Node js JWT 使用 Google 的公钥验证令牌

Question

我正在阅读https://developers.google.com/actions/identity/google-sign-in身份验证流程指南。现在我需要访问用户的个人资料信息，因此我使用 JWT 库和代码：

var decoded = jwt.verify(token, google_key,{algorithms: ['RS256'] });

指南说：

使用适合您的语言的 JWT 解码库来解码令牌，并使用 Google 的公钥（以JWK或PEM格式提供）来验证令牌的签名。

所以我决定通过使用以下代码来使用 PEM 格式：

{
  "6f6781ba71199a658e760aa5aa93e5fc3dc752b5": "-----BEGIN CERTIFICATE-----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\nKaJWL3reZU1mVb7JVBoRi8Fks19SnX753fhd4OAdgt91QzVIf7dwY1PG\n-----END CERTIFICATE-----\n",
  "a4313e7fd1e9e2a4ded3b292d2a7f4e519574308": "-----BEGIN CERTIFICATE-----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\n26EE8nUSCeP9tKKgdKsD/Q/wvuwBGQp4UVx4g/nsZHzxcdONdlhWYlVs\n-----END CERTIFICATE-----\n"
}

但实际上我不知道从这个证书中提取公钥来使用我之前说过的 verify() 指令。

（我尝试使用此 Json 变量，但出现错误:)

UnhandledPromiseRejectionWarning: Error: PEM_read_bio_PUBKEY failed

如何从证书中获取公钥？我正在使用 Nodejs。提前致谢。

Answer 1

这PUBLIC KEY是实际的字符串：

"-----BEGIN CERTIFICATE-----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\nKaJWL3reZU1mVb7JVBoRi8Fks19SnX753fhd4OAdgt91QzVIf7dwY1PG\n-----END CERTIFICATE-----\n"

在你的例子中，谷歌给了我们两个密钥。要知道必须使用哪一个，我们首先需要提取存储在 JWT 标头中的一些信息。为此，我们可以使用相同的jsonwebtoken库：

const header = jwt.decode(YOUR_JWT_HERE, { complete: true }).header;
/*
header = {
    alg: 'RS256',
    kid: '6f6781ba71199a658e760aa5aa93e5fc3dc752b5',
    typ: 'JWT'
}
*/

如您所见，header.kid匹配从 Google 检索到的证书中的项目。这是您必须用来验证 JWT 的方法。最后，代码看起来像这样：

const jwt = require('jsonwebtoken');

const token = YOUR_JWT_VALUE;
const certificates = {
    "6f6781ba71199a658e760aa5aa93e5fc3dc752b5": "-----BEGIN CERTIFICATE-----\nMIID[...]dwY1PG\n-----END CERTIFICATE-----\n",
    "a4313e7fd1e9e2a4ded3b292d2a7f4e519574308": "-----BEGIN CERTIFICATE-----\nMIID[...]hWYlVs\n-----END CERTIFICATE-----\n",
};

// Get header information from token
const header = jwt.decode(token, { complete: true }).header;
// Get the corresponding public key specified in header
const cert = certificates[header.kid];

// Verify token
jwt.verify(token, cert, { algorithms: ['RS256'] }, (err, payload) => {
    if (err) {
      // Not a valid token
      console.log('Error:', err);
      return;
    }

    // Token successfully verified
    console.log('Payload:', payload);
});

注意：Google 的证书会不时发生变化。为了简单起见，我将它们声明为常量，但您必须牢记这一点。来自谷歌：

这些钥匙会定期轮换；检查响应中的 Cache-Control 标头以确定何时应再次检索它们。

资料来源：

• 从此处获取 JWT 标头信息。
• 本指南。向阿德里安·安科纳致敬。