Abstract:
A blocking device for a magnetic-stripe or EMV® card reader, such as readers on an Automated Teller Machine (ATM), point of sale (POS) machine, or gas station pump. The blocking device securely attaches to the transaction machine such that unauthorized removal of the blocking device is difficult and likely will attract attention. The blocking device surrounds exposed portions of a magnetic-stripe card reader housing such that a skimming mold that fits over both the housing and the blocking device will stand out and be obvious to a user of the transaction machine. Also, a skimming mold fitting over the blocking device may prevent a card holder from properly inserting a magnetic-stripe card into the card reader. The difficulty of placing a skimming mold under or over the blocking device likely will deter a potential criminal skimmer from attempting to attach a skimming device in the first place.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS &amp; PRIORITY CLAIM 
     This application claims priority to U.S. Provisional Application Ser. No. 61/521,255, filed on Aug. 8, 2011, the entire contents of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     Magnetic-stripe cards are often used as credit cards, debit cards, and Automated Teller Machine (ATM) cards. These magnetic-stripe cards are used with transaction machines, such as ATMs, gas station pumps, and point-of-sale (POS) machines (for example, at a grocery store, drug store, or department store), any of which include a card reader that reads account information from the card. The magnetic-stripe cards also may be used to gain access to a transaction machine. For example, some ATMs are enclosed in a vestibule, and entry to the vestibule is provided through a locked door that may be unlocked in response to a user inserting a magnetic-stripe card in a card reader associated with the door. The card readers usually are one of three types: dip readers, swipe readers, and motorized readers. To use a dip reader, a card holder inserts the magnetic-stripe card into a slot and then immediately withdraws the card. The dip reader includes a scanning head in the slot that reads the account information on the magnetic stripe of the magnetic-stripe card as the card holder inserts and removes the card. To use a swipe reader, a card holder slides the magnetic-stripe card through a slot. The swipe reader includes a scanning head in the slot that reads the account information on the magnetic stripe of the magnetic-stripe card as the card is passed through the slot. To use a motorized reader, a card holder inserts the card into a slot. In the slot, motors and grabbing devices take hold of the magnetic-stripe card and pull the card into an internal portion of the card reader. The card reader then moves the card such that its magnetic stripe passes over a scanning head that reads the card. The motorized reader usually holds the card until the card holder has completed a transaction. Often times, in addition to passing a magnetic-stripe card through a card reader, a card holder also must enter a code (often referred to as a “personal identification number” or “PIN”) into a keypad on the transaction machine. 
     Magnetic-stripe card readers are susceptible to “skimming,” in which the account information on a magnetic-stripe card and the PIN entered onto a keypad are secretly recorded for later use by a criminal (called a “skimmer” herein). The skimmer wants the mold to be unnoticed by the card holder at the transaction device. The mold may be an exact replica of the exterior surface of the card reader that fits over the card reader. Alternatively, the mold may have a generic look. In either instance, the skimmer wants the mold to be as small as possible to minimize chances that a card holder (or any other person) recognizes that the mold is on the transaction device. The mold includes a scanning head that reads the account information off of the magnetic stripe of the magnetic-stripe card. The mold also includes a memory device coupled to the scanning head that stores the account information for later retrieval by the skimmer. Importantly, the mold must not interfere with the card holder&#39;s ability to use the card reader. If the card holder is not able to insert a magnetic-stripe card and have it read by the transaction machine, then the user likely will not attempt to enter the PIN and may be alerted to the possibility of a skimming device being used. For this additional reason, a skimming device mold must be as small as possible so that it does not interfere with a card user&#39;s use of a magnetic-stripe card in a transaction machine. 
     The skimmer also discretely places a small camera on or nearby the transaction machine that captures images of the keypad of the transaction machine so that the skimmer can get both the account information from the magnetic-stripe card and also the PIN associated with the card. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL DRAWINGS 
       The novel features of the various embodiments are set forth with particularity in the appended claims. The various embodiments, however, both as to organization and methods of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in conjunction with the accompanying drawings as follows. 
         FIG. 1A  illustrates a dip reader style of magnetic-stripe card reader. 
         FIG. 1B  illustrates a swipe reader style of magnetic-stripe reader. 
         FIG. 1C  illustrates a motorized magnetic-stripe reader. 
         FIG. 2A  is an exploded side view of a magnetic-stripe reader and a skimming mold. 
