Abstract:
A security system assesses the response time to requests for information to determine whether the responding system is in physical proximity to the requesting system. Generally, physical proximity corresponds to temporal proximity. If the response time indicates a substantial or abnormal lag between request and response, the system assumes that the lag is caused by the request and response having to travel a substantial or abnormal physical distance, or caused by the request being processed to generate a response, rather than being answered by an existing response in the physical possession of a user. If a substantial or abnormal lag is detected, for example due to the fact that the information was downloaded from the Internet, the system is configured to limit subsequent access to protected material by the current user, and/or to notify security personnel of the abnormal response lag.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to the field of data protection, and in particular to protecting data from illicit copying from a remote location. 
         [0003]    2. Description of Related Art 
         [0004]    The protection of data is becoming an increasingly important area of security. In many situations, the authority to copy or otherwise process information is correlated to the physical proximity of the information to the device that is effecting the copying or other processing. For example, audio and video performances are recorded on CDs, DVDs, and the like. If a person purchases a CD or DVD, the person traditionally has a right to copy or otherwise process the material, for backup purposes, to facilitate use, and so on, When the person who purchased the material desires to use the material, it is not unreasonable to assume that the person will have the CD or DVD within physical proximity of the device that will use the material. If, on the other hand, the person does not have proper ownership of the material, it is likely that the person will not have physical possession of the material, and hence, the material will be physically remote from the device that is intended to use the material. For example, the illicit copying or rendering of material from an Internet site or other remote location corresponds to material being physically remote from the device that is used to copy the material. 
         [0005]    In like manner, security systems are often configured to verify information associated with a user, such as verifying biometric parameters, such as fingerprints, pupil scans, and the like. In a simpler example, security systems are often configured to process information provided by a user, such as information contained on an identification tag, smartcard, etc. Generally, the information or parameters can be provided easily by an authorized user, because the authorized user is in possession of the media that contains the information. An unauthorized user, on the other hand will often not have the original media that contains the verification information, but may have a system that can generate/regenerate the security information or parameters from a remote location. 
         [0006]    Similarly, some systems, such as an office LAN, or computers in a laboratory, are configured to be secured by controlling physical access to terminals that are used to access the system. If the user has access to the system, the assumption is that the user is authorized to access the system. Some security measures, such as identification verification, are sometimes employed, but typically not as extensively as the security measures for systems that lack physical isolation. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    It is an object of this invention to provide a system or method of preventing the use of material in the absence of evidence that the material is in the physical possession of the user. It is a further object of this invention to prevent the use of material in the presence of evidence that the material is remote from the device that is intended to use the material. It is a further object of this invention to prevent access to systems in the presence of evidence that the user is remote from the system. 
         [0008]    These objects and others are achieved by providing a security system that assesses the response time to requests for information. Generally, physical proximity corresponds to temporal proximity. If the response time indicates a substantial or abnormal lag between request and response, the system assumes that the lag is caused by the request and response having to travel a substantial or abnormal physical distance, or caused by the request being processed to generate a response, rather than being answered by an existing response in the physical possession of a user. If a substantial or abnormal lag is detected, the system is configured to limit subsequent access to protected material by the current user, and/or to notify security personnel of the abnormal response lag. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The invention is explained in further detail, and by way of example, with reference to the accompanying drawing wherein: 
           [0010]      FIG. 1  illustrates an example control access system in accordance with this invention. 
       
    
    
       [0011]    Throughout the drawing, the same reference numerals indicate similar or corresponding features or functions. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    For ease of reference and understanding, the invention is presented herein in the context of a copy-protection scheme, wherein the processing of copy-protected material is controlled via a verification that the user of the material is in physical possession of the copy-protected material. 
         [0013]      FIG. 1  illustrates an example control access system  100  in accordance with this invention. The control access system  100  includes a processor  120  that is configured to process material from a physical media, such as a CD  130 , via an access device  132 , such as a reader. The storage medium  125  such as a processor  120  may be a recording device that records one or more songs from the CD  130  onto a memory stick, onto a compilation CD, and so on. The processor  120  may also be a playback device that is configured to provide an output suitable for human perception, such as images on a screen, sounds from a speaker  127 , and so on. The term “rendering” is used herein to include a processing, transformation, storage, and so on, of material received by the processor  120 . Using this context and terminology, the example processor  120  includes a renderer  122  that provides the interface with the access device  132 , and a verifier  126  that is configured to verify the presence of authorized material  130 . 
         [0014]    When a user commences the rendering of material from the media  130 , the processor  120  is configured to verify the presence of the media  130 . One method of effecting this verification is to request the access device  132  to provide evidence that the media  130  is available to provide material or information that differs from the material that the user is attempting to render. For example, if the user commences the rendering of a song, the verifier  126  may direct the renderer  122  to request a portion of a different song from the access device  132 . If the access device is unable to provide the requested portion of a different song, the verifier  126  can conclude that the media  130  is not actually present for rendering, and will terminate subsequent rendering of the material that the user intended to render, via the gate  124 . 
         [0015]    For example, a user may illicitly download a selection of different copy-protected songs from a remote site  140  on the Internet  144 , and then attempt to create a compilation CD containing these user-selected songs. Typically, the size of an entire album of material discourages the downloading of each album that contains the user-selected songs. When the verifier  126  requests a portion of a different song from the album corresponding to an actual CD  130 , the user who downloaded only the user-selected song from the album will be prevented from further rendering of the downloaded material. 
