SECURING A SECRET OF A USER

• US 20130212393A1
• Filed: 11/11/2012
• Published: 08/15/2013
• Est. Priority Date: 02/13/2012
• Status: Active Grant

• Current Assignee: AlephCloud Systems, Inc.
• Original Assignee: AlephCloud Systems, Inc.
• Inventors: D'Souza, Roy Peter
• Granted Patent: US 8,731,203 B2
• Time in Patent Office: Days
• US Class Current: 713/171
• 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 63/064 Hierarchical key distribution, e.g. by multi-tier trusted parties
• CPC Class Codes: H04L 63/0823 using certificates cryptographic mechanisms or cryptographic arrangements for entity authentication involving certificates H04L9/3263
• CPC Class Codes: H04L 63/107 wherein the security policies are location-dependent, e.g. entities privileges depend on current location or allowing specific operations only from locally connected terminals
• CPC Class Codes: H04L 9/085 Secret sharing or secret splitting, e.g. threshold schemes
• 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 9/30 Public key, i.e. encryption algorithm being computationally infeasible to invert or user's encryption keys not requiring secrecy
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority

Abstract

Methods, systems and apparatuses for securing a secret are disclosed. One method includes receiving a secret from the user and generating encrypted shares based on the secret, a policy, and a plurality of public keys. The encrypted shares are provided to a custodian, wherein the custodian verifies that the encrypted shares can be used to reconstitute the secret upon receiving the encrypted shares.

Claims

1. A method of securing a secret of a user, comprising:

receiving, by a user server, a secret from the user;

generating encrypted shares based on the secret, a policy, and a plurality of public keys;

providing the encrypted shares to a custodian server of a first custodian; and

verifying, by the custodian server, that the encrypted shares can be used to reconstitute the secret upon receiving the encrypted shares.

2. The method of claim 1, wherein generating the encrypted shares comprises:

generating a plurality of shares from the secret; and

encrypting each share utilizing a corresponding one of the plurality of public keys.

3. The method of claim 2, wherein verifying, by the custodian, that the encrypted shares can be used to reconstitute the secret upon receiving the encrypted shares comprises:

leveraging, by the first custodian, one-way cryptographic functions, wherein the first custodian can reconstruct the secret, but cannot obtain access to the secret or any of the shares.

4. The method of claim 1, further comprising a plurality of adjudicators, wherein each of the plurality of public keys has a corresponding at least one adjudicator of the plurality of adjudicators, and a corresponding secret key.

5. The method of claim 4, further comprising escrowing the corresponding secret key of one or more of the plurality of public keys.

6. The method of claim 5, wherein escrowing the corresponding secret key comprises:

generating, encrypted shares based on the corresponding secret key, a policy, and a plurality of public keys;

providing the encrypted shares to a second custodian.

7. The method of claim 5, wherein escrowing the corresponding secret key comprises:

generating, encrypted shares based on the corresponding secret key, a policy, and a plurality of public keys;

splitting the encrypted shares; and

providing the split encrypted shares between more than one custodian.

8. The method of claim 6, wherein the first custodian and the second custodian are part of a common network.

9. The method of claim 4, further comprising monitoring a loss of one or more of the plurality adjudicators.

10. The method of claim 9, further comprising providing the user with an early warning if the loss of adjudicators exceeds a threshold, thereby allowing the user to select new or different adjudicators.

11. The method of claim 1, wherein generating the encrypted shares based on the secret, a policy, and one or more public keys, is performed within a trust boundary.

12. The method of claim 1, wherein the custodian comprises a cloud network.

13. The method of claim 1, wherein verifying, by the first custodian, that the encrypted shares can be used to reconstitute the secret is based upon the encrypted shares received by the custodian, the public keys and the policy.

14. The method of claim 1, wherein the given condition comprises an event or a combination of events.

15. The method of claim 1, wherein approved parties can decrypt the shares, wherein approved parties comprise parties who have access to the encrypted shares.

16. The method of claim 1, wherein approved parties can decrypt the shares, wherein approved parties comprise parties who have secret keys that can decrypt the encrypted shares.

17. The method of claim 1, wherein the first custodian receives the encrypted shares, but cannot decrypt the secret shares.

18. The method of claim 1, further comprising:

receiving a user name, a number n of security questions, and a threshold value k from the user;

generating for each of the n security questions, key pairs SKi, PKi for encryption of subsequently created secret shares derived from the secret;

receiving N distinct questions Q[1] . . . Q[n] along with corresponding answers A[1] . . . A[n] to the N distinct questions Q[1] . . . Q[n] from the user;

wherein

generating the encrypted shares comprises;

deriving symmetric encryption keys KA[i] based on each of the answers;

encrypting each of the key pairs SKi, PKi based on a corresponding symmetric encryption key KA[i], to obtain encrypted keys ESK[1] . . . ESK[n].

19. The method of claim 18, wherein providing the encrypted shares to the first custodian comprises:

uploading the encrypted keys ESK[1] . . . ESK[n] and the distinct questions Q[1] . . . Q[n] to the custodian; and

wherein

verifying comprises;

generating secret shares SS[1] . . . SS[n];

generating encrypted shares ESS[i] by encrypting each secret share SS[1] . . . SS[n] using the corresponding public key PKi;

uploading the encrypted share ESS[1] . . . ESS[n];

generating an asymmetric key pair (PK, SK); and

obtaining an encrypted asymmetric key ESK by encrypting the secret key SK using an symmetric encryption key PWD_K derived from a passphrase password as specified by a user; and

uploading the encrypted asymmetric key ESK.

20. The method of claim 19, further comprising:

prompting the user to select and provide answers A′

[1] . . . A′

[k] to the k security questions Q[1] . . . Q[k];

downloading, by the user device, encrypted shares ESS[1] . . . ESS[k] and encrypted keys ESK[1] . . . ESK[k];

deriving keys KA[1] . . . KA[k] from the provided answers A′

[1] . . . A′

[k];

(an incorrect answer yields an incorrect key)

attempting to decrypt ESK[1] . . . ESK[k] using the keys KA[1] . . . KA[k];

obtaining the secret keys SK[1] . . . SK[k];

decrypting the encrypted shares ESS[1] . . . ESS[k] using the secret keys SK[1] . . . SK[k];

obtaining the secret shares SS[1] . . . SS[k] based on the encrypted shares ESS[1] . . . ESS[k];

recovery the password or the symmetric encryption key PWD_K using the secret shares SS[1] . . . SS[k] if the provided answers A′

[1] . . . A′

[k] are correct.

21. The method of claim 20, wherein if the provided answers are determine not to be correct, the prompting the user for a new set of k security questions and answers.

22. The method of claim 20, wherein if the provided answers are determine to be correct, than allowing the user to change the secret.

23. A system for securing a secret, comprising:

a user server operative to;

receive a secret from the user;

generate encrypted shares based on the secret, a policy, and a plurality of public keys; and

provide the encrypted shares to a custodian server;

wherein

the custodian server verifies that the encrypted shares can be used to reconstitute the secret upon receiving the encrypted shares.

24. A custodian server operating a cloud connect service, the custodian server operative to:

receive encrypted shares from a user server, wherein the encrypted shares based on a secret, a policy, and a plurality of public keys, an wherein the secret is received from a user of the user device; and

verify that the encrypted shares can be used to reconstitute the secret upon receiving the encrypted shares.