openzeppelin-solidity VS randao

pragma solidity ^0.5.0; import "https://github.com/OpenZeppelin/openzeppelin-solidity/contracts/math/SafeMath.sol"; contract MyContract { using SafeMath for uint256; function deposit() public payable { // code to deposit ether } function withdraw(uint256 _amount) public { require(this.balance.sub(_amount) >= 0, "Insufficient funds"); // code to withdraw ether } }

The basic structure could be done as follows using OZ ERC20 interface https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/token/ERC20/IERC20.sol

return c; } /** * @dev Returns the subtraction of two unsigned integers, reverting on * overflow (when the result is negative). * * Counterpart to Solidity's `-` operator. * * Requirements: * - Subtraction cannot overflow. */ function sub(uint256 a, uint256 b) internal pure returns (uint256) { require(b <= a, "SafeMath: subtraction overflow"); uint256 c = a - b; return c; } /** * @dev Returns the multiplication of two unsigned integers, reverting on * overflow. * * Counterpart to Solidity's `*` operator. * * Requirements: * - Multiplication cannot overflow. */ function mul(uint256 a, uint256 b) internal pure returns (uint256) { // Gas optimization: this is cheaper than requiring 'a' not being zero, but the // benefit is lost if 'b' is also tested. // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522 if (a == 0) { return 0; } uint256 c = a * b; require(c / a == b, "SafeMath: multiplication overflow"); return c; } /** * @dev Returns the integer division of two unsigned integers. Reverts on * division by zero. The result is rounded towards zero. * * Counterpart to Solidity's `/` operator. Note: this function uses a * `revert` opcode (which leaves remaining gas untouched) while Solidity * uses an invalid opcode to revert (consuming all remaining gas). * * Requirements: * - The divisor cannot be zero. */ function div(uint256 a, uint256 b) internal pure returns (uint256) { // Solidity only automatically asserts when dividing by 0 require(b > 0, "SafeMath: division by zero"); uint256 c = a / b; // assert(a == b * c + a % b); // There is no case in which this doesn't hold return c; } /** * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo), * Reverts when dividing by zero. * * Counterpart to Solidity's `%` operator. This function uses a `revert` * opcode (which leaves remaining gas untouched) while Solidity uses an * invalid opcode to revert (consuming all remaining gas). * * Requirements: * - The divisor cannot be zero. */ function mod(uint256 a, uint256 b) internal pure returns (uint256) { require(b != 0, "SafeMath: modulo by zero"); return a % b; }

// See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522

There's really no "forcing", in sharding validators are randomly assigned to a shard, similarly to how they're currently randomly split up into committees that attest to the validity of blocks. There's no centralizing force: the randomness into the process is provided in a decentralized fashion by the validators themselves, through a mechanism called RANDAO.

Article author here.

Great questions, should have explored the randomness beacon more. Ethereum uses [RANDAO](https://github.com/randao/randao), which is a distributed commit-reveal scheme where participants in the generation post a hash of their data on the commit portion and then at a later timestamp reveal the data preimage, and get slashed if they do not reveal a correct preimage. Then all participant data is aggregated together. This means if there is at least one honest participant the generation will be random.

A supermajority (2/3rds) of validators is required to finalize a block, in case of a 50-50 network partition blocks would stop being finalized and attestation rewards would stop. Non-participating validators would slowly leak stake through the inactivity leak until online validators once again had a supermajority. This is the "self-healing" mechanism that allows both safety and liveness.

https://github.com/randao/randao Is this what you’re referring to? It says it’s a DAO.

So according to this generating randoms for the eth chain is like validating but with shorter cycle and more profitable. Now I have even more questions like: How can I participate Is there software like prysm for using random contracts What is the minimum stake for random contracts Is anyone doing this, is it wort it

Thank you Eric, I discussed it too in the PoolTogether discord and got this reponse from one of the founders: " What you're describing is a version of "RANDAO". See here: https://github.com/randao/randao Really, the VRF is an unnecessary step if a seed is being selected by all participants If you look through the above project, you'll see they try to handle a few corner cases like if a user refuses to reveal their seed, or preventing a seed from being used twice The trouble with Randao is the amount of coordination and expense that it incurs. " I understand ETH 2.0 will be doing some implementation of RANDAO along VDFs for the Beacon chain. Algorand implements this too. I found this talk from Justin Drake talking about this algorithm: https://www.youtube.com/watch?v=zqL_cMlPjOI