Cloud storage encryption

• US 10,043,029 B2
• Filed: 11/15/2017
• Issued: 08/07/2018
• Est. Priority Date: 04/04/2014
• Status: Active Grant

• Current Assignee: Zettaset Incorporated
• Original Assignee: Zettaset Incorporated
• Inventors: Murray, Eric A.
• Primary Examiner(s): WILLIAMS, JEFFERY L
• Application Number:
  US15/813,943
• Publication Number:
  US 20180082076A1
• Time in Patent Office: 265 Days
• Field of Search: None
• CPC Class Codes: G06F 21/602 Providing cryptographic facilities or services
• CPC Class Codes: G06F 21/6218 to a system of files or objects, e.g. local or distributed file system or database
• CPC Class Codes: G06F 2221/2107 File encryption
• CPC Class Codes: H04L 2463/062 applying encryption of the keys cryptographic mechanisms or cryptographic arrangements for key distribution using key encryption key H04L9/0822
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/0435 wherein the sending and receiving network entities apply symmetric encryption, i.e. same key used for encryption and decryption cryptographic mechanisms or cryptographic arrangements for symmetric key encryption H04L9/06
• CPC Class Codes: H04L 63/061 for key exchange, e.g. in peer-to-peer networks cryptographic mechanisms or cryptographic arrangements for key agreement H04L9/0838
• CPC Class Codes: H04L 63/08 for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32
• CPC Class Codes: H04L 63/0807 using tickets, e.g. Kerberos cryptographic mechanisms or cryptographic arrangements for entity authentication using tickets or tokens H04L9/3213
• CPC Class Codes: H04L 63/10 for controlling access to devices or network resources
• CPC Class Codes: H04L 63/20 for managing network security; network security policies in general filtering policies H04L63/0227
• CPC Class Codes: H04L 9/0618 Block ciphers, i.e. encrypting groups of characters of a plain text message using fixed encryption transformation
• CPC Class Codes: H04L 9/0631 Substitution permutation network [SPN], i.e. cipher composed of a number of stages or rounds each involving linear and nonlinear transformations, e.g. AES algorithms
• CPC Class Codes: H04L 9/0637 Modes of operation, e.g. cipher block chaining [CBC], electronic codebook [ECB] or Galois/counter mode [GCM]
• CPC Class Codes: H04L 9/0643 Hash functions, e.g. MD5, SHA, HMAC or f9 MAC
• CPC Class Codes: H04L 9/0822 using key encryption key
• 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 9/14 using a plurality of keys or algorithms
• CPC Class Codes: H04L 9/3242 involving keyed hash functions, e.g. message authentication codes [MACs], CBC-MAC or HMAC

Abstract

Techniques are disclosed for securing data in a cloud storage. Plaintext files are stored as secured, encrypted files in the cloud. The ciphering scheme employs per-block authenticated encryption and decryption. A unique file-key is used to encrypt each file. The file-key is wrapped by authenticated encryption in a wrapping-key that may be shared between files. A centralized security policy contains policy definitions which determine which files will share the wrapping-key. Wrapping-keys are stored in a KMIP compliant key manager which may be backed by a hardware security module (HSM). File metadata is further protected by a keyed-hash message authentication code (HMAC). A policy engine along with administrative tools enforce the security policy which also remains encrypted in the system.

Claims

1. A computer-implemented method for securing a plaintext file F_p as an encrypted, ciphertext file F_c in a cloud storage, said method comprising the steps of:

(a) providing a user U₁ using a client device, a network-based access to said cloud storage;

(b) assigning to said plaintext file F_p, a symmetric file-key FK;

(c) using a first authenticated encryption to encrypt each block M_i of said plaintext file F_p with said file-key FK by utilizing a corresponding initialization vector IV_i to obtain a corresponding encrypted block C_i and a corresponding authentication tag T_i;

(d) storing in said cloud storage, a corresponding data block *C_i of said encrypted, ciphertext file F_c, said data block *C_i comprising a sequence number of said corresponding block M_i, said corresponding initialization vector IV_i, said corresponding encrypted block C_i and said corresponding authentication tag T_i;

(e) using a second authenticated encryption to encrypt said file-key FK by a symmetric wrapping-key WK by utilizing an initialization vector IV_FK to obtain a wrapped-file-key WFK and an authentication tag T_FK;

(f) storing said wrapping-key WK in a key manager in accordance with a security policy; and

(g) storing a rotation date of said wrapping-key WK, a wrapping-key ID of said wrapping-key WK and said wrapped-file-key WFK in a metadata of said encrypted, ciphertext file F_c.

