/**
*  @title Random Number Generator Standard
*  @author Clément Lesaege - <clement@lesaege.com>
*
*/

pragma solidity ^0.4.15;

contract RNG{

    /** @dev Contribute to the reward of a random number.
    *  @param _block Block the random number is linked to.
    */
    function contribute(uint _block) public payable;

    /** @dev Request a random number.
    *  @param _block Block linked to the request.
    */
    function requestRN(uint _block) public payable {
        contribute(_block);
    }

    /** @dev Get the random number.
    *  @param _block Block the random number is linked to.
    *  @return RN Random Number. If the number is not ready or has not been required 0 instead.
    */
    function getRN(uint _block) public returns (uint RN);

    /** @dev Get a uncorrelated random number. Act like getRN but give a different number for each sender.
    *  This is to prevent users from getting correlated numbers.
    *  @param _block Block the random number is linked to.
    *  @return RN Random Number. If the number is not ready or has not been required 0 instead.
    */
    function getUncorrelatedRN(uint _block) public returns (uint RN) {
        uint baseRN = getRN(_block);
        if (baseRN == 0)
        return 0;
        else
        return uint(keccak256(msg.sender,baseRN));
    }

}