         FIG. 2B  is a side view of a magnetic-stripe reader with a skimming mold in place. 
         FIG. 3  illustrates an embodiment of a blocking device. 
         FIG. 4  illustrates an embodiment of a blocking device. 
         FIG. 5  illustrates an embodiment of a blocking device. 
         FIGS. 6A-6D  illustrate an embodiment of a blocking device. 
         FIG. 7  illustrates an embodiment of a blocking device. 
         FIG. 8  illustrates an embodiment of a blocking device. 
         FIG. 9A  illustrates an embodiment of a blocking device. 
         FIG. 9B  illustrates an embodiment of a blocking device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to a secure blocking device that can be placed over a card reader of a transaction machine, or any other card reader, such as a card reader for a vestibule door, that resist a skimmer placing a skimming device mold over or under the blocking device. The blocking device is secure such that attempts to remove it would draw attention to the skimmer. Likewise, a skimming device mold large enough to surround a volumetric space defined by the blocking device and the card reader would need to be so large that it would look out of place to a card holder using the transaction machine. The size of the skimming device mold may also be so large (to surround the blocking device) that it prevents the card holder from using the card reader. The blocking device can be used on any type of transaction device, including different makes and models. Also, the blocking device has a simple design and simple construction, so it can easily and quickly be adapted to counter new skimming device molds that may be contrived by criminals in the future. Furthermore, the simple design results in substantially no hardware or software upgrades of the transaction machines on which they are installed, and no special training is required to install the blocking device. Also, the blocking device does not affect the underlying functionality of magnetic-stripe cards or magnetic-stripe card readers. 
       FIG. 1A  is a perspective view of a dip reader style of magnetic-stripe card reader  100  that may be used in connection with certain embodiments of the invention. The magnetic-stripe card reader  100  has a housing  102  that is attached to a surface  114  of a transaction machine, such as an Automated Teller Machine (ATM), a gas station pump, or a point of sale (POS) device, such as those commonly found at cash registers at grocery stores, drug stores, department stores, and other sales locations. The magnetic-stripe card reader  100  also may be associated with other devices, such as a door vestibule. The housing  102  of the magnetic-stripe card reader  100  includes a front surface  104  that includes a slot  106  that passes into the housing  102 . The housing  102  also includes a gap  108 . When a card holder inserts a magnetic-stripe card (not shown) into the slot  106  in the direction of arrow  116   a , the card holder&#39;s fingers (not shown) can fit into the gap  108  so that the card holder can maintain her grip on the card. When the card holder slides the magnetic-stripe card into the slot  106  in the direction of arrow  116   a  and then pulls the card out of the slot  106  in the direction of arrow  116   b , a scanning head  112  in the housing  102  reads account information from a magnetic stripe (not shown) on the magnetic-stripe card. The housing  102  may include one or more angular faces  110 . 
       FIG. 1B  is a perspective view of a swipe reader style of magnetic-stripe card reader  120  that may be used in connection with certain embodiments of the invention. The magnetic-stripe card reader  120  has a housing  122  that is attached to a surface  134  of a transaction machine, such as an Automated Teller Machine (ATM), a gas station pump, or a point of sale (POS) device, such as those commonly found at cash registers at grocery stores, drug stores, department stores, and other sales locations. The magnetic-stripe card reader  100  also may be associated with other devices, such as a door vestibule. The housing  122  of the magnetic-stripe card reader  120  includes a front surface  124  that includes a slot  126  that passes from a first side  134   a  of the housing  122  to a second side  134   b  of the housing  122  such that the slot  126  has open ends  130   a,b . When a card holder inserts the magnetic stripe (not shown) of a magnetic-stripe card (not shown) into the second open end  130   b  of the slot  126  and pulls (or swipes) the card in the direction of arrow  132 , a scanning head  128  in the housing  122  reads account information stored on the magnetic stripe of the magnetic-stripe card. Typically, the card holder swipes the card in the direction of arrow  132  until the card exits through the first open end  130   a  of the slot  126 . 
