CONTROLLING ACCESS TO PROTECTED OBJECTS

• US 20120321087A1
• Filed: 06/17/2011
• Published: 12/20/2012
• Est. Priority Date: 06/17/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Fleischman, Eric, Rouskov, Yordan, Kamel, Tarek
• Granted Patent: US 10,333,711 B2
• Time in Patent Office: Days
• US Class Current: 380/279
• CPC Class Codes: H04L 9/3213 using tickets or tokens, e.g. Kerberos network architectures or network communication protocols for entities authentication using tickets in a packet data network H04L63/0807
• CPC Class Codes: H04L 9/3231 Biological data, e.g. fingerprint, voice or retina network architectures or network communication protocols for supporting authentication of entities using biometrical features in a packet data network H04L63/0861
• CPC Class Codes: H04L 9/3234 involving additional secure or trusted devices, e.g. TPM, smartcard, USB or software token network architectures or network communication protocols for supporting authentication of entities using an additional device in a packet data network H04L63/0853

Abstract

A device operated by a user may store an object to which access is to be regulated, which may be achieved by encrypting the object with an encryption key and sending the key to a server having a key store. When a user of the device requests access to the object, the server may authenticate the user (e.g., according to a credential submitted by the user) and verify a trust identifier of the device (e.g., authorization to access the object through the device, and/or the integrity of the device), before sending to the device a ticket granting access to the key. The device may send the ticket to the server, receive the key from the server, decrypt the stored encrypted object, and provide the object to the user. This mechanism promotes rapid access upon request and efficient use of the server, and enables remote revocation of access.

Claims

1. A method of regulating access, by a server having a processor and a key store that stores a key, to an object encrypted with the key and stored on a device operated by a user, the method comprising:

executing on the processor instructions configured to;

store the key in the key store;

upon receiving a request from the device to access the key;

authenticate the user;

verify a trust identifier of the device; and

upon authenticating the user and verifying the trust identifier of the device;

generate a ticket granting access to the key, and

send the ticket to the device; and

upon receiving the ticket from the device;

verify the ticket, and

upon verifying the ticket, send the key to the device.

2. The method of claim 1:

the server configured to store at least one credential of the user; and

authenticating the user comprising;

receiving a submitted credential from the user, and

comparing the submitted credential with the at least one credential of the user.

3. The method of claim 2, at least one credential of the user selected from a credential set comprising:

a secret known by the user;

a token possessed by the user;

a contact identifier whereby the user may be contacted; and

a biometric identifier identifying at least one physiological feature of the user.

4. The method of claim 1, comprising:

generating the key, and

instructing the device to encrypt at least one object with the key.

5. The method of claim 1, comprising:

receiving from the device a key generated by the device and with which at least one object has been encrypted.

6. The method of claim 1, verifying the trust identifier of the device comprising:

verifying a device integrity of the device.

7. The method of claim 1:

the ticket having a duration; and

verifying the ticket comprising;

verifying the duration of the ticket.

8. The method of claim 1:

the device having at least one device identifier;

the ticket specifying at least one device identifier of the device to which the ticket is issued; and

verifying the ticket comprising;

receiving at least one device identifier of the device, and

verifying that the ticket specifies at least one device identifier received from the device.

9. The method of claim 1, the instructions configured to, upon failing to identify a ticket received from a device:

re-authenticate the user using the at least one credential;

re-verify a trust identifier of the device; and

upon re-authenticating the user and re-verifying the trust identifier of the device;

generate a renewed ticket granting access to the key, and

send the renewed ticket to the device.

10. The method of claim 1, the instructions configured to, upon detecting an unauthorized access attempt relating to the object:

send to the device a request to encrypt the object with a second key; and

upon receiving the second key from the device, replace the first key in the key store with the second key.

