Source: http://www.google.com/patents/US20050154918?dq=6,952,563
Timestamp: 2015-04-01 15:17:46
Document Index: 336474025

Matched Legal Cases: ['art 100', 'art 100', 'art 120', 'art 100', 'art 150', 'art 180']

Patent US20050154918 - Distributed delegated path discovery and validation - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsProviding path validation information for a system includes determining paths between a subset of certificate of the system and at least one trust root, storing each of the paths in a table prior to a request for path validation information, and fetching the validation information stored in the table...http://www.google.com/patents/US20050154918?utm_source=gb-gplus-sharePatent US20050154918 - Distributed delegated path discovery and validationAdvanced Patent SearchPublication numberUS20050154918 A1Publication typeApplicationApplication numberUS 10/993,131Publication dateJul 14, 2005Filing dateNov 19, 2004Priority dateNov 19, 2003Also published asCA2544273A1, CN101124765A, CN101124765B, EP1692596A2, EP1692596A4, US8707030, WO2005052752A2, WO2005052752A3Publication number10993131, 993131, US 2005/0154918 A1, US 2005/154918 A1, US 20050154918 A1, US 20050154918A1, US 2005154918 A1, US 2005154918A1, US-A1-20050154918, US-A1-2005154918, US2005/0154918A1, US2005/154918A1, US20050154918 A1, US20050154918A1, US2005154918 A1, US2005154918A1InventorsDavid EngbergOriginal AssigneeDavid EngbergExport CitationBiBTeX, EndNote, RefManReferenced by (13), Classifications (8), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetDistributed delegated path discovery and validation
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS Techniques for providing individual certificate status information are known as are techniques for verifying certificates and/or authorities that digitally sign certificates. See, for example, the disclosure provided in U.S. Pat. Nos. 5,420,927; 5,604,804; 5,610,982; 6,097,811; 6,301,659; 5,793,868; 5,717,758; 5,717,757; 6,487,658; and 5,717,759, all of which are incorporated by reference herein. The system described herein may use techniques disclosed in one or more of these patents, possibly in combination with one or more other appropriate techniques. Techniques that may be used include, alone or in any combination, full CRL's, partitioned CRL's, delta CRL's, OCSP responses (individually and in groups), mini CRL's (bitwise compressed CRL's), VTokens (one-way hash chain), and various Merkle tree or other tree incarnations. Path discovery relates to the process of finding a trust path (trust relationship) between an arbitrary certificate and one of a user's trust roots, which are digital certificates corresponding to authorities trusted by a user. A trust path is a chain of authorizations from one certificate to another having a target certificate at one end and a trust root at the other. For example, if certificate C1 corresponds to a trusted authority A1, and A1 signs C2 for unknown authority A2 and authority A2 signs certificate C3 for unknown authority A3 that signed the target certificate, then a trust path from C1 (the trust root) to the target certificate is C1 to C2, C2 to C3, and C3 to the target certificate. In some cases, path discovery may be performed locally in a fairly straight-forward manner by the user whenever all of the certificates in a trust path are locally available. However, in some cases, including those with a federated trust model based on cross-certification, users may not have all of the information needed to perform local path discovery. Note also that, even when a complete trust path has been found between a trust root and a target certificate, there still may be a concern that one or more of the certificates on the trust path may have been revoked since the issuance thereof. Path validation refers to confirming the current status of all of the certificates in a trust path, including the validity thereof (revocation status) of the certificates as well as taking into account any and all rules and/or constraints corresponding to use of the certificates (e.g., checking security policies). Assembling the revocation status information for each certificate in the trust path may be relatively difficult for some users in some situations (e.g. those in special firewall settings preventing access to public networks). Accordingly, it is useful to be able to provide a service that can verify a certificate in a single transaction. This may be done by first determining the trust path, receiving revocation information (and/or constraint information) about the certificates in the trust path, and processing the received information to verify the target certificate. Referring to FIG. 1, an untrusted delegated path discovery/validation (UDPDV) server 30 receives, as input, information identifying one or more trust roots (certificates for trusted authorities) and an identifier corresponding to a target certificate (or perhaps some other information/data) that a user desires to validate. Optionally, the UDPDV server 30 may be pre-configured with trust roots in addition to, or instead