       FIG. 1C  is a cross-sectional side view of a motorized reader style of magnetic-stripe card reader  140  that may be used in connection with certain embodiments of the invention. The magnetic-stripe card reader  140  includes a housing  142  mounted to a machinery housing  156 . The machinery housing  156  is in an interior space  158  of the transaction machine and the housing  142  extends through an opening  162  in a surface  156  of the transaction machine such that at least a portion of the housing  142  is in an exterior space  160  of the transaction machine. A front face  144  of the housing  142  includes a slot  146  that is arranged to accept a magnetic-stripe card (not shown). The card holder inserts a magnetic-stripe card into the slot  146  in the direction of arrow  164 . When the magnetic-stripe card has been inserted into the slot  146  by a certain amount, rollers  148   a,b , powered by electric motors (not shown), grab the magnetic-stripe card and pull the card into the interior of the machinery housing  156 . Additional sets of rollers  150   a,b  and  152   a,b  may also be placed in the machinery housing  156  to further move the magnetic-stripe card within the machinery housing  156  in the directions of arrows  166 . As the magnetic-stripe card is moved in the directions of arrows  166 , a reader head  154  reads account information from the magnetic stripe of the magnetic-stripe card. When the card holder has completed a transaction the rollers  148   a,b ,  150   a,b , and  152   a,b  return the magnetic-stripe card to the card holder through the slot  146 . 
     Some magnetic-stripe cards also may include EMV® Integrated Circuit Cards. Accordingly, some magnetic-stripe card readers may include EMV® Integrated Circuit Card readers. EMV® is an acronym based on the names of the original organizations that created it: Europay, MasterCard®, and Visa®. EMV® uses an integrated circuit chip embedded in the card that communicates with the EMV® reader. The terms “magnetic-stripe card reader” and “card reader” used herein refer to any card reader that reads a card having a magnetic stripe (including card readers that also incorporate EMV® readers) and also any card reader that will accept a magnetic-stripe card form factor, such as, for example, an EMV®-only reader that is capable of accepting, but not reading, a magnetic-stripe card. Likewise, the term “magnetic-stripe card” used herein refers to cards with magnetic stripes and also to cards that have technology, such as, for example, an EMV® integrated circuit, in addition to a magnetic stripe. 
       FIG. 2A  is an exploded cross-sectional side view of an example skimming device  202  and a magnetic-stripe card reader  204 . The magnetic-stripe card reader  204  is shown as a dip reader style of magnetic-stripe card reader, but a person having ordinary skill will appreciate that the magnetic-stripe card reader  204  also could be a swipe reader or a motorized reader. The magnetic-stripe card reader  204  includes a housing  206  on a surface  220  of a transaction machine. The housing  206  has a slot  208  and a reader head  210  in the slot  208 . The skimming device  202  has an outer mold  212  that includes an opening  214 . A reader head  216  is located on the mold  212  at the opening  214 . The mold includes surfaces  222  and  224  that align with or conform to surfaces of the housing  206  and of the surface  220  of the transaction machine. The skimmer attaches the skimming device  202  by placing the skimming device mold  212  over the magnetic-stripe card reader  204  as indicated by arrows  218 . The skimmer may place an adhesive on surfaces  222  and/or  224  of the skimming device mold  212  to adhere to mating surfaces of the card reader housing  206 . 
       FIG. 2B  shows the skimming device  202  placed over the magnetic-stripe card reader  204 . The opening  214  in the skimming device mold  212  of the skimming device  202  aligns with the slot  208  of the magnetic-stripe card reader  204 . Also, in the direction of arrows  230  and  232 , reader head  216  of the skimming device  202  is aligned with the reader head  210  of the magnetic-stripe card reader  204 . When a card holder inserts a magnetic-stripe card (not shown) into the combined skimming device  202  and magnetic-stripe card reader  204 , the card passes through the opening  214  in the skimming device and into the slot  208  of the magnetic-stripe card reader  204 , and both the reader head  216  of the skimming device  202  and the reader head  210  of the magnetic-stripe card reader  204  read the account information stored on the magnetic stripe of the card. Because the skimming device  202  fits so closely over the profile of the magnetic-stripe card reader  204 , the card holder likely will not notice its presence. Also, because the skimming device  202  and its reader head  216  do not interfere with the reader head  210  of the magnetic-stripe card reader  204 , the transaction machine will function normally, and the card holder is unlikely to notice that something is amiss. 
