{"id":2591,"date":"2024-08-14T00:23:00","date_gmt":"2024-08-13T16:23:00","guid":{"rendered":"https:\/\/systw.net\/note\/?p=2591"},"modified":"2025-08-24T14:04:28","modified_gmt":"2025-08-24T06:04:28","slug":"sc-insecure-randomness","status":"publish","type":"post","link":"https:\/\/systw.net\/note\/archives\/2591","title":{"rendered":"Insecure Randomness"},"content":{"rendered":"\n<p>\u96a8\u6a5f\u6578\u751f\u6210\u5728\u8af8\u5982\u8ced\u535a\u3001\u904a\u6232\u8d0f\u5bb6\u9078\u64c7\u6216\u96a8\u6a5f\u7a2e\u5b50\u751f\u6210\u7b49\u61c9\u7528\u4e2d\u81f3\u95dc\u91cd\u8981\u3002\u7136\u800c\uff0c\u5728\u4ee5\u592a\u574a\u4e0a\u751f\u6210\u96a8\u6a5f\u6578\u662f\u4e00\u9805\u6311\u6230\uff0c\u56e0\u70ba\u4ee5\u592a\u574a\u7684\u5340\u584a\u93c8\u662f<strong>\u78ba\u5b9a\u6027\u7684<\/strong>\uff08Deterministic\uff09\uff0c\u5373\u6240\u6709\u7bc0\u9ede\u5fc5\u9808\u5c0d\u540c\u4e00\u8f38\u5165\u7522\u751f\u76f8\u540c\u7d50\u679c\uff0c\u9019\u4f7f\u5f97\u751f\u6210\u771f\u6b63\u7684\u96a8\u6a5f\u6578\u5e7e\u4e4e\u4e0d\u53ef\u80fd\u3002\u56e0\u6b64\uff0cSolidity \u901a\u5e38\u4f9d\u8cf4\u507d\u96a8\u6a5f\uff08Pseudorandom\uff09\u56e0\u7d20\u4f86\u6a21\u64ec\u96a8\u6a5f\u6027\u3002\u6b64\u5916\uff0cSolidity \u4e2d\u7684\u8907\u96dc\u8a08\u7b97\u6703\u6d88\u8017\u5927\u91cf gas\uff0c\u589e\u52a0\u4e86\u8a2d\u8a08\u96a8\u6a5f\u6578\u751f\u6210\u5668\u7684\u6210\u672c\u3002<\/p>\n\n\n\n<p>\u958b\u767c\u8005\u5e38\u4f7f\u7528\u5340\u584a\u93c8\u76f8\u95dc\u8cc7\u8a0a\u4f86\u751f\u6210\u96a8\u6a5f\u6578\uff0c\u4f46\u9019\u4e9b\u65b9\u6cd5\u4e0d\u5b89\u5168\uff0c\u56e0\u70ba\u5b83\u5011\u53ef\u80fd\u88ab\u7926\u5de5\uff08Miners\uff09\u6216\u653b\u64ca\u8005\u64cd\u7e31\u3002\u5e38\u898b\u7684\u4e0d\u5b89\u5168\u96a8\u6a5f\u6578\u751f\u6210\u4f86\u6e90\u5305\u62ec\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong><code>block.timestamp<\/code><\/strong>\uff1a\u7576\u524d\u5340\u584a\u7684\u6642\u9593\u6233\u3002<\/li>\n\n\n\n<li><strong><code>blockhash(uint blockNumber)<\/code><\/strong>\uff1a\u6307\u5b9a\u5340\u584a\u7684\u54c8\u5e0c\u503c\uff08\u50c5\u9650\u6700\u8fd1 256 \u500b\u5340\u584a\uff09\u3002<\/li>\n\n\n\n<li><strong><code>block.difficulty<\/code><\/strong>\uff1a\u7576\u524d\u5340\u584a\u7684\u6316\u7926\u96e3\u5ea6\u3002<\/li>\n\n\n\n<li><strong><code>block.number<\/code><\/strong>\uff1a\u7576\u524d\u5340\u584a\u7de8\u865f\u3002<\/li>\n\n\n\n<li><strong><code>block.coinbase<\/code><\/strong>\uff1a\u7576\u524d\u5340\u584a\u7684\u7926\u5de5\u5730\u5740\u3002<\