Abstract:
An apparatus for preventing tampering into an electrical device container in which a power circuit is at least partially enclosed includes a housing having a first end that is adapted to be positioned adjacent to the power circuit, and a second end that is adapted to be coupled to the container. The apparatus also comprises an electrical switch adapted to be coupled to the power circuit and having a main body portion that is secured within the housing and extends substantially from the first end to the second end.

Description:
TECHNICAL FIELD  
       [0001]     The present invention generally relates to data terminals such as personal identification number (PIN) pad transaction devices, telecommunication equipment, scanners, and other devices that receive, store, or transmit data. More particularly, the present invention relates to devices and methods for making such electrical modules tamper resistant.  
       BACKGROUND  
       [0002]     Many electrical devices store or transmit data that may be encrypted or otherwise secured. Such devices often include mechanical or electrical tamper resistance equipment to prevent a security breach. Tamper resistance equipment sometimes includes a mechanism to block or disconnect a communication line or a power line when security is breached. For instance, if the electrical device is opened in an unauthorized manner the device may be programmed or equipped to shut down entirely or in part.  
         [0003]     One type of tamper resistance apparatus includes a switch that is connected to a power source. The switch is included in a housing that is mounted on a circuit board that includes the power circuit. The housing maintains electrical contact between the switch and the power source as long as the apparatus is structurally intact. If the device is opened or has its structural integrity compromised in some other way, the housing is displaced. The switch is displaced along with the housing, causing a break in the power circuit. The loss of power is one way that data retrieval from the apparatus is prevented.  
         [0004]     Although the above-described tamper resistance apparatus is very effective in most cases, some people have attempted to find ways to open electrical devices without breaking the power circuit. One possible way to maintain the power circuit may be to drill into the device interior and break any joints that would normally pull the tamper resistance apparatus away from the power circuit when the device is opened. Another possible way to maintain the power circuit may be to insert glue into the device interior to adhere the circuit housing to a circuit board so that the switch is not pulled away when the device is opened. Yet another possible way to prevent the power circuit from breaking may be to insert a conductive fluid into the housing interior. The conductive fluid will complete the power circuit even if the switch is pulled away from the circuit board.  
         [0005]     Although the above attempts for opening the electrical device without breaking the power circuit would not be very effective, it is desirable to provide an improved tamper resistance apparatus. In addition, it is desirable to provide an efficient and cost effective way to manufacture the improved tamper resistance apparatus. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.  
       BRIEF SUMMARY  
       [0006]     An apparatus is provided to prevent tampering into an electrical device container in which a power circuit is at least partially enclosed. The apparatus comprises a housing having a first end that is adapted to be positioned adjacent to the power circuit, and a second end that is adapted to be coupled to the container. The apparatus also comprises an electrical switch adapted to be coupled to the power circuit and having a main body portion that is secured within the housing and extends substantially from the first end to the second end.  
         [0007]     A tamper resistant electrical device is also provided. The device comprises a container, a substrate disposed inside the container, a power circuit formed on the substrate, and an apparatus to prevent tampering into the container. The apparatus to prevent tampering comprises a housing having a first end positioned adjacent to the power circuit, and a second end that is coupled to the container. The apparatus also comprises an electrical switch coupled to the power circuit and having a main body portion that is secured within the housing and extends substantially from the housing first end to the housing second end.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and  
         [0009]      FIG. 1  is an exploded view of a circuit board and a tamper resistance apparatus mounted thereon during use according to an embodiment of the present invention;  
         [0010]      FIG. 2  is an isometric view of a tamper resistance apparatus according to an embodiment of the present invention;  
         [0011]      FIG. 3  is a transparent isometric view of a tamper resistance apparatus according to an embodiment of the invention; and  
         [0012]      FIG. 4  is an exploded view of a tamper resistance apparatus according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]     The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.  
         [0014]     The present invention includes a tamper resistance apparatus, including an electrical switch that is held in place within an electrical device interior and completes a power circuit until the device&#39;s structural integrity is compromised. The tamper resistance apparatus can be utilized with any suitable electrical device, and exemplary devices include data terminals such as personal identification number (PIN) pad transaction devices, telecommunication equipment, scanners, and other devices that receive, store, or transmit private or sensitive data.  FIG. 1  is an exploded view of a circuit board  30  having a surface  34  with a tamper resistance apparatus  10  mounted thereon during use according to one embodiment of the invention. The circuit board  30  is coupled to the device housing (not shown), and includes power circuit contacts  31  that are coupled to at least one power source. In the embodiment depicted in  FIG. 1 , two of the power circuit contacts  31   a  are connected to an external power source and two other power circuit contacts  31   b  are connected to an internal power source such as a battery. A ground material  32  surrounds the power circuit contacts  31 , and defines a mounting area  33  on the circuit board surface  34 .  