       FIG. 3  is a perspective view of an embodiment of a blocking device  300  for a transaction machine, such as an ATM, gas station pump, or a POS machine. The transaction machine includes a card reader housing  304  mounted to a first surface  302  of the transaction machine. The transaction machine includes a second surface  303  at an angle relative to the first surface  302  along a common edge  324 . The card reader housing  304  includes a front face  306  and slot  308  for receiving a magnetic-stripe card (not shown). The blocking device  300  includes a base portion that includes members  310   a - f . In this embodiment, members  301   a - f  are made of heavy-gauge metal wire or metal rod. The metal may be any metal, such as steel or aluminum. Because some transaction machines are placed in outdoor locations that are exposed to the elements, metals that do not rust may be preferable. The members  301   a - f  may be joined together by welding or they may comprise a single piece of wire or rod that is bent at the junction of two members. Members  310   a - c  lie substantially in a plane parallel to surface  302  and members  310   d - f  lie substantially in a plane parallel to surface  303  such that when the blocking device  300  is installed on the transaction machine, the base portion substantially conforms to surfaces  302  and  303  of the transaction machine. 
     The blocking device  300  also includes a cage portion that includes members  312   a - f , which protrude from the base, and members  314   a - g , which connect distal ends of members  312   a - f . Members  312   a - f  and  314   a - g  also may be made of heavy-gauge metal wire or metal rod. The cage portion includes additional members  316   a  and  316   b , which are attached to members  314   a  and  314   c , and which form an aperture  322  around the slot in the front face  306  of the card reader housing  304 . The aperture  322  provides at least sufficient space for a magnetic-stripe card to be passed therethrough for placement in the slot  308  of the card reader housing  304 . The aperture  322  also may provide sufficient space for a card holder&#39;s hand (or a part of the hand) to fit through if necessary for the card holder to be able to insert the card into the slot  308 . However, the aperture  322  is not so large as to permit a skimming device to be passed therethrough for application to the card reader housing  304 . Members  312   a - f ,  314   a - g , and  316   a - b  form a cage that surrounds the card reader housing  304  and that forms a volumetric space such that a skimming device mold, such as that shown in  FIGS. 2A and 2B , placed over the cage would be so large as to look out of place and draw attention to itself. 
     The entire blocking device  300  may be coated in a plastic, rubber, or other material that prevents the card-holders&#39; hands from coming in contact with sharp and/or hard metal. Such a coating also may protect the metal wire or rod material from corrosion damage. The coating also may carry a brand logo of the transaction device or the transaction device operator. The coating also could be formed in a color that matches brand colors for the transaction device or the transaction device operator. The blocking device  300  also includes multiple mounting locations  318   a - d , shown in  FIG. 3  as loops  318   a - d  with holes  320   a - d  therein. Screws, bolts, rivets, or other fasteners can be placed through the holes  320   a - d  to secure the blocking device  300  to the surfaces  302 ,  303  of the transaction machine.  FIG. 4  shows similar mounting locations with screws  424   a - d  aligned with holes  422   a - d  of loops  420   a - d . The loops  318   a - d  may be formed of portions of wire or metal rod, or they may be formed of washers or the like that are welded to base members  310   a - f . As used herein, the term “secure” does not necessarily mean that the blocking device  300  cannot be removed. Instead, “secure” means that the effort required by a skimmer to remove the blocking device  300  likely would draw unwanted attention to his actions. Alternatively, the mounting locations may be plates that provide a surface for applying a strong adhesive for affixing the blocking device  300  to the surfaces  302 ,  303 . Use of an adhesive may be preferable if drilling holes in the surfaces  302 ,  303  at the positions of the mounting locations  318   a - d  in an installed configuration would cause damage to internal components of the transaction machine. For example, the internal components in the machinery housing  156  shown in  FIG. 1C  may be damaged by holes being drilled into surface  156  for mounting a blocking device over the card reader housing  142 . 
     The blocking device  30  may substantially fill an operating volume in which a card holder must be able to manipulate a magnetic-stripe card to pass it into or through a card reader slot  308 . Put another way, the card holder must be able to hold onto the card up to a distance away from the card reader housing  304  where the card reader reads the card (in the case of dip readers and swipe readers, examples of which are described above with respect to  FIGS. 1A  and  1 B) or where the card reader grabs the card (in the case of motorized readers, examples of which are described above with respect to  FIG. 1C ). The boundaries defined by this distance away from the card reader housing  304  form the operating volume. Certain embodiments of the blocking device  300  are sized so that a card holder may reach into the operating volume, such as, for example, through aperture  322 , to manipulate the card, but a volume added by attaching a skimming device outside of the blocking device  300  may prevent the user from manipulating the card in the operating volume, thereby preventing the user&#39;s card from being read. Certain embodiments of other blocking devices disclosed herein also may be similarly sized. 