/li>\n<\/ul>\n\n\n\n<p>\u9019\u4e9b\u4f86\u6e90\u5bb9\u6613\u88ab\u7926\u5de5\u64cd\u7e31\uff08\u4f8b\u5982\uff0c\u8abf\u6574\u6642\u9593\u6233\u6216\u9078\u64c7\u6709\u5229\u5340\u584a\uff09\uff0c\u5f9e\u800c\u5f71\u97ff\u5408\u7d04\u7684\u96a8\u6a5f\u6578\u751f\u6210\u7d50\u679c\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u5f71\u97ff<\/h4>\n\n\n\n<p>\u4e0d\u5b89\u5168\u7684\u96a8\u6a5f\u6578\u751f\u6210\u53ef\u80fd\u5c0e\u81f4\u4ee5\u4e0b\u56b4\u91cd\u5f8c\u679c\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u4e0d\u516c\u5e73\u7684\u904a\u6232\u6216\u5f69\u7968\u7d50\u679c<\/strong>\uff1a\u653b\u64ca\u8005\u53ef\u4ee5\u9810\u6e2c\u6216\u64cd\u7e31\u96a8\u6a5f\u6578\uff0c\u7372\u5f97\u4e0d\u516c\u5e73\u7684\u512a\u52e2\uff0c\u5f9e\u800c\u5728\u8ced\u535a\u3001\u5f69\u7968\u6216\u5176\u4ed6\u4f9d\u8cf4\u96a8\u6a5f\u6027\u7684\u61c9\u7528\u4e2d\u7372\u52dd\u3002<\/li>\n\n\n\n<li><strong>\u8cc7\u91d1\u640d\u5931<\/strong>\uff1a\u5982\u7bc4\u4f8b\u6240\u793a\uff0c\u653b\u64ca\u8005\u53ef\u80fd\u731c\u4e2d\u96a8\u6a5f\u6578\uff0c\u63d0\u53d6\u5408\u7d04\u4e2d\u7684\u8cc7\u91d1\uff0c\u5c0e\u81f4\u5176\u4ed6\u53c3\u8207\u8005\u6216\u5354\u8b70\u640d\u5931\u3002<\/li>\n\n\n\n<li><strong>\u4fe1\u4efb\u5371\u6a5f<\/strong>\uff1a\u4e0d\u5b89\u5168\u7684\u96a8\u6a5f\u6578\u7834\u58de\u4e86\u5408\u7d04\u7684\u516c\u5e73\u6027\u548c\u5b8c\u6574\u6027\uff0c\u5c0e\u81f4\u7528\u6236\u5c0d\u5354\u8b70\u5931\u53bb\u4fe1\u4efb\uff0c\u5f71\u97ff\u5176\u63a1\u7528\u7387\u548c\u751f\u614b\u7cfb\u7d71\u3002<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-dots\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">\u7bc4\u4f8b1\uff08\u5b58\u5728\u6f0f\u6d1e\u7684\u5408\u7d04\uff09<\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>function roll() external returns(uint256){\n uint256 seed = uint256(keccak256(abi.encode(block.timestamp,block.number)));\n return seed % 6 + 1;\n}<\/code><\/pre>\n\n\n\n<p>\u9019\u500b\u5408\u7d04\u6709\u4e00\u500b\u540d\u70ba <code>roll()<\/code> \u7684\u51fd\u5f0f\uff0c\u5176\u76ee\u7684\u662f\u6a21\u64ec\u4e00\u500b\u9ab0\u5b50\u904a\u6232\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong><code>keccak256(abi.encode(block.timestamp, block.number))<\/code><\/strong>: \u9019\u662f\u751f\u6210\u300c\u96a8\u6a5f\u6578\u300d\u7684\u95dc\u9375\u3002\u5b83\u5c07**\u5340\u584a\u6642\u9593\u6233\uff08<code>block.timestamp<\/code>\uff09<strong>\u548c<\/strong>\u5340\u584a\u7de8\u865f\uff08<code>block.number<\/code>\uff09**\u9019\u5169\u500b\u516c\u958b\u3001\u53ef\u9810\u6e2c\u7684\u93c8\u4e0a\u6578\u64da\u9032\u884c\u54c8\u5e0c\u904b\u7b97\uff0c\u7522\u751f\u4e00\u500b\u770b\u4f3c\u96a8\u6a5f\u7684\u7a2e\u5b50\uff08<code>seed<\/code>\uff09\u3002<\/li>\n\n\n\n<li><strong><code>seed % 6 + 1<\/code><\/strong>: \u9019\u884c\u7a0b\u5f0f\u78bc\u5c07\u7a2e\u5b50\u6578\u503c\u5c0d 6 \u53d6\u9918\u6578\uff0c\u4e26\u52a0\u4e0a 1\uff0c\u7d50\u679c\u6703\u662f\u4e00\u500b\u4ecb\u65bc 1 \u5230 6 \u4e4b\u9593\u7684\u6578\u5b57\uff0c\u6a21\u64ec\u4e00\u500b\u516d\u9762\u9ab0\u5b50\u7684\u7d50\u679c\u3002<\/li>\n<\/ul>\n\n\n\n<p><strong>\u6f0f\u6d1e\u9ede\uff1a<\/strong> \u5340\u584a\u93c8\u4e0a\u7684\u6240\u6709\u8cc7\u8a0a\u90fd\u662f\u516c\u958b\u7684\u3002<code>block.timestamp<\/code> \u548c <code>block.number<\/code> \u5728\u4e00\u7b46\u4ea4\u6613\u88ab\u6253\u5305\u4e4b\u524d\uff0c\u90fd\u53ef\u4ee5\u88ab\u9810\u6e2c\u3002\u9019\u610f\u5473\u8457\uff0c\u4efb\u4f55\u4eba\u90fd\u53ef\u4ee5<strong>\u5728\u93c8\u4e0b<\/strong>\u7cbe\u78ba\u5730\u8a08\u7b97\u51fa <code>roll()<\/code> \u51fd\u5f0f\u5c07\u6703\u8fd4\u56de\u4ec0\u9ebc\u6578\u5b57\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">\u653b\u64ca\u8005\u5408\u7d04\uff08exploit contract\uff09<\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>function exploit() external{\n  uint256 seed = uint256(keccak256(abi.encode(block.timestamp,block.number)));\n  if ( seed % 6+1=6){\n       victim.roll();\n   }\n}<\/code><\/pre>\n\n\n\n<p>\u9019\u500b\u5408\u7d04\u662f\u70ba\u4e86\u5229\u7528 <code>victim contract<\/code> \u7684\u6f0f\u6d1e\u800c\u8a2d\u8a08\u7684\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong><code>uint256 seed = uint256(keccak256(abi.encode(block.timestamp,block.number)));<\/code><\/strong>: \u653b\u64ca\u8005\u5728\u9019\u88e1\u91cd\u73fe\u4e86\u53d7\u5bb3\u8005\u5408\u7d04\u7684\u96a8\u6a5f\u6578\u751f\u6210\u908f\u8f2f\u3002\u7531\u65bc\u9019\u6bb5\u7a0b\u5f0f\u78bc\u548c\u53d7\u5bb3\u8005\u5408\u7d04\u7684\u908f\u8f2f\u5b8c\u5168\u4e00\u6a23\uff0c\u5b83\u8a08\u7b97\u51fa\u7684 <code>seed<\/code> \u4e5f\u6703\u5b8c\u5168\u4e00\u6a23\u3002<\/li>\n\n\n\n<li><strong><code>if (seed % 6 + 1 == 6)<\/code><\/strong>: \u9019\u662f\u653b\u64ca\u7684\u95dc\u9375\u3002\u5728\u547c\u53eb\u53d7\u5bb3\u8005\u5408\u7d04\u7684 <code>roll()<\/code> \u51fd\u5f0f\u4e4b\u524d\uff0c\u653b\u64ca\u8005\u6703\u5148\u6aa2\u67e5\u81ea\u5df1\u9810\u5148\u8a08\u7b97\u7684\u7d50\u679c\u3002\u5982\u679c\u9019\u500b\u7d50\u679c\u662f 