         [0015]     FIGS.  2  to  4  illustrate the tamper resistance apparatus  10 , which includes a generally nonconductive boss  19  that houses electrical contacts  14  and is partially surrounded by a nonconductive skirt  20 .  FIGS. 2 and 3  are isometric views of the apparatus  10 , with  FIG. 3  providing a transparent view to depict the interior components as well as the apparatus exterior. An exploded view of the apparatus  10  is depicted in  FIG. 4 . The boss  19  is typically formed of a nonconductive material such as a hard molded resin to prevent a short in the power circuit. A groove  11  can be molded or otherwise formed in the resin or other generally nonconductive material to engage with a chassis or other device component (not shown) when the tamper resistance apparatus  10  is installed. A structure such as the square-edged body  13  inside the groove  11  further enables a secure coupling with a portion of the chassis or other device component that is adapted to match with the square-edged body  13 . If the electrical device&#39;s structural integrity is subject to tampering or otherwise compromised, a lip  12  on one side of the groove  11  will be pulled by the device chassis or other engaging component, and the entire tamper resistance apparatus  10  will be separated from the circuit board mounting area  32 .  
         [0016]     At least one electrical switch  14  is secured partially inside the boss  19 . Each switch  14  includes a main body portion  18  that is housed inside the boss  19  when the apparatus  10  is intact, and two contacts  15  that extend outside the boss  19 . In an exemplary embodiment, each contact  15  bends inwardly or outwardly from the point where contact  15  exits the boss  19 , and they preferably flange at an angle that allows each contact  15  to lie flatly against the circuit board mounting area  32 . Each contact  15  is preferably made of a bendable conductive metal strip that is sufficiently rigid to retain its shape after bending. When the boss  19  is installed, each contact  15  bends slightly as it is pressed against the circuit board  30 , and the spring force for the contact  15  to retain its original shape also secures contact between the contact  15  and the circuit contact  31 . The apparatus  10  is assembled by sliding each switch  14  through respective slots  16  formed in the boss walls  17  so that the switch contacts  15  can extend outside the boss  19  to the circuit board mounting area  32  and complete the power circuit by coupling with the power circuit contacts  31 .  
         [0017]     Each switch  14  is rigidly mounted in a slot  16  and is consequently separated from the power circuit contacts  31  if the boss  19  is repositioned. Although mounting flanges are shown in  FIGS. 3 and 4  protruding from the switch main body portion  18  to rigidly mount each switch  14 , nonconductive adhesive compounds or additional ribs, flanges, and other mechanical structures can be used to secure each switch  14  with respect to the boss  19 . Further, boss  19  may be molded or otherwise formed around each switch  14  when the boss  19  is manufactured, thereby removing the need for slots  16  in the boss walls  17 .  
         [0018]     Each slot  16  and switch main body portion  18  is approximately U-shaped in an exemplary embodiment of the invention. When installed, the main body portion  18  of each switch  14  enters the boss  19  through a wall  17  that is to be near a power circuit contact  31 . The main body portion  18  then extends entirely across the boss  19  and bends just before it reaches the groove  11  that engages with a chassis or other device component (not shown) when the tamper resistance apparatus  10  is installed. After bending away from the groove  11 , the main body portion  18  extends back toward another power circuit contact  31  and exits the boss  19  through a wall  17 . Thus, the main body portion  18  of each switch  14  spans almost entirely across a width of the boss  19 .  
         [0019]     One way that the boss may be repositioned is by separating the circuit board  30  from the chassis (not shown) that engages with the boss groove  11 . The circuit board  30  and the chassis are typically separated if the electrical device is being tampered with, and the tamper resistance apparatus  10  causes power to be disconnected if such tampering occurs. As mentioned above, one way to separate the circuit board  30  from the chassis (not shown) that engages with the boss and still maintain the power circuit is to cut or drill through the boss  19  in a manner that leaves each switch  14  intact. The present invention circumvents this approach by spanning each switch from one end of the boss  19  to the other end. With each switch  14  formed in a U-shape or other shape that extends across the boss  19 , any drilling or cutting will likely sever the switch  14  and disconnect the power circuit that the switch completed. The U-shaped switch  14  approaches the groove  11  so closely that it is difficult to cut any part of the boss  19  without disconnecting the power circuit and thereby disabling the entire electrical device in which the tamper resistance apparatus is disposed.  