of, receiving trust roots as input. Of course, if the user already trusts an authority that issued the target certificate and the user has access to reliable revocation information for the target certificate (and possibly the trusted authority's certificate), then the user can verify the target certificate with that information and it may not be necessary to use the UDPDV server 30. Accordingly, the UDPDV server 30 is useful in instances where a user wants to verify the status of a target certificate for which the user does not trust (know) the authority that issued the target certificate and/or for which the user does not posses reliable revocation information about the target certificate (and possibly the certificate of the authority that issued the target certificate). The UDPDV server 30 processes the inputs thereto to determine one or more trust paths between the target certificate and a trust root (either input or preconfigured into the UDPDV server 30, as described above). Note that, in many instances, it may also be useful to confirm that none of the certificates in a trust path have been revoked (indicating, for example, compromise of an authority's secret key). In such a case, it may be useful to have the UDPDV server 30 also provide proofs in the form of authenticated revocation information (e.g., CRL's or OCSP responses). Accordingly, in some embodiments, the UDPDV server 30 may also provide proofs for certificates in a trust path. Thus, in the embodiment disclosed in FIG. 1, the UDPDV server 30 assembles the trust path information for the target certificate and, optionally, also assembles revocation information for path elements. The output of the UDPDV server 30 to the user may not be independently authenticated (e.g. signed). Instead, the UDPDV server 30 returns all of the individual elements of the trust path (and, optionally, proofs) to the user, who may then independently verify the correctness of the trust path and the validity of the elements (certificates) thereof. Operation of the UDPDV server 30 is described in more detail elsewhere herein. Referring to FIG. 2, a trusted delegated path discovery/validation server 40 receives, as input, a user's trust roots and an identifier corresponding to a target certificate (or perhaps some other information/data) that a user desires to verify. Optionally, the trusted delegated path discovery/validation server 40 may be pre-configured with trust roots in addition to, or instead of, receiving the trust roots as input. The trusted delegated path discovery/validation server 40 outputs a result indicating whether or not the target certificate (or other information/data) is valid. In an embodiment described herein, the server 40 performs its own cryptographic authentication of the information that is provided to the user. In this embodiment, the server 40 may sign responses provided thereby, which would allow the server 40 to provide a small volume of data to the user (e.g. �Yes, you can trust certificate X�). However, such an implementation provides that the user explicitly trust the integrity and correctness of the internal operations of the trusted delegated path discovery/validation server 40. If the server 40 is compromised, the server 40 could be improperly used to authenticate responses that validate any certificate, regardless of source or current status. The servers 30, 40 may be provided by computer workstations having processors and internal storage for storing executable code and data, one or more software modules provided in a general purpose computer, dedicated hardware, or any combination of hardware and software capable of providing the functionality described herein. For the system described herein, the UDPDV server 30 may be provided by one or more lightweight servers that do not need to have authentication capabilities (e.g. private keys for digital signatures). The UDPDV server 30 may be periodically configured with lists of information of two types. The first type of list contains a set of certificates which may be used in path validation and, in an embodiment herein, represents all or nearly all certificates accessible (e.g., via a network) to the UDPDV server 30. In another embodiment, the first type of list contains certificates only for authorities that issue certificates and revocation information and for authorities that vouch for those authorities, without necessarily contain all or even any end user certificates. The first type of lists may contain self-signed root certificates (trusted roots) which serve as trust anchors. The trusted roots may be signed by authorities trusted by the user(s) of the system. The first type of lists may also contain issuer (aka �certificate authority�) certificates for authorities that issue certificates, authorities that issue revocation information, and/or authorities that vouch for other authorities. In one embodiment, the first type of lists may also contain end user certificates while in another embodiment, the first type of lists does not contain end user certificates. The first type of lists of certificates may be used to