Efficient and secure data currentness systems

• US 9,143,330 B1
• Filed: 11/12/2012
• Issued: 09/22/2015
• Est. Priority Date: 05/13/2003
• Status: Expired due to Fees

• Current Assignee: Assa Abloy AB
• Original Assignee: Assa Abloy AB
• Inventors: Micali, Silvio, Libin, Phil, Volbright, Brandon
• Primary Examiner(s): Hirl, Joseph P
• Assistant Examiner(s): BEHESHTI SHIRAZI, SAYED ARESH
• Application Number:
  US13/674,322
• Time in Patent Office: 1,044 Days
• Field of Search: 713/156, 713/176, 713/178, 380/277, 380/278, 705/40, 705/51, 705/64
• US Class Current: 1/1
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3265 using certificate chains, trees or paths; Hierarchical trust model

Abstract

Indicating data currentness includes, on any date of a sequence of dates, issuing a proof indicating the currentness status of the data during a particular time interval. The proof may be a digital signature. The time interval may be in the form of a current date and an amount of time. The proof may include a digital signature of the time interval. The proof may include a digital signature of the time interval and the data. The proof may include a digital signature of the time interval and a compact form of the data, such as a hash. Indicating data currentness may also include distributing the proofs to a plurality of unsecure units that respond to requests by users for the proofs. Indicating data currentness may also include gathering a plurality of separate pieces of data and providing a single proof for the separate pieces of data. The data may be electronic documents.

Claims

1. A method of conveying information about a document comprising:

prior to a request for document i, and for every document i of a plurality of documents, having a currentness authority, using hardware processor, compute individual currentness status information Ci about i by digitally signing information identifying i, date j and an indication whether i continues to be valid,

providing the digitally signed currentness status information Ci to a responder;

for each document i in a plurality of documents, having the responder store the latest received Ci; and

in response to an inquiry about currentness status of document i, having the responder provide the latest received Ci.

2. A method, according to claim 1, wherein digitally signing includes digitally signing with respect to a public verification key pk, which is digitally signed by the document authority with respect to another public verification key PK.

3. A method, according to claim 2, wherein the public verification key pk, is contained as part of the document i.

4. A method, according to claim 1, wherein the currentness status information Ci of an obsolete document i includes a signature indicating that i has been revoked together with i'"'"'s revocation date.

5. A method, according to claim 1, wherein the currentness status information Ci of an obsolete document i includes a signature indicating a more current version of the document.

6. A method, according to claim 1, wherein the responder is not trusted and can not make an obsolete or suspend document current and cannot make a current document obsolete or suspended.

7. A method, according to claim 1, wherein information identifying i is i itself.

8. A method, according to claim 1, wherein information identifying i is a compact representation of i.

9. A method, according to claim 8, wherein the compact representation is computed via a hash function.

10. A method, according to claim 1, wherein information identifying i is a serial number.

11. A method, according to claim 1, wherein the currentness authority receives updates of document currentness from the document authority and uses them in order to compute the currentness status of documents.

12. A method, according to claim 11, wherein the currentness authority computes the status of each document as valid until the updates inform otherwise.

13. A method, according to claim 11, wherein the currentness authority computes the status of each document as valid until a prespecified date and time.

14. A method, according to claim 1, wherein each date in the sequence of dates is determined by the document authority.

15. A method, according to claim 1, wherein the document i contains information on the currentness authority responsible for updating the currentness status.

16. A method, according to claim 3, wherein the currentness authority produces the public key pk and makes it available to the document authority, while retaining the corresponding secret key sk.

17. A method, according to claim 1, wherein the currentness authority is the same entity as document authority.

18. A method of conveying information about a document comprising:

prior to a request for document i, and for every document i of a plurality of documents, computing using hardware processor, individual currentness status information Ci about i by digitally signing information identifying i, date j and an indication whether i continues to be valid, or is obsolete, or is suspended;

for each document i in a plurality of documents, storing the latest Ci; and

in response to an inquiry about currentness status of document i, providing the latest received Ci.