Patent Publication Number: US-2010111294-A1

Title: Verification of movement of items

Description:
The present invention relates to processing, for example monitoring, verifying, securing, and so on, movement of items along a route, e.g. a supply chain, between different entities. The present invention also relates to apparatus for implementing such processing. The present invention relates in particular, but not exclusively, to securing or verifying a route of an RFID (radio frequency identification) tag attached to an item of interest. 
     Processes are known for verifying movement of an item between different entities. For example, there is a commercial and safety requirement for a supply chain of branded goods, in particular pharmaceutical products, to be verified to avoid counterfeit products being introduced into an authorized supply chain. 
     RFID tags are well known. RFID tags are circuits in the form of label-like items that can be read (and sometimes also written on) by reader (and writer) units communicating with the tags at RF frequencies. Further details of RFID tag technology can found in, for example, Landt, Jerry (2001), “Shrouds of Time: The history of RFID”, AIM, Inc. 
     It is known to attach RFID tags, written with batch or unique codes, to items, and to monitor received items for authenticity by reading the RFID tag attached thereto. Conventionally, read-out data is sent to remote parties for comparison with stored data of valid items. 
     It is known to establish an electronic pedigree (also called an e-pedigree). An e-pedigree provides a record of data such as arrival and departure times of specific items, e.g. during manufacture, shipping and so on. An entity in a supply chain or other route receiving an item can access e-pedigree to evaluate the item&#39;s authenticity. A proposed standardized e-pedigree approach using RFID technology is known as EPCglobal, further details of which van be found at, for example, www.epcglobalinc.org or from GS1 US, Princeton Pike Corporate Center, 1009 Lenox Drive, Suite 202, N.J. 08648 Lawrenceville. 
     EPCglobal has proposed an architecture where each tag is given a 96-bit unique code and where each entity in the supply chain can publish information about the product through a so-called EPC information service. An EPC information service is a database that provides a standardized query interface. To enable the end-to-end visibility of information across different entities, two approaches are suggested. One approach is to replicate or “push” fragments of e-pedigree information into a database operated by a trusted third party. Entities would use an EPC information service interface to this database to access and validate e-pedigree information. A second approach is to operate a so-called discovery service that references distributed EPC information services operated by individual supply chain participants. The entity would use the discovery service to identify the location of fragments of e-pedigree information and retrieve them from different EPC information services. 
     Referring to prior patent publications, Canadian application CA2556843 (“Assa Abloy”) is directed towards secure access systems. Specifically, a method and system is disclosed that is intended to allow a control panel of a secure access system to verify the authenticity and fidelity of a reader within the secure access system by utilizing a rolling code agreed upon by the reader and the control panel. 
     United States application US 2007/126578 (“Broussard”) relates to a method for applying at least one RFID product tag to each of a plurality of products and to a product-containing container. 
     International application WO 2006/057390 (“NEC”) relates to a distribution channel authenticating system intended to enable detection of counterfeiting and false alteration of distribution channel information by a false third party. 
     The present inventors have realized that approaches such as e-pedigree, and particularly when involving approaches such as use of a discovery service, exhibit a disadvantage that different entities in a route, e.g. a supply chain, are required to divulge information that may otherwise be confidential. Furthermore, the present inventors have realized that ongoing verification requires ongoing querying of remote centralised information resources, hence there is a potential for large levels of disruption of service when a centralised resource is unavailable. 
     In a first aspect the present invention provides a method of verifying a route taken during movement of an RFID tag between different entities of an authorized route; the method comprising: first verification apparatus associated with a first entity of the authorized route using a first private key to provide, for a given RFID tag identity, a first encrypted signature that is written to an RFID tag; second verification apparatus associated with a second entity of the authorized route using a public key to decrypt the encrypted signature from data read out from the RFID; and the second verification apparatus verifying whether the decrypted signature corresponds to an entity from which the second entity is authorized to receive a tag with the given RFID tag identity. 
     The method may further comprise the second verification apparatus, responsive to the verifying step determining that the decrypted signature does correspond to an entity from which the second entity is authorized to receive a tag with the given RFID tag identity, using a second private key to provide, for the given RFID tag identity, a second encrypted signature that is written to the RFID tag. 
     The method may further comprise the second verification apparatus reporting the outcome of the verifying step to one or more third parties. 
     One third party of the one or more third parties may be a controller apparatus from which the second verification apparatus received the public key. 
     One third party of the one or more third parties may be an electronic pedigree service. 
     The method may further comprise the second verification apparatus raising an alarm responsive to the verifying step determining that the decrypted signature does not correspond to an entity from which the second entity is authorized to receive an RFID tag with the given RFID tag identity. 
