U.S. patents available from 1976 to present.
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Efficient techniques for sharing a secret

Patent 7167565 Issued on January 23, 2007. Estimated Expiration Date: Icon_subject May 11, 2021. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Patent References

Method for securely distributing a conditional use private key to a trusted entity on a remote system Patent #: 5991399
Issued on: 11/23/1999
Inventor: Graunke, et al.

Inventor

Assignee

Application

No. 09853913 filed on 05/11/2001

US Classes:

380/282, By public key method380/278, Key distribution380/279Key distribution center

Examiners

Primary: Moise, Emmanuel L.
Assistant: Pyzocha, Michael

Attorney, Agent or Firm

International Classes

H04L 9/30
H04L 9/14

Abstract

An n person secret sharing solution computes n unique keys to be distributed to the secret owners along with an exponentiated version of the secret. The custodian performs an exponent/modulo operation each time one of the keys is received from one of the secret owners. Alternatively, n+1 keys are created by the custodian, and the custodian retains one key after distributing the remaining n keys to the secret owners. After the custodian has received and processed the n keys from the secret owners, he performs an exponent/modulo operation using his own retained key. According to another aspect, a k out of n secret sharing solution involves computing and storing a database having an entry for each unique combination of k keys that could be returned from among the n keys. After k keys have been received, the custodian looks up in the database the entry corresponding to the particular unique combination of secret owners who returned keys. The custodian performs another exponent/modulo operation using the entry retrieved from the database in order to reconstruct the original secret. According to an embodiment, the custodian computes n+1 keys, distributes n of the keys to the secret owners, and keeps one of the keys for himself. The custodian retrieves his own key and performs a final exponent/modulo operation in order to reconstruct the original secret. According to another aspect, a k out of n secret sharing solution involves encrypting the original secret before applying any conventional k out of n secret sharing solution.

Other References

  • Shoup et al, “Securing Threshold Cryptosystems against Chosen Ciphertext Attack”, Nov. 22, 1999, pp. 1-14.
  • Schneier, “Applied Cryptoagraphy”, 1996, pp. 184-185, 466-474, 527.
  • “Modular arithmetic,” Wikipedia, pp. 1-3.
  • Schneier, Bruce, Applied Cryptography, 1996, pp. 181-182.
  • A. Shamir, “How to Share a Secret,” Communications of the ACM 22(11), Nov. 1979, pp. 612-613.
  • Bruce Schneier, Applied Cryptography, Second Edition: protocols, algorithms, and source code in C, 1996, p. 472, John Wiley & Sons, Inc., NY, USA.
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