Abstract:
A system and method of operating a device to securely update the control firmware controlling the device. Downloading a firmware update package to a first microcontroller of the device. Determining a firmware update portion and an encrypted hash portion of the firmware update package wherein the encrypted hash portion is cryptographically signed by a signatory. Confirm that the encrypted hash portion conforms to the firmware update by independently computing the hash of the encrypted firmware update portion on the first microcontroller and comparing that value to the signed hash. Other systems and methods are disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to the following patent applications co-filed herewith: 
         [0000]    &lt;&lt;List of the other six applications to be added by amendment&gt;&gt; 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates generally to secure USB flash memory devices and more particularly to USB flash memory devices having both a microcontroller and a smart card. 
         [0003]    With the small physical size of computer memories having large address spaces, it has become possible to store relatively large quantities of data on small portable memory devices. This portability has made it possible for users to literally carry their important data in their pocket either for the purpose of sharing the data with other individuals or to have information available without carrying bulkier and less portable forms of data storage. 
         [0004]    USB flash drives are one example of such small portable devices that are becoming a very popular mechanism for storing computerized information and for physically moving the stored information from one computer to another. There are many popular uses; some common uses include personal data transport and data transfer. 
         [0005]    With the portability of data storage devices come security risks. There have been several highly publicized cases of private data being lost from misplaced or stolen laptop computers. Similar risks arise with the use of USB flash drives: being small, they are easily misplaced, often they are carried in a user&#39;s pocket and can then, like other small items carried in that fashion, inadvertently fall out of the pocket undetected. In the event of loss of the device, if the owner of the device has stored sensitive private information on it, that person would be more comfortable knowing that the private data could not be accessed without authorization, e.g., without being authenticated as the owner of the device. 
         [0006]    There is also a growing culture of using USB flash drives to move data to computers belonging to persons other than the owner of the USB flash drive. In that scenario the owner of the USB flash drive provides the USB flash drive to another person for connection to that persons computer via a USB port either for the purpose of receiving data files from the owner of the computer or vice versa. However, because the owner of the USB flash drive does not typically have control of the computer, the USB flash drive owner is subjected to having data moved, intentionally or unintentionally, from the USB flash drive to the computer to which it is being attached, or viewed by the owner of the computer. Furthermore, the owner of the computer could, again either with intent or inadvertently, cause information stored on the USB flash drive to be deleted or corrupted. 
         [0007]    Thus it is desirable to avoid the threat of being subjected to some form of attack from the computer to which the drive is attached. 
         [0008]    Encryption technology is available on many computers. Thus, one way to avoid some of the aforementioned problems is to use the encryption processing capabilities to encrypt and decrypt files stored on the USB flash memory device. While that solution may work to solve specific needs of particular users, it is not a good general solution to the data security problems that arise with USB flash memory devices. One problem is that multiple encryption standards exist. Thus, the encryption technology used to encrypt a file on one computer may not be available when the same file is to be decrypted on another computer. A more severe issue is that often a user would store the encryption key on the computer with which the USB flash memory device is most often used. Thus, the likelihood that the computer and USB flash memory device are lost together or stolen together is high and consequently a hacker may be able to find the encryption key for the USB flash memory device somewhere on the computer. 
         [0009]    To address the above-mentioned concerns, several manufacturers, including, Lexar Media, Inc. of Fremont, Calif. and Kingston Technology Company, Inc. of Fountain Valley, Calif., have introduced USB flash memory devices that provide encryption of a data zone having private data. The encryption and decryption is performed by the USB flash memory microcontroller and the encryption key is stored inside the microcontroller. While this solution provides a higher level of security than USB flash memory devices that have no security features and also improves security with respect to using a host computer for encryption and decryption, it is a solution that is vulnerable to certain attacks. For example, denial of service attacks may be launched against files in the private data zone by deleting files from that area of the device. As discovered by the smart card industry, hackers have developed many clever techniques for deducing the activity inside a microcontroller, for example, examining power consumption patterns, and can use those techniques for determining encryption keys. 
         [0010]    From the foregoing it will be apparent that there is still a need for a USB flash memory device that provides yet a higher level of data security to protect data stored on thereon. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a block diagram illustrating a use scenario of a USB flash memory device. 