     The first and second verification apparatus may receive the keys from a controller apparatus. 
     The second verification apparatus may receive the public key from the first verification apparatus. 
     The first verification apparatus may receive the first private key from the second verification apparatus. 
     At least one of the first verification apparatus and the second verification apparatus may comprise a trusted platform module. 
     The method may further comprise the controller apparatus remotely attesting the first verification apparatus and/or the second verification apparatus. 
     In a further aspect, the present invention provides a method of setting up a system for verifying a route taken during movement of an RFID tag, the method comprising: a controller apparatus distributing public keys, private keys and entity-specific policies to a plurality of verification apparatus, each verification apparatus being associated with a respective entity of a plurality of entities of an authorized route for a given RFID tag identity; wherein a private key distributed to the verification apparatus associated with a first entity corresponds to a public key distributed to the verification apparatus associated with a second entity according to a policy distributed to the verification apparatus associated with the second entity, for the given RFID tag identity. 
     The controller apparatus may determine the entity-specific policies by deconstructing a specification of an authorized route comprising plural entities. 
     The controller apparatus may distribute the public keys, private keys and entity-specific policies to the plurality of verification apparatus via a plurality of temporary communication links. 
     At least one of the plurality of verification apparatus may comprise a trusted platform module. 
     One or more of the keys and policies may be distributed to a sealed storage in the verification apparatus. 
     In a further aspect, the present invention provides verification apparatus for use in verification of a route taken during movement of an RFID tag, the verification apparatus comprising: one or more stores for storing a private key, a public key, and a policy; and one or more processors arranged to: (i) receive, from an RFID tag reader, data read-out from the RFID tag and comprising an RFID tag identity and an encrypted signature; (ii) use the public key to decrypt the encrypted signature from the data read-out from the RFID tag; (iii) verify that the decrypted signature corresponds to a first entity from which, according to the policy, a second entity associated with the verification apparatus is authorized to receive an RFID tag with the given RFID tag identity; (iv) use the private key to provide, for the given RFID tag identity, a new encrypted signature; and (v) forward data comprising the new encrypted signature to an RFID tag writer for writing to the RFID tag. 
     The verification apparatus may further comprise the RFID tag reader and the RFID tag writer. 
     The one or more processors may be further arranged to report the verification to one or more third parties. 
     The verification apparatus may further comprise sealed storage, and at least one of the one or more stores may be provided in the sealed storage. 
     The verification apparatus may further comprise a trusted platform module. 
     In a further aspect, the present invention provides a system for verifying a route taken during movement of an RFID tag, the system comprising: a first verification apparatus according to any of the above described verification apparatus; and a second verification apparatus, the second verification apparatus comprising: a store for storing a private key; and one or more processors arranged to: (i) use the private key to provide, for the given RFID tag identity, an encrypted signature; and (ii) forward data comprising the encrypted signature to an RFID tag writer for writing to the RFID tag. 
     In a further aspect, the present invention provides a system for verifying a route taken during movement of an RFID tag, the system comprising: a first verification apparatus according to any of the above described verification apparatus; and a third verification apparatus, the third verification apparatus comprising: a store for storing a public key and a policy; and one or more processors arranged to: (i) receive, from an RFID tag reader, data read-out from the RFID tag and comprising the RFID tag identity and the encrypted signature; (ii) use the public key to decrypt the encrypted signature from the data read-out from the RFID tag; and (iii) verify that the decrypted signature corresponds to an entity from which, according to the policy, a third entity associated with the third verification apparatus is authorized to receive an RFID tag with the given RFID tag identity. 
     For the avoidance of confusion, it should be noted in relation to the systems set out in the previous two paragraphs that the first verification apparatus would in general be at a stage on the route downstream of the second verification apparatus and upstream of the third verification apparatus. 
     Thus aspects of the present invention provide a verification process or system which is relatively resilient and has low vulnerability to single point failure. Only a low level of information needs to be exchanged between adjacent entities in a supply chain. Moreover, no information needs to be shared between non-adjacent entities. The invention may be implemented using standard RFID tag technology. 
     Various other advantages provided by aspects of the invention are outlined in the following description of embodiments of the invention. 
