Abstract
A (k,n) threshold based secret sharing scheme has been used to improve both safety and reliability of highly confiden-tial information. When this scheme is applied to preservation of secret key in public key cryptography, there is a risk of the reconstructed secret key being stolen. To overcome such a drawback, a (k,n) threshold based encoding scheme for ElGamal encryption system has been proposed. In this work, we developed a threshold decoding system for El-Gamal encryption using NFC (Near Field Communication). The developed system distributes secret keys of ElGamal cryptographic system to NFC devices such as IC cards and Android smartphones using (k,n) threshold scheme. We confirmed that the developed system can decode cryptograms without reconstructing the secret key.
https://ror.org/02f0psx94 