           [0012]      FIG. 2  is a block diagram illustrating a high-level view of the architecture of a prior art USB flash memory device having a USB flash memory microcontroller and a NAND memory storage area. 
           [0013]      FIG. 3  is a block diagram illustrating a high-level view of the architecture of a USB flash drive incorporating a smart card circuit operating in cooperation with a USB microcontroller. 
           [0014]      FIG. 4  is a block diagram illustrating an exemplary layout of the addressable space of the memory of the flash memory of the USB flash drive of  FIG. 3 . 
           [0015]      FIG. 5  is a block diagram illustrating a high-level view of the architecture of a smart card module of  FIG. 3 . 
           [0016]      FIG. 6  is a schematic illustrating of a computer network and illustrates the participants in a firmware update for a USB flash drive of  FIG. 3 . 
           [0017]      FIG. 7  is a timing sequence diagram illustrating the interaction between the various entities of  FIG. 6  to ensure that only a valid and certified firmware update is installed. 
           [0018]      FIG. 8  which is a block diagram illustrating the components of the firmware update package 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    In the following detailed description, reference is made to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that the various embodiments of the invention, although different, are not necessarily mutually exclusive. For example, a particular feature, structure, or characteristic described herein in connection with one embodiment may be implemented within other embodiments without departing from the spirit and scope of the invention. In addition, it is to be understood that the location or arrangement of individual elements within each disclosed embodiment may be modified without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, appropriately interpreted, along with the full range of equivalents to which the claims are entitled. In the drawings, like numerals refer to the same or similar functionality throughout the several views. 
         [0020]    In an embodiment of the invention, a USB flash drive having a smart card module operating in conjunction with the USB flash drive microcontroller provides an hitherto unavailable level of security. Furthermore, a USB flash drive having a smart card as described herein provides for a secure mechanism to confirm that any firmware updates to the USB flash drive have been independently verified in terms of integrity and authenticity. 
         [0021]      FIG. 1  is a schematic diagram illustrating a typical use of a USB flash drive  101 . A user  111  operates a computer  103 . On that computer the user  111  has stored certain files (not shown). It is often the case that a computer user  111  needs to access these same files at other locations. For example, a user  111  may need to access a file, which was created on a work computer, using his home computer  103 . One way to transfer the file would be via a computer network or by sending the file via electronic mail. However, that may not always be practical. 
         [0022]    An alternative is to physically move a copy of the file on a storage medium. USB flash drives  101  is one such storage medium. In the example of  FIG. 1 , a USB flash drive  101   a  having a USB connector  105  is inserted into a USB port of the user&#39;s computer  103   a . The USB flash drive  101   a  then enumerates on the user&#39;s computer  103   a   1 .  1 Herein, letter suffixes are used in conjunction with reference numerals to designate specific instantiations of a class of objects having common generic features. The class is referred to using numerals only. Thus,  103   a  is a specific computer  103 . Any reference to a device solely by a numerical reference is meant to apply equally to all members of the class unless the context prohibits such an interpretation. 
         [0023]    USB enumeration process includes performing a reset operation of a USB flash drive  101  and the USB flash drive  101  is assigned a unique identifier. In the case of a USB mass storage device, like a USB flash drive  101 , a drive letter is assigned to the USB flash drive  101  so that a user  111  can access the USB flash drive  101  from his computer. Thus, at the conclusion of the enumeration process the USB flash drive  101  has been assigned a drive letter, e.g., “H:” or “K:”, by which the USB flash drive  101  is uniquely identified in the computer&#39;s operating system. 
         [0024]    After the user  111  has inserted the USB flash drive  101   a  into the computer  103   a  and the USB flash drive  101   a  has enumerated, the user  111  can copy files from the computer  103   a  to the USB flash drive  101   a . At this point, the files have become physically portable and the user  111  can move the files to another computer  103   b  by inserting the USB flash drive  101   a  into a USB port of that computer  103   b . The user  111  can now read the file using the file browser or application programs on that computer  103   b.    
         [0025]    Of course, as with other storage drives on a computer, a USB flash drive  101  may be used to create, read, delete and otherwise manipulate files as permitted by the operating system and application programs running on the computers to which it is connected  103 . 
