Design of Secure Fair Bidding Scheme Based on Threshold Elliptic Curve ElGamal Cryptography

The lowest price winning approach is used in some procurement bidding, which greatly saves the procurement cost, but in reality, there exists the problem of collusion between the purchaser and a bidding supplier, so it is very important to prevent the problem of conspiracy before the bid opening. This paper proposes a bidding scheme based on threshold elliptic curve ElGamal cryptosystem, the bidders jointly generate the public key and use elliptic curve ElGamal to encrypt the bidding price, in the bid opening stage, use the threshold joint decryption. In order to reduce the complexity of encryption and decryption, this paper proposes to group the bidding price numbers, quickly find out the minimum value of the two-digit integers so as to find out the lowest bidder. At the same time, ECDSA digital signature technology is used to achieve the integrity, non-repudiation and public verifiability of the price. By comparing and analyzing the security and performance of this scheme with homomorphic encryption algorithm, it is proved that this scheme improves the security and fairness of the price in the bidding process.