Patent Publication Number: US-10325121-B2

Title: Shape actuation encapsulant of a cryptographic module

Description:
FIELD OF THE INVENTION 
     Embodiments of the invention generally relate to computer systems and more particularly to encapsulating a cryptographic module in a shape actuation encapsulant. 
     DESCRIPTION OF THE RELATED ART 
     A cryptograph module is the set of hardware, software, firmware, or some combination thereof that implements cryptographic logic or cryptographic processes, including cryptographic algorithms, and is contained within the cryptographic boundary of the module. U.S. Government Federal Information Processing Standard (FIPS) 140-2 Security Requirements for Cryptographic Modules-(Level 4) is a standard that specifies security requirements for cryptographic modules. This standard requires that physical security mechanisms provide a complete envelope of protection around the cryptographic module with the intent of detecting and responding to all unauthorized attempts at physical access. 
     A non exhaustive list of a cryptographic modules is as follows: cryptographic coprocessor, cryptographic accelerator, cryptographic daughter card, cryptographic field programmable gate array (FPGA), memory storing cryptographic accelerator data, etc. 
     In a particular example of a cryptographic module, a cryptographic coprocessor is a secure cryptoprocessor that performs cryptographic operations used by application programs and by data handling operations, such as SSL (Secure Sockets Layer) private key transactions associated with SSL digital certificates. The cryptoprocessor includes a tamper-responding hardware security module that provides secure storage for storing crypto keys and other sensitive data. Cryptoprocessor applications may include financial PIN (Personal Identification Number) transactions, bank-to-clearing-house transactions, EMV (Europay®, MasterCard®, and Visa®) transactions for integrated circuit (chip) based credit cards, basic SET (Secure Electronic Transaction) block processing, and general-purpose cryptographic applications using symmetric key, hashing, and public key algorithms. The crypto keys may be generated in the cryptoprocessor and may be saved in a keystore file encrypted under a master key of that cryptoprocessor. 
     SUMMARY 
     In an embodiment of the present invention, a method of fabricating a crypto card is presented. The crypto card includes a printed circuit board, a tamper sensing encapsulant, and a daughter card. The method includes forming the tamper sensing encapsulant. The tamper sensing encapsulant is formed by forming an electrically conductive first trace element associated with a first shape actuation layer, forming an electrically conductive second trace element associated with a second shape actuation layer, and positioning the first shape actuation layer against the second shape actuation layer such that the first trace element and the second trace element do not physically touch at a predetermined operational temperature and do physically touch when the first shape actuation layer and the second shape actuation layer are thermally loaded. The method also include surrounding the daughter card with the tamper sensing encapsulant. 
     In another embodiment of the present invention, a method of detecting an unauthorized attempt of physical access of a crypto card is presented. The crypto card includes a printed circuit board, a tamper sensing encapsulant, and a daughter card. The method includes physically contacting a first trace element associated with a first shape actuation layer of the tamper sensing encapsulant that surrounds the daughter card with a second trace element associated with a second shape actuation layer of the tamper sensing encapsulant that surrounds the daughter card to form a circuit, as a result of thermal loading of the crypto card. The first shape actuation layer is positioned against the second shape actuation layer such that the first trace element and the second trace element do not physically touch at a predetermined operational temperature and do physically touch when the first shape actuation layer and the second shape actuation layer are thermally loaded. The daughter card is configured to interconnect with the printed circuit board and includes a secure crypto component. 
     In yet another embodiment of the present invention, a crypto card is presented. The crypto card includes a printed circuit board, a tamper sensing encapsulant, a daughter card that includes a crypto component, and a secure crypto module. The secure crypto module includes a shell and tamper sensing encapsulant surrounding the daughter card. The tamper sensing encapsulant includes a first shape actuation layer associated with an electrically conductive first trace element and a second shape actuation layer associated with an electrically conductive second trace element. The first shape actuation layer is positioned against the second shape actuation layer such that the first trace element and the second trace element do not physically touch at a predetermined operating temperature and do physically touch when the first shape actuation layer and the second shape actuation layer are thermally loaded. 
     These and other embodiments, features, aspects, and advantages will become better understood with reference to the following description, appended claims, and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary crypto card including a secure crypto module that may utilize various embodiments of the present invention. 