         [0026]      FIG. 2  is a high-level block diagram illustrating the basic components of a prior art USB flash drive  101 . A USB flash drive  101  typically has a hard shell housing  201 , e.g., plastic or aluminum, to contain and protect the internal components of the USB flash drive  101 . At one end, the USB flash drive  101  has a connector for connecting the USB flash drive  101  to a host computer  103  and to provide a communications interface to the host computer  103  to which it is connected. 
         [0027]    A prior art USB flash drive  101  further contains a USB mass storage controller  203 . Flash memories are block-oriented and are subject to wear (a limit on the number of read-write cycles that a flash memory can handle). The USB mass storage controller  203  implements a USB host controller and provides a linear interface to block-oriented serial flash devices while hiding the complexities of block-orientation, block erasure, and wear leveling, or wear balancing. The controller contains a small RISC microprocessor  205  and a small amount of on-chip ROM  207  and RAM  209 . 
         [0028]    A USB flash drive  101  further contains a flash memory chip  211 , typically a NAND flash memory chip, for storing data, e.g., computer files. 
         [0029]    A USB flash drive  101  further contains a crystal oscillator for producing a clock signal, and may contain LEDs, write protect switches, and a myriad of non-electrical components for aesthetic or portability purposes. These are not important to the present discussion. 
         [0030]    As discussed hereinabove, the mainstream prior art USB flash drive  101  is extremely vulnerable to security threats. These devices provide no defense against the risk that the data stored thereon would come into the wrong hands if the device is stolen or lost. Furthermore, when inserted into a stranger&#39;s computer  103 , the data on a USB flash drive  101  may be either inadvertently or intentionally copied to that computer  103  or be deleted from the USB flash drive  101 . 
         [0031]    As further discussed hereinabove, there are prior art approaches to provide a certain level of security through the use of encryption services provided directly on the microcontroller  205 . An alternative, that provides yet higher security, using a smart card module for providing certain security features is presented here. 
         [0032]      FIG. 3  is a block diagram illustrating a high-level view of the architecture of a USB flash drive  101  incorporating a smart card module for providing security functionality, e.g., authentication and cryptographic services, to enhance the security of data stored on the USB flash drive  101  (referred to hereinafter as a USB flash drive SC). 
         [0033]    As with the prior art USB flash drive  101 , a USB flash drive SC  301  is constructed with a USB connector  105  at one end, and has a USB flash drive microcontroller  303  having a microprocessor  305 , a ROM  307 , and a RAM  309 , as well as a flash memory chip  311 . Additionally the USB flash drive SC  301  contains a smart card module  313  connected to the USB flash drive microcontroller  303 . 
         [0034]    In one embodiment, the smart card module  313  is used by the USB flash drive SC  301  to authenticate a user and to provide certain cryptographic capabilities. Thus, for example, when the USB flash drive SC  301  is inserted into a computer  103 , a logon screen may be presented to the user  111  requesting the user  111  to authenticate himself using a PIN or password. Authentication is then entirely a negotiation between the host computer  103  and the smart card module  313  with only the result presented to the USB flash drive microcontroller  303 . 
         [0035]    In one embodiment, the communication between the host the computer  103   
         [0000]    and the USB flash drive SC  301  is performed using the USB mass storage protocol and the USB CCID (Chip Card Interface Device) protocol. 
         [0036]    Operations of the USB flash drive microcontroller  303  are according to instructions stored in a firmware control program  315  stored in the flash memory  311 . The firmware control program  315  contains start-up instructions executed on initialization of the USB flash drive SC  301 . Several of the start-up procedures are discussed in greater detail hereinbelow. 
         [0037]    As discussed hereinabove, USB enumeration is one function performed during startup. The USB flash drive SC  301  enumerates itself as a plurality of a USB mass storage drives and as a smart card interface device (akin to a USB smart card reader) to allow for communication using the CCID protocol. The firmware control program  315  contains the necessary instructions to act as a CCID device when the host computer  103  directs communication to the smart card module  313 . 
         [0038]      FIG. 4  is a block diagram illustrating an exemplary layout of the addressable space of the memory of the flash memory  311 . In one embodiment, the addressable space of the flash memory is partitioned into three partitions: a read only partition  401 , a private data partition  403 , and a public data partition  405 . 