provide path discovery services, as described herein. The second type of list provided in the UDPDV server 30 may include pre-generated certificate status proofs. Each proof may contain the status of one or more certificates (from the first list) for a fixed interval of time, and the proof may be securely authenticated, e.g. using a digital signature. The proofs may be used to provide path validation services, as described elsewhere herein. The proofs may be provided by any appropriate means, including CRL's, OCSP responses, VTokens, etc. Checking a path between a trusted root and a target certificate is known in the art and well documented in certificate standards (e.g., RFC 3280). However, finding a trust path through a large number of certificates may take exponential time based on the number of certificates in the pool. This may be acceptable in some situations and/or for small collections of certificates, but may be unacceptably in other situations, such as a large community of federated authorities. The system described herein is designed to perform path discovery in logarithmic or constant time at the time of a discovery request by first pre-calculating trust paths between each trusted root certificate and all other reachable certificates for authorities that issue certificates and/or vouch for other authorities. When the UDPDV server 30 receives a new list of certificates (or is coupled to a source of new certificates), the server may pre-compute an M by N matrix where M is the number of trusted roots and N is the total number of certificates. Each cell in the matrix (e.g., at row r1 and column c1) may contain one or more legitimate paths from the specific trusted root indicated by the row r1 to the specific certificate indicated by the column c1, or else contain an empty set to indicate that no paths are possible. Optionally, each cell (or each cell of an analogous table) may also contain appropriate proofs to provide validation. When a user request for verification of a target certificate arrives, the UDPDV server 30 uses the pre-computed matrix to look up the trusted root(s) for the user and to look up the authority that issued the target certificate and, optionally, to an authority that issued revocation information for the target certificate (if different from the issuing authority) to find one or more valid paths therebetween. This may be performed in a constant time look-up since the paths have been pre-calculated and stored in the UDPDV server 30. Note that if there is more than one possible trust path or if there are constraints associated with a trust path (e.g. name or policy constraints) that limit in any way the usage of any of the certificates in the trust path, then the path policies need to be applied against any trust path(s) found. By pre-computing all possible paths, the UDPDV server 30 may offer path discovery for large communities with relatively high performance and scalability. In addition to path discovery, the UDPDV server 30 may also provide validation information (proofs) for elements (certificates) of a trust path. In one embodiment, the UDPDV server 30 obtains the proofs (e.g. in the form of a CRL or OCSP response) in real time for each element (certificate) in a trust path which is then provided to the user. Although it may be possible to improve performance by caching proofs, there still may be the potential for non-optimal performance at the time of a request when proofs are obtained in real time. In another embodiment, there may be a path validation mechanism in the UDPDV server 30 that receives at regular intervals pre-generated, fine-grained status proofs for each certificate used by the UDPDV server 30 in connection with generating trust paths. For this embodiment, the UDPDV server 30 may be able to quickly access all needed validation information that may be provided to relying parties without requiring any extra processing time to retrieve the certificate status information for validation at real time. Note also that, if the proofs are pushed to the UDPDV server 30 (e.g. in the form of pre-signed OCSP responses), the UDPDV server 30 may have instant local access to the status of every certificate in a trust path. For some embodiments, the UDPDV server 30 confirms the status of the trust path before returning the trust path for path delegation. The UDPDV server 30 may also optionally return the status proofs to the user to permit local complete validation of the trust path by the user. The individualized, pre-generated nature of the proofs (e.g. pre-generated OCSP responses) may allow an efficient use of networking resources while avoiding any security risks that may be associated with trusted online servers. Referring to FIG. 3, a diagram 50 shows a first area 52 and a separate second area 54. The areas 52, 54 may be interconnected by any appropriate means (e.g., a network or direct connection) to enable an exchange of signals therebetween. The first area 52 includes a plurality of certificates 62-64. The second area 54 includes a plurality of different certificates 66-68. The first area 52 represents