Information security architecture for encrypting documents for remote access while maintaining access control

• US 6,978,376 B2
• Filed: 12/15/2000
• Issued: 12/20/2005
• Est. Priority Date: 12/15/2000
• Status: Expired due to Term

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: Authentica, Inc. (Dell Technologies Inc.)
• Inventors: Sharko, John, Giroux, David
• Primary Examiner(s): Sheikh, Ayaz
• Assistant Examiner(s): Chai, Longbit
• Application Number:
  US09/736,229
• Publication Number:
  US 20020078361A1
• Time in Patent Office: 1,831 Days
• Field of Search: 713164-167, 713193-194, 713/189, 713200-201, 707/104, 707/100, 380277-279, 380/282, 380/281, 380/284, 712/209, 705/57
• US Class Current: 713/189
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/062 for key distribution, e.g. centrally by trusted party cryptographic mechanisms or cryptographic arrangements for key distribution involving a central third party H04L9/0819
• CPC Class Codes: H04L 63/068 using time-dependent keys, e.g. periodically changing keys cryptographic mechanisms or cryptographic arrangements for controlling usage of secret information H04L9/088
• CPC Class Codes: H04L 63/10 for controlling access to devices or network resources
• CPC Class Codes: H04L 9/083 involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]
• CPC Class Codes: H04L 9/088 Usage controlling of secret information, e.g. techniques for restricting cryptographic keys to pre-authorized uses, different access levels, validity of crypto-period, different key- or password length, or different strong and weak cryptographic algorithms network architectures or network communication protocols for using time-dependent keys in a packet data network H04L63/068

Abstract

A method of controlling distribution of a segment of encrypted electronic information is presented. A key server receives a protected copy of a decryption key for the segment. The segment is retrieved at a user location. The protected copy of the decryption key is accessed. In response to the accessing, the segment is decrypted using the accessed copy of the decryption key at the user location. The accessed copy of the decryption key is destroyed at the user location in response to the decrypting. The decrypted segment is displayed in response to the decrypting. The decrypted segment is destroyed in response to the displaying.

Claims

1. A method of controlling distribution of a segment of encrypted electronic information, comprising:

receiving, from a key server, a protected decryption key associated with the segment;

retrieving, at a user location, the segment;

obtaining an unprotected copy of the decryption key from the protected decryption key;

decrypting, in response to said obtaining, the segment using the unprotected copy of the decryption key;

destroying the unprotected copy of the decryption key at the user location in response to said decrypting;

displaying the decrypted segment in response to said decrypting; and

destroying the decrypted segment in response to said displaying.

2. The method of claim 1, further comprising:

saving, in response to said receiving, the protected decryption key;

wherein said destroying the unprotected copy of the decryption key does not effect the protected copy of the decryption key.

3. The method of claim 1, further comprising:

said receiving further comprising receiving at least one access policy associated with at least one of the key server, the user location, the segment, the decryption key, and a user, the at least one access policy including at least one fixed time limitation;

said determining comprising determining whether current operating conditions, including the current time, satisfy the at least one access policy.

4. The method of claim 1, further comprising:

saving, in response to said receiving, the protected decryption key in memory; and

rendering the protected copy of the decryption key inaccessible after an expiration time in the at least one access policy.

5. The method of claim 1, further comprising:

logging said obtaining in a log; and

sending, from the user location to a remote server, the log.

6. The method of claim 5, further comprising logging a time of said obtaining in the log.

7. A method of controlling distribution of electronic information, comprising:

sending, from a user location to a key server, a request to access a protected segment, and a first information;

receiving, at the user location from the key server, an encrypted voucher and a second information, said voucher including at least a decryption key associated with the segment;

retrieving, at a user location, the segment;

obtaining a decrypted copy of the decryption key using the first and second information;

accessing, in response to said decrypting, the segment using the at least a portion of the voucher;

destroying, in response to said accessing, the decrypted copy of the decryption key.

8. The method of claim 7, further comprising:

displaying the accessed segment in response to said accessing; and

destroying the accessed segment in response to said displaying.

9. The method of claim 7, wherein the voucher includes access policies, the method further comprises:

determining, in response to said decrypting, whether operating parameters satisfy the access policies; and

said accessing being responsive to said operating parameters being determined to satisfy the access policies;

wherein said accessing is responsive to said decrypting through said determining.