       FIG. 4  is a perspective view of an embodiment of a blocking device  400  covering a card reader  410  mounted to a first surface  402  of a transaction machine. The blocking device includes a base portion that includes members  412   a - d . The first surface  402  of the transaction machine has a curved surface as can be seen by edge  426  that is shared with a second surface  404 . Members  412   a  and  412   c  are curved to match the contours of the first surface  402 . The blocking device  400  includes a cage portion like the cage portion of  FIG. 3 , including having an aperture  416  over a slot  428  in the card reader housing  410 . Members  414   a  and  414   b  of the cage portion are shown having a curve that matches the curve of members  412   a  and  412   c  of the base portion. Alternatively, members  414   a  and  414   b  may have a different curvature from members  412   a  and  412   c.    
     The base portion also includes extension members  418   a - d  that extend away from the blocking device and include mounting locations  420   a - d  at their ends, shown in  FIG. 4  as loops  420   a - d  with holes  422   a - d  therein. The extension members  418   a - d  extend beyond edges  426 ,  430  of the first surface  402  and the extension members  418   a - d  include bends or curves to place the mounting locations  420   a - d  onto the second surface  404  and a third surface  406 . Screws  424   a - d  are placed in holes  422   a - d  of the mounting locations for mounting to the transaction machine. By moving the mounting locations away from the card reader  410  and, in the example embodiment shown in  FIG. 4 , onto separate surfaces  404  and  406 , the chances of inadvertently damaging internal components of the card reader are reduced. 
       FIG. 4  shows curved members  412   a  and  412   c  in the same blocking device with extension members  418   a - d . However, the curved members  412   a  and  412   c  may be used in a blocking device without the extension members  418   a - d  and vice versa. 
       FIG. 5  is a perspective view of an embodiment of a blocking device  500  mounted on a surface  502  of a transaction machine. The card reader housing  504  is shown in dashed lines. The blocking device  500  includes a first base plate  510   a  and a second base plate  510   b . Each of the two base plates  510   a,b  substantially conforms to contours at the location on the surface  502  on which each is mounted. Plates  512   a  and  512   b  protrude from respective base plates  510   a,b  on sides of a card reader housing  504 . Plates  514   a  and  514   b  extend from ends of respective plates  512   a,b  in front of the face  506  of the card reader housing  504 . The plates  514   a,b  have respective edges  518   a,b  that are arranged on ends  516   a,b  of the card slot  508 . The space between edges  518   a,b  comprises an aperture  520  through which a magnetic-stripe card (not shown) may pass to be placed into the slot  508  of the card reader housing  504 . The edges  516   a,b  are spaced from respective ends  516   a,b  of the card slot such that a magnetic-stripe card may be placed into the slot. Preferably, the edges  516   a,b  are sufficiently close to respective ends  516   a,b  of the slot  508  so that if a skimming device were placed over the blocking device  500 , then the portions of the skimming device covering the edges  516   a,b  of plates  514   a,b  also will partially cover the ends  516   a,b  of the slot  508  and thereby prevent a magnetic-stripe card from being inserted into the slot  508 . Base plate  510   a , plate  512   a , and plate  514   a  may be made of a single piece of metal that is bent. Alternatively, base plate  510   a , plate  512   a , and plate  514   a  may start as three pieces of metal that are joined together, for example, by welding. Similarly, base plate  510   b , plate  512   b , and plate  514   b  may be made of a single piece of metal that is bent or may be welded together. 
     In  FIG. 5 , plates  510   a  and  510   b  have a height H 1  that is greater than a height H 2  of the card reader housing  504 . Alternatively, plates  510   a,b  may have a height H 1  that is equal to or less than a height H 2  of the card reader housing  504 . 
     Plates  510   a  and  510   b  may be securely affixed to surface  502  using an adhesive. Alternatively, plates  510   a,b  may be securely affixed to surface  502  using screws, bolts, rivets, or the like. 