a locality that may be managed and accessed locally by a user therein. Similarly, the second area 54 represents a separate locality that may be managed and accessed locally by a different user therein. Thus, for example, a user in the area 52 may locally access any or all of the certificates 62-64. At the area 52, the certificate 62 is a self-certifying root certificate (trusted root) for an authority A1. The certificate 62 also certifies the certificate 63 for an authority A2 by, for example, having A1 sign the certificate 63. The certificate 63 certifies the certificate 64 for an authority A3. Note that, in this example, if a user trusts A1, then the user should also trust A2 (vouched for by A1) and should also trust A3 (vouched for by A2). At the area 54, the certificate 66 is a self-certifying root certificate (trusted root) for an authority A1′. The certificate 66 also certifies the certificate 67 for an authority A2′ and the certificate 67 certifies the certificate 68 for an authority A3′. The certificate 62 is cross-certified with the certificate 66 so that each of the certificates 62, 66 certifies the other one of the certificates 62, 66. If a user at the area 52 is presented with a target certificate signed by A3′, the user may not be able to immediately verify that the target certificate is valid if the user at the area 52 only initially knows about (and trusts) A1, A2, and A3. However, note that the authority A2′ vouches for the authority A3�and that the authority A1� vouches for the authority A2′. Note also that the authority A1 vouches for the authority A1′. Thus, assuming a local user at the area 52 trusts A1, then there is a trust path for the user from the certificate 62 to the certificate 66 to the certificate 67 to the certificate 68 to the target certificate that has been signed by A3′. Thus, the user may accept the target certificate signed by the authority A3′ because of the trust path from the target certificate to the certificate 62 that has been signed by the trusted authority A1. Also, as discussed elsewhere herein, it is possible to provide validation information (proof of validity) for each of the certificates along the trust path as well as for any authority that issued revocation information (if different from the issuing authority) so that, in the example the user that receives the trust path may also receive up-to-date revocation information for the certificates 62, 66-68. Referring to FIG. 4, a diagram 80 illustrates a user 82 receiving certificate information (including trust path information and possibly validation information) from one or more of a plurality of data storage devices 84-86 coupled to the user 82 by a network 88. In an embodiment herein, the network 88 may be the Internet, although other suitable networks may be used, including networks that provide direct connections between the user and one or more of the data storage devices 84-86. Note also that the user 82 may locally store some certificate information. In an embodiment herein, the user 82 may be presented with one or more certificates that the user desires to determine the validity thereof. In some cases, the user 82 may determine the validity of the certificates using local data. However, as described elsewhere herein, it may be necessary in other cases for the user 82 to obtain certificate information from other sources like the data storage devices 84-86. In such cases, certificate information and requests therefor may be communicated between the user and the storage devices 84-86 over the network 88 in a straight-forward manner. Of course, any appropriate connectivity and information request/transmission techniques may be used to provided the functionality described herein. Referring to FIG. 5, a flow chart 100 illustrates initializing the UDPDV server 30 to contain all of the paths between the trusted roots (root certificates for trusted authorities) and one or more other certificates that issue certificates and/or vouch for other authorities. As discussed elsewhere herein, each of the trust paths may be pre-computed so that when a user presents a target certificate, the UDPDV server may consult a table, look up the authority that issued the target certificate (or look up the target certificate itself), and provided a pre-computed trust path from the target certificate to a trusted root certificate. As also discussed herein, the UDPDV server 30 may optionally provide, for the certificates in the trust path, proofs indicating that the certificates have not been revoked. Processing for the flow chart 100 begins at a first step 102 where a directed graph is constructed for all of the certificates for which information is to be stored. A directed graph is a mathematical construct that is well-known in the art. For an embodiment herein, all of the certificates in a system, including end user certificates, are used. For another embodiment, end user certificates are not included or, alternatively, only some end user certificates are included. At the step 102, the directed graph that is constructed represents a trust relationship between certificates where an edge (connecting line) of the graph indicates that a first authority (corresponding to a certificate connected at one end of the edge) has vouched for a second authority (corresponding to a certificate connected at the other end of the edge). Following the step 102 is a step 104 where an index variable, I, is set equal to one. The index variable, I, is used to iterate through each of the trusted root certificates for the UDPDV server 30. As discussed elsewhere herein, the trusted root certificates are provided as an input to or are pre-configured in the UDPDV server 30. Following the step 104 is a test step 106 where it is determined if the index variable, I, is greater than the number of trusted root certificates. If so, then processing is complete. Otherwise, control transfers from the test step 106 to a step 108 to determine all of the paths from the trusted root certificate (corresponding to the index variable, I) to all of the other certificates in the directed graph. The step 108 is discussed in more detail elsewhere herein. Following the step 108 is a step 112 wherein the index variable, I, is incremented. Following the step 112, control transfers back to the test step 106, discussed above. Referring to FIG. 6, a flow chart 120 illustrates in more detail processing performed in connection with the step 108 of the flow chart 100 of FIG. 5. For each of the trusted roots, a depth-first acyclic search of the directed graph is performed to find all of the trust paths. For each certificate that is found in each path, an entry is made in a table indicating the trusted path from the certificate to the trusted root. Processing begins at a first step 122, where it is determined if there are more paths to be examined. Note that, in some instances, it may be possible to have a trusted root with no paths thereto. However, in most cases, it is expected that each of the trusted roots will have at least one path thereto. If it is determined at the test step 122 that there are no more paths to be examined (processed), then processing is complete. Otherwise, control transfers from the test step 122 to a step 124 wherein the next path is determined using the depth-first acyclic search of the directed graph. Following the step 124 is a step 126 where a certificate pointer, CP, is set to point to the end of the path being examined (processed). Following the step 126 is a test step 128 which determines if CP points to the trusted root, thus indicating that the entire path has been traversed. If so, then control transfers from the test step 128 back to the step 122, discussed above, to begin the next iteration. Otherwise, control transfers from the test step 128 to a step 132 where the path from CP to the trusted root is recorded in the table (discussed elsewhere herein) that stores certificates and trusted paths thereto. In one embodiment, at a portion of the table indexed by the certificate pointed to by CP, the path from CP to the trusted root is recorded at the step 132. Following the step 132 is a step 134 where CP is set to point to the previous certificate in the path. Thus, CP initially points to the end of the path and then subsequently points to previous certificates in the path working backwards toward the trusted root. Following the step 134, control transfers back to the test step 128, discussed above. Referring to FIG. 7A, a table 140 includes a first portion 142 indexed by certificates in the system and having, as elements, trusted paths to each of the certificates. The table 140 may also include a second portion 144 that is also indexed by certificates in the system. The second portion has elements that describe proofs (e.g., OCSP responses, CRL's, etc.) indicating the revocation status for each of the corresponding certificates. In an embodiment described herein, the proofs provided in the second portion 144 correspond to the index certificate so that, for example, the table entry indexed by C2 corresponds to a proof for C2. In another embodiment, the proofs provided in the second portion 144 correspond to all of the certificates in all of the paths for a particular entry in the first portion 142. Thus, for example, the proofs provided in the second portion 144 in connection with certificate C2 correspond to all of the certificates in the trust paths provided in the entry for C2 in the first portion 142. In some embodiments, it may be possible to eliminate one of the portions 142, 144. Thus, for example, in embodiments with only the portion 142, the UDPDV server 30 provides pre-calculated trust paths, but not proofs. For such embodiments, users may either forgo proofs altogether, obtain proofs in real time, or some combination thereof (i.e., obtain proofs for some certificates in the paths but not others). For embodiments with only the portion 144, trust paths may be determined in real time and the pre-calculated proofs from the portion 144 may be provided by the UDPDV server 30. Referring to FIG. 7B, another embodiment uses a single table 140′ indexed according to certificates, where both the trust paths and the proofs are