10. A method for controlling distribution of electronic information, comprising:

retrieving, at a user location, a segment of encrypted electronic information;

receiving, from a key server, an encrypted decryption key for the segment;

saving said encrypted decryption key in a memory;

obtaining a decrypted copy of the decryption key in response to an authorized user request to access the segment;

accessing the segment using the decrypted copy of the decryption key at the user location for the segment; and

destroying the decrypted copy of the decryption key at the user location in response to said accessing without destroying the encrypted decryption key in memory.

11. The method of claim 10, further comprising:

displaying the decrypted segment in response to said accessing; and

destroying the decrypted segment in response to one of said displaying.

12. A method of accessing a protected segment of electronic information, the segment having an associated key, comprising:

retrieving, at the user location, the segment;

receiving, at the user location from the remote server, the key;

accessing the segment, in response to said receiving, using the key;

displaying the segment as accessed;

destroying the key in response to one of said displaying and said accessing, wherein the key is momentarily stored in memory at a user location between said receiving and said destroying;

receiving, at the user location from the remote server, an encrypted key lease including the key;

saving the encrypted key lease in a memory;

breaking a connection between the user location and the remote server; and

during a period of the broken connection;

retrieving, at the user location, the segment;

obtaining a decrypted copy of the key from the key lease;

accessing the segment in response to said obtaining;

displaying the segment as accessed; and

destroying the decrypted copy of the key in response to one of said displaying and said accessing.

13. The method of claim 12, further comprising restoring a connection between the user location and the remote server.

14. The method of claim 13, further comprising revoking the key lease after said restoring.

15. The method of claim 13, further comprising:

logging said obtaining in a log; and

sending, after said restoring, the log from the user location to the remote server.

16. The method of claim 15, further comprising detecting, at one of the user location and the remote server, from the contents of the log, any tampering at the user location relating to at least one of the key lease, the segment, and operating conditions at the user location.

17. A method of viewing a segment of encrypted electronic information on a display, comprising:

receiving, from a remote server, an encrypted decryption key for the segment;

retrieving, at a user location, a segment of encrypted electronic information;

first decrypting the encrypted decryption key in response to the presence of authorized conditions;

second decrypting the segment using the decrypted decryption key;

destroying, at the user location, all copies of the decrypted decryption key in response to said second decrypting, without destroying the encrypted decryption key;

displaying the segment as decrypted on the display; and

destroying, at the user location, the segment as decrypted in response to said displaying.

18. A method of controlling distribution of a segment of encrypted electronic information, the segment having a first and second portion, the method comprising:

receiving, from a key server, an encrypted voucher, the voucher including first and second decryption keys associated with the first and second portions, respectively,

retrieving, at a user location, the segment;

accessing the protected copy of the first decryption key;

decrypting, in response to said accessing, the first portion of the segment using the accessed copy of the first decryption key;

destroying the accessed copy of the first decryption key at the user location in response to said decrypting;

displaying the decrypted segment in response to one of said decrypting and said destroying;

destroying the decrypted first portion in response to said displaying;

accessing the protected copy of the second decryption key after said destroying the first decrypted segment; and

decrypting, in response to said accessing the protected copy of the second decryption key, the second portion of the segment using the accessed copy of the second decryption key.

19. A method of limiting access to a segment of encrypted information, comprising:

saving, at a remote server, a decryption key for the segment, the segment being at a location other than the remote server;

receiving a request from an authorized user for the decryption key;

sending a copy of the decryption key from the remote server to a source of the request;

destroying the decryption key at the remote server in response to the elapse of a predetermined period of time; and

preventing the source from retaining the copy of the decryption key, wherein said destroying leaves said segment permanently inaccessible absent breaking of the encryption protecting of the segment.

20. A system for accessing a protected segment of electronic information, comprising:

means for receiving, from a key server, a protected decryption key associated with said segment;

means for retrieving, at a user location, said segment;

means for obtaining an unprotected copy of said decryption key from said protected decryption key;

means for decrypting, in response to said obtaining, said segment using said unprotected copy of said decryption key;

means for destroying said unprotected copy of said decryption key at said user location in response to said decrypting;

means for displaying said decrypted segment in response to said decrypting; and

means for destroying said decrypted segment in response to said displaying.

21. The method of claim 20, further comprising:

means for saving, in response to said receiving, said protected decryption key;

wherein said means for destroying said unprotected copy of said decryption key does not effect said unprotected copy of said decryption key.