Loading...

Multi Stage Multi-Secret Sharing Schemes

Fatemi, Mitra | 2009

653 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39925 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Aref, Mohammad Reza
  7. Abstract:
  8. The subject of Secret Sharing refers to the methods that a secret information is shared (by a dealer) among a number of parties, so called participants, each having one or more shares, such that the predefined subsets of the participants, called authorized subsets, are able to regenerate the secret using their shares. A more general scheme which is called Multi Stage Secret Sharing (MSSS) is to share multiple secrets among the participants such that the authorized subsets can reconstruct the secrets in the consecutive stages; in these schemes, in addition to the individual shares, the dealer should provide the participants with a number of public values regarding the secrets. A Multi-Secret Sharing (MSS) scheme is a special case of the previous MSSS scheme that all secrets are disclosed at the same stage. An important feature in these schemes is the number of public values. While the MSSS schemes are able to provide computational security, it is shown in this thesis that the MSS schemes fail to do so. Furthermore, by introducing two new MSSS methods, we show that the previous schemes can be improved either in the size of the shares or the number of the public values. The first scheme which reduces the size of the shares related to each secret is based on the all-or-nothing transforms while the second, decreases the number of public values by employing the linear one-way functions. The latter scheme is also a multi-use approach and compared to the previous MSSS schemes, has less complexity in the process of shares distribution. Finally, using bilinear maps in the proposed scheme, the participants are provided with the ability of verifying the released shares from other participants. To the best of our knowledge, this is the first verifiable MSSS scheme which does not require a secure communication channel.

  9. Keywords:
  10. Computational Complexity ; Secret Sharing ; Multi-Secret Shairing ; Multistage Multisecret Sharing ; Public Values

 Digital Object List

 Bookmark