6\uff08\u5047\u8a2d\u9019\u662f\u8d0f\u5f97\u904a\u6232\u7684\u689d\u4ef6\uff09\uff0c\u653b\u64ca\u8005\u624d\u57f7\u884c\u4e0b\u4e00\u6b65\u3002<\/li>\n\n\n\n<li><strong><code>victim.roll()<\/code><\/strong>: \u5982\u679c\u9810\u5148\u8a08\u7b97\u7684\u7d50\u679c\u662f 6\uff0c\u653b\u64ca\u8005\u5c31\u6703\u547c\u53eb\u53d7\u5bb3\u8005\u5408\u7d04\u7684 <code>roll()<\/code> \u51fd\u5f0f\u3002\u7531\u65bc\u53d7\u5bb3\u8005\u5408\u7d04\u7684\u908f\u8f2f\u548c\u653b\u64ca\u8005\u4e00\u6a23\uff0c\u5b83\u4e5f\u6703\u5f97\u5230 6 \u9019\u500b\u7d50\u679c\u3002<\/li>\n<\/ul>\n\n\n\n<p><strong>\u653b\u64ca\u539f\u7406\uff1a<\/strong> \u9019\u662f\u4e00\u7a2e\u5178\u578b\u7684<strong>\u9810\u5148\u8a08\u7b97\u653b\u64ca\uff08Pre-computation Attack\uff09<\/strong>\u3002\u653b\u64ca\u8005\u4e0d\u6703\u76f2\u76ee\u5730\u547c\u53eb\u53d7\u5bb3\u8005\u5408\u7d04\u3002\u76f8\u53cd\uff0c\u4ed6\u5011\u6703\u5148\u5728\u81ea\u5df1\u7684\u5408\u7d04\u4e2d\uff0c\u5229\u7528\u8207\u53d7\u5bb3\u8005\u5408\u7d04\u76f8\u540c\u7684\u516c\u958b\u6578\u64da\uff0c\u9810\u6e2c\u300c\u96a8\u6a5f\u300d\u7d50\u679c\u3002\u53ea\u6709\u7576\u9810\u6e2c\u7d50\u679c\u5c0d\u81ea\u5df1\u6709\u5229\u6642\uff0c\u624d\u767c\u52d5\u653b\u64ca\u3002\u9019\u6bb5\u7a0b\u5f0f\u78bc\u7684\u908f\u8f2f\u53ef\u4ee5\u7c21\u5316\u70ba\uff1a\u300c<strong>\u7576\u4e14\u50c5\u7576\u6211\u77e5\u9053\u81ea\u5df1\u6703\u8d0f\u7684\u6642\u5019\uff0c\u6211\u624d\u4e0b\u6ce8\u3002<\/strong>\u300d<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-dots\"\/>\n\n\n\n<h4 class=\"wp-block-heading\">\u7bc4\u4f8b2\uff08\u5b58\u5728\u6f0f\u6d1e\u7684\u5408\u7d04\uff09<\/h4>\n\n\n\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528\u4e0d\u5b89\u5168\u96a8\u6a5f\u6578\u751f\u6210\u7684\u5408\u7d04\u7bc4\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ SPDX-License-Identifier: MIT\npragma solidity ^0.8.24;\n\ncontract Solidity_InsecureRandomness {\n    constructor() payable {}\n\n    function guess(uint256 _guess) public {\n        uint256 answer = uint256(\n            keccak256(\n                <mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-red-color\">abi.encodePacked(block.timestamp, block.difficulty, msg.sender) \/\/ Using insecure mechanisms for random number generation<\/mark>\n            )\n        );\n\n        if (_guess == answer) {\n            (bool sent,) = msg.sender.call{value: 1 ether}(\"\");\n            require(sent, \"Failed to send Ether\");\n        }\n    }\n}<\/code><\/pre>\n\n\n\n<p><strong>\u6f0f\u6d1e\u5206\u6790<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong><code>guess<\/code> \u51fd\u6578<\/strong>\uff1a\u4f7f\u7528 <code>block.timestamp<\/code>\u3001<code>block.difficulty<\/code> \u548c <code>msg.sender<\/code> \u7d50\u5408 <code>keccak256<\/code> \u4f86\u751f\u6210\u96a8\u6a5f\u6578\u3002<\/li>\n\n\n\n<li><strong>\u554f\u984c<\/strong>\uff1a\n<ul class=\"wp-block-list\">\n<li>\u7926\u5de5\u53ef\u4ee5\u64cd\u7e31 <code>block.timestamp<\/code>\uff08\u5728\u5408\u7406\u7bc4\u570d\u5167\u8abf\u6574\u6642\u9593\u6233\uff09\u6216 <code>block.difficulty<\/code>\uff0c\u5f71\u97ff <code>keccak256<\/code> \u7684\u8f38\u51fa\u3002<\/li>\n\n\n\n<li>\u653b\u64ca\u8005\u53ef\u80fd\u9810\u6e2c\u6216\u901a\u904e\u8a66\u9a57\u63a8\u5c0e\u51fa\u96a8\u6a5f\u6578\uff08\u7279\u5225\u662f\u5728\u5340\u584a\u6578\u64da\u516c\u958b\u5f8c\uff09\u3002<\/li>\n\n\n\n<li>\u9019\u7a2e\u96a8\u6a5f\u6578\u751f\u6210\u65b9\u5f0f\u4e26\u975e\u771f\u6b63\u7684\u96a8\u6a5f\uff0c\u5bb9\u6613\u88ab\u64cd\u63a7\uff0c\u5c0e\u81f4\u653b\u64ca\u8005\u80fd\u4ee5\u9ad8\u6a5f\u7387\u731c\u4e2d <code>answer<\/code>\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-dots\"\/>\n\n\n\n<h4 class=\"wp-block-heading\">\u4fee\u5fa9\u65b9\u6cd5<\/h4>\n\n\n\n<p>\u70ba\u78ba\u4fdd\u96a8\u6a5f\u6578\u751f\u6210\u7684\u516c\u5e73\u6027\u548c\u5b89\u5168\u6027\uff0c\u958b\u767c\u8005\u53ef\u63a1\u7528\u4ee5\u4e0b\u65b9\u6cd5\uff1a<\/p>\n\n\n\n<p><strong>\u4f7f\u7528\u5916\u90e8\u9810\u8a00\u6a5f\uff08Oracles\uff09<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u901a\u904e\u53ef\u4fe1\u7684\u5916\u90e8\u96a8\u6a5f\u6578\u4f86\u6e90\uff08\u5982 Oraclize\uff09\u63d0\u4f9b\u96a8\u6a5f\u6578\u3002\u4f46\u9700\u8b39\u614e\u9078\u64c7\u53ef\u4fe1\u7684\u9810\u8a00\u6a5f\uff0c\u6216\u4f7f\u7528\u591a\u500b\u9810\u8a00\u6a5f\u4f86\u964d\u4f4e\u55ae\u9ede\u6545\u969c\u98a8\u96aa\u3002<\/li>\n<\/ul>\n\n\n\n<p><strong>\u627f\u8afe\u65b9\u6848\uff08Commitment Schemes\uff09<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u63a1\u7528\u300c\u627f\u8afe-\u63ed\u793a\u300d\uff08Commit-Reveal\uff09\u65b9\u6cd5\uff0c\u53c3\u8207\u8005\u5148\u63d0\u4ea4\u52a0\u5bc6\u627f\u8afe\uff0c\u5f8c\u63ed\u793a\u7d50\u679c\uff0c\u9632\u6b62\u63d0\u524d\u64cd\u7e31\u3002\u4f8b\u5982\uff0cRANDAO \u662f\u4e00\u7a2e\u57fa\u65bc\u591a\u65b9\u627f\u8afe\u7684\u96a8\u6a5f\u6578\u751f\u6210\u65b9\u6848\uff0c\u9069\u7528\u65bc\u53bb\u4e2d\u5fc3\u5316\u61c9\u7528\u3002<\/li>\n<\/ul>\n\n\n\n<p><strong>Chainlink