Policy enforcement with associated data

• US 9,547,771 B2
• Filed: 02/12/2013
• Issued: 01/17/2017
• Est. Priority Date: 02/12/2013
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Roth, Gregory Branchek, Wren, Matthew James, Brandwine, Eric Jason, Pratt, Brian Irl
• Primary Examiner(s): POTRATZ, DANIEL B
• Application Number:
  US13/764,995
• Publication Number:
  US 20140230007A1
• Time in Patent Office: 1,435 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 21/602 Providing cryptographic facilities or services
• 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: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/20 for managing network security; network security policies in general filtering policies H04L63/0227
• 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
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/3242 involving keyed hash functions, e.g. message authentication codes [MACs], CBC-MAC or HMAC

Abstract

Requests submitted to a computer system are evaluated for compliance with policy to ensure data security. Plaintext and associated data are used as inputs into a cipher to produce ciphertext. Whether a result of decrypting the ciphertext can be provided in response to a request is determined based at least in part on evaluation of a policy that itself is based at least in part on the associated data. Other policies include automatic rotation of keys to prevent keys from being used in enough operations to enable cryptographic attacks intended to determine the keys.

Claims

1. A computer-implemented method for enforcing policy, comprising:

under the control of one or more computer systems configured with executable instructions,

using an authenticated encryption mode of a cipher to generate an authenticated ciphertext based at least in part on a key, a plaintext, and associated data, the authenticated ciphertext including a message authentication code and a ciphertext, wherein the message authentication code is calculated using the plaintext and the associated data;

associating a policy with the key, the policy specifying a value for the associated data, for providing the plaintext;

receiving, in connection with a request to decrypt the plaintext, a ciphertext, a purported message authentication code, and a purported associated data;

verifying that the purported messaged authentication code matches the message authentication code based at least in part on the received ciphertext and the purported associated data;

as a result of verifying that the purported message authentication code matches the message authentication code, determining, based at least in part on the purported associated data, whether the purported associated data matches the value for the associated data specified by the policy; and

providing the plaintext as a result of determining that the policy allows providing the plaintext, where the policy allows for providing the plaintext if the purported associated data matches the value for the associated data specified by the policy.

2. The computer-implemented method of claim 1, wherein the purported associated data is generated based at least in part on a user identifier.

3. The computer-implemented method of claim 2, wherein the purported associated data further includes an encoding of the user identifier.

4. The computer-implemented method of claim 1, wherein the authenticated ciphertext is generated based at least in part a symmetric block cipher supporting the authenticated encryption mode.

5. A computer-implemented method for enforcing policy, comprising:

under the control of one or more computer systems configured with executable instructions,

receiving a request to decrypt a ciphertext, the ciphertext having been generated using an authenticated encryption mode of a cipher to generate an authenticated ciphertext based at least in part on a plaintext, a key, and associated data, the authenticated ciphertext including a message authentication code and the ciphertext, wherein the message authentication code is calculated using the plaintext and the associated data;

as a result of verifying that the purported message authentication code matches the message authentication code based at least in part on the ciphertext and a purported associated data, determining, based at least in part on the purported associated data, whether the purported associated data matches a value for the associated data specified by a policy associated with the key, wherein the policy allows providing the plaintext in response to the request if the purported associated data matches the value for the associated data specified by the policy; and

providing at least the plaintext in response to determining that the policy allows providing the plaintext.

6. The computer-implemented method of claim 5, wherein the policy further specifies one or more restrictions on use of the key.

7. The computer-implemented method of claim 5, wherein the message authentication code is further based at least in part on data associated with the ciphertext.

8. The computer-implemented method of claim 7, wherein the ciphertext is further based at least in part on data verifiable with the ciphertext and the key.

9. The computer-implemented method of claim 7, wherein the policy further requires a characteristic of the request to match the data associated with the ciphertext for providing the plaintext to be allowable.

10. The computer-implemented method of claim 5, wherein the associated data encodes the policy and determining whether the policy allows providing the plaintext includes obtaining the policy from the associated data.

11. The computer-implemented method of claim 5, wherein the ciphertext encodes the policy and determining whether the policy allows providing the plaintext includes obtaining the policy from the ciphertext.

12. The computer-implemented method of claim 5, wherein the associated data encodes one or more attributes and determining whether the policy allows providing the plaintext includes checking whether the one or more attributes match attributes of the policy.