         [0016]    A variety of techniques may be employed to assure that the material provided in response to the request corresponds to the material that is contained on the actual CD  130 . For example, international patent application WO 01/59705 (Attorney Docket US000040) teaches a self-referential data set wherein each section of a data set, such as a copy-protected album, is uniquely identified by a section identifier that is securely associated with each section. To assure that a collection of sections are all from the same data set, an identifier of the data set is also securely encoded with each section. Using exhaustive or random sampling, the presence of the entirety of the data set is determined, either absolutely or with statistical certainty, by checking the section and data-set identifiers of selected sections. 
         [0017]    The verification provided by the verifier  126  as described above can be defeated, however, by responding to the requests from the renderer  122  from the remote site  140  that contains the entirety of the album. That is, rather than downloading the entire album from the remote site  140 , the illicit user need only download the desired song, and imitate the presence of the actual CD  130  by providing a CD imitator  142  that provides access to requested material or portions of material via the Internet  144 . When the verifier  126  requests a portion of a song, or section of a data set, the CD imitator  142  transforms the request into a download request from the remote site  140 , and the requested section is provided to the renderer  122 , as if it was provided from the CD  130 . Assuming that, for practical purposes, the verifier  126  will be configured to only check for a few sections in an album, the use of the CD imitator  142  will result in a substantially reduced amount of data transfer, compared to the downloading of the entire album, and thus preferable for the illicit download of select songs. 
         [0018]    In accordance with this invention, the processor  120  includes a timer  128  that is configured to measure the time between a request from the verifier  126  and a response from an external source, either the actual CD  130 , or the remote source  140 , to facilitate an assessment by the verifier  126  of the physical proximity of the source of the response. In a preferred embodiment, the verifier  126  is configured to filter or average the response times, so as to allow for minor perturbations in the response time from an authorized source  130 , while still being able to distinguish a response from a physically remote source  140 . For example, using conventional statistical techniques, the verifier  126  may continue to request sections from the unknown source until a statistically significant difference from the expected response time of a local source  130  is detected. In a simpler embodiment, if the response time is below a delay threshold N out of M times, the verifier  126  is configured to conclude that the source must be local. These and other techniques for assessing physical proximity based on temporal proximity will be evident to one of ordinary skill in the art in view of this disclosure. 
         [0019]    The principles of this invention are applicable to other applications as well. In an analogous application, for example, the renderer  122  and access device  132  may be challenge-response devices that are configured to exchange security keys, using for example, a smart card as the media  130 . If an unauthorized user attempts to exchange keys by processing the challenge-responses via access to a system that is potentially able to overcome the security of the exchange, the timer  128  will be able to detect the abnormal lag between the challenge and response, and terminate the key-exchange. In like manner, if a system expects all accesses to be from terminals that are in a common physically secured area, the timer  128  will be able to detect abnormal lags if the system becomes a target of a remote access ‘hacker’ or other attempted accesses from outside the physically secured area. 
         [0020]    Preferably, the verifier  126  is configured to request random source information. In the example of a CD media  130 , the verifier  126  is configured to request access to randomly selected sections on the media  130  until sufficient confidence is gained whether the source is local or remote. In other applications, the verifier  126  is configured to merely monitor, and time, transactions that routinely occur between a requesting device  122  and an access device  132 , to detect abnormally long response times. In other applications, the verifier  126  may merely control the order of occurrence of routine data access requests. For example, when reading information from an user&#39;s identification device, the verifier  126  may be configured to sometimes ask for the user&#39;s name first, identification number next, fingerprint next, and so on: at a next session, the verifier  126  may ask for the identification number first, a voiceprint next, and so on, thereby preventing a pre-recorded sequence of responses. 
         [0021]    Similarly, in an application intended to prevent the downloading of data from a remote site, the verifier  126  in the example of  FIG. 1  may merely request portions of the requested data in a different order sequence, to determine whether the requested data is local or remote. In like manner, to prevent the unauthorized download of information from a network, the verifier and time may be placed at the remote site, and configured to measure the transport time of the data. For example, in a conventional network having error-detection capabilities, the verifier may be configured to purposely transmit erroneous data, or an erroneous sequence of data, and measure the time duration until a request-for-retransmission occurs. If the receiving site is local, the request-for-retransmission should occur substantially quicker than if the receiving site is remote. In this example, the erroneous transmission constitutes a “requests” for a “response” from the receiving system. These and other timing schemes will be evident to one of ordinary skill in the art. 
         [0022]    The foregoing merely illustrates the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are thus within its scope. For example, although the invention is presented in the context of detecting responses that are abnormally slow, the principles of the invention can also be applied for detecting responses that are abnormally fast. For example, if a system is configured to read information from a magnetic strip on a card, there is an expected lag associated with the swiping of the card. If the information is provided without this lag, for example, from a computer that is configured to bypass the magnetic strip reader, a security alert may be warranted. These and other system configuration and optimization features will be evident to one of ordinary skill in the art in view of this disclosure, and are included within the scope of the following claims. 
         [0023]    The invention can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer