Method and system for providing document retention using cryptography

• US 8,613,102 B2
• Filed: 03/30/2004
• Issued: 12/17/2013
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: Citrix Systems, Inc. (Cloud Software Group)
• Original Assignee: Intellectual Ventures I LLC (Intellectual Ventures LLC)
• Inventors: Nath, Satyajit
• Primary Examiner(s): Abrishamkar, Kaveh
• Application Number:
  US10/815,251
• Publication Number:
  US 20050223242A1
• Time in Patent Office: 3,549 Days
• Field of Search: 713/193, 713/168, 713/171, 713/158
• US Class Current: 726/27
• CPC Class Codes: G06F 21/6209 to a single file or object, e.g. in a secure envelope, encrypted and accessed using a key, or with access control rules appended to the object itself
• CPC Class Codes: G06F 2221/2137 Time limited access, e.g. to a computer or data

Abstract

Techniques for utilizing security criteria to implement document retention for electronic documents are disclosed. The security criteria can also limit when, how and where access to the electronic documents is permitted. The security criteria can pertain to keys (or ciphers) used to secure (e.g., encrypt) electronic files (namely, electronic documents), or to unsecure (e.g., decrypt) electronic files already secured. At least a portion of the security criteria can be used to implement document retention, namely, a document retention policy. After a secured electronic document has been retained for the duration of the document retention policy, the associated security criteria becomes no longer available, thus preventing subsequent access to the secured electronic document. In other words, access restrictions on electronic documents can be used to prevent access to electronic documents which are no longer to be retained.

Claims

1. A method of electronic document retention, comprising:

assigning a document retention policy to the electronic document, the document retention policy being based on a future event that is unscheduled;

cryptographically associating, by encrypting at least a data portion of the electronic document using a cryptographic key, the document retention policy with the electronic document, wherein the cryptographic key is a document retention key or a key encrypted with the document retention key, and wherein the cryptographic key is protected by a document access policy comprising access rules which provide restrictive access to the cryptographic key and the encrypted data portion of the electronic document by deactivating the cryptographic key at a future time; and

permitting the deactivating to be overridden so that the electronic document can remain accessible even after a document retention period.

2. The method as recited in claim 1, further comprising:

determining whether the future event has occurred; and

cryptographically preventing access to the electronic document in accordance with the document retention policy based on the future event occurring.

3. The method as recited in claim 2, wherein the determining is performed periodically.

4. The method as recited in claim 2, wherein the determining comprises interacting with a network accessible resource, wherein the network accessible resource is one or more of a server, an application, a client computing device, or a storage device.

5. The method as recited in claim 2, wherein the determining comprises interacting with a web accessible resource, wherein the web accessible resource is one or more of a web server, an application, a client computing device, or an external storage device.

6. The method as recited in claim 5, wherein the determining comprises:

supplying a future event description of the future event to the web accessible resource; and

determining, at the web accessible resource, whether the future event has occurred.

7. The method as recited in claim 6, wherein the supplying is achieved by a universal resource locator associated with the future event description.

8. The method as recited in claim 5, wherein the determining comprises:

supplying the future event description to a contract management system; and

determining, at the contract management system, whether the future event has occurred.

9. The method as recited in claim 1, wherein:

the document retention policy specifies the document retention period based on the future event.

10. The method as recited in claim 9, wherein the document retention policy specifies a document retention period that expires a predetermined period of time after the future event has occurred.

11. The method as recited in claim 9, further comprising:

deactivating the cryptographic key in response to determining that the document retention period has expired, thereby preventing further access to the electronic document.

12. The method, as recited in claim 4, wherein the determining comprises:

supplying a future event description of the future event to the network accessible resource; and

determining, at the network accessible resource, whether the future event has occurred.

13. A computer-implemented method for distributing cryptographic keys used in a file security system, comprising:

receiving, at a computing device, a request for a document retention key that is necessary to gain access to a cryptographically secured electronic document;

identifying, by the computing device, a document retention period having been cryptographically associated with the secured electronic document by encrypting at least a data portion of the secured electronic using the document retention key, the document retention period being dependent on a future event that was unscheduled when the document retention period was associated with the secured electronic document, wherein the document retention key is protected by a document access policy comprising access rules which provide restrictive access to the document retention key and the encrypted data portion of the secured electronic document by deactivating the document retention key at a future time;

determining, by the computing device, whether the document retention period associated with the document retention key has been exceeded; and

refusing to distribute the document retention key in response to determining that the document retention period for the electronic document has been exceeded, except a system administrator is allowed access the document retention key by extending the document retention period or setting a new retention period.