    
    
     
       Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic illustration in block diagram form of a first embodiment of a supply chain verification system  1 ; 
         FIG. 2  is a schematic illustration in block diagram form showing a verification and re-sign unit, and a reader-writer, of the system of  FIG. 1 ; 
         FIG. 3  is a schematic representation of a tag memory  7  of an RFID tag  4 ; 
         FIG. 4  is a schematic representation of contents of a policy store of the verification and re-sign unit of  FIG. 2 ; 
         FIG. 5  is a flowchart showing process steps carried out by various elements of the supply chain verification system of  FIG. 1  in a set-up procedure; 
         FIG. 6  is a process flowchart showing process steps carried out in an embodiment of a supply chain verification process; 
         FIG. 7  is a process flowchart showing process steps which in combination provide one of the processing steps of the process of  FIG. 6 ; and 
         FIG. 8  is a schematic illustration in block diagram form showing a further verification and re-sign unit, and a reader-writer. 
     
    
    
       FIG. 1  is a schematic illustration in block diagram form of a first embodiment of a supply chain verification system  1 . In this embodiment, an authorized supply chain comprises three entities, namely a first entity, a second entity and a third entity. The first entity is authorized to pass a specific item  2  to the second entity. The second entity is authorized to receive the item  2  from the first entity. The second entity is also authorized to pass the item  2  to the third entity. The third entity is authorized to receive the item  2  from the second entity. The item  1  has a re-writable RFID tag  4  attached to it. 
     The supply chain verification system  1  of this embodiment comprises a supply chain controller  6 , and three verification and re-sign units, namely a first verification and re-sign unit  10 , a second verification and re-sign unit  20 , and a third verification and re-sign unit  30 . The first verification and re-sign unit  10  is located at, and controlled by, the first entity. The second verification and re-sign unit  20  is located at, and controlled by, the second entity. The third verification and re-sign unit  30  is located at, and controlled by, the third entity. 
     Each verification and re-sign unit  10 ,  20 ,  30  is coupled to a respective RFID reader-writer (i.e. a device that is able to read out the information on the RFID tag  2  and also rewrite new information to the RFID tag  2 ). In more detail, the first verification and re-sign unit  10  is coupled to a first RFID reader-writer  12 ; the second verification and re-sign unit  20  is coupled to a second RFID reader-writer  22 ; and the third verification and re-sign unit  30  is coupled to a third RFID reader-writer  32 . Each respective RFID reader-writer  12 ,  22 ,  32  is located at the entity where the respective verification and re-sign unit  10 ,  20 ,  30  is located. 
     The first verification and re-sign unit  10  is coupled to the supply chain controller  6  by a first communications link  14 . The second verification and re-sign unit  20  is coupled to the supply chain controller  6  by a second communications link  24 . The third verification and re-sign unit  30  is coupled to the supply chain controller  6  by a third communications link  34 . As will be explained in more detail below, the communications links  14 ,  24 ,  34  do not need to be continually available for typical ongoing operation of the system  1 . 
     As will be explained in more detail below, when the item  1  is passed down the supply chain from entity to entity, at each entity the RFID tag  4  attached to the item  2  is read and/or written by that entity&#39;s RFID reader-writer according to processing carried out by that entity&#39;s verification and re-sign unit  10 ,  20 ,  30 . The movement of the item  2  down the supply chain, and the processing of the item by the respective verification and re-sign unit&#39;s along the chain, is represented schematically in  FIG. 1  by the dotted line arrows and dotted line representations of the item  2  with RFID tag  4  positioned at the respective verification and re-sign units as it is passed physically down the supply chain. 
       FIG. 2  is a schematic illustration in block diagram form showing in more detail, by way of example, the second verification and re-sign unit  20  and the second reader-writer  22 . In this embodiment, each verification and re-sign unit  10 ,  20  and  30  is essentially the same, and hence the following description applies to the first and third units also. Hence, for convenience, in the following description of  FIG. 2 , the second verification and re-sign unit  20  and the second RFID reader-writer  22  are referred to more simply as verification and re-sign unit  20  and RFID reader-writer  22 . 
     The verification and re-sign unit  20  comprises conventional computing and processing hardware and software, including storage media arranged to provide functional modules, functional stores, and functional connections. 
     In more detail, the verification and re-sign unit  20  comprises a platform core module  40 , a verification module  42 , and a re-sign module  48 . The verification and re-sign unit  20  further comprises a public key store  50 , a policy store  52 , and a private key store  54 . 
     The above modules and stores are coupled as follows. The platform core module  40  is coupled to the verification module  42  and the re-sign module  48 . The verification module  42  is further coupled to the public key store  50 , to the policy store  52 , to the re-sign module  48 , and to the RFID reader-writer  22 . The re-sign module  48  is further coupled to the policy store  52 , to the private key store  54 , and to the RFID reader-writer  22 . The public key store  50 , the policy store  52  and the private key store  54  are each coupled via the communications link  24  to the supply chain controller  6  (as mentioned above, this coupling to the supply chain controller need not be continually available for typical ongoing operation of the system  1 ). 
