Paper 2021/548

Secure Computation by Secret Sharing Using Input Encrypted with Random Number (Full Paper)

Keiichi Iwamura and Ahmad Akmal Aminuddin Mohd Kamal


Typically, unconditionally secure computation using a (k,n) threshold secret sharing scheme is considered impossible when n<2k-1. Therefore, in our previous work, we first took the approach of finding the conditions required for secure computation under the setting of n<2k-1 and showed that secure computation using a secret sharing scheme can be realized with a semi-honest adversary under the following three preconditions: (1) the result of secure computation does not include 0; (2) random numbers reconstructed by each server are fixed; and (3) each server holds random numbers unknown to the adversary and holds shares of random numbers that make up the random numbers unknown to the adversary. In this paper, we show that by leaving condition (3), secure computation with information-theoretic security against a semi-honest adversary is possible with k&#8804;n<2k-1. In addition, we clarify the advantage of using secret information that has been encrypted with a random number as input to secure computation. One of the advantages is the acceleration of the computation time. Namely, we divide the computation process into a preprocessing phase and an online phase and shift the cost of communication to the preprocessing phase. Thus, for computations such as inner product operations, we realize a faster online phase, compared with conventional methods.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Major revision. 18th International Conference on Security and Cryptography (SECRYPT 2021)
Secure computationMultiparty computationSecret sharingn<2k-1Information theoretical securityFast computation
Contact author(s)
ahmad @ sec ee kagu tus ac jp
iwamura @ ee kagu tus ac jp
2021-04-27: received
Short URL
Creative Commons Attribution


      author = {Keiichi Iwamura and Ahmad Akmal Aminuddin Mohd Kamal},
      title = {Secure Computation by Secret Sharing Using Input Encrypted with Random Number (Full Paper)},
      howpublished = {Cryptology ePrint Archive, Paper 2021/548},
      year = {2021},
      note = {\url{}},
      url = {}
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