       FIG. 6A  is a perspective view of an embodiment of a blocking device  600  for a card reader housing  604  mounted on a surface  602  of a transaction machine. The card reader housing  604  is shown in dashed lines. The blocking device  600  includes a first base plate  610   a  and a second base plate  610   b . Each of the two base plates  610   a,b  conforms to contours at the location on the surface  602  on which each is mounted. The transaction machine includes a second surface  626  at an angle relative to the first surface  602  and sharing a common edge  624  with the first surface  602 . In this example embodiment, the first base plate  610   a  terminates at an edge  627  that is aligned with the edge  624  between the first surface  602  and the second surface  626  of the transaction machine. A third base plate  610   c  is attached to the first base plate  610   a  at the edge  626 . The third base plate  610   c  may be attached to the first base plate  610   a  by welding, or the first and third base plates  610   a,c  may be formed from a single piece of metal that is bent at line  626 . The third base plate  610   c  is at an angle relative to the first plate  610   a  that is substantially equal to the relative angle between first and second surfaces  602 ,  626 . As such, when the base plates  610   a,c  are installed on surfaces  602 ,  626  of the transaction machine, the base plates  610   a,c  conform to the respective surfaces  602 ,  626 . Plates  612   a  and  612   b  protrude from respective base plates  610   a,b  on sides of a card reader housing  604 . Plates  614   a  and  614   b  extend from ends of respective plates  612   a,b  in front of the face  606  of the card reader housing  604 . The plates  614   a,b  have respective edges  618   a,b  that are arranged on ends  616   a,b  of the card slot  608 . The space between edges  618   a,b  is an aperture through which a magnetic-stripe card (not shown) may pass to be placed into the slot  608  of the card reader housing  604 . The edges  616   a,b  are spaced from respective ends  616   a,b  of the card slot such that a magnetic-stripe card may be placed into the slot. Preferably, the edges  616   a,b  are sufficiently close to respective ends  616   a,b  of the slot  608  so that if a skimming device were placed over the blocking device  600 , then the portions of the skimming device covering the edges  616   a,b  of plates  614   a,b  also will partially cover the ends  616   a,b  of the slot  608  and thereby prevent a magnetic-stripe card from being inserted into the slot  608 . Plates  620   a,b  and  622   a,b  also extend from ends of respective plates  612   a,b . Plates  620   a,b  are positioned on the end of respective plates  612   a,b  such that they are above the card reader housing  604  and are angled relative to respective plates  612   a,b . The angle of the plates  620   a,b  relative to respective plates  612   a,b  results in the plates  620   a,b  crossing over the top of the card reader housing  604  in the direction of the surface  602 . Likewise, plates  622   a,b  are positioned on the end of respective plates  612   a,b  such that they are below the card reader housing  604  and are angled relative to respective plates  612   a,b  such that the plates  622   a,b  cross over the bottom of the card reader housing  604  in the direction of the surface  602 . Base plate  610   a , plate  612   a , plate  614   a ,  620   a , and  622   a  may be made of a single piece of metal that is bent (and cut) to form the shape depicted in  FIG. 6A . Alternatively, base plate  610   a , plate  612   a , plate  614   a ,  620   a , and  620   b  may start as multiple pieces of metal that are joined together, for example, by welding. Similarly, base plate  610   b , plate  612   b , plate  614   b , plate  620   b , and  622   b  may be made of a single piece of metal that is bent (and cut) or may be welded together. 
     The geometry of the blocking device  600  in this embodiment provides no view (as shown by  FIGS. 6A-6D ) in which at least a portion of the card reader housing  604  is not blocked by a portion of the blocking device  600 .  FIGS. 6B ,  6 C, and  6 D show top, front, and left side views, respectively, of the embodiment of a blocking device  600  shown in  FIG. 6A .  FIG. 6B  shows plates  620   a,b  above the card reader housing  604  with plates  612   a,b  on sides of the card reader housing  604  and plates  618   a,b  in front of the card reader housing  604 . Plates  622   a,b  are not shown in  FIG. 6B  but are beneath the card reader housing  604 . Plates  622   a,b  may be of similar length and at a similar angle relative to the card reader housing  604  as plates  620   a,b  or they may be of different length and angle. Plates  620   a,b  partially block a view of the card reader housing  604  from above and plates  622   a,b  partially block a view of the card reader housing  604  from below.  FIG. 6C  shows plates  614   a,b  on sides of the card reader housing  604  and partially covering the front face  606  of the card reader housing  604 . The edges  618   a,b  of respective plates  614   a,b  are close to ends  616   a,b  of the card slot  608  in the card reader.  FIG. 6C  also shows plates  620   a,b  above the card reader housing  604  and plates  622   a,b  below the card reader housing  604 . Plates  614   a,b  partially block a view of the card reader housing  604  from the front.  FIG. 6D  shows a left side view of the blocking device  600  and shows plate  612   a  extending from base plate  610   a  away from surface  602  and extending past the front face  606  of the card reader housing  604 . Plate  612   a  also extends above the top of the card reader housing  604  and below the bottom of the card reader housing  604 . Plate  612   a  at least partially blocks a view of card reader housing  604  from the right. It is apparent from the drawings that plate  612   b  at least partially blocks a view of the card reader housing  604  from the left. Because there is no view in which the blocking device  600  does not at least partially block the card reader housing  604 , it is very difficult for a skimmer to place a skimming device mold between the card reader housing  604  and the blocking device  600 . Any mold that could be placed between the card reader housing  604  and the blocking device  600  likely would require multiple pieces that would be assembled on the card reader housing and/or would look out of place on the card reader. 