         FIG. 2  illustrates a cross section of an exemplary crypto card that includes a cryptographic module surrounded by various encapsulant layers, according to various embodiments of the present invention. 
         FIG. 3  illustrates a shape actuation encapsulant layer associated with various circuit trace elements, according to various embodiments of the present invention. 
         FIG. 4  illustrates a shape actuation encapsulant layer associated with various circuit trace elements in a thermal loading state, according to various embodiments of the present invention. 
         FIG. 5  illustrates various shape actuation encapsulant layers associated with various circuit trace elements, according to various embodiments of the present invention. 
         FIG. 6  illustrates various shape actuation encapsulant layers associated with various circuit trace elements in a thermal loading state, according to various embodiments of the present invention. 
         FIG. 7  and  FIG. 8  illustrate cross section views of a portion of a secure crypto module and thermal gradients therethrough during respective thermal loading states, according to various embodiments of the present invention. 
         FIG. 9A  and  FIG. 9B  illustrate a shape actuation encapsulant layer associated with at least one trace element and a stationary encapsulant layer associated with at least one trace element, according to various embodiments of the present invention. 
         FIG. 10  illustrates multiple encapsulant layers associated with at least one trace element, according to various embodiments of the present invention. 
         FIG. 11  illustrates a block circuit diagram of a secure crypto module, according to various embodiments of the present invention. 
         FIG. 12  illustrates of block diagram of a computer including a crypto card, according to various embodiments of the present invention. 
         FIG. 13  and  FIG. 14  illustrate exemplary methods of detecting and responding to an unauthorized attempt of physical access of a secure crypto module, according to various embodiments of the present invention. 
         FIG. 15  illustrates an exemplary method of fabricating secure crypto module encapsulant layers, according to various embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments are related to providing a physical security mechanism that forms a complete envelope of protection around a cryptographic module to detect and respond to an unauthorized attempt at physical access thereof. A tamper sensing encapsulant generally encapsulates the cryptographic module. The tamper sensing encapsulant includes a first shape actuation layer associated with an electrically conductive first trace element and a second shape actuation layer associated with an electrically conductive second trace element. The first shape actuation layer is positioned against the second shape actuation layer such that the first trace element and the second trace element do not physically touch at an operating temperature of the cryptographic module and do physically touch when the first shape actuation layer and the second shape actuation layer are thermally loaded. Upon first trace element and the second trace element touching, a circuit is formed that disables the cryptographic module. 
     Referring to the Drawings, wherein like numbers denote like parts throughout the several views,  FIG. 1  illustrates a crypto card  100  that includes a secure crypto module  106 . Crypto card  100  includes a printed circuit board  102  and connector  104  that can be inserted into an electrical connector, or expansion slot on a computer motherboard, backplane or riser to add functionality to the computer via an expansion bus. Printed circuit board  102  provides mechanical support for various electronic components as well as conductive pathways to provide for electrical communication (e.g., data transfer, etc.) there between and to and from the motherboard. The computer motherboard, backplane or riser, hereinafter referred to as a motherboard, provides mechanical support for computer components such as a processor and memory and provides conductive pathways to provide for electrical communication to and from the computer components. The expansion bus, a particular conductive pathway, is a computer bus which moves information between the internal hardware of the computer (e.g., the processor and memory) and peripheral devices. 
     Secure crypto module  106  provides a complete envelope of protection around a cryptographic module  110  (not shown in  FIG. 1 ) to detect and respond to unauthorized attempts at physical access or tampering therewith. 
       FIG. 2  illustrates a cross section of crypto card  100 . Secure crypto module  106  may include cryptographic module  110 , shield  120 , and tamper sensing encapsulant  130  generally surrounding cryptographic module  110 . Cryptographic module  110  is a collective set of hardware, software, firmware, or some combination thereof that implements cryptographic logic or cryptographic processes, including cryptographic algorithms, and is contained within the boundary or shield  120  of the secure crypto module  106 . 