       FIG. 2  also shows schematically data that is passed between the above described elements during operation of the verification and re-sign unit  20 , as follows. Read-out data  60  is passed from the RFID reader-writer  22  to the verification module  42 . A public key  64  is passed from the public key store  50  to the verification module  42 . A policy  62  is passed from the policy store  52  to the verification module  42 , and also to the re-sign module  48 . Verification outcome data  66  is passed from the verification module  42  to the re-sign module  48 . A private key  68  is passed from the private key store  54  to the re-sign module  48 . Write data  70  is passed form the re-sign module  48  to the RFID reader-writer  22 . 
     Further referring to  FIG. 2 , the RFID tag  4  of the item  2  comprises a tag memory  7 , which is explained in more detail below with reference to  FIG. 3 . 
       FIG. 3  is a schematic representation of the tag memory  7  of the RFID tag  4 . The tag memory comprises a tag identifier  8  and a signature  9 . In the example shown in  FIG. 3 , the tag identifier has value 0001234, and the signature  9  is shown represented as “E_s_previous_holder_key (ID)”. 
       FIG. 4  is a schematic representation of contents of the policy store  52 . A policy comprises various entries of values or instructions for different respective values of tag identifier  8 . In this example the entries are “public key”, “approved entity” and “private key”. In this example the policy store  52  stores the policy data in the form of a look-up table, which therefore in this example has the following columns: tag identifier column  90 , public key column  92 , approved entity column  94 , and private key column  96 . The public key column  92  and the private key column  96  comprise indications of appropriate key to be used, however the actual keys are stored in the separate public key store  50  and private key store  54  respectively. 
       FIG. 5  is a flowchart showing process steps carried out by various elements of the supply chain verification system  1  in a set-up procedure that may be employed with this embodiment. 
     At step s 2 , the supply chain controller  6  receives a supply chain specification. This may specify, for example, authorized supply routes in terms of tag identifier value of RFID tags, e.g. in ranges of values, and then details of which entities are authorized to pass these tags (and hence the items these tags are attached to) to which other different entities along a supply chain. 
     At step s 4 , the supply chain controller  6  generates keys, more particularly public keys  64  and private keys  68 . 
     At step s 6 , the supply chain controller  6  decomposes the supply chain specification into entity-specific policies, such as described above in relation to  FIG. 4 . 
     At step s 8 , a communications link is set up from the supply chain controller  6  to a first one of the entities in the supply chain. For ease of description, we will assume in this example the supply chain controller  6  first sets up the first communication link  14  to the first verification and re-sign unit  10  of the first entity, however in other examples this setting-up of the different communication links to the different entities (i.e. their verification and re-sign units) can be done in any order. 
     At step s 10  the supply chain controller  6  transmits the policies, and public and private keys, over the first communications link  14  to the first verification and re-sign unit  10 . 
     At step s 12 , the first verification and re-sign unit  10  receives the policies and keys. 
     At step s 14 , the first verification and re-sign unit  10  stores the received policies and keys i.e. stores the received policies in its policy store  52 , stores the received public keys in its public key store  50 , and stores the received private keys in its private key store  54 . 
     At step s 16 , the communications link  14  is removed, although in other examples the link may be retained for convenience. 
     At step s 18  the supply chain controller  6  determines whether all the verification and re-sign units of the present supply chain specification have been processed. In this example, they have not, so the process returns to step s 8 . 
     At step s 8 , a communications link is set up from the supply chain controller  6  to a next one of the entities in the supply chain; in this example the third communications link  34  is set up to the third verification and re-sign unit  30  (i.e. in this set-up process the “next” unit to be processed need not be the next one in the sense of the supply chain flow). Thereafter steps s 10  to s 16  as described above are accordingly repeated for the third verification and re-sign unit  30 , with policies and keys appropriate to this unit  30  being sent to it, and so on. 
     At step s 18  the supply chain controller  6  determines whether all the verification and re-sign units of the present supply chain specification have been processed. In this example, again, they have not, so the process returns to step s 8 . 
     At step s 8 , a communications link is set up from the supply chain controller  6  to a next one of the entities in the supply chain; i.e. the second communications link  24  is set up to the second verification and re-sign unit  20 . Thereafter steps s 10  to s 16  as described above are accordingly repeated for the second verification and re-sign unit  20 , with policies and keys appropriate to this unit  20  being sent to it, and so on. 
     This time at step s 18 , the supply chain controller  6  determines that all the verification and re-sign units of the present supply chain specification have been processed, and hence the set-up process is completed. 