     Plates  610   a  and  610   b  may be securely affixed to surface  602  using an adhesive. Alternatively, plates  610   a,b  may be securely affixed to surface  602  using screws, bolts, rivets, or the like. 
       FIG. 7  is a perspective view of an embodiment of a blocking device  700  for a swipe reader style of card reader housing  704  on a surface  702  of a transaction machine. The card reader housing  704  is shown in dashed lines. The card reader housing  704  includes a slot  708  with open ends  716   a,b . As described above with respect to  FIG. 1B , a magnetic-stripe card is slid through the slot from a first open end  716   a  to a second open end  716   b  to be read. The blocking device  700  includes base plates  710   a,b  and plates  712   a,b  protruding from respective base plates  710   a,b . Plates  714   a  and  714   b  extend from ends of respective plates  712   a,b  in front of the face  706  of the card reader housing  704 . The plates  714   a,b  have respective edges  718   a,b  that are arranged on sides  724   a,b  of the card slot  708 . The space between edges  718   a,b  is an aperture through which a magnetic-stripe card (not shown) may slide in the slot  708  of the card reader housing  704 . The edges  716   a,b  are spaced from respective sides  724   a,b  of the card slot such that a magnetic-stripe card may be placed into the slot. Preferably, the edges  716  sufficiently close to respective ends  724   a,b  of the slot  708  so that if a skimming device were placed over the blocking device  700 , then the portions of the skimming device covering the edges  716   a,b  of plates  714   a,b  also will partially cover the sides  724   a,b  of the slot  708  and thereby prevent a magnetic-stripe card from being inserted into the slot  708 . Plates  720   a,b  and  722   a,b  also extend from ends of respective plates  712   a,b . Plates  720   a,b  are positioned on the end of respective plates  712   a,b  such that they are at ends of the card reader housing  704  and are angled relative to respective plates  712   a,b . The angle of the plates  720   a,b  relative to respective plates  712   a,b  results in the plates  720   a,b  crossing over an end of the card reader housing  704  in the direction of the surface  702 . Likewise, plates  722   a,b  are positioned on the end of respective plates  712   a,b  such that they are on an opposite end of the card reader housing  704  and are angled relative to respective plates  712   a,b  such that the plates  722   a,b  cross over the side of the card reader housing  704  in the direction of the surface  702 . Base plate  710   a , plate  712   a , plate  714   a ,  720   a , and  722   a  may be made of a single piece of metal that is bent (and cut) to form the shape depicted in  FIG. 7 . Alternatively, base plate  710   a , plate  712   a , plate  714   a ,  720   a , and  720   b  may start as multiple pieces of metal that are joined together, for example, by welding. Similarly, base plate  710   b , plate  712   b , plate  714   b , plate  720   b , and  722   b  may be made of a single piece of metal that is bent (and cut) or may be welded together. 
     Plates  710   a  and  610   b  may be securely affixed to surface  702  using an adhesive. Alternatively, plates  710   a,b  may be securely affixed to surface  702  using screws, bolts, rivets, or the like. 
