US5261002A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of issuance and revocation of certificates of authenticity used in public key networks and other systems
Assignee: Hewlett Packard Development Co LP
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Filing: 1992-03-13
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Granted: 1993-11-09
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Expires: 2012-03-13
Abstract
Abstract A technique for issuing and revoking user certificates of authenticity in a public key cryptography system, wherein certificates do not need expiration dates, and the inconvenience and overhead associated with routine certificate renewals are minimized or avoided entirely. A Certification Authority issues certificates as required, and issues a blacklist having a start date, an expiration date, and an entry for every invalid certificate issued after the start date. Users assume that every certificate issued prior to the blacklist start date is invalid, and that invalid certificates issued after the start date will be included in the current blacklist. A new blacklist is issued prior to expiration of the current one, and the blacklist start date is changed only when the blacklist becomes unmanageably long.
Inventors
- 👤 Radia J. Perlman
- 👤 Charles W. Kaufman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:32
CPC Classifications
G; G07; G07F; G07F7/00; G07F7/08; G07F7/10; G07F7/1016; H; H04; H04L; H04L9/00; H04L9/32; H04L9/3263
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
188 words
A method for authenticating users of an information system, comprising the steps of: issuing a signed certificate for each user of an information system, wherein the signed certificate contains an issue date, a unique public key associated with the user, and other public information pertaining to the user, and wherein a valid certificate is one that authenticates an association between the user and the public key contained in the certificate, and an invalid certificate is one for which the association between the user and the public key is no longer valid; issuing a signed list of invalid certificates, referred to as a blacklist, containing a blacklist start date, a blacklist expiration date, and an entry for each user whose certificate was issued after the blacklist start date and is invalid; and determining whether a user's certificate is valid by first obtaining a copy of the certificate and a copy of the signed blacklist, then determining whether the blacklist has expired, and then, if the blacklist has not expired, determining whether the certificate issued after the blacklist start date and is not on the blacklist, and is therefore valid.
Claim 2
Independent Claim
188 words
A method for authenticating users of an information system, comprising the steps of: issuing a signed certificate for each user of an information system, wherein the signed certificate contains an issue date, a unique public key associated with the user, and other public information pertaining to the user, and wherein a valid certificate is one that authenticates an association between the user and the public key contained in the certificate, and an invalid certificate is one for which the association between the user and the public key is no longer valid; issuing a signed list of invalid certificates, referred to as a blacklist, containing a blacklist start date, a blacklist expiration date, and an entry for each user whose certificate was issued after the blacklist start date and is invalid; and determining whether a user's certificate is valid by first obtaining a copy of the certificate and a copy of the signed blacklist, then determining whether the blacklist has expired, and then, if the blacklist has not expired, determining whether the certificate issued after the blacklist start date and is not on the blacklist, and is therefore valid.
Claim 3
Dependent Claim
21 words
A method as defined in claim 1, and further comprising: if the blacklist has expired, concluding that the certificate is invalid.
Claim 4
Dependent Claim
78 words
A method as defined in claim 1, and further comprising: if the blacklist has expired, determining whether the blacklist has a default expiration date that has passed; if the blacklist has a default expiration date that has not passed, concluding that the certificate is invalid; and if the blacklist has a default expiration date has not passed, continuing with the step of determining whether the certificate issued after the blacklist start date and is not on the blacklist.
Claim 5
Dependent Claim
74 words
A method as defined in claim 1, and further comprising: if the blacklist has expired, determining whether the blacklist expired more than a selected time earlier; if the certificate expired more than a selected time earlier, concluding that the certificate is invalid; and if the certificate expired less than a selected time earlier, continuing with the step of determining whether the certificate issued after the blacklist start date and is not on the blacklist.
Claim 6
Independent Claim
19 words
A method as defined in claim and further comprising: issuing a new blacklist prior to the blacklist expiration date.
Claim 7
Dependent Claim
68 words
A method as defined in claim 5, wherein the step of issuing a new blacklist includes: determining whether the current blacklist is longer than a selected length; and, if so, selecting a new start date for the new blacklist, to provide for a shorter blacklist, and advising holders of valid certificates issued prior to the new blacklist start date that these certificates must be renewed to remain valid.
Claim 8
Independent Claim
192 words
A method for authenticating users of a public key cryptographic system, comprising the steps of: issuing a signed certificate for each user of a public key cryptographic system, wherein the signed certificate contains an issue date, a unique public key associated with the user, and other public information pertaining to the user, and wherein a valid certification is one that authenticates an association between the user and the public key contained in the certificate, and an invalid certificate is one for which the association between the user and the public key is no longer valid; issuing a signed list of invalid certificates, referred to as a blacklist, containing a blacklist start date, a blacklist expiration date, and an entry for each user whose certificate was issued after the blacklist start date and is invalid; and determining whether a user's certificate is valid by first obtaining a copy of the certificate and a copy of the signed blacklist, then determining whether the blacklist has expired, and then, if the blacklist has not expired, determining whether the certificate issued after the blacklist start date and is not on the blacklist, and is therefore valid.