     Cryptographic module  110  may include a daughter card  122 , battery  126 , crypto components  124 , and connector  128 . Daughter card  122  provides mechanical support for battery  126  and secure crypto components  124  and includes conductive pathways to provide for electrical communication between secure crypto components  124  and or between secure crypto components  124  and printed circuit board  102  via connector  128  and printed circuit board  102  connector  103 . The various connectors and conductive pathways contemplated herein generally allow for secure crypto components  124  to electrically communicate with one or more computer components of the motherboard. Battery  126  provides electric potential to a circuit formed by trace elements touching within tamper sensing encapsulant  130 . The battery  126  may further provide backup power to one or more features of the cryptographic module  110  and may be active from the time of factory initialization until the end of the cryptographic module  110  expected product life. Crypto components  124  are hardware computer components that implement cryptographic logic or cryptographic processes or otherwise store cryptographic data. Exemplary crypto components  124  may be a coprocessor, memory (DRAM, Flash, ROM, RAM, etc.), FPGA, etc. 
     Shield  120  is an enclosure, chassis, envelope, or other shell that generally surrounds and protects the internal cryptographic module  110 . Shield  120  may be void of access or air flow cutouts to limit access the internal cryptographic module  110 . In some implementations where a crypto component  124  may be cooled, a heat sink may be thermally attached to the crypto component  124  and the fins or pins of the heat sink may protrude through the shield  120 . In an embodiment, shield  120  may surround the cryptographic module  110  on at least five sides, the sixth side of cryptographic module  110  being protected by the printed circuit board  102 . In another embodiment, shield  120  may surround the cryptographic module  110  on all six sides of the cryptographic module  110 . In embodiments, the shield  120  may be formed from sheet metal. By surrounding the internal cryptographic module  110 , shield  120  generally protects the cryptographic module  110  by limiting physical penetration thereto. Shield  120  may also incorporate a detection wire mesh such that upon damage to the wire mesh, an immediate zeroization of area(s) of the one or more crypto components  124  where sensitive data is stored and the one or more crypto components  124  are permanently disabled, such that the one or more crypto components  124  are rendered inoperable. 
     Tamper sensing encapsulant  130  generally surrounds cryptographic module  110  between shield  120  and cryptographic module  110 . Tamper sensing encapsulant  130  acts as a temperature sensor to detect and respond to unauthorized attempts at physical access to the encapsulated cryptographic module  110 . Tamper sensing encapsulant  130  includes multiple encapsulant layers with each encapsulant layer being associated with at least one trace element. For clarity, the term “associated” when used with reference to a trace element and an encapsulant layer means that the trace element may be formed directly upon the encapsulant layer, formed within the encapsulant layer, formed partially within encapsulant layer, etc. 
     In embodiments, two types of trace elements are present within tamper sensing encapsulant  130 . One type of trace element is electrically connected to battery  126 . Another type of trace element is electrically connected to one or more destruct features within respective crypto components  124 . A trace element, generally, is a length of electrically conductive material, such as copper, aluminum, etc. 
     In a normal operating state, the encapsulant layers and trace elements are arranged so that distinct trace elements types are not in physical contact. In a thermally loaded state, at least one of the encapsulant layers expands or contracts moving the associated trace element to be in physical contact with a distinct type trace element. The thermally loaded state may be caused by artificial heating (i.e., heating not associated with normal operation of the cryptographic module  110 , etc.) or artificial cooling (i.e., cooling not associated with normal operation of the cryptographic module  110 , etc.) of the secure crypto module  106 . Upon touching, the distinct trace elements form a short circuit between battery  126  and the destruct features, whereby the enablement of the destruct features causes an immediate zeroization of area(s) of the one or more crypto components  124  where sensitive data is stored and permanent disablement of the one or more crypto components  124 . 
       FIG. 3  illustrates a shape actuation encapsulant layer  140  of the tamper sensing encapsulant  130  that is associated with a battery connected (BC) trace element  150  and a crypto component connected (CC) trace element  160  in a normal operating state. BC trace element  150  is electrically connected to battery  126 . CC trace element  160  is electrically connected to one or more destruct features within respective crypto components  124 . The one or more destruct features within respective crypto components  124  are also electrically connected to the battery  126 . Therefore, upon BC trace element  150  and CC trace element  160  touching, a circuit is formed whereby current passes across the one or more destruct features thereby enabling the one or more destruct features. 