     Operation of the supply chain verification system  1  according to an embodiment of a process of supply chain verification will now be described below with reference to  FIGS. 6 and 7 . This process assumes that a set-up process, for example such as that described above with reference to  FIG. 5 , has been performed. Any appropriate set-up process may have been employed. 
       FIG. 6  is a process flowchart showing process steps carried out in this embodiment of a supply chain verification process. This process will be described in terms of a verification and re-sign unit that is neither the first unit, nor the last unit, of the authorized supply chain of units in terms of the flow of the authorized chain. Thus in this example, the process will be described in terms of the second verification and re-sign unit  20 , at the second entity. 
     At step s 20 , the second verification and re-sign unit  20  of the authorized supply chain receives the item  2  which has previously been processed by the first verification and re-sign unit  10 . As described above, the RFID tag  4 , comprising the tag memory  7 , is attached to the item  2 . 
     At step s 22 , the second RFID reader-writer  22  reads out the information contained on the RFID tag  4 ; in more detail the second RFID reader-writer  22  reads out the information in the tag memory  7  thereby providing read-out data  60  as shown in  FIG. 2 . As explained above, the tag memory  7  comprises a tag identifier  8 , e.g. an identifying number, and a signature  9 . The signature is an encrypted signature provided by the previous verification and re-sign unit of the supply chain, i.e. the last unit that has processed the RFID tag  2 , which in this example was the first verification and re-sign unit  10  which previously processed the tag at the first entity. 
     At step s 24 , the second verification and re-sign unit  20  processes the read-out data  60 . This processing step verifies that the second verification and re-sign unit  20  is authorized to receive the specific identified tag from the first entity and further provides new write data  70  (shown in  FIG. 2 ) to be written in to the tag memory  7  of the RFID tag  4 . The new write data  70  comprises a new signature  9  which is an encrypted signature of the second verification and re-sign unit  20 . Further details of this processing step s 24  are described below with reference to  FIG. 7 . 
     At step s 26 , the second verification and re-sign unit  20  determines whether it is the last unit of the authorized supply chain. If it were the last unit of the supply chain, then the present process would be ended. In particular, assuming the result of verifying that the second verification and re-sign unit  20  is authorized to receive the specific identified tag from the first entity was positive, then this would be the final verification stage of the supply chain as a whole. Note, in this case, it would not be necessary to produce the new write data  70  mentioned above. Also, other optional actions could then be taken afterwards, if desired, as will be discussed later below. However, in this example the second verification and re-sign unit  20  is not the last unit of the authorized supply chain, hence the above mentioned write data  70  is produced and the process moves to step s 28 . 
     At step s 28 , the newly provided write data  70 , in particular the encrypted signature of the second verification and re-sign unit  20 , is written to the tag memory  7  of the RFID tag  4 ; in more detail the newly provided write data  70  is received by the second RFID reader-writer  22  which writes the data to the signature  9  field of the tag memory  7 . 
     At step s 30 , the item  2  with RFID tag  4  attached thereto is passed to the next verification and re-sign unit  20  of the authorized supply chain, i.e. the third verification and re-sign unit  30 . The process then in effect returns to step s 20 , where the next verification and re-sign unit, in this case the third verification and re-sign unit, receives the item  2  and then implements steps  22 - 30  as described above, until the unit in question fulfills the criteria at the decision stage of step s 26  of being the last unit in the supply chain (as indeed is the case for the third verification and re-sign unit  30  in this example). 
     Further details of the above mentioned processing step s 24  will now be described with reference to the process flowchart of  FIG. 7 , which shows process steps s 40 -s 64  providing in combination processing step s 24 . 
     At step s 40 , the second verification and re-sign unit  20 , more particularly the verification module  42 , receives the read-out data  60  from the second RFID reader-writer  22 . As described above, the read-out data contains the tag identifier  8  and the current encrypted signature  9 . 
     At step s 42 , the verification module  42  ascertains the identity of the tag from the tag identifier  8  information part of the read-out data  60 . 
     At step s 44 , the verification module  42  extracts, from the policy store  52 , the policy  62  that corresponds to ascertained tag identity. 
     At step s 46 , the verification module  42  ascertains from the extracted policy  62 , for example by interrogating or querying the extracted policy  62 , the identity of the public key that is to be used to decipher the current encrypted signature  9 . 
     At step s 48 , the verification module  42  extracts the identified public key  64  from the public key store  50 . 
     At step s 50 , the verification module  42  deciphers the encrypted signature  9  using the extracted public key  64 . 
     At step s 52 , the verification module  42  verifies that the deciphered signature corresponds to an entity (i.e. verification and re-sign unit) that the second entity (i.e. the second verification and re-sign unit  20 ) is authorized under the policy  62  to receive the specific identified RFID tag  4  from. This is performed, for example, by accessing the “approved entity” entry (as previously stored in column  94  of the policy store  52 ) of the extracted policy  62 . 