       FIG. 8  is a perspective view of another blocking device  800  for a card reader housing  808  that is placed at an intersection of three surfaces  802 ,  804 ,  806  of a transaction machine. The card reader housing  808  is shown in dashed lines. The blocking device  800  includes a base plate  812  and a plate  814  extending from the base plate  812  along an exposed side of the card reader housing  808  opposite one of the walls (in the example shown in  FIG. 8 , opposite wall  806 ). The plate  814  extends beyond the front face  818  and the top face  820  of the card reader housing  808 . The plate  814  optionally also includes angled portions  816   a,b  at corners. The plate  814 , by itself, enlarges the dimensions that a skimming mold must accommodate to discretely cover the card reader housing  808 . If a skimming device were to be placed over the blocking device, the volumetric space of the combined blocking device and skimming device may make it difficult or impossible for a card holder to insert a magnetic-stripe card (not shown) into the card slot  810  in the housing  808 . The angled portions  816   a,b  further alter dimensions that the skimming mold must accommodate. Furthermore, the angled portions  816   a,b  may make it difficult or impossible for a skimmer to discretely attach a skimming mold over the card reader housing  808 . Without the angled portions  816   a,b , a skimmer may attempt to adhere a skimming mold to the outer face of plate  814  (the visible face in  FIG. 8 ) because the large flat surface provides for good adhesion. However, the angled portions  816   a,b  act to hold a skimming mold away from the flat surface of plate  814  unless the skimming mold were to include bulges, humps, or other protrusions to accommodate the angled portions  816   a,b . Thus, a skimmer would be faced with a choice of either using a skimming mold that does not adhere very well or to using a skimming mold with unusual-looking bulges or humps that draw unwanted attention to the skimming device. 
       FIG. 9A  is a perspective view of another blocking device  900  for a card reader housing  930  that is placed at an intersection of three surfaces  902 ,  904 ,  906  of a transaction machine. The blocking device  900  includes a base plate  912  mounted to surface  904 . A plate  914  extends from the base plate  812  along an exposed side of the card reader housing  930  opposite one of the walls (in the example shown in  FIG. 9 , opposite wall  906 ). The plate  914  extends beyond the front face  928  and the top face  926  of the card reader housing  930 . A third plate  916  extends from plate  914  and extends in front of the front face  928  of the card reader housing  930 . The plate  916  optionally also includes bent portions  922   a,b  at corners. The blocking device  900  also includes a second base plate  918  mounted to surface  906 , and a plate  920  attached to the second base plate  918  that extends in front of the front face  928  of the card reader housing  930 . The plate  920  optionally includes bent portions  924   a,b . The plates  912 ,  914 ,  916  enlarge the dimensions that a skimming mold must accommodate to discretely cover the combination of the card reader housing  930  and the blocking device. These increased dimensions may make it difficult or impossible for a card holder to insert a magnetic-stripe card (not shown) into the card slot  910  in the housing. The bent portions  922   a,b  and  924   a,b  bend towards the card reader housing  930  and provide no view of the card reader housing  930  that is not blocked by a portion of the blocking device  900 . 
     If the card reader housing  930  is not located at a corner of three surfaces, e.g., if surface  906  is absent from its shown location and surface  904  continues to the right of  FIG. 9A , then the blocking device  900  may include a second side that is similar or identical to base plate  912 , plates  914  and  916 , and bent portions  922   a,b.    
       FIG. 9B  shows a top view an alternative embodiment of base plate  912  in which a free end of the base plate  912  includes a curl  932  away from surface  904 . The curl  932  adds additional dimensions over which a skimming device must cover, again making it more difficult for a skimming device to be discretely placed on the card reader housing  930 . Also, the curl  932  at least partially eliminates the base plate  912  as a flat surface to which a skimming device may be adhered, making it less likely that a skimming device can be securely adhered to the card reader housing  930  and the blocker  900 . Although only shown in  FIG. 9B , a person having ordinary skill understands that the curl  932  may be added to any of the free ends of base plates shown in any of the figures of this application. 
     It should be noted that the above-described embodiments are not limited in application or use to the details of construction and arrangement of parts illustrated in the accompanying drawings and description. The illustrative embodiments may be implemented or incorporated in other embodiments, variations and modifications, and may be practiced or carried out in various ways. For example, the blocking devices disclosed above are illustrative only and not meant to limit the scope or application thereof. Furthermore, unless otherwise indicated, the terms and expressions employed herein have been chosen for the purpose of describing the illustrative embodiments for the convenience of the reader and are not to limit the scope thereof. 
     Certain exemplary embodiments have been described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those of ordinary skill in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the various embodiments is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the claims. 
     Although various embodiments have been described herein, many modifications and variations to those embodiments may be implemented. For example, different types of end effectors may be employed. Also, where materials are disclosed for certain components, other materials may be used. The foregoing description and following claims are intended to cover all such modification and variations.