Implementing carbon nanotube based sensors for cryptographic applications

A method and circuit for implementing security protection with carbon nanotube based sensors for cryptographic applications, and a design structure on which the subject circuit resides are provided. A carbon nanotube layer is incorporated with a polymeric encapsulation layer of a security card. Electrical connections to the carbon nanotube layer are provided for electrical monitoring of electrical resistance of the carbon nanotube layer.

FIELD OF THE INVENTION

The present invention relates generally to the data processing field, and more particularly, relates to a method and circuit for implementing security protection with carbon nanotube based sensors for cryptographic applications, and a design structure on which the subject circuit resides.

DESCRIPTION OF THE RELATED ART

Current security devices, such as IBM's X-crypto, are implemented to protect against data theft in both high end and personal computing systems. These devices utilize special high priced security features that drive up production cost and present many processing challenges during manufacturing. Current X-Crypto devices use expensive circuitry mats and a long processing time is required for limited quantity. Current X-Crypto circuitry mats are also susceptible to destruction during handling.

It is important though to recognize that each device must meet the U.S. Government Federal Information Processing Standards (FIPS), which are used as means to determine the protection offered from proposed and currently used security devices. For example, some security devices must meet high level requirements for security protection contained in the U.S. Government Federal Information Processing Standard (FIPS) 140-2 Security Requirements for Cryptographic Modules—(Level 4). The standard states that: “At this security level, the 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” (FIPS Pub 140-2).

A need exists for a circuit having efficient and effective sensors for security protection for cryptographic applications.

SUMMARY OF THE INVENTION

Principal aspects of the present invention are to provide a method and circuit for implementing security protection with carbon nanotube based sensors for cryptographic applications, and a design structure on which the subject circuit resides. Other important aspects of the present invention are to provide such method, circuit and design structure substantially without negative effects and that overcome many of the disadvantages of prior art arrangements.

In brief, a method and circuit for implementing security protection with carbon nanotube based sensors for cryptographic applications, and a design structure on which the subject circuit resides are provided. A carbon nanotube layer is incorporated with a polymeric encapsulation layer of a security card. Electrical connections to the carbon nanotube layer are provided for electrical monitoring of the electrical resistance of the carbon nanotube layer.

In accordance with features of the invention, the carbon nanotube layer is formed through the deposition of carbon nanotubes in high concentration to create a film structure defining the carbon nanotube layer. The carbon nanotube layer has a known resistance in the unstrained state. When strained from compression or tension the resistance of the carbon nanotube layer changes. Temperature change can be used to cause the polymer encapsulation layer to flow, which also results in a resistance change of the carbon nanotube layer. A predefined resistance change is identified to shutdown and, or erase the security card, or to continue operation of the security card.

In accordance with features of the invention, the polymeric encapsulation layer can be implemented with any polymer.

In accordance with features of the invention, the carbon nanotube layer can be used as functional fillers to strengthen the polymeric encapsulation layer. Other additives can be added to this layer such as fillers with flame retardant properties.

In accordance with features of the invention, carbon nanotube sensors measure resistance change based upon compression, tension, electrical shorts, and temperature changes, providing enhanced tamper detection.

In accordance with features of the invention, carbon nanotubes are cast to form the carbon nanotube layer, and encapsulated into the polymeric encapsulation layer without shorting out the security card. Electrical contacts optionally are made by inserting wires into the carbon nanotube layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with features of the invention, a method and circuit for implementing sensors for security protection for cryptographic applications, and a design structure on which the subject circuit resides are provided. The circuit includes a carbon nanotube layer provided within an encapsulation layer used to encapsulate a security card and electrical connections for monitoring of the resistance of the nanotube layer.

Example Preparation of Carbon Nanotube Based Sensor

Having reference now to the drawings, inFIG. 1, there is shown a flow chart illustrating example steps generally designated by reference character100manufacturing a carbon nanotube based sensor for circuits used for security protection for cryptographic applications in accordance with the preferred embodiment.

As indicated at a block102, carbon nanotubes (single or carbon nanotubes containing a plurality of concentric rings) are mixed in an organic compound, such as, N,N′-dimethylformamide, with the formula (CH3)2NC(O)H, or other solvent/organic compounds known to those in the art which disperse carbon nanotubes in organic media. As indicated at a block104, the mixture is then filtered, for example, in a preformed shape containing a Teflon filter and dried. After drying, the film is then peeled off the filter and further dried under vacuum and heat for a set time, such as 24 hours, as indicated at a block106. This is just a single example of carbon nanotube film formation, other processes to those known in the art to form carbon nanotube films may be used, such as solvent casts carbon nanotube films.