     When verification has been successful, at step s 54 , the verification module  42  forwards the verification outcome  66  (i.e. approval) and indication of the tag identity to the re-sign module  48 . 
     At step s 56 , the re-sign module  48  extracts, from the policy store  52 , the policy  62  that corresponds to ascertained tag identity. (Alternatively, the policy  62  can be forwarded by the verification module.) 
     At step s 58 , the re-sign module  48  ascertains from the extracted policy  62 , for example by interrogating or querying the extracted policy  62 , the identity of the private key that is to be used to encipher the new encrypted signature  9 . 
     At step s 60 , the re-sign module  48  extracts the identified private key  68  from the private key store  54 . 
     At step s 62 , the re-sign module  48  creates a new encrypted signature  9  corresponding to its own identity (i.e. the second verification and re-sign unit  20 ) and encrypted using the extracted private key  68 . 
     At step s 64 , the re-sign module  48  outputs or provides the new encrypted signature  9 , in this example by forwarding the new encrypted signature  9  in the form of write data  70  to the second RFID reader-writer  22 . 
     By virtue of the above described steps s 40 -s 64 , processing step s 24  of  FIG. 6  is implemented. 
     In the above description of the supply chain verification process of this embodiment, the description has concentrated primarily on operation of the second verification and re-sign unit  20  as this unit is neither the first unit, nor the last unit, of the authorized supply chain of units in terms of the flow of the authorized chain. Thus the second verification and re-sign unit  20  (and its associated second RFID reader-writer  22 ) carries out a first aspect of reading and verification to verify the previous “upstream” entity as well as a second aspect of writing of the new encrypted signature to provide data that can be verified by the next “downstream” entity. However, as mentioned in passing above, the verification and re-sign units at the start and the end of the supply chain do not need to implement both aspects, and hence need not comprise all the elements described above. In other words, the first verification and re-sign unit  10 , being at the entity that is at the start of the supply chain, does not need to carry out the first aspect of reading and verification, as there is no previous “upstream” entity to verify. Hence the first verification and re-sign unit  10  does not need to contain, for example, a verification module or a public key store. Furthermore, the verification and re-sign unit  10  can be used in conjunction with just a RFID writer rather than an RFID reader-writer. Similarly, the third verification and re-sign unit  30 , being at the entity that is at the end of the supply chain, does not need to carry out the second aspect writing and encrypting a new signature, as there is no next “upstream” entity to provide data to for verification. Hence the third verification and re-sign unit  30  does not need to contain, for example, a re-sign module or a private key store. Furthermore, the verification and re-sign unit  30  can be used in conjunction with just a RFID reader rather than an RFID reader-writer. In either case, it may nevertheless be convenient to use a unit that provides both functions, so that a common unit can be provided, and also as there may be occasions where any given entity lies at different positions within different authorized supply chains. 
     It should be noted that certain of the process steps depicted in the flowcharts of  FIGS. 5 ,  6  and  7  and described above may be omitted or such process steps may be performed in differing order to that presented above and shown in  FIGS. 5 ,  6  and  7 . Furthermore, although all the process steps have, for convenience and ease of understanding, been depicted as discrete temporally-sequential steps, nevertheless some of the process steps may in fact be performed simultaneously or at least overlapping to some extent temporally. 
     In this embodiment, the public and private key encrypting and deciphering, and form of the signature  9 , is implemented as per the well known RSA algorithm, further details of which may be found in R. Rivest, A. Shamir, L. Adleman, “A Method for Obtaining Digital Signatures and Public-Key Cryptosystems”, Communications of the ACM, Vol. 21 (2), pp. 120-126, 1978. However, in other embodiments, other public/private key algorithms or protocols can be used. 
     Thus a system and process is provided by virtue of which a downstream entity can verify that an item has arrived along an authorized upstream path. In the above first main embodiment, the process involves the receiving entity learning details of the previous upstream entity, including its identity. In a second main embodiment which will now be described, the downstream entity is still able to verify that an item has arrived along an authorized upstream path, however confidentiality aspects can be preserved since there are further restrictions in what additional information the receiving entity is able to learn. Also, this second main embodiment tends to prevent an authorized receiving entity from then maliciously introducing e.g. counterfeit items into the supply chain thereafter, for example by misusing one or more of the private keys issued to it. 
     In the second main embodiment, the supply chain verification system  1 , the set-up procedure and supply chain verification process are the same as those illustrated in  FIGS. 1-7  and described above for the first main embodiment except where stated otherwise below. 