provided as elements of the table 140′. Referring to FIG. 7C, yet another embodiment illustrates another configuration for the table 140″. The table 140″ may be indexed according to a particular trusted root certificate TR1, TR2, . . . TRN and other certificates C1, C2, . . . CN. The elements at an entry of the table 140″ contain trust paths and (optionally) proofs �P/P� so that, for example, an entry for trusted root TRx and certificate Cy contains one or more trust paths (if any exist) from Cy to TRx and, optionally, one or more proofs for just Cy (in one embodiment) or for all of the certificates in the trust path(s) (in another embodiment). Referring to FIG. 8, a flow chart 150 illustrate steps for processing in connection with the UDPDV server 30 servicing a request from a user for a trust path and, optionally, proofs for certificates thereof. As discussed elsewhere herein, the UDPDV server 30 may be presented with a particular target certificate for which the UDPDV server 30 provides a trust path and optionally proofs indicating the status out each certificate in the trust path. In one embodiment, the trust path is provided to a certificate for an authority that issued the target certificate and, optionally, to a certificate for an authority that issued revocation information for the target certificate (if different from the issuing authority). In another embodiment, the UDPDV server 30 provides a trust path and optional revocation information for the target certificate itself. Processing begins at a first step 152 where it is determined if there are any trust paths available at all for the target certificate or the issuer thereof. If not, then control transfers from the step 152 to a step 154 where special processing is performed. The special processing performed at the step 154 may include posting an error message and/or indicating to a user in some other way that no trust path has been found for the target certificate. Following the step 154, processing is complete. If it is determined at the test step 152 that there are trust paths available, then control transfers from the test step 152 to a step 156 where the next trust path is chosen for processing. In an embodiment herein, the system may iterate through each of the trust paths (provided by the table 140, the table 140′, or the table 140″) to find an appropriate trust path between the target certificate (or issuer thereof) and one or more of the trusted root certificates. The next trust path chosen at the step 156 may be chosen using any of a number of possible criteria, such as shortest path, path containing particular certificates, etc. Following step 156 is a test step 158 which determines if there are constraints on the particular trust path (certificates of the trust path) chosen at the step 156. As discussed elsewhere herein, there may be one or more constraints that prevent use of a particular trust path such as, for example, one or more certificates not being acceptable for certain purposes. If it is determined at the test step 158 that there are constraints that make the trust path being examined unacceptable, then control transfers from the test step 158 back to the step 152, discussed above. Otherwise, control transfers from the test step 158 to a step 162 where it is determined if proofs for the certificates in the trust path have been requested. If not, then control transfers from the step 162 to a step 164 where the trust path between the target certificate (or issuer thereof) and the trusted root certificate is returned to the user. Following step 164, processing is complete. If it is determined at the test step 162 that proofs have been requested, then control transfers from the test step 162 to a step 166 where the proofs (from the table 140, the table 140′, or the table 140″) are obtained. In other embodiments, the proofs may be obtained in real time. Following the step 166 is a step 168 where the trust path and the proofs are returned. Following step 168, processing is complete. As discussed elsewhere herein, in some instances, a user may desire to use the trusted distributed delegated path discovery and validation server 40 that returns a signed (or otherwise authenticated) message indicating whether or not a particular certificate is valid. The server 40 may sign a message indicating that a particular certificate is acceptable or not. The user may rely on the signed response from the server 40 without necessarily knowing or examining the path and/or the validation information first hand. Referring to FIG. 9, a flow chart 180 illustrates steps performed by the server 40 in connection with constructing and returning a signed message indicating whether or not a particular target certificate is valid. Processing begins at a first step 182 where the trusted path and proofs are obtained in accordance with the description elsewhere herein. Following the step 182 is a test step 184 wherein the trust path and the proofs are examined to determine if the target certificate is valid. The determination at the step 184 may be made using the trust path and proofs obtained at the