13. The computer-implemented method of claim 5, wherein the ciphertext encodes one or more attributes and determining whether the policy allows providing the plaintext includes checking whether the one or more attributes match attributes of the policy.

14. The computer-implemented method of claim 5, wherein the computer implemented method further comprises:

providing the plaintext includes providing the ciphertext to a security module; and

obtaining the plaintext from the security module.

15. A computer system, comprising:

one or more processors; and

memory including instructions that, when executed by the one or more processors, cause the computer system to;

receive a request to decrypt a ciphertext, the ciphertext having been generated using an authenticated encryption mode of a cipher to generate an authenticated ciphertext based at least in part on a plaintext, a key, and associated data, the authenticated ciphertext including a message authentication code and the ciphertext, wherein the message authentication code is calculated using the plaintext and the associated data;

as a result of verifying that the purported message authentication code matches the message authentication code based at least in part on the ciphertext and a purported associated data, determine, based at least in part on the purported associated data, whether the purported associated data matches a value for the associated data specified by a policy associated with the key, wherein the policy allows providing the plaintext in response to the request if the purported associated data matches the value for the associated data specified by the policy; and

provide at least the plaintext in response to determining that the policy allows providing the plaintext.

16. The system of claim 15, wherein verify that the purported message authentication code matches the message authentication code further includes using the message authentication code to check the authenticity of information associated with the request.

17. The system of claim 15, wherein the policy is encoded in a structured extensible data format.

18. The system of claim 15, wherein the cipher is generated using an advanced encryption standard cipher operated in either Galois/Counter Mode or cipher block chaining mode.

19. The system of claim 15, wherein providing at least the plaintext in response to determining that the policy allows providing the plaintext further comprises:

providing the ciphertext to a security module; and

obtaining the plaintext from the security module.

20. The system of claim 15, wherein the system is hosted by a computing resource service provider.

21. The system of claim 20, wherein the request to decrypt the cipher text is provided on behalf of a customer from one or more other computer systems hosted by the computing resource service provider.

22. The system of claim 15, wherein the policy is associated with a customer.

23. The system of claim 15, wherein verifying that the purported message authentication code further comprises verifying a submitted electronic signature included in the request.

24. A non-transitory computer-readable storage medium having stored thereon instructions that, when executed by one or more processors of a computer system, cause the computer system to:

receive a request to decrypt a ciphertext, the ciphertext having been generated using an authenticated encryption mode of a cipher to generate an authenticated ciphertext based at least in part on a plaintext, a key, and associated data, the authenticated ciphertext including a message authentication code and the ciphertext, wherein the message authentication code is calculated using the plaintext and the associated data;

verify that a purported message authentication code matches the message authentication code based at least in part on the ciphertext and a purported associated data;

as a result of verifying that the purported message authentication code matches the message authentication code, determine, based at least in part on the purported associated data, whether the purported associated data matches a value for the associated data specified by a policy associated with the key, wherein they policy allows providing the plaintext in response to the request if the purported associated data matches the value for the associated data specified by the policy; and

provide the plaintext in response to determining that the policy allows providing the plaintext.

25. The non-transitory computer-readable storage medium of claim 24, wherein:

the computer system is hosted by a service provider; and

the request is submitted on behalf of a customer of the service provider.

26. The non-transitory computer-readable storage medium of claim 25, wherein:

the instructions further cause the computer system to receive information encoding the policy from the customer; and

determining whether the purported associated data matches a value for the associated data specified by the policy is performed as a result of having received the information encoding the policy.

27. The non-transitory computer-readable storage medium of claim 24, wherein providing the plaintext includes providing the ciphertext to a security module and obtaining the plaintext from the security module.

28. The non-transitory computer-readable storage medium of claim 24, wherein evaluating the policy is further based at least in part on additional information obtained in connection with the request.

29. The non-transitory computer-readable storage medium of claim 24, wherein the policy further comprises a set of attributes encoded in a standardized data format.

30. The non-transitory computer-readable storage medium of claim 24, wherein the associated data encodes the policy.

31. The non-transitory computer-readable storage medium of claim 24, wherein determining that the policy allows providing the plaintext further comprises verifying a submitted electronic signature included in the request is within a predetermined amount of time from a current time.