     In an embodiment, a plurality of CC trace elements  160  may be electrically interconnected via a switch pad, or equivalent, that electrically connects to daughter card  122 , whereby a particular conductive pathway of the daughter card may electrically connect the switch pad and one or more crypto components  124 . Likewise, a plurality of BC trace elements  150  may be electrically interconnected via a switch pad, or equivalent that electrically connects to daughter card  122 , whereby particular conductive pathway of the daughter card may electrically connect the switch pad and battery  126 . 
     In the embodiment depicted in  FIG. 3 , BC trace element  150  and CC trace element  160  are formed upon shape actuation encapsulant layer  140 . Such formation techniques are generally known in the art. For instance BC trace element  150  and CC trace element  160  may be formed by a masking processes whereby a mask, such as a photoresist, is applied to shape actuation encapsulant layer  140  and patterned to form trenches within which the BC trace element  150  and CC trace element  160  may be formed by deposition, plating, etc. Though shown as having a rectangular cross section, BC trace element  150  and CC trace element  160  may have a triangular cross section, a “T” shape cross section, etc. BC trace element  150  and CC trace element  160  may each further include extension portions extending from the exposed surfaces of the BC trace element  150  and CC trace element  160 . 
     As the tamper sensing encapsulant  130  is depicted in a normal operating state, BC trace element  150  and CC trace element  160  are arranged so that BC trace element  150  and CC trace element  160  are not in physical contact. 
     Shape actuation encapsulant layer  140  is a single-phase, two-way shape actuator layer that, in the absence of an external load, elongates upon cooling and contracts upon heating. Shape actuation encapsulant layer  140  may be formed by a fabrication process where a partially cross-linked, semicrystalline poly(ε-caprolactone) (PCL) network is melted, stretched to several hundred percent strain, and further cross-linked. Upon removal of the applied load, the elastic double network adopts a “state-of-ease” that retains part of its former strain. When cooled, internal stress-induced crystallization of shape actuation encapsulant layer  140  causes further elongation of configurationally biased chains. When heated, crystallites melt, and shape actuation encapsulant layer  140  contracts. 
       FIG. 4  illustrates a shape actuation encapsulant layer  140  of the tamper sensing encapsulant  130  associated with BC trace element  150  and CC trace element  160  in a thermal heating state  160 . The thermally heated state  160  may be caused by artificial heating of crypto card  100 , etc. (i.e., heating not associated with normal operation of the cryptographic module  110 , etc.). For example, crypto card  100  may be placed in a solder reflow oven by an unauthorized party in an attempt to remove components thereon, etc. The heat from the oven transfers to tamper sensing encapsulant  130  and to shape actuation encapsulant layer  140  which causes the contraction thereof and relative movement between BC trace element  150  and CC trace element  160 . 
     In the thermally heated state  160 , shape actuation encapsulant layer  140  contracts moving BC trace element  150  and CC trace element  160  to be in physical contact. For example, an extension portion extending from a side surface of BC trace element  150  may touch an extension portion extending from a facing side surface of CC trace element  160 . 
     Upon touching, BC trace element  150  and CC trace element  160  form a short circuit between battery  126  and the destruct feature within one or more crypto components  124 , thereby enabling the destruct feature. The enablement of the destruct feature causes an immediate zeroization of area(s) of the one or more crypto components  124  where sensitive data is stored and the permanent disablement of the one or more crypto components  124 . 
       FIG. 5  illustrates a first shape actuation encapsulant layer  140 A of the tamper sensing encapsulant  130  associated with BC trace element  150  and a second shape actuation encapsulant layer  140 B of the tamper sensing encapsulant  130  associated with CC trace element  160  upon the layer  140 A in a normal operating state. In the embodiment depicted in  FIG. 5 , BC trace element  150  is formed within first shape actuation encapsulant layer  140 A and CC trace element  160  is formed within second shape actuation encapsulant layer  140 B. Such formation techniques are generally known in the art. For instance BC trace element  150  and CC trace element  160  may be formed by a masking processes whereby a mask, such as a photoresist, is applied to the appropriate shape actuation encapsulant layer  140  and patterned to form trenches within which the BC trace element  150  and or CC trace element  160  may be formed by deposition, plating, etc. As the tamper sensing encapsulant  130  is depicted in a normal operating state, BC trace element  150  and CC trace element  160  so that BC trace element  150  and CC trace element  160  are not in physical contact. 
