Pyramid

Pyramid.js

// A transparent Pyramid scheme
contract Pyramid {
    @state
    PubKeyHash schemer;

    // satoshi amount required to enter the scheme
    int entryFee;

    // dust limit
    static const int DUST = 1;

    // recruite two members to get double payout
    public function recruit(PubKeyHash recruit0, PubKeyHash recruit1, SigHashPreimage txPreimage) {
        // use ANYONECANPAY so recruits can deposit
        SigHashType sigHashType = SigHash.ANYONECANPAY | SigHash.ALL | SigHash.FORKID;
        require(Tx.checkPreimageSigHashType(txPreimage, sigHashType));

        // commission payout: double the original entry fee
        bytes commissionScript = Utils.buildPublicKeyHashScript(this.schemer);
        bytes commissionOutput = Utils.buildOutput(commissionScript, 2 * this.entryFee);

        // keep the scheme going from recruit0
        this.schemer = recruit0;
        bytes recruitScript0 = this.getStateScript();
        bytes recruitOutput0 = Utils.buildOutput(recruitScript0, DUST);

        // keep the scheme going from recruit1
        this.schemer = recruit1;
        bytes recruitScript1 = this.getStateScript();
        bytes recruitOutput1 = Utils.buildOutput(recruitScript1, DUST);

        bytes output = commissionOutput + recruitOutput0 + recruitOutput1;
        require(hash256(output) == SigHash.hashOutputs(txPreimage));
    }
}