Merge pull request #322 from yusufidimaina9989/master

Add confidentialVoting.ts

src/contracts/confidentialVoting.ts

@@ -0,0 +1,155 @@
+import {
+    Addr,
+    ByteString,
+    FixedArray,
+    HashedMap,
+    HashedSet,
+    PubKey,
+    Sha256,
+    Sig,
+    SmartContract,
+    Utils,
+    assert,
+    hash256,
+    int2ByteString,
+    method,
+    prop,
+} from 'scrypt-ts'
+
+export type ConfVotingCandidate = {
+    name: ByteString
+    address: Addr
+    votesReceived: bigint
+}
+
+export class ConfidentialVoting extends SmartContract {
+    @prop()
+    voters: HashedSet<PubKey>
+
+    @prop(true)
+    voteCommits: HashedMap<PubKey, Sha256>
+
+    @prop(true)
+    voteRevealed: boolean
+
+    @prop(true)
+    candidates: FixedArray<ConfVotingCandidate, 2>
+
+    @prop()
+    VoteDeadline: bigint
+
+    @prop()
+    revealDeadline: bigint
+
+    @prop(true)
+    voteFinished: boolean
+
+    constructor(
+        voters: HashedSet<PubKey>,
+        candidates: FixedArray<ConfVotingCandidate, 2>,
+        voteCommits: HashedMap<PubKey, Sha256>,
+        voteDeadline: bigint,
+        revealDeadline: bigint
+    ) {
+        super(...arguments)
+        this.voters = voters
+        this.voteRevealed = false
+        this.voteCommits = voteCommits
+        this.VoteDeadline = voteDeadline
+        this.revealDeadline = revealDeadline
+        this.voteFinished = false
+        this.candidates = candidates
+    }
+
+    @method()
+    public vote(
+        voter: PubKey,
+        salt :ByteString,
+        candidateIdx: bigint,
+        sig: Sig
+    ) {
+        // Check if voting is still allowed
+        assert(!this.voteRevealed, 'Voting is already closed')
+
+        const voteCommitment = Sha256(int2ByteString(candidateIdx) + salt)
+        // check if the passed public key is in the set of chosen voters
+        assert(this.voters.has(voter), 'pubkey not in the set of chosen voters')
+
+        // Verify if the voter is elliglble
+        assert(!this.voteCommits.has(voter))
+
+        // Store the commit associated with the voter
+        this.voteCommits.set(voter, voteCommitment)
+
+        // Check voter signature
+        assert(this.checkSig(sig, voter))
+
+        //propagate the state
+        let output =
+            this.buildStateOutput(this.ctx.utxo.value) +
+            this.buildChangeOutput()
+
+        assert(hash256(output) == this.ctx.hashOutputs, 'hashOutputs mismatch')
+    }
+
+    @method()
+    public reveal(
+        voter: PubKey,
+        vote: Sha256,
+        salt: ByteString,
+        candidateIdx: bigint
+    ) {
+        const voteCommitment = hash256(vote + salt)
+
+        if (this.voteCommits.size === this.voters.size) {
+            // Marked voting as revealed
+            this.voteRevealed = true
+            //check if the pubkey contained the passed commitment
+            assert(this.voteCommits.canGet(voter, voteCommitment))
+
+            // Update vote count
+            assert(
+                candidateIdx >= 0 && candidateIdx < 2,
+                'Invalid candidate index'
+            )
+            this.candidates[Number(candidateIdx)].votesReceived++
+        } else {
+            this.voteRevealed = false
+        }
+
+        // Check if voting deadline has passed
+        assert(
+            this.timeLock(this.VoteDeadline),
+            'Voting deadline has not passed'
+        )
+    }
+
+    @method()
+    public finish(candidateIdx: bigint) {
+        // candidate with the most votes wins
+
+        if (
+            Number(this.candidates[Number(0)].votesReceived) >
+            Number(this.candidates[Number(candidateIdx)].votesReceived)
+        ) {
+            // pay out winning candidate
+            Utils.buildPublicKeyHashOutput(
+                this.candidates[Number(0)].address,
+                10n
+            )
+            // log the winner
+            console.log('Winner:', this.candidates[Number(0)].name)
+        } else {
+            // pay out winning candidate
+            Utils.buildPublicKeyHashOutput(
+                this.candidates[Number(candidateIdx)].address,
+                10n
+            )
+            // log the winner
+            console.log('Winner:', this.candidates[Number(candidateIdx)].name)
+        }
+        this.voteFinished = true
+        // Ensure voting has been revealed
+        assert(this.voteRevealed, 'Voting has not been revealed yet')
+    }
+}