       FIG. 6  illustrates first shape actuation encapsulant layer  140 A of the tamper sensing encapsulant  130  associated with BC trace element  150  and second shape actuation encapsulant layer  140 B of the tamper sensing encapsulant  130  associated with CC trace element  160  upon the layer  140 A in a thermal cooling state  190 . 
     The thermally cooling state  190  may be caused by artificial cooling of crypto card  100 , etc. (i.e., cooling not associated with normal operation of the cryptographic module  110 , etc.). For example, crypto card  100  may be placed in a freezer by an unauthorized party in an attempt make various materials with crypto card  100  brittle to ease the removal of components thereon, etc. Heat from the encapsulant  130  transfers to the artificially cool environment outside of the secure crypto module  106  which causes the expansion of first shape actuation encapsulant layer  140 A and second shape actuation encapsulant layer  140 B and relative movement between BC trace element  150  and CC trace element  160 . 
     In the thermally cooling state  190 , due to heat transfer thermal gradients, the shape actuation encapsulant layer  140  nearest the cool environment cools more quickly and therefore elongates at a faster rate than a shape actuation encapsulant layer  140  at a greater distance away from the cool environment. For example, first shape actuation encapsulant layer  140 A may elongate more quickly relative to second shape actuation encapsulant layer  140 B. The relative movement between BC trace element  150  and CC trace element  160  results in BC trace element  150  and CC trace element  160  to be in physical contact. Upon this contact, the destruct feature within one or more crypto components  124  is enabled and area(s) of the one or more crypto components  124  where sensitive data is stored are zeroed and the one or more crypto components  124  are permanent disabled. 
       FIG. 7  illustrates a cross section view of a portion of secure crypto module  106  and a thermal gradient there through during a thermal heating state  160 . When artificially heated, thermal energy from the environment transfers into secure crypto module  106 . Thus the encapsulant layers or portions of encapsulant layers nearest the perimeter of secure crypto module  106  are heated more quickly relative to encapsulant layers or portions of encapsulant layers furthest away from the perimeter of secure crypto module  106 . For example, shape actuation encapsulant layer  140 G is heated more quickly relative to shape actuation encapsulant layers  140 F- 140 C and therefore elongates at a faster rate than the other shape actuation encapsulant layers. 
     Also shown in  FIG. 7 , in embodiments, multiple BC trace elements  150  and CC trace elements  160  are arranged in a trace element array within tamper sensing encapsulant  130 , such that a particular trace element is nearest to opposite type trace elements. For example, CC trace elements  160  in shape actuation encapsulant layer  140 E is nearest to BC trace elements  150  in shape actuation encapsulant layer  140 E in an upper right and upper left position, respectively, and is nearest to BC trace elements  150  in shape actuation encapsulant layer  140 D in an lower right and lower left position. 
       FIG. 8  illustrates a cross section view of a portion of secure crypto module  106  and a thermal gradient there through during a thermal cooling state  190 . When artificially cooled, thermal energy from tamper sensing encapsulant  130  transfers into the cool environment surrounding secure crypto module  106 . Thus, the encapsulant layers or portions of encapsulant layers nearest the perimeter of secure crypto module  106  are cooled more quickly relative to encapsulant layers or portions of encapsulant layers furthest away from the perimeter of secure crypto module  106 . For example, shape actuation encapsulant layer  140 G is cooled more quickly relative to shape actuation encapsulant layers  140 F- 140 C and therefore contracts at a faster rate than the other shape actuation encapsulant layers. 
       FIG. 9A  and  FIG. 9B  illustrate shape actuation encapsulant layer  1401  associated with at least one trace element upon a stationary encapsulant layer  220  associated with at least one trace element. Stationary layer  220  is a layer that does not elongate and/or contract in response to a thermal load relative to shape actuation encapsulant layer  1401 . Stationary layer  220  may be a polymer layer, etc. As shown in  FIG. 9A , a BC trace element  150  may be associated with stationary layer  220  and CC trace element  160  may be associated with shape actuation encapsulant layer  1401 . As shown in  FIG. 9B , a CC trace element  160  may be associated with stationary layer  220  and BC trace element  150  may be associated with shape actuation encapsulant layer  1401 . 