Electrical connections or leads are then attached to each end of the carbon nanotube layer to be used for electrical resistance measurements as indicated at a block108. The newly formed carbon nanotube sensor is placed into a polymeric resin used to encase a security card, such as a security daughter card as indicated at a block110.

In accordance with features of the invention, the use of carbon nanotubes allows electrical resistance to be measured for tamper detection. Carbon nanotubes can easily be cast into films and encapsulated into the polymeric encapsulation layer for a security card. The carbon nanotube layer can be used to strengthen the polymeric encapsulation layer.

In accordance with features of the invention, the carbon nanotube sensors measure resistance change based on compression, tension, shorts, and temperature changes. Monitoring resistance changes due to temperature prevents someone from using liquid nitrogen or heat to delaminate the polymeric encapsulation layer. Carbon nanotube resistance can be measured at a macro scale thus making the carbon nanotube sensors more sensitive than other strain gauges. Carbon nanotube sensors advantageously are used with various algorithms or security protection functions designed to shutdown power and, or erase contents of security card based on predefined electrical resistance changes. When a security card is encapsulated into polymeric resin containing a carbon nanotube respondent layer, the card becomes, for example, Level 4 FIPS secured. When the encapsulated card is placed into a metal security can, Level 3 FIPS is also achievable. Carbon nanotube sensors of the invention preferably are used for security protection circuitry, while other conductive materials having a measurable resistance could be used, such as carbon fibers, carbon black, a conducting polymer and conducting polymer fibers.

It should be understood that other embodiments of carbon nanotube sensors are provided in accordance with features of the invention. For example, in another embodiment of this invention the conductive carbon nanotube material optionally is blended into the polymeric resin with varying density encompassing low density encapsulates such as foams to high density encapsulates such as neat resin, for example, to form a resistive coating. Electrical contacts are made by inserting wires into this layer. Another embodiment of this invention includes the incorporation of the conductive carbon nanotube material into a foam that when compressed or expanded the foam's resistance changes thus resulting in a detected breach. The carbon nanotubes may be functionalized via covalent modification or non-covalent modification through the use of surfactants to aid in dispersing the carbon nanotube in resins used to encapsulate the card being secured.

In accordance with features of the invention, the carbon nanotube layer has a known resistance that is determined in the unstrained state prior to installation and a resistance change of the carbon nanotube layer is used to provide security protection. The amount of carbon nanotubes needed to form the carbon nanotube layer for a particular application easily can be determined by one skilled in the art. The carbon nanotube layer also acts as a functional filler to strengthen the polymeric encapsulation layer.

Referring toFIG. 2, there are shown example steps for implementing a method and circuit for security protection for cryptographic applications using the carbon nanotube based sensor in accordance with a preferred embodiment generally designated by the reference character200. As indicated at an initial step202, a carbon nanotube layer is encapsulated into the polymeric security card encapsulation layer without shorting out the security card. The carbon nanotube layer can be formed, for example, using the example process ofFIG. 1, and various techniques from generally inexpensive film formation to various more expensive templating techniques.

As indicated at a block204, a measured resistance of the carbon nanotube sensor is compared with an unstrained resistance of the sensor.

In accordance with features of the invention, the carbon nanotube layer has a known resistance that is determined in the unstrained state prior to installation. In an embodiment of the invention, a baseline resistance for the carbon nanotube layer in the unstrained state is determined the first time the security card is powered up. When strained through compression or tension, the electrical resistance changes. This electrical change is monitored through a security protection function or algorithm that determines when a breach is occurring and erases and/or shuts down the security card, such as, a security daughter card and/or an associated primary card.

In accordance with features of the invention, the resistance change of the carbon nanotube layer also monitors temperature based upon the change in electrical conductivity of the carbon nanotube layer. When compressed, pulled, gouged, scraped, frozen, or heated the security protection function or algorithm processes the resulting change in electrical resistance of the carbon nanotube layer and determine whether to erase all data and/or shut down power to one or both boards.

As indicated at a block206, a breach is identified by a predefined resistance change of the carbon nanotube sensor. As indicated at a block208, responsive to the identified breach, the security card is shut down which optionally includes erasing all data. This then renders the card unusable.

It should be understood that various techniques and processes can be used to prepare the carbon nanotube based sensors of the invention, and various security protection functions or algorithms can be used in a circuit for implementing security protection for cryptographic applications in accordance with the invention.