11. A method of accessing objects on a device operated by a user and having a processor and a data store using a server having a key store, the method comprising:

executing on the processor instructions configured to;

receive a key;

encrypt the object with the key to generate an encrypted object;

store the encrypted object in the data store;

send the key to the server;

upon receiving a request from the user to access the object;

submit to the server;

at least one credential authenticating the user, and

a trust identifier of the device; and

upon receiving a ticket from the server;

send the ticket to the server, and

upon receiving a key from the server;

decrypt the encrypted object with the key to generate an unencrypted object, and

present the unencrypted object in response to the request.

12. The method of claim 11, receiving the key comprising:

receiving the key from the server.

13. The method of claim 11:

the device comprising a biometric sensor configured to detect at least one biometric identifier of a user;

the at least one credential authenticating the user comprising a biometric identifier stored by the server and representing the user; and

submitting the at least one credential authenticating the user to the server comprising;

using the biometric sensor, detecting at least one biometric of the user, and

submitting the at last one biometric to the server for comparison with a corresponding biometric identifier of the user.

14. The method of claim 11:

the device configured to test at least one device component of the device to generate a component integrity credential identifying a component integrity of the device component;

the trust identifier of the device comprising a verified component integrity credential of the device stored by the server and representing a component integrity of the device component; and

submitting the trust identifier of the device to the server comprising;

detecting at least one component integrity credential of at least one device component, and

submitting the at least one component integrity credential to the server for comparison with a corresponding verified component integrity credential.

15. The method of claim 11:

the device comprising a secured data store; and

the instructions configured to;

upon receiving a key, store the key in the secured data store;

upon generating the unencrypted object, store the unencrypted object in the secured data store; and

upon receiving a request to perform an operation on the object;

verify the ticket, and

upon verifying the ticket, perform the operation on the object.

16. The method of claim 11, the instructions configured to, after decrypting an encrypted object:

re-verify the ticket, and

upon failing to re-verify the ticket;

discard the key, and

discard the unencrypted object.

17. The method of claim 16, the instructions configured to, upon failing to re-verify the ticket:

resubmit to the server;

at least one credential authenticating the user, and

a trust identifier of the device; and

receive a renewed ticket from the server.

18. The method of claim 11, the instructions configured to, upon detecting an unauthorized access attempt related to an object:

discard tickets, keys, and unencrypted objects associated with the object, and

report the unauthorized access attempt to the server.

19. The method of claim 11, the instructions configured to, upon receiving from the server a request to encrypt the object with a second key:

generate a second key;

decrypt the object using the key;

encrypt the object using the second key to generate a second encrypted object;

store the second encrypted object in the data store; and

send the second key to the server.

20. A computer-readable storage medium comprising instructions that, when executed on a processor of a server comprising a key store configured to store at least one key and a credential store configured to store at least one credential of at least one user, provide an object to a user of a device having a device identifier by:

upon receiving a key, storing the key in the key store;

upon receiving a credential of a user, store the credential of the user in the credential store;

upon receiving a request from the device to access the key;

authenticating the user by;

receiving a submitted credential from the user, and

comparing the submitted credential with the at least one credential of the user;

verifying a trust identifier delegated to the device by a user of the device; and

upon authenticating the user and verifying the trust identifier of the device;

generating a ticket granting access to the key and having a duration and at least one device identifier of the device, and

sending the ticket to the device; and

upon receiving the ticket from the device;

verifying the ticket by;

receiving at least one device identifier of the device;

verifying that the ticket specifies at least one device identifier received from the device; and

verifying the ticket duration;

upon verifying the ticket, sending the key to the device;

upon failing to identify a ticket received from a device;

re-authenticating the user using the at least one credential;

re-verifying a trust identifier of the device; and

upon re-authenticating the user and re-verifying the trust identifier of the device;

generating a renewed ticket granting access to the key, and

sending the renewed ticket to the device; and

upon detecting an unauthorized access attempt relating to the object;

sending to the device a request to encrypt the object with a second key; and

upon receiving the second key from the device, replacing the first key in the key store with the second key.