strawstack/secure_dice_roll.html

## secure_dice_roll.html
<html>
    <head>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/4.2.0/crypto-js.min.js" integrity="sha512-a+SUDuwNzXDvz4XrIcXHuCf089/iJAoN4lmrXJg18XnduKK6YlDHNRalv4yd1N40OKI80tFidF+rqTFKGPoWFQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
    </head>
    <body>
        <script>
            function rollDice() {
                return (Math.floor(Math.random() * 6) + 1).toString();
            }

            function getSecret() {
                const lookup = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
                const secret = [];
                for (let i = 0; i < 30; i++) {
                    secret.push(
                        lookup[Math.floor(Math.random() * lookup.length)]
                    );
                }
                return secret.join("");
            }

            function encrypt(number, secret) {
                return CryptoJS.AES.encrypt(number, secret);
            }

            function decrypt(message, secret) {
                return CryptoJS.AES.decrypt(message, secret);
            }

            // Only dm can access dm values
            const dm = {};

            // DM Calculate offset value
            dm.offset = rollDice();

            // DM generate secret
            dm.secret = getSecret();

            // DM encrypt offset value
            dm.encrypted_offset = encrypt(dm.offset, dm.secret);

            // Only player can access player values
            const player = {};

            // Player stores copy of dm encyptyed offset
            player.encrypted_dm_offset = dm.encrypted_offset;

            // Player rolls dice
            player.offset = rollDice();

            // DM stores copy of player roll
            dm.player_offset = player.offset;

            //
            // Once player receives secret, both parties decrypt and compare answer
            //

            // Player stores dm secret
            player.secret = dm.secret;

            // Player calculated roll
            const offset = decrypt(player.encrypted_dm_offset, player.secret);
            player.roll = ((offset + player.offset) % 6) + 1;

            // DM calculated roll
            dm.roll = ((dm.offset + dm.player_offset) % 6) + 1;

            console.log(
                `dm: ${dm.roll}\nplayer: ${player.roll}`
            );
        </script>
    </body>
</html>
	<html>
	<head>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/4.2.0/crypto-js.min.js" integrity="sha512-a+SUDuwNzXDvz4XrIcXHuCf089/iJAoN4lmrXJg18XnduKK6YlDHNRalv4yd1N40OKI80tFidF+rqTFKGPoWFQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
	</head>
	<body>
	<script>
	function rollDice() {
	return (Math.floor(Math.random() * 6) + 1).toString();
	}

	function getSecret() {
	const lookup = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	const secret = [];
	for (let i = 0; i < 30; i++) {
	secret.push(
	lookup[Math.floor(Math.random() * lookup.length)]
	);
	}
	return secret.join("");
	}

	function encrypt(number, secret) {
	return CryptoJS.AES.encrypt(number, secret);
	}

	function decrypt(message, secret) {
	return CryptoJS.AES.decrypt(message, secret);
	}

	// Only dm can access dm values
	const dm = {};

	// DM Calculate offset value
	dm.offset = rollDice();

	// DM generate secret
	dm.secret = getSecret();

	// DM encrypt offset value
	dm.encrypted_offset = encrypt(dm.offset, dm.secret);

	// Only player can access player values
	const player = {};

	// Player stores copy of dm encyptyed offset
	player.encrypted_dm_offset = dm.encrypted_offset;

	// Player rolls dice
	player.offset = rollDice();

	// DM stores copy of player roll
	dm.player_offset = player.offset;

	//
	// Once player receives secret, both parties decrypt and compare answer
	//

	// Player stores dm secret
	player.secret = dm.secret;

	// Player calculated roll
	const offset = decrypt(player.encrypted_dm_offset, player.secret);
	player.roll = ((offset + player.offset) % 6) + 1;

	// DM calculated roll
	dm.roll = ((dm.offset + dm.player_offset) % 6) + 1;

	console.log(
	`dm: ${dm.roll}\nplayer: ${player.roll}`
	);
	</script>
	</body>
	</html>