README.md

Tangerine Network RNG Library

Introduction

Tangerine Network provides on-chain randomness through a precompiled contract. Using a precompiled contract instead of introducing a new OP code ensures that we are compatible with EVM, and eliminates the need to maintain a separate toolchain.

The precompiled contract is located at 0xc327ff1025c5b3d2deb5e3f0f161b3f7e557579a, which is the first 20 bytes of Keccak256Hash("Tangerine Network Random"). The gas cost for each invocation is 64.

To use the random library, simply include the library file then call Random.rand() to get the random number.

Example

import "github.com/tangerine-network/random-lib/RandomLib.sol";

contract UseRandom {
    event Win();
    event Lose();

    function readRand() public view returns (uint256) {
        return Random.rand();
    }

    function bet() public {
        if (Random.rand() % 100 >= 50) {
            emit Win();
        } else {
            emit Lose();
        }
    }
}