         [0020]     In another embodiment of the invention, the boss  19  itself is manufactured at least in part from a conductive material that completes the power circuit. Severing the boss  19  will disconnect the power circuit and thereby disable the entire electrical device. Insulation material is placed between the boss  19  and other conductive structures in order to prevent a short in the power circuit. In an exemplary embodiment, the conductive material also approaches the groove  11  so closely that it is difficult to cut any part of the boss  19  without disconnecting the power circuit and thereby disabling the entire electrical device.  
         [0021]     In yet another embodiment of the invention that may be used in conjunction with either of the embodiments set forth above, the electrical device can include a security processor that is coupled to the power circuit. When the power circuit is disconnected, an interrupt signal is transmitted to the processor that instructs the processor to erase any sensitive information from selected memory locations. The security processor may be powered by a separate power source in order to perform this active security feature.  
         [0022]     Another way to maintain the power circuit during tampering is to insert glue into the device interior to adhere the boss  19  to the circuit board  30  so that the switch contacts  14  are not displaced when the device is opened. Another possible way to prevent the power circuit from breaking is to insert a conductive fluid into the device. The conductive fluid completes the power circuit even if the switch contacts  14  are pulled away from the circuit board  30 . In order to prevent glue or conductive fluid from disabling the tamper resistance apparatus  10 , the skirt  20  is provided about the boss periphery. The skirt  20  is shaped to conform to the boss dimensions. More particularly, the skirt depicted in the figures includes a wall  23  that snugly surrounds at least a portion of the boss wall  17 .  
         [0023]     In an exemplary embodiment of the invention, an outwardly flaring portion  22  of the wall  17  extends outwardly at one end of the skirt  20 . The outwardly flaring portion  22  also defines a circular edge  24  that abuts the circuit board  30  to shield the circuit board mounting area  33  from glue or conductive fluid. The flaring portion  22  has an increasing diameter as it approaches the mounting area, and consequently directs any glue or other fluid away from the mounting area  32 . In a further exemplary embodiment, the circular edge  24  is sized to surround the ground material  32  that defines the mounting area  32 , and to thereby create a fluid-impermeable seal around the power circuit contacts  31  in the mounting area  32 .  
         [0024]     In yet another exemplary embodiment of the invention, the skirt  20  includes a soft shoulder portion  21  that defines an opening  25  through which the boss lip  12  and grove  11  extend. The soft shoulder portion  21  allows the groove  11  to remain exposed for engagement with the device chassis (not shown), but creates a substantially fluid-impermeable seal with the boss  19  to prevent glue or conductive fluid from reaching the skirt interior. The opening  25  can have a substantially circular shape, with a diameter that is smaller than the soft shoulder portion  21  to allow the soft shoulder portion  21  to form around the boss  19  and create the substantially fluid impermeable seal.  
         [0025]     The skirt  20  is made of a suitable nonconductive material, and typically is made of a soft rubber such as polyurethane or another soft material. In an exemplary embodiment the entire skirt  20  is uniformly made of a single rubber material, including the flaring portion  22  and the soft shoulder portion  21 . Alternatively, the skirt  20  may be formed primarily from a relatively rigid material as long as the soft shoulder portion  21  is made of the made of a sufficiently soft and pliable material to allow the entire boss  19  to be pulled through the opening  21  in the event that the boss  19  is pulled away from the circuit board  30 . Therefore, if the electrical device has its structural integrity compromised such that the circuit board and a chassis (not shown) engaging with the groove  11  are separated, the boss  19  can separate from the circuit board  30  without hindrance from the skirt  20 . If glue or conductive fluid has been inserted into the device interior as an attempt to hold the boss  19  in place, the skirt will prevent the glue or conductive fluid from contacting the boss  19 . If the skirt  20  becomes glued in place before the electrical device is opened, the boss  19  will be pulled through the opening  25  or sufficiently displaced to disconnect the power circuit. Consequently, the skirt  20  in combination with the boss provides a tamper resistance apparatus  10  that prevents sensitive data from being removed from the electrical device due to tampering.  
         [0026]     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.