[BidSecure]

[Sandesh-Pyakurel]

Show and tell project type

Builder Bounty Submission

Github Repo Link

https://github.com/Sandesh-Pyakurel/Bidding/

Video Walkthough Link

https://github.com/Sandesh-Pyakurel/Bidding?tab=readme-ov-file#demo

Project Description

BidSecure is a secure web application designed for online auctions. Bidders can place bids on available auctions, and auctioneers can post items for auction. BidSecure leverages Nillion network to ensure secure bidding, and to find out the highest bidder without revealing the bid amount. It is inspired from TinyBid.

What problems does your project solve? How does it preserve privacy for users?

Problem

Auction with open bidding reveals the bid amounts and could raises concerns about fairness and bid manipulation.

Solution

We use nillion network to store bid amounts, where it is stored as encrypted value and computation is done using the encrypted value. So in any moment the secret is maintained. So, at the end of the auction we can know who is the highest bidder but the bid amount is never revealed.

How does the project use Nillion? Describe and link to any Nada programs

We use nillion to store bid as secrets. The auctioneer stores the nada program in the network. Bidders input their bids and give the auctioneer compute permission. At the end of the auction auctioneer compute the program and determines the winner. In nada program we determine the winner by traversing the array to find the maximum amount and in the next pass find all the maximum bids. Here is the nada program:

from nada_dsl import *

# Initialize input bids variables.
def initialize_bids(n_bids, party):
    bids = []

    for i in range(n_bids):
        bids.append(SecretInteger(Input(name="bid"+str(i+1), party=party)))

    return bids


"""
Function to find the highest bid ammount. First maximum bid amount is determined
and all the bids having the maximum amount is set to 2 in output list.
"""
def find_winners(n_bids, bids, party):
    max_value = bids[0]

    for i in range(1, n_bids):
        max_value = (max_value < bids[i]).if_else(bids[i], max_value)

    output = []
    for i in range(n_bids):
        val = (bids[i] == max_value).if_else(Integer(2), Integer(1))
        output.append(Output(val, "output"+str(i+1), party=party))

    return output


def nada_main():
    n_bids = 10 # number of input bids.

    party = Party('Party1')
    bids = initialize_bids(n_bids, party)

    output = find_winners(n_bids, bids, party)

    return output

To handle the auction having bids less than maximum number of bids, auctioneer passes the minimum amount as compute time secret. All the interfacing python code can be found here.

Is there anything else you want to share?

No response

Optional - Link your project and team members' social handles

https://www.linkedin.com/in/susheelthapa/
https://www.linkedin.com/in/subash-lamichhane-162868299/
https://www.linkedin.com/in/sandesh-pyakurel-714394154/

Optional - Team ETH Address(es)

No response