Slot vRNG

Cartridge's Verifiable Random Number Generator provides cheap, atomic, verifiable randomness for onchain games. Randomness is generated and verified within a single transaction.

Contract Addresses

Network Address

Mainnet 0x051fea4450da9d6aee758bdeba88b2f665bcbf549d2c61421aa724e9ac0ced8f

Sepolia 0x051fea4450da9d6aee758bdeba88b2f665bcbf549d2c61421aa724e9ac0ced8f

Cairo Interface

#[starknet::interface] trait IVrfProvider<TContractState> { fn request_random(self: @TContractState, caller: ContractAddress, source: Source); fn consume_random(ref self: TContractState, source: Source) -> felt252; }

#[derive(Drop, Copy, Clone, Serde)] pub enum Source { Nonce: ContractAddress, Salt: felt252, }

Source Types

• Source::Nonce(ContractAddress) : Uses the address's internal nonce. Each request generates a different seed.

• Source::Salt(felt252) : Uses a provided salt. Same salt = same random value.

Usage in Contracts

const VRF_PROVIDER_ADDRESS: starknet::ContractAddress = starknet::contract_address_const::<0x051fea4450da9d6aee758bdeba88b2f665bcbf549d2c61421aa724e9ac0ced8f>();

fn roll_dice(ref self: ContractState) { let vrf_provider = IVrfProviderDispatcher { contract_address: VRF_PROVIDER_ADDRESS }; let player_id = get_caller_address(); let random_value = vrf_provider.consume_random(Source::Nonce(player_id)); // Use random_value in game logic }

Executing vRNG Transactions

request_random must be the first call in the multicall. The Cartridge Paymaster wraps the multicall with submit_random and assert_consumed .

const call = await account.execute([ // First: request_random { contractAddress: VRF_PROVIDER_ADDRESS, entrypoint: 'request_random', calldata: CallData.compile({ caller: GAME_CONTRACT, // Source::Nonce(address) source: { type: 0, address: account.address }, // Or Source::Salt(felt252) // source: { type: 1, salt: 0x123 }, }), }, // Then: your game call { contractAddress: GAME_CONTRACT, entrypoint: 'roll_dice', // ... }, ]);

The source in request_random must match the source in consume_random .

Controller Policy

Add the vRNG contract to your Controller policies:

const policies: Policy[] = [ // ... your existing policies ... { target: VRF_PROVIDER_ADDRESS, method: "request_random", description: "Allows requesting random numbers from the VRF provider", }, ];

Security

Phase 0 assumes the Provider has not revealed the private key and does not collude with players. Future plans include moving the Provider to a Trusted Execution Environment (TEE).