     In the second main embodiment, the verification and re-sign units  10 ,  20 ,  30  are as shown in  FIG. 8 , and will again, for convenience, be described in terms of the second verification and re-sign unit  20 . The units are the same as those described above, and the same reference numerals are used to signify the same components, except that in this second main embodiment the public key store  50 , policy store  52 , and private key store  54  are located in a sealed storage  80  which is part of the earlier mentioned storage media. 
     According to the second main embodiment, the computing and processing hardware and software, including storage media (including a sealed storage  80 ) arranged to provide the above described functional modules, functional stores, and functional connections, of the verification and re-sign unit  20 , includes a Trusted Platform Module (TPM) chip. The TPM contains information required to permit the verification and re-sign unit  20  to perform the above described process of creating a new encrypted signature (i.e. to prove to the next entity downstream that the item, and its supply, is authentic). TPMs are tamper-resistant and encompass various different security functionalities. TPM chips are commercially available, and are currently used for example in personal computers. The verification and re-sign unit  20  may be built on top of a TPM-aware Linux (registered trademark) kernel, such as Enforcer (registered trademark) or on top of IBM Trusted Computing Linux (registered trademark). Software for supporting the TPM is available as open source release and hence may be readily accessed by the skilled person, or new software written as desired. 
     This second main embodiment uses two main functions of the TPM module: remote attestation and sealed storage, i.e. the sealed storage  80 . 
     Remote attestation allows a remote party to verify that the verification and re-sign unit  20  is running with a correct software stack. The remote attestation is implemented by instructing the TPM to generate a certificate stating what software is currently running on the verification and re-sign unit  20 . The verification and re-sign unit  20  can then present this certificate to a remote party to show that the software has not been modified. In this second main embodiment the supply chain controller  6  only sends policies and private keys to verification and re-sign units that run the correct re-signing software. The supply chain controller  6  can also perform random audit operations to ensure that the verification and re-sign unit  20  is operating correctly and has not been compromised. 
     The sealed storage  80  enables the protection of private information stored in the verification and re-sign unit  20 . The private information is encrypted using a key that is unique to the software and hardware being used. This means that the data can only be read by the same combination of software and hardware. For example, the policies and private keys sent from the supply chain controller  6  to the verification and re-sign unit  20  can only be accessed when the verification and re-sign unit  20  is using the correctly authorized software application. The TPM functionalities running on the verification and re-sign unit  20  prevent a malicious application locating the private key, reading it and sending to an unauthorized entity. In our case we assume that the verification and re-sign unit  20  is required to employ a specified configuration comprising a specific operating system and specified software that implements the verification module  42  and the re-sign module  48 . Then, if the configuration unexpectedly changes, for example if it has been compromised by an adversary (perhaps with the purpose of injecting counterfeited products into the supply chain), the TPM will deny access to the key and hence prevent the re-signing operation. 
     Further implementation details related to the TPM are as follows. A main feature of the platform core module  40  is the operating system. The operating system is required to interface with the TPM. Further well known elements, e.g. a BIOS (Basic Input/Output System) and a boot-loader, are configured to be TPM aware to ensure the integrity of the operating system. 
     In general, according to the second main embodiment the verification and re-sign unit  20  can effectively act as a secure proxy for the supply chain controller  6 . 
     As a further possibility when implementing the second embodiment, multiple entities, e.g. multiple service providers can use a given trusted verification and re-sign unit to perform their own supply chain validation checks. 
     Alternatively or additionally, a given chain entity dealing with several “upstream” entities may allow each upstream entity to install its own keys and policies onto the trusted verification and re-sign unit of the given entity. Thereafter, one or more of the upstream entities can remotely interrogate the attestation functionality of the TPM of the trusted verification and re-sign unit of the given entity. 
     Furthermore, a given supply chain entity dealing with several upstream entities may install its own keys and policies onto the trusted verification and re-sign unit of the upstream entity. In other words, a peer-wise trusted supply chain may be formed in either direction. 
     In the above described second main embodiment, the public key store, the policy store and the private key store are each located in the sealed storage  80 . In other versions of the second main embodiment other configurations are possible however. For example, in one configuration only the private key store is located in sealed storage. This can reduce the amount of sealed storage required but still ensures that at least the private key is secure. 
     In the above described embodiments, the various processes described above are implemented by modules configured as described. However, in other embodiments, the various functions can be provided in differing module arrangements, as required. 
     Furthermore, some or all of the functional modules described above may be implemented in distributed equipment, using directly connected connections or coupled via networks. However, it is preferred to locate the modules in specific apparatus as described above as this provides advantages such as reduced processing time, and in particular improved localized robustness and continuity of service, while retaining security and control. 