VRF<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u4f7f\u7528 Chainlink \u7684\u53ef\u9a57\u8b49\u96a8\u6a5f\u51fd\u6578\uff08VRF\uff09\uff0c\u9019\u662f\u4e00\u7a2e\u7d93\u904e\u8b49\u660e\u516c\u5e73\u4e14\u53ef\u9a57\u8b49\u7684\u96a8\u6a5f\u6578\u751f\u6210\u5668\uff0c\u5c08\u70ba\u667a\u80fd\u5408\u7d04\u8a2d\u8a08\uff0c\u78ba\u4fdd\u96a8\u6a5f\u6578\u4e0d\u88ab\u64cd\u7e31\u3002<\/li>\n<\/ul>\n\n\n\n<p><strong>Signidice \u6f14\u7b97\u6cd5<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u9069\u7528\u65bc\u6d89\u53ca\u96d9\u65b9\u7684\u507d\u96a8\u6a5f\u6578\u751f\u6210\uff08PRNG\uff09\uff0c\u4f7f\u7528\u52a0\u5bc6\u7c3d\u540d\u4f86\u78ba\u4fdd\u96a8\u6a5f\u6027\uff0c\u9069\u5408\u7279\u5b9a\u5834\u666f\u3002<\/li>\n<\/ul>\n\n\n\n<p><strong>\u6bd4\u7279\u5e63\u5340\u584a\u54c8\u5e0c<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u901a\u904e\u5982 BTCRelay \u7684\u9810\u8a00\u6a5f\uff0c\u5f9e\u6bd4\u7279\u5e63\u5340\u584a\u93c8\u7372\u53d6\u5340\u584a\u54c8\u5e0c\u4f5c\u70ba\u96a8\u6a5f\u6027\u4f86\u6e90\u3002\u4f46\u9700\u6ce8\u610f\uff0c\u7926\u5de5\u53ef\u80fd\u5f71\u97ff\u6bd4\u7279\u5e63\u5340\u584a\u5167\u5bb9\uff0c\u56e0\u6b64\u9700\u8b39\u614e\u5be6\u73fe\u3002<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">\u5b89\u5168\u96a8\u6a5f\u6578\u7684\u7bc4\u4f8b\u5408\u7d04<\/h4>\n\n\n\n<p>\u4ee5\u4e0b\u662f\u4f7f\u7528 Chainlink VRF \u7522\u751f\u5b89\u5168\u7684\u96a8\u6a5f\u6578\u751f\u6210\u5408\u7d04\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ SPDX-License-Identifier: MIT\npragma solidity ^0.8.24;\n\nimport \"@chainlink\/contracts\/src\/v0.8\/VRFConsumerBase.sol\";\n\ncontract Solidity_InsecureRandomness is VRFConsumerBase {\n    bytes32 internal keyHash;\n    uint256 internal fee;\n    uint256 public randomResult;\n\n    constructor(address _vrfCoordinator, address _linkToken, bytes32 _keyHash, uint256 _fee) \n        VRFConsumerBase(_vrfCoordinator, _linkToken) \n    {\n        keyHash = _keyHash;\n        fee = _fee;\n    }\n\n    function requestRandomNumber() public returns (bytes32 requestId) {\n        require(LINK.balanceOf(address(this)) &gt;= fee, \"Not enough LINK\");\n        return requestRandomness(keyHash, fee);\n    }\n\n    function fulfillRandomness(bytes32 requestId, uint256 randomness) internal override {\n        randomResult = randomness;\n    }\n\n    function guess(uint256 _guess) public {\n        require(randomResult &gt; 0, \"Random number not generated yet\");\n        if (_guess == randomResult) {\n            (bool