         [0039]    The read only partition  401  contains the control program firmware  315  and a CCID module  407  for managing interaction with the host computer  103  over the CCID protocol. In alternative implementations, the communication with the smart card module  313  is carried over the USB Human Interface Device (HID) protocol, or any other suitable communications protocol. For such alternatives, the CCID module  407  would be replaced with communications modules appropriate for such protocols allowing the USB flash drive SC  301  to enumerate as such a device, e.g., as an HID device. 
         [0040]    The read only partition  401  also contains a host computer application program, the unlock application  409 . The unlock application  409  may be an autorun application that automatically launches on the host computer  103  or may appear as a launchable application when the read only partition  401  is browsed to using the host computer  103  operating system. 
         [0041]    The unlock application  409  may be used by a user  111  to perform several tasks associated with managing the USB flash drive SC  301 . The unlock application  409  may, for example, be used by the user  111  to authenticate to the USB flash drive SC  301 . 
         [0042]    The USB flash drive SC  301  enumerates as three USB mass storage partitions, one corresponding to the read only partition  401 , one as the private partition  403  and one as the public partition  405 . 
         [0043]    Upon initialization of the USB flash drive SC  301 , the private partition  403  enumerates as a drive without media, i.e., a user  111  would be able to see a drive letter designated for the drive, however, it would appear as an empty disk drive. 
         [0044]    Through the unlock application  409  the user  111  may unlock the private partition  403  to have access to files stored therein. In one embodiment, data in the private partition  403  is encrypted using an AES key (e.g., a 256 bit key). The AES key is stored in the smart card module  313 . When the user  111  has authenticated using the unlock application  409  the smart card module  313  encrypts the AES key in a manner in which the USB flash drive microcontroller  303  can decrypt. The USB flash drive microcontroller  303  then uses the decrypted AES key to decrypt information stored in the private drive. The USB flash drive microcontroller  303  stores the AES key only temporarily. Thus, when the USB flash drive SC  301  is removed from the host computer  103  the AES key is only stored in the smart card module  313 . 
         [0045]      FIG. 5  is a block diagram illustrating a high-level view of the architecture of a smart card module  313  used in the USB flash drive SC  301 . The smart card module  313  contains a central processing unit  501 , a RAM  503 , and a non-volatile memory  505 . These components are connected via a bus  507 . Also connected to the bus  507  is a communications interface  509  for providing a connection between the bus  507 , and consequently, the CPU  501 , RAM  503 , and non-volatile memory  505 , and the USB flash drive microcontroller  303 . 
         [0046]    In one embodiment communication between the USB flash drive microcontroller  303  and the smart card module  313  is over the ISO-7816 APDU protocol. Several special instructions are added to facilitate particular interactions required for coordinating the operations of the smart card module  313  and the USB flash drive microcontroller  303 . 
         [0047]    An important feature of smart cards is their resistance to attacks to discern the information stored therein. Smart cards employ various techniques to avoid attempts at unauthorized access thereto. Furthermore, When microprocessor-based smart cards are used for strong authentication, they offer several advantages, including data storage capacity, processing power, portability and ease-of-use. Smart card-based solutions are inherently more secure than other types of security tokens because they can be used to create a unique, non-reusable password for each authentication event, store personal data, and they do not transmit personal or private data over the network. When used for PKI applications, the smart card device provides core PKI services, including encryption, digital signature and private key generation and storage. 
         [0048]    It is often desirable to improve the functionality of a firmware-controlled device by allowing for updates to the firmware. In the context of the USB flash drive SC  301  firmware updates could be called for to add new functionality, to maintain compatibility with host computer  103  operating system changes, to provide compatibility with new operating systems, to correct bugs, or even security holes unknown at the time of initial deployment. 
         [0049]    On initial start up, the USB flash drive SC  301  boots up using a ROM based firmware stored in the ROM of the USB flash drive microcontroller  303 . From there, the firmware  315  is bootstrapped into the RAM  309  thereby overriding firmware instructions permanently stored in the ROM  307 . 
         [0050]    In prior art USB flash drives  101 , firmware updates do not present a security issue because no data security is provided for in such USB flash drives  101 . However, in the case of USB flash drive SC  301 , to ensure the benefits described above of using a smart card module  313 , in one embodiment, the security of the USB flash drive SC  301  is further ensured by protecting the integrity and authenticity of the firmware  315  so that a malicious third party does not cause the installation of a firmware  315  that circumvents or bypasses the security features provided by the smart card module  313 . 