Claim 9
Independent Claim
192 words
A method for authenticating users of a public key cryptographic system, comprising the steps of: issuing a signed certificate for each user of a public key cryptographic system, wherein the signed certificate contains an issue date, a unique public key associated with the user, and other public information pertaining to the user, and wherein a valid certification is one that authenticates an association between the user and the public key contained in the certificate, and an invalid certificate is one for which the association between the user and the public key is no longer valid; issuing a signed list of invalid certificates, referred to as a blacklist, containing a blacklist start date, a blacklist expiration date, and an entry for each user whose certificate was issued after the blacklist start date and is invalid; and determining whether a user's certificate is valid by first obtaining a copy of the certificate and a copy of the signed blacklist, then determining whether the blacklist has expired, and then, if the blacklist has not expired, determining whether the certificate issued after the blacklist start date and is not on the blacklist, and is therefore valid.
Claim 10
Dependent Claim
21 words
A method as defined in claim 7, and further comprising: if the blacklist has expired, concluding that the certificate is invalid.
Claim 11
Dependent Claim
78 words
A method as defined in claim 7, and further comprising: if the blacklist has expired, determining whether the blacklist has a default expiration date that has passed; if the blacklist has a default expiration date that has passed, concluding that the certificate is invalid; and if the blacklist has a default expiration date that has not passed, continuing with the step of determining whether the certificate issued after the blacklist start date and is not on the blacklist.
Claim 12
Dependent Claim
74 words
A method as defined in claim 7, and further comprising: if the blacklist has expired, determining whether the blacklist expired more than a selected time earlier; if the certificate expired more than a selected time earlier, concluding that the certificate is invalid; and if the certificate expired less than a selected time earlier, continuing with the step of determining whether the certificate issued after the blacklist start date and is not on the blacklist.
Claim 13
Dependent Claim
20 words
A method as defined in claim 7, and further comprising: issuing a new blacklist prior to the blacklist expiration date.
Claim 14
Dependent Claim
68 words
A method as defined in claim 11, wherein the step of issuing a new blacklist includes: determining whether the current blacklist is longer than a selected length; and, if so, selecting a new start date for the new blacklist, to provide for a shorter blacklist, and advising holders of valid certificates issued prior to the new blacklist start date that these certificates must be renewed to remain valid.
Claim 15
Independent Claim
206 words
A method for authenticating users of a public key cryotpgraphic system, comprising the steps of: issuing a signed certificate for each user of a public key cryptographic system, wherein the signed certificate contains an issue sequence number, a unique public key associated with the user, and other public information pertaining to the user, and wherein a valid certificate is one that authenticates an association between the user and the public key contained in the certificate, and an invalid certificate is one for which the association between the user and the public key is no longer valid; issuing a signed list of invalid certificates, referred to as a blacklist, containing a blacklist start sequence number, a blacklist expiration date, and an entry for each user whose certificate has a sequence number greater than the blacklist start sequence number and is to be considered invalid; and determining whether a user's certificate is valid by first obtaining a copy of the certificate and a copy of the signed blacklist, then determining whether the blacklist has expired, and then, if the blacklist has not expired, determining whether the certificate has a sequence number greater than the blacklist start sequence number and is not on the blacklist, and is therefore valid.
Claim 16
Independent Claim
206 words
A method for authenticating users of a public key cryotpgraphic system, comprising the steps of: issuing a signed certificate for each user of a public key cryptographic system, wherein the signed certificate contains an issue sequence number, a unique public key associated with the user, and other public information pertaining to the user, and wherein a valid certificate is one that authenticates an association between the user and the public key contained in the certificate, and an invalid certificate is one for which the association between the user and the public key is no longer valid; issuing a signed list of invalid certificates, referred to as a blacklist, containing a blacklist start sequence number, a blacklist expiration date, and an entry for each user whose certificate has a sequence number greater than the blacklist start sequence number and is to be considered invalid; and determining whether a user's certificate is valid by first obtaining a copy of the certificate and a copy of the signed blacklist, then determining whether the blacklist has expired, and then, if the blacklist has not expired, determining whether the certificate has a sequence number greater than the blacklist start sequence number and is not on the blacklist, and is therefore valid.
Claim 17
Dependent Claim
21 words
A method as defined in claim 13, and further comprising: if the blacklist has expired, concluding that the certificate is invalid.
Claim 18
Dependent Claim
83 words
A method as defined in claim 13, and further comprising: if the blacklist has expired, determining whether the blacklist has a default expiration date that has passed; if the blacklist has a default expiration date that has passed, concluding that the certificate is invalid; and if the blacklist has a default expiration date that has not passed, continuing with the step of determining whether the certificate has a sequence number greater than the blacklist starting sequence number and is not on the blacklist.
Claim 19
Dependent Claim
79 words
A method as defined in claim 13, and further comprising: if the blacklist has expired, determining whether the blacklist expired more than a selected time earlier; if the certificate expired more than a selected time earlier, concluding that the certificate is invalid; and if the certificate expired less than a selected time earlier, continuing with the step of determining whether the certificate has a sequence number greater than the blacklist staring sequence number and is not on the blacklist.
Claim 20
Dependent Claim
20 words
A method as defined in claim 13, and further comprising: issuing a new blacklist prior to expiration of the blacklist.
Claim 21
Dependent Claim
73 words
A method as defined in claim 17, wherein the step of issuing a new blacklist includes: determining whether the current blacklist is longer than a selected length; and, if so, selecting a new start sequence number for the new blacklist, to provide for a shorter blacklist, and advising holders of valid certificates issued with sequence numbers smaller than the new blacklist start sequence number that these certificates must be renewed to remain valid.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-11-08 | 1997-05-10 | 1997-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-11-08 | 2001-05-10 | 2001-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-11-08 | 2005-05-10 | 2005-11-09 | $7700.00 | Window Closed / Lapsed |