使用RS256算法时JWT签名无效问题排查（Azure AD场景）

云原生阿岚

2026-7-9

Azure AD OAuth2.0 Access Token生成失败排查：Node.js JWT签名验证问题

在为Azure AD通过JWT令牌验证生成OAuth2.0 access token时遇到问题，已确认向Azure应用添加了正确证书，但始终报错。为排查根源，编写了本地Node.js程序测试JWT签名验证，结果失败证书的验证不通过；而有效证书在本地验证成功，且能从Azure AD生成access token。

重要提示：使用Java（bouncycastle和jose4j）时，两个证书都能正常工作，求排查TypeScript实现中遗漏的点。

测试代码片段

import crypto from 'crypto';
import fs from 'node:fs';
import jwt from "jsonwebtoken";

function verifySign() {

    let certificatePaths = {
      "validPublicCert" : '/Users/<my-path>/certs/certificate.pem',
      "validPrivateKey" : '/Users/<my-path>/certs/privateKey.pem',
      "failingPublicCert" : '/Users/<my-path>/certs/failing-public.pem',
      "failingPrivateKey" : '/Users/<my-path>/certs/failing-prv-key.key'
    };


    // read and create public certificate
    let publicCertificateBuffer = Buffer.from(fs.readFileSync(certificatePaths.failingPublicCert, 'utf8'));
    let x509publicCert = new crypto.X509Certificate(publicCertificateBuffer);

    // base64 encode sha1 hash of certificate
    let sha = crypto.createHash("SHA1");
    sha.update(x509publicCert.raw);
    let encodedCertificate = sha.digest('base64url');
    console.log("Encoded base64 public certificate is: " + encodedCertificate);

    // prepare jwt headers
    let jwtHeaders = {
        'x5t': encodedCertificate,
        'alg' : 'RS256',
        'typ' : 'JWT'
    };

    // prepare jwt payload
    const now = Math.floor(Date.now() / 1000);
    const expiresIn = now + 3 * 60; 
    let jwtPayload = {
        "iss": "d2057bd6-1560-4b16-9988-790e1f698d9b",
        "aud": "https://login.microsoftonline.com/<my-azure-ad-tenant-domain>/oauth2/v2.0/token",
        "sub": "d2057bd6-1560-4b16-9988-790e1f698d9b",
        "x5t": encodedCertificate,
        "typ": "JWT",
        "alg": "RS256",
        "exp" : expiresIn,
        "iat" : now,
        "nbf": now
      }

      // read encrypted private key and fetch/ build private key from it
      let encryptedPrivateKeyBuffer = fs.readFileSync(certificatePaths.failingPrivateKey, 'utf8');
      let encryptedKeyPassPhrase = '<my pass phrase>';
      let encryptedKey = crypto.createPrivateKey({
        key: encryptedPrivateKeyBuffer, 
        passphrase: encryptedKeyPassPhrase
      });
      let decryptedKey = encryptedKey.export({
        format: 'pem',
        type: 'pkcs1'
    });


    let assertion = jwt.sign(jwtPayload, decryptedKey, {
      algorithm: "RS256",
      header: jwtHeaders
  });

  console.log("JWT assertion created after signing: " + assertion);

  try {
    jwt.verify(assertion, publicCertificateBuffer);
  }catch(error: any) {
    console.log(error);
  }
  
}

verifySign();

证书与密钥对比

有效公钥

有效私钥

-----BEGIN ENCRYPTED PRIVATE KEY-----
MII
<Remaining - Key>............
EUF7uoapGpNxXMFcqU18OQ==
-----END ENCRYPTED PRIVATE KEY-----

失败公钥

失败私钥

密钥格式差异

可以看到有效私钥采用的是PKCS#8加密格式（-----BEGIN ENCRYPTED PRIVATE KEY-----），而失败私钥是PKCS#1加密格式（-----BEGIN RSA PRIVATE KEY-----），由于对加密和JWT不熟悉，无法定位问题。

内容的提问来源于stack exchange，提问作者theimpatientcoder

使用RS256算法时JWT签名无效问题排查（Azure AD场景）

测试代码片段 #

证书与密钥对比 #

有效公钥 #

有效私钥 #

失败公钥 #

失败私钥 #

密钥格式差异 #