Resharing of a split secret

• US 9,768,953 B2
• Filed: 09/30/2015
• Issued: 09/19/2017
• Est. Priority Date: 09/30/2015
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Pure Storage, Inc.
• Inventors: Bernat, Andrew R., Miller, Ethan L.
• Primary Examiner(s): Shepperd, Eric W
• Application Number:
  US14/871,662
• Publication Number:
  US 20170093564A1
• Time in Patent Office: 720 Days
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/085 Secret sharing or secret splitting, e.g. threshold schemes
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying

Abstract

A processor-based method for secret sharing in a computing system is provided. The method includes encrypting shares of a new secret, using a previous secret and distributing unencrypted shares of the new secret and the encrypted shares of the new secret, to members of the computing system. The method includes decrypting at least a subset of the encrypted shares of the new secret, using the previous secret and regenerating the new secret from at least a subset of a combination of the unencrypted shares of the new secret and the decrypted shares of the new secret.

Claims

1. A processor-based method for secret sharing in a computing system, comprising:

encrypting, by an encryption/decryption unit, shares of a new secret, using a previous secret;

distributing unencrypted shares of the new secret and the encrypted shares of the new secret, to members of the computing system;

decrypting, by the encryption/decryption unit, at least a subset of the encrypted shares of the new secret, using the previous secret; and

regenerating the new secret from at least a subset of a combination of the unencrypted shares of the new secret and the decrypted shares of the new secret, wherein each member of the computing system receives an unencrypted share of the new secret and an encrypted, differing share of the new secret.

2. The method of claim 1, further comprising:

regenerating the previous secret from shares of the previous secret.

3. The method of claim 1, further comprising:

determining whether all members of the computing system have received the distributed shares of the new secret; and

encrypting a key, using the new secret, in response to determining that all of the members of the computing system have received the distributed shares of the new secret.

4. The method of claim 1, further comprising:

encrypting data, using a data encryption key; and

decrypting the data encryption key, using the new secret.

5. The method of claim 1, further comprising:

regenerating at least one share of the new secret from the new secret; and

distributing the at least one regenerated share of the new secret to at least one member of the computing system that does not have a share of the new secret.

6. The method of claim 1, further comprising:

determining whether all of the members of the computing system have received shares of the new secret; and

deleting the previous secret, responsive to a positive result of the determining.

7. The method of claim 1, further comprising:

iterating the encrypting, distributing, decrypting and regenerating for a plurality of further new secrets.

8. A tangible, non-transitory, computer-readable media having instructions thereupon which, when executed by a processor, cause the processor to perform a method comprising:

encrypting, with a previous secret, shares of a new secret;

distributing encrypted shares and unencrypted shares of the new secret;

decrypting, with the previous secret, available encrypted shares of the new secret; and

reproducing the new secret from at least a subset of available unencrypted shares of the new secret and the decrypted shares of the new secret, wherein each member of the computing system receives an unencrypted share of the new secret and an encrypted, differing share of the new secret.

9. The computer-readable media of claim 8, wherein the method further comprises:

reproducing the previous secret from previously generated shares of the previous secret.

10. The computer-readable media of claim 8, wherein the method further comprises:

repeating the encrypting, distributing, decrypting and reproducing in an iterative manner for further new secrets.

11. The computer-readable media of claim 8, wherein the method further comprises:

encrypting and decrypting data, with a data encryption key; and

encrypting and decrypting the data encryption key, with the new secret.

12. The computer-readable media of claim 8, wherein the method further comprises:

determining that all members of a system have received the shares of the new secret; and

deleting the previous secret, responsive to the determining.

13. The computer-readable media of claim 8, wherein the method further comprises:

determining whether members of a system have received the encrypted and unencrypted shares of the new secret; and

encrypting a key with the new secret, responsive to the determining.

14. The computer-readable media of claim 8, wherein the distributing includes sending at least one share of the new secret to off-site storage.

15. The computer-readable media of claim 8, wherein the method further comprises:

verifying that all of the shares of the new secret are stored; and

deleting shares of the previous secret, responsive to the verifying.

16. A computing system with a shared secret, comprising:

a secret generator, configured to generate and regenerate secrets;

a share splitter, configured to split a secret into a plurality of shares;

an encryption/decryption unit, configured to encrypt and decrypt; and

one or more processors, configured to perform actions comprising;

encrypting shares of a second secret, using a first secret and the encryption/decryption unit;

sending encrypted shares and unencrypted shares of the second secret to members of the computing system;

decrypting at least a subset of the encrypted shares of the second secret, using the encryption/decryption unit and the first secret; and

regenerating the second secret, using the secret generator and unencrypted shares and decrypted shares of the second secret,

wherein each member of the computing system receives an unencrypted share of the second secret and an encrypted, differing share of the second secret.

17. The computing system of claim 16, further comprising:

a memory having a header section configured to store keys and shares of secrets; and

the memory further having a data storage configured for storage of encrypted data, distinct from the header section.

18. The computing system of claim 16, wherein the actions further comprise:

regenerating the first secret from shares of the first secret, using the secret generator, so that the first secret can be used for encrypting the shares of the second secret.

19. The computing system of claim 16, wherein the actions further comprise:

regenerating at least one share of the second secret; and

updating at least one member of the computing system that is missing the at least one share of the second secret.