step 182. If it is determined at the test step 184 that the target certificate is valid, then control transfers from the test step 184 to a step 186 where a positive message, indicating that the target certificate is valid, is created. Otherwise, if it is determined at the test step 184 that the target certificate is not valid, then control transfers from the test step 184 to a step 188 where a negative message is created. Following either the step 186 or the step 188 is a step 192 where the message is digitally signed by the server 40. Following the step 192 is a step 184 where the signed result is returned to the user. Following step 194, processing is complete. The system described herein may be implemented using any appropriate combination of hardware and/or software, including software provided in a storage medium (e.g., disk, tape, CD ROM, removable memory, etc.). The software may run on specialized hardware, on a general purpose computer, or an appropriate combination thereof. While the invention has been disclosed in connection with various embodiments, modifications thereon will be readily apparent to those skilled in the art. Accordingly, the spirit and scope of the invention is set forth in the following claims. Referenced byCiting PatentFiling datePublication dateApplicantTitleUS8041943 *Oct 3, 2006Oct 18, 2011Nds LimitedRevocation list improvementUS8130146Jul 29, 2008Mar 6, 2012Motorola Solutions, Inc.Method for measuring the time of arrival of radio signalsUS8321841 *Jan 8, 2008Nov 27, 2012International Business Machines CorporationValidation framework for service oriented architecture (SOA) application adoptionUS8380985 *Jun 29, 2010Feb 19, 2013Hitachi, Ltd.Certificate validation method and certificate validation server and storage mediumUS8473737 *Jan 18, 2008Jun 25, 2013Seiko Epson CorporationAuthentication device and method using electronic certificate files having hierarchical relationshipUS8595484Jul 29, 2008Nov 26, 2013Motorola Solutions, Inc.Method and device for distributing public key infrastructure (PKI) certificate path dataUS8819417 *Feb 28, 2012Aug 26, 2014Hitachi, Ltd.Validation server, validation method, and programUS20080091940 *Dec 23, 2005Apr 17, 2008Qinetiq LimitedPublic Key InfrastructureUS20090019519 *Jan 18, 2008Jan 15, 2009Seiko Epson CorporationAuthentication device and method using electronic certificate files having hierarchical relationshipUS20090177508 *Jan 8, 2008Jul 9, 2009International Business Machines CorporationValidation framework for service oriented architecture (soa) application adoptionUS20110004763 *Jun 29, 2010Jan 6, 2011Sato AkaneCertificate validation method and certificate validation server and storage mediumUS20120159158 *Feb 28, 2012Jun 21, 2012Hitachi, Ltd.Validation server, validation method, and programEP2271049A2 *Jun 30, 2010Jan 5, 2011Hitachi, Ltd.Certificate validation method and certificate validation server and storage medium* Cited by examinerClassifications U.S. Classification726/4, 713/156International ClassificationG06F, H04L9/32, G06F11/30Cooperative ClassificationH04L9/3268, H04L9/3265European ClassificationH04L9/32TLegal EventsDateCodeEventDescriptionMar 11, 2014ASAssignmentOwner name: ASSA ABLOY AB, SWEDENFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CORESTREET LTD;REEL/FRAME:032404/0759Effective date: 20131217Oct 8, 2013ASAssignmentOwner name: CORESTREET, LTD., CALIFORNIAFree format text: RELEASE BY SECURED PARTY;ASSIGNOR:ASSA ABLOY AB;REEL/FRAME:031361/0975Effective date: 20131007Jan 26, 2007ASAssignmentOwner name: ASSA ABLOY AB, SWEDENFree format text: ASSIGNMENT OF SECURITY AGREEMENT;ASSIGNOR:ASSA ABLOY IDENTIFICATION TECHNOLOGY GROUP AB;REEL/FRAME:018806/0814Effective date: 20061001Owner name: ASSA ABLOY AB,SWEDENFree format text: ASSIGNMENT OF SECURITY AGREEMENT;ASSIGNOR:ASSA ABLOY IDENTIFICATION TECHNOLOGY GROUP AB;US-ASSIGNMENT DATABASE UPDATED:20100203;REEL/FRAME:18806/814Free format text: ASSIGNMENT OF SECURITY AGREEMENT;ASSIGNOR:ASSA ABLOY IDENTIFICATION TECHNOLOGY GROUP AB;US-ASSIGNMENT DATABASE UPDATED:20100209;REEL/FRAME:18806/814Free format text: ASSIGNMENT OF SECURITY AGREEMENT;ASSIGNOR:ASSA ABLOY IDENTIFICATION TECHNOLOGY GROUP AB;US-ASSIGNMENT DATABASE UPDATED:20100511;REEL/FRAME:18806/814Dec 16, 2005ASAssignmentOwner name: ASSA ABLOY IDENTIFICATION TECHNOLOGY GROUP AB, SWEFree format text: SECURITY AGREEMENT;ASSIGNOR:CORESTREET, LTD.;REEL/FRAME:016902/0444Effective date: 20051212Owner name: ASSA ABLOY IDENTIFICATION TECHNOLOGY GROUP AB,SWEDFree format text: SECURITY AGREEMENT;ASSIGNOR:CORESTREET, LTD.;US-ASSIGNMENT DATABASE UPDATED:20100203;REEL/FRAME:16902/444Free format text: SECURITY AGREEMENT;ASSIGNOR:CORESTREET, LTD.;US-ASSIGNMENT DATABASE UPDATED:20100209;REEL/FRAME:16902/444Free format text: SECURITY AGREEMENT;ASSIGNOR:CORESTREET, LTD.;US-ASSIGNMENT DATABASE UPDATED:20100511;REEL/FRAME:16902/444Mar 21, 2005ASAssignmentOwner name: CORESTREET, LTD., MASSACHUSETTSFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ENGBERG, DAVID;REEL/FRAME:016378/0012Effective date: 20050315RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services