     Also contemplated is the utilization of shape actuation encapsulant layers that singularly respond to thermal loading. For example, tamper sensing encapsulant  130  may include a first single response shape actuation encapsulant layer associated with a trace element that elongates during thermal heating but does not contract during thermal cooling and a second single response shape actuation encapsulant layer associated with a trace element that does not elongate during thermal heating but contracts during thermal cooling. Thus, in a thermal heating state, the first single response shape actuation encapsulant layer moves relative to the second single response shape actuation encapsulant layer, thereby enabling the touching of the associated trace elements. Likewise, in a thermal cooling state, the second single response shape actuation encapsulant layer moves relative to the first single response shape actuation encapsulant layer, thereby enabling the touching of the associated trace elements. 
       FIG. 10  illustrates multiple shape actuation encapsulant layers  140 J- 140 L associated with at least one trace element in a normal operating state. In the embodiment shown in  FIG. 10 , BC trace elements  150  are formed upon shape actuation encapsulant layer  140 J and upon shape actuation encapsulant layers  140 L. An opening, gap, space, or void exists between these BC trace elements  150 . CC trace elements  160  are formed upon shape actuation encapsulant layer  140 K. The multiple shape actuation encapsulant layers  140 J- 140 L are arranged such that CC trace elements  160  are positioned within the opening between BC trace elements  150 . For clarity, in this present paragraph, BC trace element  150  may take the place of CC trace element  160 , and visa versa. 
       FIG. 11  illustrates a block circuit diagram of various components of secure crypto module  106 . In a normal operating, state an open circuit exists between the battery  126 , tamper sensing encapsulant  130 , and one or more crypto components  124 . More specifically, the BC trace element  150  is electrically connected to battery  126  and CC trace element  160  is electrically connected to one or more destruct features  125  within respective crypto components  124 . The one or more destruct features  125  within respective crypto components  124  are also electrically connected to the battery  126  via connection  170 . As a result of thermal loading causing the BC trace element  150  and CC trace element  160  to touch, a closed circuit is formed, whereby current passes across the one or more destruct features  125  thereby enabling the one or more destruct features  125 . In a particular embodiment, destruct feature  125  may be a fuse, one time programmable logic device, or the like. 
       FIG. 12  illustrates of block diagram of a computer  200  including a crypto card  100  installed on motherboard  202 . In addition to computer components such as memory, processor, etc., motherboard  202  may also include a sense circuit  204  and a destruct circuit  206 . The sense circuit  204  senses, monitors, or otherwise detects that destruct feature  125  has been enabled. Destruct circuit  206  is connected to a power supply, such as the power supply of computer  200 . Upon sense circuit  204  determining destruct feature  125  has been enabled, destruct circuit  206  zeros area(s) of the computer  200  where sensitive data is stored (e.g., a hard drive, memory, etc.) and one or more functions of the computer  200  are permanently disabled. For example, the processor or memory may be disabled; an application program interface associated with crypto functions of secure crypto module  106  may be disabled, a bus connecting the processor and the crypto card  100  may be disabled, etc. 
       FIG. 13  illustrates an exemplary method  300  of detecting and responding to an unauthorized attempt of physical access of a secure crypto module  106 . Method  300  may be carried out by a computer, crypto card  100 , or other electronic device, such as a cash machine, or the like. Method  300  may begin at block  302  and continues by a first trace element physically touching a second element forming a circuit (block  304 ). For example, BC trace element  150  and CC trace element  160  associated with one or more encapsulation layers within tamper sensing encapsulant  130  physically contact and completes a closed circuit between battery  126  and one or more crypto components  124 . The physical contact of BC trace element  150  and CC trace element  160  is generally caused by thermal loading of secure crypto module  106  resulting in relative movement and touching of BC trace element  150  and CC trace element  160 . 
     Method  300  may continue by the closed circuit causing a fault within crypto component  124  (block  306 ). For example, the completion of the closed circuit between battery  126  and one or more crypto components  124  enables one or more destruct features  125  within the one or more crypto components  124 . 
     Method  300  may continue by disabling the crypto component  124  (block  308 ). For example, enabling of the destruct feature  125  results in area(s) of the one or more crypto components  124  where sensitive data is stored being zeroed and the one or more crypto components  124  becoming non functional. Method  300  ends at block  310 . 
