Merge pull request ethereum#67 from thanhson1085/master

add randomize contract

contracts/randomize/contract/TomoRandomize.sol

@@ -0,0 +1,60 @@
+pragma solidity ^0.4.21;
+
+import "./libs/SafeMath.sol";
+
+contract TomoRandomize {
+    using SafeMath for uint256;
+    uint256 public epochNumber;
+    uint256 public blockTimeSecret;
+    uint256 public blockTimeOpening;
+
+    mapping (address=>bytes32[]) randomSecret;
+    mapping (address=>bytes32[]) randomOpening;
+
+    function TomoRandomize (uint256 _epochNumber, uint256 _blockTimeSecret, uint256 _blockTimeOpening) public {
+        epochNumber = _epochNumber;
+        blockTimeOpening = _blockTimeOpening;
+        blockTimeSecret = _blockTimeSecret;
+    }
+
+    function setSecret(bytes32[] _secret) public {
+        require(_secret.length == epochNumber);
+
+        uint256 _blockNum = block.number;
+        uint256 _epoch = _blockNum.sub(_blockNum.div(epochNumber).mul(epochNumber));
+
+        require(_epoch <= blockTimeSecret);
+
+        randomSecret[msg.sender] = _secret;
+    }
+
+    function setOpening(bytes32[] _opening) public {
+        require(_opening.length == epochNumber);
+
+        uint256 _blockNum = block.number;
+        uint256 _epoch = _blockNum.sub(_blockNum.div(epochNumber).mul(epochNumber));
+
+        require(_epoch > blockTimeSecret && _epoch <= blockTimeOpening);
+
+        randomOpening[msg.sender] = _opening;
+
+    }
+
+    function getSecret(address _validator) public view returns(bytes32[]) {
+        uint256 _blockNum = block.number;
+        uint256 _epoch = _blockNum.sub(_blockNum.div(epochNumber).mul(epochNumber));
+
+        require(_epoch > blockTimeSecret);
+
+        return randomSecret[_validator];
+    }
+
+    function getOpening(address _validator) public view returns(bytes32[]) {
+        uint256 _blockNum = block.number;
+        uint256 _epoch = _blockNum.sub(_blockNum.div(epochNumber).mul(epochNumber));
+
+        require(_epoch > blockTimeOpening);
+
+        return randomOpening[_validator];
+    }
+}

contracts/randomize/contract/libs/SafeMath.sol

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+pragma solidity ^0.4.21;
+
+/**
+ * @title SafeMath
+ * @dev Math operations with safety checks that throw on error
+ */
+library SafeMath {
+
+  /**
+  * @dev Multiplies two numbers, throws on overflow.
+  */
+  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
+    if (a == 0) {
+      return 0;
+    }
+    uint256 c = a * b;
+    assert(c / a == b);
+    return c;
+  }
+
+  /**
+  * @dev Integer division of two numbers, truncating the quotient.
+  */
+  function div(uint256 a, uint256 b) internal pure returns (uint256) {
+    // assert(b > 0); // Solidity automatically throws when dividing by 0
+    // uint256 c = a / b;
+    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
+    return a / b;
+  }
+
+  /**
+  * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
+  */
+  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
+    assert(b <= a);
+    return a - b;
+  }
+
+  /**
+  * @dev Adds two numbers, throws on overflow.
+  */
+  function add(uint256 a, uint256 b) internal pure returns (uint256) {
+    uint256 c = a + b;
+    assert(c >= a);
+    return c;
+  }
+}