Referring toFIG. 3, there is shown an example circuit in accordance withFIGS. 1 and 2generally designated by the reference character300for implementing security protection for cryptographic applications in accordance with the preferred embodiment.

Circuit300includes a polymeric resin generally designated by the reference character302, which can be implemented by generally any polymer. As shown, the polymeric resin302contains a carbon nanotube layer304. The polymeric resin302is used to encapsulate a security card generally designated by the reference character306. Circuit300includes a plurality of cables or other suitable electrical connections308electrically connecting to the carbon nanotube layer304and the security card306for monitoring the electrical resistance of the carbon nanotube layer304and, various electrical connections, for example, electrically connecting security card306to another security card, such as a primary security card (not shown). The security card306includes an available power source, such as a battery and/or a capacitor connected to the carbon nanotube layer304for operation when the security card306otherwise is powered off.

An operational state of the carbon nanotube layer304is identified by monitoring the electrical resistance of the carbon nanotube layer304, for example, as illustrated and described with respect toFIGS. 4A and 4B.

Referring toFIGS. 4A, and4B, there are shown a respective example carbon nanotube sensor and sensor operation respectively generally designated by the reference characters410,420inFIG. 4A, and respectively generally designated by the reference characters430,440inFIG. 4Bfor implementing security protection in accordance with the preferred embodiment.

As shown inFIG. 4A, the carbon nanotube sensor304is shown in a normal operation state410and the sensor operation chart420includes a zero strain level (%) shown with the horizontal axis, and a zero stress level (%) and a resistance change level (%) shown with respect to a respective vertical axis.

As shown inFIG. 4B, the carbon nanotube sensor304is shown in a breached operation state430indicated by an arrow labeled FORCE, and the sensor operation chart440illustrates an increasing strain level (%) shown with the horizontal axis, and an increasing stress level (%) and an increasing resistance change level (%) shown with respect to a respective vertical axis.

FIG. 5is a flow diagram of a design process used in semiconductor design, manufacturing, and/or test.FIG. 5shows a block diagram of an example design flow500. Design flow500may vary depending on the type of IC being designed. For example, a design flow500for building an application specific IC (ASIC) may differ from a design flow500for designing a standard component. Design structure502is preferably an input to a design process504and may come from an IP provider, a core developer, or other design company or may be generated by the operator of the design flow, or from other sources. Design structure502comprises circuit300in the form of schematics or HDL, a hardware-description language, for example, Verilog, VHDL, C, and the like. Design structure502may be contained on one or more machine readable medium. For example, design structure502may be a text file or a graphical representation of circuit300. Design process504preferably synthesizes, or translates, circuit100into a netlist506, where netlist506is, for example, a list of wires, transistors, logic gates, control circuits, I/O, models, etc. that describes the connections to other elements and circuits in an integrated circuit design and recorded on at least one of machine readable medium. This may be an iterative process in which netlist506is resynthesized one or more times depending on design specifications and parameters for the circuit.

Design process504may include using a variety of inputs; for example, inputs from library elements504which may house a set of commonly used elements, circuits, and devices, including models, layouts, and symbolic representations, for a given manufacturing technology, such as different technology nodes, 42 nm, 45 nm, 90 nm, and the like, design specifications510, characterization data512, verification data515, design rules516, and test data files518, which may include test patterns and other testing information. Design process504may further include, for example, standard circuit design processes such as timing analysis, verification, design rule checking, place and route operations, and the like. One of ordinary skill in the art of integrated circuit design can appreciate the extent of possible electronic design automation tools and applications used in design process504without deviating from the scope and spirit of the invention. The design structure of the invention is not limited to any specific design flow.

Design process504preferably translates embodiments of the invention as shown inFIGS. 1,2,3,4A and4B, along with any additional integrated circuit design or data (if applicable), into a second design structure520. Design structure520resides on a storage medium in a data format used for the exchange of layout data of integrated circuits, for example, information stored in a GDSII (GDS2), GL1, OASIS, or any other suitable format for storing such design structures. Design structure520may comprise information such as, for example, test data files, design content files, manufacturing data, layout parameters, wires, levels of metal, vias, shapes, data for routing through the manufacturing line, and any other data required by a semiconductor manufacturer to produce an embodiment of the invention as shown inFIGS. 1,2,3,4A and4B. Design structure520may then proceed to a stage522where, for example, design structure520proceeds to tape-out, is released to manufacturing, is released to a mask house, is sent to another design house, is sent back to the customer, and the like.