Systems and methods for distributing and securing data

• US 20080137857A1
• Filed: 11/07/2007
• Published: 06/12/2008
• Est. Priority Date: 11/07/2006
• Status: Active Grant

• Current Assignee: Security First Innovations, LLC
• Original Assignee: Security First Corp
• Inventors: Bellare, Mihir, Rogaway, Philip
• Granted Patent: US 8,155,322 B2
• Time in Patent Office: Days
• US Class Current: 380/255
• CPC Class Codes: G06F 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: H04L 2209/24 Key scheduling, i.e. generating round keys or sub-keys for block encryption
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 9/0816 Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
• CPC Class Codes: H04L 9/085 Secret sharing or secret splitting, e.g. threshold schemes
• CPC Class Codes: H04L 9/0894 Escrow, recovery or storing of secret information, e.g. secret key escrow or cryptographic key storage
• CPC Class Codes: H04L 9/14 using a plurality of keys or algorithms
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority
• CPC Class Codes: H04L 9/3218 using proof of knowledge, e.g. Fiat-Shamir, GQ, Schnorr, ornon-interactive zero-knowledge proofs
• CPC Class Codes: H04L 9/3231 Biological data, e.g. fingerprint, voice or retina network architectures or network communication protocols for supporting authentication of entities using biometrical features in a packet data network H04L63/0861

Abstract

A robust computational secret sharing scheme that provides for the efficient distribution and subsequent recovery of a private data is disclosed. A cryptographic key may be randomly generated and then shared using a secret sharing algorithm to generate a collection of key shares. The private data may be encrypted using the key, resulting in a ciphertext. The ciphertext may then be broken into ciphertext fragments using an Information Dispersal Algorithm. Each key share and a corresponding ciphertext fragment are provided as input to a committal method of a probabilistic commitment scheme, resulting in a committal value and a decommittal value. The share for the robust computational secret sharing scheme may be obtained by combining the key share, the ciphertext fragment, the decommittal value, and the vector of committal values.

Claims

1. A method for securing data by generating a collection of fragments from the data, the method comprising:

applying a sharing mechanism of a computational secret sharing scheme to the data to produce a collection of shares;

generating a random or pseudo-random value;

computing a set of committal values and a set of decommittal values from the random or pseudo-random value and the collection of shares;

producing each fragment in the collection of fragments by combining a share, a decommittal value, and at least one committal value of the set of committal values; and

storing each fragment on at least one data repository.

2. The method of claim 1 wherein producing each fragment in the collection of fragments comprises combining a share, a decommittal value, and the entire set of committal values.

3. The method of claim 1 wherein storing each fragment on at least one data repository comprises storing each fragment at different geographic locations.

4. The method of claim 1 wherein storing each fragment on at least one data repository comprises storing each fragment at different physical locations on the at least one data repository.

5. The method of claim 1 wherein the at least one data repository comprises a distributed file system.

6. The method of claim 1 wherein the computational secret sharing scheme is selected from the group consisting of the Shamir, Blakley, and Krawczyk secret sharing schemes.

7. The method of claim 1 wherein computing a set of committal values and a set of decommittal values comprises employing a probabilistic commitment scheme.

8. The method of claim 1 further comprising transmitting the produced fragments over a plurality of communication channels.

9. The method of claim 8 wherein transmitting the produced fragments over a plurality of communication channels comprises transmitting each produced fragment over a different communication channel.

10. A method for securing data, the method comprising:

applying the sharing mechanism of a computational secret sharing scheme to the data to produce a collection of shares;

using a probabilistic commitment scheme to compute a set of committal values and a set of decommittal values from the collection of shares;

producing a plurality of fragments, wherein each fragment comprises a share of the collection of shares, a decommittal value of the set of decommittal values, and the set of committal values; and

storing each fragment on at least one data repository.

11. The method of claim 10 wherein storing each fragment on at least one data repository comprises storing each fragment at different geographic locations.

12. The method of claim 10 wherein storing each fragment on at least one data repository comprises storing each fragment at different physical locations on the at least one data repository.

13. The method of claim 10 wherein the at least one data repository comprises a distributed file system.

14. The method of claim 10 wherein the computational secret sharing scheme is selected from the group consisting of the Shamir, Blakley, and Krawczyk secret sharing schemes.

15. The method of claim 10 further comprising transmitting the produced fragments over a plurality of communication channels.

16. The method of claim 15 wherein transmitting the produced fragments over a plurality of communication channels comprises transmitting each produced fragment over a different communication channel.

17. A method for securing data comprising:

generating a cryptographic key;

encrypting the data with the cryptographic key to create a ciphertext;

producing a collection of n key shares by applying a secret sharing scheme to the cryptographic key;

producing a collection of n ciphertext chunks by applying an information dispersal algorithm to the ciphertext;

computing n committal values and n decommittal values by applying a probabilistic commitment scheme to each of the n key shares and n ciphertext chunks;

producing n data fragments, wherein each data fragment is a function of a key share, a ciphertext chunk, a decommittal value, and the committal values; and

storing the n data fragments on different logical storage devices, whereby the data is recoverable from a predefined number of the data fragments.

18. The method of claim 17 wherein storing the n data fragments on different logical storage devices comprises storing the n data fragments on n different logical storage devices.

19. The method of claim 17 further comprising transmitting the n data fragments over n communication channels before storing the n data fragments.

20. A method for recovering data from a collection of purported shares comprising:

receiving a designated purported share of the collection of purported shares, wherein the designated purported share is asserted to be valid;

separating each purported share into a content portion and a vector of checksums;

using the vector of checksums associated with the designated purported share to classify each share of the collection of purported shares as an actual share or as a bogus share; and

applying the recovery algorithm of a computational secret sharing scheme to the shares classified as actual shares to recover the data.