         [0051]      FIG. 6  is a schematic illustrating of a computer network and illustrates the participants in a firmware update for a USB flash drive SC  301 . A firmware update  315 ′ is created by an Entity A  601 . Typically the entity A  601  is a manufacturer of the USB flash drive microcontroller  303 . Only in rare circumstances would a third party update the firmware  315 . The firmware update  315 ′ may be stored on a server computer  603 . The Entity A  601  then transmits, for example, via a network  603  over email or ftp (file transfer protocol), the firmware update  315 ′ to an Entity B  605  that has authority to validate a firmware update  315 ′. Only if validated by the authorized entity, i.e., in this example, by Entity B  605  does the smart card module  313  allow the firmware update  315 ′ to be installed. The Entity B  605  creates a validated firmware update  315 ″ and makes it available for download by the user  111  operating the USB flash drive SC  301  on an host computer  103 . 
         [0052]    There are various mechanisms by which a user  111  may become aware of the availability of a firmware update  315 ′. For example, if connected to the network  603 , the firmware  315  itself may poll Entity B  605  to determine availability of a firmware update  315 ″. 
         [0053]      FIG. 7  is a timing sequence diagram illustrating the interaction between the various entities of  FIG. 6  to ensure that only a valid and certified firmware update  315 ″ is installed. 
         [0054]    The Entity A  601  creates a firmware update  315 ′, step  701 , and encrypts the firmware update  315 ′ using a static key L, e.g., an AES key, step  703 . The encrypted firmware is transmitted to the validating authority, Entity B  605 , step  705 . 
         [0055]    To ensure that the firmware update  315 ′ is not manipulated after it has validated the firmware update  315 ′, the validating authority Entity B  605  computes a cryptographic hash, hash, over the code of the firmware update  315 ′ using a pre-agreed-upon algorithm, e.g., SHA-1, SHA-2, or MD5, step  709 . Such hashing algorithms are wellknown and have as a common characteristic in that it is nearly impossible to make any changes to the input without altering the computed hash value. Thus, a third party or Entity A  601  would not be able to make any changes to the firmware update  315 ′ without affecting the hash value. In other words, hash=hashfunction ({FW} L }) where FW is the firmware code and L is the symmetric key of Entity A  605 . L is not known to Entity B, 
         [0056]    Next the Entity B  605  cryptographically signs the hash value, [hash] KB , step  711 . The Entity B  605  cryptographically signs the hash value by decrypting the hash using its private key KB. The signed hash value [hash] KB  is then appended to the firmware update  315 ′ producing a firmware update package  315 ″ illustrated in  FIG. 8  which is a block diagram illustrating the components of the firmware update package  315 ″, step  713 . The firmware update package  315 ″ consists of the encrypted firmware update  315 ′ and the signed hash of the encrypted firmware update  315 ′. 
         [0057]    In one embodiment of firmware update discussed herein, the Entity B  605  signs the hash value using an asymmetric cryptography algorithm such as RSA. In that embodiment the Entity B  605  signs the hash using the private key of Entity B  605 . The corresponding private key is securely stored in the smart card module  313  and only known to the smart card module  313 . 
         [0058]    The firmware update package  315 ″ is next published to allow end-users of the USB flash drive SC  301  to download and install the firmware update package  315 ″. Prior to being able to install the firmware update package  315 ″, the user  111  should be authenticated to the smart card module  313 , step  707 . To further enhance the authentication, the authentication could be made mutual so that the user can be certain that smart card module  313  has not been compromised, e.g., clandestinely replaced with an impostor smart card module that always provides an authentication verification, i.e., a so-called yes machine. The authentication status is transmitted to the USB flash drive microcontroller  303 , step  708 . If the authentication status is OK, step  710 , the download and install procedure may continue; otherwise, the process terminates with an error message, step  712 . 
         [0059]    To further enhance the security of the download and install of the firmware operation, a secure communication channel is established between the USB flash drive microcontroller  303  and the smart card module  313 . This secure communication channel also ensures that the smart card module  313  has not been replaced with a yes machine and that snooping on the communication path between the smart card module  313  and the USB flash drive microcontroller  303  does not provide a mechanism for illicit appropriation of the firmware update  315 ′ or other information exchanged between the USB flash drive microcontroller  303  and the smart card module  313 . 