       FIG. 14  illustrates an exemplary method  320  of detecting and responding to an unauthorized attempt of physical access of a secure crypto module  106 . Method  320  may be carried out by a computer, crypto card  100 , or other electronic device, such as a cash machine, or the like. Method  320  may begin at block  322  and continues by a first trace element physically touching a second element forming a circuit (block  324 ). For example, BC trace element  150  and CC trace element  160  associated with one or more encapsulation layers within tamper sensing encapsulant  130  physically contact and complete a closed circuit between battery  126  and one or more crypto components  124 . The physical contact of BC trace element  150  and CC trace element  160  is generally caused by thermal loading of secure crypto module  106  resulting in relative movement and touching of BC trace element  150  and CC trace element  160 . 
     Method  320  may continue by the closed circuit causing a fault within crypto component  124  (block  326 ). For example, the completion of the closed circuit between battery  126  and one or more crypto components  124  enables one or more destruct features  125  within the one or more crypto components  124 . 
     Method  320  may continue by a mother board sensing the fault within the one or more crypto components  124  (block  328 ). For example, a processor upon mother board  202  determines the crypto component  124  is faulted. In another example, a sense circuit  204  within mother board  202  determines that one or more destruct features  125  within the one or more crypto components  124  have been enabled resulting in the fault of crypto component  124 . 
     Method  320  may continue by the mother board disabling one or more of its functions (block  330 ). For example, destruct circuit  206  zeros area(s) of the mother board  202  where data associated with secure crypto module  106  is stored (e.g., mother board hard drive, mother board memory, etc.) and one or more functions of the mother board  202  are permanently disabled. For example, the processor upon the mother board  202  or memory upon mother board  202  may be disabled; an application program interface of the mother board  202  associated with crypto functions of secure crypto module  106  may be disabled, a bus of mother board  202  connecting the processor and the crypto card  100  may be disabled, etc. Method  320  ends at block  332 . 
       FIG. 15  illustrates an exemplary method  340  of fabricating secure crypto module  106  encapsulant layers. Method  340  may be utilized to form tamper sensing encapsulant  130  that may subsequently surround cryptographic module  110  between shield  120  and cryptographic module  110  within secure crypto module  106 . Method  340  begins at block  342  and continues with forming a first trace element associated with a first encapsulant layer (block  344 ). For example, a BC trace element  150  or a CC trace element  160  may be formed within, partially within, upon, etc. the first encapsulant layer. 
     The first encapsulant layer may be a two way layer that respectively elongates and contracts in response to heating or cooling. The first encapsulant layer may be a one way layer shape actuation layer that either elongates in response to heating or contracts in response to cooling, or visa versa. Still the first encapsulant layer may be a stationary layer that maintains its shape in response to heating or cooling. 
     Method  340  may continue with forming a second trace element associated with a second encapsulant layer (block  346 ). For example, a BC trace element  150  or a CC trace element  160  may be formed within, partially within, upon, etc. the second encapsulant layer. 
     The second encapsulant layer may be a two way layer that respectively elongates and contracts in response to heating or cooling. The second encapsulant layer may be a one way shape actuation layer that either elongates in response to heating or contracts in response to cooling, or visa versa. In this embodiment, the second one way shape actuation layer responds oppositely if the first encapsulant layer is also a one way shape actuation layer. For example, if the first one way shape actuation layer elongates the second one way shape actuation layer contracts, or visa versa. Still the second encapsulant layer may be a stationary layer that maintains its shape in response to heating or cooling. If the second encapsulant layer is a stationary layer, the first encapsulant layer should not also be a stationary layer. In the possible configurations of the first layer and the second layer, this results in relative movement of the associated trace elements towards each other during thermal loading. 
     Method  340  may continue with juxtaposing or otherwise positioning the first layer and the second layer such that the first trace element and the second trace element do not physically touch in a normal operating state or temperature but do physically contact in a thermally loaded state or temperature (block  348 ). The juxtaposed first layer and second layer may subsequently be placed within shell  102  and electric terminals associated with BC trace element  150  or a CC trace element  160  may be connected to daughter card during crypto card  100  fabrication. 
     The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over those found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.