     In the above described embodiments, the separate processes of reading and writing the RFID tag are carried out by a single combined RFID reader-writer device. In other embodiments, instead of a combined reader-writer device, separate RFID reader and RFID writer devices may be used. 
     Also, in addition to the data read out and written as per the above described processes for the purpose of authorized route verification, the RFID reader-writer (whether a combined device or separate read and write devices) may also be used for additional, conventionally known, item movement and storage control functions. In such instances, the RFID tag memory will comprise additional fields as required. 
     A further possibility is that the RFID reader-writer may be integrated in the verification and re-sign unit. This would provide the possibility for further security to be provided to protect the integrity of the verification and re-sign process, particularly when applied to the above described second main embodiment. 
     In the above described embodiments the authorized supply chain is simple, comprising only three entities and further comprising only one authorized route between the three entities. However, the present invention may be applied to larger and/or more complicated supply routes between entities. For example, there may be more than three entities. Also, there may be more than one authorized route through a number of entities, i.e. a given entity may be authorized to receive a specific tag identity from more than one upstream entity, and/or there may be more than one downstream entity for which a given entity is authorized to forward a specific tag identity to. 
     Another possibility is that not every entity of e.g. a supply chain is required to carry out the above described verification and re-signing process, i.e. only specific entities may be required to carry out the processes. 
     In the above embodiments, the authorized supply route, and provision of the various policies and keys, is centrally controlled by the supply chain controller. However, in other embodiments, some or all of these functions can be implemented on a peer-to peer, i.e. entity-to-entity basis. For example, according to one possibility, entities which are authorized to pass an item between them (at least in one direction) are partnered. Exchange of key information takes place to allow the downstream partner to check that a received item has arrived from an expected upstream partner. Each supply chain partner acts as a local service provider to configure only the immediate upstream or downstream leg of the supply chain. The upstream partner creates the public-private key pair for use by the downstream partner in re-signing operations. According to a further possibility, the downstream party can provide the private key to the upstream party, although this approach suffers from the aspect that the re-signing operation must know the intended downstream path for the item (and hence which key to use). 
     In the above described embodiments relatively simple policies are employed, i.e. a policy comprises entries for different respective values of the tag identifier, the entries being public key, approved entity and private key. However, in other embodiments, the policy can contain more features. One general possibility is that the policy specifies additional actions to take place dependent upon the results of the deciphering and verifying steps. For example, a policy can stipulate that if a verification fails, an alarm should be raised, and/or information should automatically be sent to the supply chain controller and/or a separate third party, for example a conventional e-pedigree service. Also, a policy can stipulate, for example, that some or all instances of successful verification should be reported to the supply chain controller and/or a separate third party, for example a conventional e-pedigree service. 
     Furthermore, any of the above embodiments can be used in conjunction with, or instead of, a conventional e-pedigree process. 
     By way of example, a scenario in which the present invention may advantageously be implemented will now be described. A pharmaceutical company manufactures a specific drug that is tagged with RFID technology. The manufacturer wishes control the distribution of the drug from the point of production until the retailer (e.g. hospital, pharmacy, local GP, etc.). A goal of the manufacturer is to ensure that the drug is only handled by authorized parties. If any unauthorized party intercepts the supply chain, or if any authorized supplier acts maliciously or even in error, the drugs may be directed towards unauthorized parties. If this happens, then by virtue of implementation of the present invention, the drug will be ultimately be detected as unauthorized. 
     Further advantages that tend to be provided by at least some aspects of the present invention are as follows. 
     The verification process is relatively resilient. The process has low vulnerability to single point failure. For example, in most of the above described embodiments, a centralized server, e.g. the supply chain controller, need only be used to set up the verification system, but is not required for ongoing operation of the system. 
     A low level of information needs to be exchanged between adjacent entities in a supply chain. Moreover, no information needs to be shared between non-adjacent entities. 
     The above described embodiments can be implemented using standard RFID tag technology. The above described embodiments do not require any additional computational power to be given to a conventional RFID tag, and also do not require any changes to standardized data reading, writing and storing protocols for RFID tags. However, it is also possible to adapt such protocols for use-specific reasons if desired. 
     Any counterfeit goods injected into a supply chain will lack the required upstream credentials and can be detected quickly by a downstream supply chain entity. Such quick detection can allow more effective action to be taken against counterfeiters. 
     Since each entity only verifies that items have arrived from an authorized adjacent upstream entity, the approach is highly scalable, both in terms of trace information on the RFID tag, and the number of cryptographic keys that are held for the validation and re-signing processes.