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Shamir’s Threshold Scheme

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Encyclopedia of Cryptography and Security

Related Concepts

Secret Sharing Schemes; Threshold Cryptography

Definition

A technique by means of polynomials to let k people recover a secret, while any combination of up to k − 1 people does not even have partial information about that secret.

Background

In Ref. [1], A. Shamir proposed an elegant “polynomial” construction of a perfect threshold schemes . An (n, k)-threshold scheme is a particular case of a secret sharing scheme when any set of k or more participants can recover the secret exactly while any set of less than k particiants gains no additional, that is, a posteriori, information about the secret. Such threshold schemes are called perfect and they were constructed in Refs. [ 21]. Shamir’s construction is the following.

Theory

Assume that the set S 0 of secrets is some finite field GF(q) of q elements (hence q should be prime power) and that the number of participants of SSS n < q. The dealer chooses n different nonzero elements (points) \({x}_{1},\ldots,{x}_{n} \in...

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Recommended Reading

  1. Shamir A (1979) How to share a secret. Commun ACM 22(1): 612–613

    Article  MATH  MathSciNet  Google Scholar 

  2. Blakley R (1979) Safeguarding cryptographic keys. In: Proceedings of AFIPS 1979 national computer conference, New York, vol 48, pp 313–317

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  3. McEliece RJ, Sarwate DV (1981) On secret sharing and Reed-Solomon codes. Commun ACM 24:583–584

    Article  MathSciNet  Google Scholar 

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Blakley, G.R., Kabatiansky, G. (2011). Shamir’s Threshold Scheme. In: van Tilborg, H.C.A., Jajodia, S. (eds) Encyclopedia of Cryptography and Security. Springer, Boston, MA. https://doi.org/10.1007/978-1-4419-5906-5_390

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