sent,) = msg.sender.call{value: 1 ether}(\"\");\n            require(sent, \"Failed to send Ether\");\n        }\n    }\n}<\/code><\/pre>\n\n\n\n<p><strong>\u4fee\u5fa9\u5167\u5bb9<\/strong>\uff1a<\/p>\n\n\n\n<p><strong>\u4f7f\u7528 Chainlink VRF<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5408\u7d04\u7e7c\u627f <code>VRFConsumerBase<\/code>\uff0c\u901a\u904e <code>requestRandomness<\/code> \u5411 Chainlink VRF \u8acb\u6c42\u96a8\u6a5f\u6578\u3002<\/li>\n\n\n\n<li><code>fulfillRandomness<\/code> \u56de\u8abf\u51fd\u6578\u63a5\u6536\u751f\u6210\u7684\u96a8\u6a5f\u6578\uff0c\u5b58\u5132\u5728 <code>randomResult<\/code> \u4e2d\u3002<\/li>\n<\/ul>\n\n\n\n<p><strong>\u6aa2\u67e5\u689d\u4ef6<\/strong>\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>guess<\/code> \u51fd\u6578\u8981\u6c42 <code>randomResult<\/code> \u5df2\u751f\u6210\uff08<code>&gt; 0<\/code>\uff09\uff0c\u78ba\u4fdd\u96a8\u6a5f\u6578\u6709\u6548\u3002<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">\u7e3d\u7d50<\/h4>\n\n\n\n<p>\u4e0d\u5b89\u5168\u7684\u96a8\u6a5f\u6578\u751f\u6210\uff08\u5982\u4f9d\u8cf4 <code>block.timestamp<\/code> \u6216 <code>block.difficulty<\/code>\uff09\u5728\u4ee5\u592a\u574a\u7684\u78ba\u5b9a\u6027\u74b0\u5883\u4e2d\u5bb9\u6613\u88ab\u64cd\u7e31\uff0c\u5c0e\u81f4\u4e0d\u516c\u5e73\u7684\u904a\u6232\u7d50\u679c\u3001\u8cc7\u91d1\u640d\u5931\u548c\u4fe1\u4efb\u5371\u6a5f\u3002\u653b\u64ca\u8005\u53ef\u901a\u904e\u9810\u6e2c\u6216\u5f71\u97ff\u96a8\u6a5f\u6578\u7372\u53d6\u4e0d\u7576\u5229\u76ca\u3002\u4fee\u5fa9\u65b9\u6cd5\u5305\u62ec\u4f7f\u7528 Chainlink VRF\u3001\u627f\u8afe\u65b9\u6848\u6216\u53ef\u4fe1\u9810\u8a00\u6a5f\u4f86\u78ba\u4fdd\u96a8\u6a5f\u6578\u7684\u516c\u5e73\u6027\u548c\u5b89\u5168\u6027\u3002\u4fee\u5fa9\u5f8c\u7684\u5408\u7d04\u5c55\u793a\u4e86\u5982\u4f55\u6574\u5408 Chainlink VRF\uff0c\u63d0\u4f9b\u53ef\u9a57\u8b49\u7684\u96a8\u6a5f\u6578\uff0c\u9632\u6b62\u64cd\u7e31\u4e26\u4fdd\u8b77\u5408\u7d04\u7684\u5b8c\u6574\u6027\u3002\u958b\u767c\u8005\u61c9\u907f\u514d\u4f7f\u7528\u5340\u584a\u93c8\u5167\u90e8\u8cc7\u6599\u4f5c\u70ba\u96a8\u6a5f\u6578\u4f86\u6e90\uff0c\u4e26\u9032\u884c\u5168\u9762\u6e2c\u8a66\u4ee5\u78ba\u4fdd\u96a8\u6a5f\u6027\u5b89\u5168\u3002<\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u96a8\u6a5f\u6578\u751f\u6210\u5728\u8af8\u5982\u8ced\u535a\u3001\u904a\u6232\u8d0f\u5bb6\u9078\u64c7\u6216\u96a8\u6a5f\u7a2e\u5b50\u751f\u6210\u7b49\u61c9\u7528\u4e2d\u81f3\u95dc 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