Saving and Retrieving Data Based on Symmetric Key Encryption

• US 20070067624A1
• Filed: 11/08/2006
• Published: 03/22/2007
• Est. Priority Date: 04/17/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: England, Paul, Peinado, Marcus
• Granted Patent: US 7,587,589 B2
• Time in Patent Office: Days
• US Class Current: 713/164
• CPC Class Codes: G06F 21/6218 to a system of files or objects, e.g. local or distributed file system or database

Abstract

In accordance with certain aspects, data is received from a calling program. Ciphertext that includes the data is generated, using a symmetric cipher, in a manner that allows only one or more target programs to be able to obtain the data from the ciphertext. In accordance with other aspects, a bit string is received from a calling program. An identifier of the calling program is checked to determine whether the calling program is allowed to access data encrypted in ciphertext of the bit string. The integrity of the data is also verified, and the data is decrypted using a symmetric key. The data is returned to the calling program only if the calling program is allowed to access the data and if the integrity of the data is successfully verified.

Claims

1. A system comprising:

a plurality of hierarchical layers including a lowest layer that guards a root resource;

wherein the plurality of hierarchical layers further includes one or more intermediate layers that act as principals that request access to the root resource from the next lower layer and that act as guards to the root resource toward principals in the next higher layer; and

allowing access to the root resource only to principals authorized to access the root resource.

2. A system as recited in claim 1, wherein the plurality of hierarchical layers comprises four layers, wherein the lowest layer comprises a security kernel layer, wherein a next lowest layer comprises a basic input/output system layer, wherein a next lowest layer comprises an operating system layer, and wherein a highest layer comprises an application layer.

3. A system as recited in claim 1, wherein the allowing comprises using a Seal operation to securely seal the root resource and an UnSeal operation to retrieve the root resource.

4. A system as recited in claim 1, wherein the root resource comprises a cryptographic key.

5. A system comprising:

a plurality of hierarchical layers including a lowest layer that guards a root resource;

a plurality of guards included in each of the plurality of hierarchical layers, wherein each guard is a service guard or a disclosure guard;

wherein each service guard allows principals in the next higher layer to request operations to be performed with protected data, and wherein the service guard performs the operation only if a condition is satisfied; and

wherein each disclosure guard allows principals in the next higher layer to request protected data to be disclosed to the principals, and wherein the disclosure guard discloses the protected data only if another condition is satisfied.

6. A system as recited in claim 5, wherein each of the principals in the next higher layer is a service guard or a disclosure guard.

7. A system as recited in claim 5, wherein one or more guards are implemented by obtaining protected data from a guard in the layer below it.

8. A system as recited in claim 5, wherein one or more guards are implemented by requesting a service from a guard in the layer below it.

9. A system as recited in claim 5, wherein the protected data are cryptographic keys.

10. A system as recited in claim 5, wherein one or more service guards expose, on protected data, one or more of encryption, decryption, digital signing, Message Authentication Code (MAC), and combined digital signing and integrity verification.

11. A system comprising:

a plurality of hierarchical layers including a lowest layer that guards a root resource;

wherein the plurality of hierarchical layers further includes one or more intermediate layers that,

act as principals that request, from the next lower layer, operations to be performed using the root resource, and

act as guards to the root resource toward principals in the next higher layer; and

allowing the operations to be performed using the root resource only for principals authorized to access the root resource.

12. A system as recited in claim 11, wherein the plurality of hierarchical layers comprises four layers, wherein the lowest layer comprises a security kernel layer, wherein a next lowest layer comprises a basic input/output system layer, wherein a next lowest layer comprises an operating system layer, and wherein a highest layer comprises an application layer.

13. A system as recited in claim 11, wherein the root resource comprises a cryptographic key.