2. The method of claim 1, implementing said security policy by utilizing a policy engine and administrative tools.

3. The method of claim 2, routing said network-based access via a proxy server residing in the same network as said policy engine.

4. The method of claim 1, storing said initialization vector IV_FK and said authentication tag T_FK in said metadata of said encrypted, ciphertext file F_c.

5. The method of claim 1, using Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM) for said first authenticated encryption and said second authenticated encryption.

6. The method of claim 1, performing said step (c) in a shim layer configured above an application programming interface (API) of said cloud storage, said shim layer intercepting and servicing storage requests generated on said client device.

7. The method of claim 6, providing said storage requests to comprise one or more of a Get, a Put and a Copy operation.

8. The method of claim 6, configuring said shim layer to perform authenticated decryption of said encrypted block C_i to obtain corresponding said block M_i of said plaintext file F_p.

9. The method of claim 1, providing a representational state transfer (REST) server to perform said step (c).

10. The method of claim 1, cryptographically protecting said metadata from modification by computing a hash message authentication code (HMAC).

11. The method of claim 1, configuring said key manager to also reside in the same cloud where said cloud storage resides.

12. The method of claim 1, encrypting said wrapping-key WK by a master key stored in a physical and hardened hardware security module (HSM).

13. A cloud storage encryption system comprising at least one memory device storing computer-readable instructions, at least one microprocessor coupled to said at least one memory device for executing said computer-readable instructions, said system further comprising a client device with network-based access to a cloud storage and said at least one microprocessor configured to:

(a) assign a symmetric file-key FK to a plaintext file F_p;

(b) use a first authenticated encryption to encrypt each block M_i of said plaintext file F_p with said file-key FK by utilizing a corresponding initialization vector IV_i to obtain a corresponding encrypted block C_i and a corresponding authentication tag T_i;

(c) store in said cloud storage a corresponding data block *C_i of an encrypted, ciphertext file F_c, said data block *C_i comprising a sequence number of said corresponding block M_i, said corresponding initialization vector IV_i, said corresponding encrypted block C_i and said corresponding authentication tag T_i;

(d) in accordance with a security policy, use a second authenticated encryption to encrypt said file-key FK by a symmetric wrapping-key WK by utilizing an initialization vector IV_FK to obtain a wrapped-file-key WFK and an authentication tag T_FK, and store said wrapping-key WK in a key manager; and

(e) store a rotation date of said file-key FK, a rotation date of said wrapping-key WK, a wrapping-key ID of said wrapping-key WK and said wrapped-file-key WFK in a metadata of said encrypted, ciphertext file F_c.

14. The cloud storage encryption system of claim 13 wherein said cloud storage is hosted at one of an Amazon Web Services (AWS) data centers, Google Cloud data centers and Microsoft Azure data centers.

15. The cloud storage encryption system of claim 13, wherein a policy engine and administrative tools are utilized to enforce said security policy.

16. The cloud storage encryption system of claim 13, wherein said network-based access of said client device to said cloud storage is routed via a representational state transfer (REST) proxy server.

17. The cloud storage encryption system of claim 13, wherein said first authenticated encryption and said second authenticated encryption are performed using Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM).

18. The cloud storage encryption system of claim 13 wherein said cloud storage is hosted at the data centers of multiple cloud storage vendors.

19. The cloud storage encryption system of claim 13, wherein said first authenticated encryption is performed in a shim layer provided above an application programming interface (API) of said cloud storage, and wherein said shim layer intercepts and services storage requests from said client device, and wherein said storage requests comprise one or more of a Get, a Put and a Copy operation.

20. The cloud storage encryption system of claim 19, wherein said metadata is cryptographically protecting by a hash message authentication code (HMAC).

21. The cloud storage encryption system of claim 20, wherein a physical hardware security module (HSM) is used for storing a master key that is used for encrypting said wrapping-key WK.