         [0060]    The firmware update package  315 ″ is downloaded to the USB flash drive SC  301 , in particular to the USB flash drive microcontroller  303 , step  715 . The location of the encrypted and signed hash value is known. For example, a SHA-1 message digest (hash) is 160 bits long. With padding, it may be preordained that the last 256 bits of the firmware update package  315 ″ contains the signed encrypted hash. 
         [0061]    The transmission step  715  may be initiated from the host computer  103  using, for example, the unlock application  409 . 
         [0062]    The USB flash drive microcontroller  303 , having received the firmware update package  315 ″, partitions the firmware update package  315 ″ into the encrypted firmware update  315 ′ {FW} L  and the signature, namely, the signed hash of the encrypted firmware update  315 ′, hash S , step  717 . flash driveflash driveTo verify that the version of the firmware update  315 ′ that has been validated by the Entity B  605 , it is possible to re-compute the hash over the encrypted firmware update  315 ′ and ask the smart card module  313  to confirm that the recomputed hash value corresponds to the signed hash value, hash S . Accordingly, the USB flash drive microcontroller  303  independently computes the hash value over the encrypted firmware update  315 ′, hash′, step  719 , and transmits both the signed hash value, hash S , and the by-the USB flash drive microcontroller  303  computed hash value, hash′, to the smart card module  313  as a request to validate the firmware update  315 ′, step  721 . 
         [0063]    Normally all commands for the smart card module  313  that are received by the USB flash drive microcontroller  303  from the host computer  103  are passed directly (after appropriate stripping of headers on the carrying protocol frames) to the smart card module  313 . However, certain commands that are only relevant to the interaction of the USB flash drive microcontroller  303  and smart card module  313  are not permitted to be issued by the host computer  103  (or any upstream network devices). The command to request validation of the firmware update  315 ′ is one such command that may only be sent by the USB flash drive microcontroller  303 . Thus, if another entity, notably the host computer  103 , attempts to transmit the request validation command to the smart card module  313  the USB flash drive microcontroller  303  traps that instruction and does not permit the instruction to be transmitted to the smart card module  313 . 
         [0064]    Having received the request to validate firmware update  315 ′ instruction, the smart card module  313  encrypts the signed hash, {hash S }, and thereby recovers the hash value computed by Entity B  605  in step  711 , step  723 . 
         [0065]    The smart card module  313  compares the two hash values, the hash value computed by Entity B  605 , hash, and the hash value computed by the USB flash drive microcontroller  303 , hash′. If the hash values hash and hash′ are equal, step  725 , the smart card module  313  has confirmed integrity and authenticity of the firmware update  315 ′, in which case the smart card module  313  sends an “OK” acknowledgement to the USB flash drive microcontroller  303 , step  727 . Otherwise, the smart card module  313  indicates its disapproval of the firmware update package  315 ″ by responding with a “NOK” message, step  729 . 
         [0066]    If the USB flash drive microcontroller  303  receives an “OK” from the smart card module  313 , the USB flash drive microcontroller  303  installs the firmware update  315 ′ by overwriting the firmware module  315  in the flash memory  311 , otherwise, the USB flash drive microcontroller  303  informs the host computer  103  that the firmware update package  315 ″ was rejected. 
         [0067]    It should be noted that while the description of the process of  FIG. 7  is described herein as actions taken by certain entities involved, e.g., the USB flash drive microcontroller  303  and the smart card module  313 , in one embodiment, these actions are performed by the USB flash drive microcontroller  303  and smart card module  313  under direction of control software. Thus, the operations of the USB flash drive microcontroller  303  are directed by instructions in the firmware  315  to perform the aforementioned tasks carried out by the USB flash drive microcontroller  303 . Similarly, the actions of the smart card module  313  described hereinabove are carried out in response to instructions in the control software for the smart card module  313  typically stored in the non-volatile memory  505  of the smart card module  313 . 
         [0068]    Although specific embodiments of the invention have been described and illustrated, the invention is not to be limited to the specific forms or arrangements of parts so described and illustrated. The invention is limited only by the claims.