining information about the (context) environment surrounding the token  102  and the user  10 . Such context might include motion, trajectory, animate surroundings, and inanimate surroundings. Exemplary context sensors  216  include accelerometers, humidity and temperature sensors, and video sensors. The token  102 , agent  104  or security control mechanism  110  may use the context information to determine whether the user  10  and the asset  12  are in an authorized or hostile environment, how the asset  12  is being used, etc. For example, if the token  102  is in a hostile environment, the token  102  could decide to expunge all security information from its data storage  206  and thereby break the first leg  106  of the security path. The additional information provided by the context sensors  216  can increase the accuracy of the security decisions. 
     Reference is now made to  FIG. 3 . An exemplary security system  310  will now be described in connection with first and second people (users)  10   a  and  10   b  attempting to gain access to different assets. The assets include a room  12   a  and a secure computer  12   b  within the room  12   a . The secure computer  12   b  is not provided with an agent. An agent  104   a  in the form of a smart door lock is provided for the room  12   a . The tokens are security badges  102   a  and  102   b . The security control mechanism  110  includes a security guard  312 , a biometric scanner  314 , and a security control computer  316 . 
     Each person  10   a  and  10   b  approaches the security guard  312 . The security guard  312  removes first and second security badges  102   a  and  102   b  from a tray containing multiple security badges. At this point, each security badge  102   a  and  102   b  contains no security information. Before the security badges  102   a  and  102   b  are given to the two people  10   a  and  10   b , different encryption keys are stored in the two security badges  102   a  and  102   b . The encryption keys (e.g., symmetric keys) will be used for secure communication with the badges  102   a  and  102   b.    
     The first person  10   a  clips on the first security badge  102   a . Once the attachment sensor and processor establish that the first badge  102   a  has been clipped onto the first person  10   a , the first badge  102   a  informs the security control computer  316  that it is ready to is ready to receive the security information. An attribute (e.g., a fingerprint, retina, iris, voice, face) of the first person  12   a  is scanned by the biometric scanner  314 . In addition or in the alternative, a form of identification is supplied to the security control computer  316  (e.g., a drivers license number, a password). The security control computer  316  retrieves security information based on the biometric and identification information, and sends the security information to the first security badge  102   a . In this example, the security control information includes a personal identifier, a time stamp, and an access code. The first security badge  102   a  stores the security information and, therefore, assumes the persona of the first person  10   a . A first leg of a security path is formed between the first person  10   a  and the first badge  102   a . For as long as the first person  10   a  wears the first security badge  102   a , the first leg of the security path is maintained. 
     The second person  10   b  clips on the second security badge  102 . In the same manner, the second badge  102   b  receives and stores security information about the second person  10   b . For as long as the second person  10   b  wears the second security badge  102   b , a first leg of a security path between the second person  10   b  and the second badge  102   b  is maintained. 
     The two people  10   a  and  10   b  approach the room  12   a . Both security badges  102   a  and  102   b  transmit their access codes to the smart door lock  104   a . The access codes indicate that the first person  10   a  is authorized to enter the room  12   a  alone, but the second person  10   b  can only enter the room  12   a  if accompanied by the first person  10   a . Based on the access codes that it receives from both badges  102   a  and  102   b , the smart door lock  104   a  allows both people  10   a  and  10   b  to enter the room  12   a  together. 
     As the first person  10   a  approaches the computer  102   a , the first badge  102   a  transmits the personal identifier and access code to the first computer  12   b . The computer  12   b  limits the first person&#39;s access to files and other computer resources according to the personal identifier. Moreover, the computer  12   b  may personalize the graphical user interface according to the identifier. 
     Depending upon the security parameters, the computer  12   b  may deny access if unknown or unauthorized persons (either not having sensing devices or having such devices but not having permissions) are in the room  12   a . For example, the second person  10   b  is not allowed to access any resources on the computer  12   b . Therefore, the computer  12   b  makes its terminal go blank if the first person  10   a  is not facing the terminal, or if the second person  10   b  is within viewing range of the terminal. The computer  12   b  might automatically shut down if the second person  10   b  attempts to access the computer  12   b . Or, the computer  12   b  might contact the security control computer  316 , which would alert a security guard. 
     Later, the first person  10   a  leaves the room  12   a , unclips the first badge  102   a , and returns the first badge  102   a  to the security guard  312 . As soon as the first badge  102   a  is unclipped, it expunges all of its security information. The first badge  10   a  becomes a clean slate, and is placed back in the tray for later use. 
     The second person  10   b  leaves the room  12   a  but forgets to unclip and return the second badge  10   b . However, the second badge  102   b  has a time stamp (which was transmitted along with the personal identifier and the access code). The second badge  102   b  determines when the time stamp has expired (the badge  102   b  might have an internal clock or it might receive times from an external source). As soon as the time stamp expires, the second badge  102   b  expunges all of its security information. Therefore, the second person  10   b  cannot use the second badge  102   b  to re-enter the room  12   a  or access any other assets. 
     If the second person  10   b  unclips the second badge  102   b  and gives the unclipped badge  102   b  to a third party, the second badge  102   b  will detect the event and expunge all security information. Therefore, the third party cannot use the second badge  102   b  to enter the room  12   a  or access any assets. 
     An encryption key need not be stored in a badge before the badge is given to a person. In another exemplary security system, a person takes a badge completely empty of any identity, encryption and security information. The badge may be taken, for example, from a tray located in a lobby of a building. The badge detects that is being worn by the person, and then detects that it is in the presence of a device for performing user identification and providing security information. Once the presence of the device is detected, the badge automatically generates a unique, one-time use encryption key (the one-time encryption key is designed to prevent replay attacks). After the person has been positively identified, the badge sends the key to the device, and the device uses the key to encrypt the security information and sends the encrypted security information to the badge. At the end of the day, the person removes the badge and tosses it back into the tray. Eliminated is the need for a security guard or other person to give the badge to the person. 
     While wearing the badge, a person never sees or handles security information, doesn&#39;t have to interact with door-locking mechanisms, enter additional passwords into computers, etc. The security information is transmitted between the security badge, door lock mechanism, and computer. The security information is encrypted. Therefore, the security information is protected against eavesdroppers. 
     The uses for the security system are varied and numerous. The security system may be used in a hospital to electronically grant and deny access into certain locked rooms, or medicine cabinets. As to a location tracking application, if the security center is configured to triangulate specific sensors, the security center can exactly determine an individual&#39;s location. In a hospital, such a system could exactly determine the location of a doctor or patient. 
     The security system may be used for aviation security. Tokens could be attached to pilots. The first leg of the security path could be broken not only if a token is removed from a pilot, but if the token detects that the pilot is dead or incapacitated. 
     The security system may be used in an amusement park or ski area where all guests are given devices on a temporary (i.e., daily basis). The system could immediately identify a guest&#39;s location and whether the guest is still wearing the device. 
     The security system may be used to “personalize” a device. One such device is an Internet appliance. The token sends security parameters to the Internet appliance. The security parameters might indicate name, password, and a context. The Internet appliance configures itself according to the security parameters and, thereby, becomes personal to the user. 
     There are no limitations on the security information. The security information can be different from user to user, place to place, task to task, and instant to instant. The security information can specify who, where and when, how assets are used, and what the assets are used in conjunction with. 
     There is no limitation as to how a token communicates with an agent or asset. Wireless communication is but one example. 
     The present invention is not limited to the specific embodiments described above. Instead, the present invention is construed according to the claims that follow.