14. The computer-implemented method as recited in claim 13, wherein the document retention period is a predetermined period of time after the future event has occurred.

15. The computer-implemented method as recited in claim 13, wherein the computing device is a server, and wherein the request for the document retention key is from a client module that is connectable to the server via a network.

16. A file security system comprising:

a processor;

a memory having instructions stored thereon, that, in response to execution by the processor, cause the processor to restrict access to electronic files comprising respective encrypted data portions, the instructions comprising;

instructions for storing a plurality of cryptographic key pairs in a key store, each of the cryptographic key pairs including a public key and a private key, at least one of the cryptographic key pairs pertaining to a retention policy, the retention policy being dependent on a future event, wherein the cryptographic key pairs are document retention keys or keys encrypted with a document retention key, and wherein the cryptographic key pairs are protected by a document access policy comprising access rules which provide restrictive access to the cryptographic key pairs and the encrypted data portions of the electronic files by deactivating the private keys at a future time;

instructions for determining whether the private key of the at least one of the cryptographic key pairs pertaining to the retention policy is permitted to be provided to a requestor based on whether the future event has occurred; and

instructions for permitting the private key to be provided to a system administrator even after the future event has occurred,

wherein the requestor requires the private key of the at least one of the cryptographic key pairs pertaining to the retention policy to access a secured electronic file, and wherein the secured electronic file was previously cryptographically associated with the retention policy by encrypting at least a data portion of the secured electronic file using the public key of the at least one of the cryptographic key pairs pertaining to the retention policy, and at the time the electronic file was so secured, the future event was unscheduled.

17. The file security system as recited in claim 16, wherein the instructions for determining comprise instructions for preventing the private key of the at least one of the cryptographic key pairs pertaining to the predetermined time from being provided to the requestor after a predetermined retention period following an occurrence of the future event.

18. The file security system as recited in claim 16, wherein the requestor is a client module that operatively connects to the electronic files over a network.

19. The file security system as recited in claim 16, wherein the file security system further comprises:

at least one client module configured to assist in selecting the retention policy and secure the electronic file using the public key of the at least one of the cryptographic key pairs pertaining to the retention policy so as to cryptographically impose the retention policy.

20. The file security system as recited in claim 16, wherein the file security system further comprises:

at least one client module, the client module assisting with unsecuring the secured electronic file by acquiring the private key of the at least one of the cryptographic key pairs that pertains to the retention policy from the key store if permitted, and then unsecuring the secured electronic file using the private key of the at least one of the cryptographic key pairs that pertains to the retention policy.

21. A non-transitory computer readable medium having computer-executable instructions stored thereon for providing data retention for electronic data, the computer-executable instructions comprising:

instructions to assign a data retention policy to the electronic data, the data retention policy being based on a future event that is unscheduled;

instructions to cryptographically associate, by using a cryptographic key to encrypt at least a data portion of the electronic data, the data retention policy with the electronic data, wherein the cryptographic key is a document retention key or a key encrypted with the document retention key, and wherein the cryptographic key is protected by a document access policy comprising access rules which provide restrictive access to the cryptographic key and the encrypted data portion of the electronic data by deactivating the cryptographic key at a future time; and

instructions to permit the deactivating to be overidden so that the electronic document remains accessible even after a document retention period.

22. The computer readable medium as recited in claim 21, wherein the instructions further comprise:

instructions to cryptographically prevent access to the electronic data in accordance with the data retention policy based on the future event occurring.

23. The computer readable medium as recited in claim 22, wherein the electronic data is an electronic file.

24. The computer readable medium as recited in claim 22, wherein the electronic data is an electronic document.

25. The computer readable medium as recited in claim 21 wherein

the data retention policy specifies the document retention period based on the future event.

26. The computer readable medium as recited in claim 25 wherein:

the data retention policy specifies the document retention period expires a predetermined period of time after the future event has occurred, and

the instructions further comprise;

instructions to determine whether the document retention period has expired; and

instructions to deactivate the cryptographic key in response to determining that the data retention period has expired, thereby preventing further access to the electronic data.