无法使用从AzureKeyVault读取的证书写入JWTToken

我们正在使用自签名证书创建JwtSecurityToken。我们目前正在手动将证书上载到Azure应用程序服务，然后使用此代码查找它

 X509Store certStore = new X509Store(StoreName.My, StoreLocation.CurrentUser);
 certStore.Open(OpenFlags.ReadOnly);
 X509Certificate2Collection certCollection = certStore.Certificates.Find(
                                            X509FindType.FindByThumbprint,
                                            signingCertThumbprint,
                                            false);
 return new X509SigningCredentials(certCollection[0]);

这可以很好地工作，但是我们不想让证书安装在运行appservice的机器上，而是从Azure Key Vault读取证书。附加的好处是，这意味着应用程序服务可以在开发者机器上本地运行，而无需共享和安装证书

我们可以使用从Azure密钥库获取证书

var certificateClient = new CertificateClient(new Uri("https://ourkeyvault.vault.azure.net/"), new DefaultAzureCredential());

var b2cInviteCertificate = certificateClient.GetCertificate("B2CInvite");

return new X509SigningCredentials(new X509Certificate2(b2cInviteCertificate.Value.Cer));

FWIW我还尝试了加载到

X509Certificate2

接受密码的ctor

根据这些凭证，我们创建了一个JwtSecurityToken

JwtSecurityToken token = new JwtSecurityToken(
                    issuer.ToString(),
                    audience,
                    claims,
                    DateTime.Now,
                    DateTime.Now.AddDays(7),
                    JwtService.signingCredentials.Value);

然后，我们使用JwtSecurityTokenHandler获取令牌字符串

JwtSecurityTokenHandler jwtHandler = new JwtSecurityTokenHandler();
return jwtHandler.WriteToken(token);

调用WriteToken会导致以下错误消息

InvalidOperationException:IDX10638:无法创建 SignatureProvider“key.HasPrivateKey”为false，无法创建签名

---

为什么会发生这种情况？

这不起作用的原因是从KeyVault检索的证书上的PrivateKey为空。如果需要私钥，则需要将证书作为“机密”提取

---

为了解释原因并更详细地引用另一个答案

同意Pat Longs的答案，只有当您将公钥作为证书获得时，才能获得公钥。是的，这毫无意义！通过秘密绕道只是感觉很愚蠢

无论如何，我最终从Azure key Vault获得私钥证书的代码如下所示：

    /// <summary>
    /// Load a certificate (with private key) from Azure Key Vault
    ///
    /// Getting a certificate with private key is a bit of a pain, but the code below solves it.
    /// 
    /// Get the private key for Key Vault certificate
    /// https://github.com/heaths/azsdk-sample-getcert
    /// 
    /// See also these GitHub issues: 
    /// https://github.com/Azure/azure-sdk-for-net/issues/12742
    /// https://github.com/Azure/azure-sdk-for-net/issues/12083
    /// </summary>
    /// <param name="config"></param>
    /// <param name="certificateName"></param>
    /// <returns></returns>
    public static X509Certificate2 LoadCertificate(IConfiguration config, string certificateName)
    {
        string vaultUrl = config["Vault:Url"] ?? "";
        string clientId = config["Vault:ClientId"] ?? "";
        string tenantId = config["Vault:TenantId"] ?? "";
        string secret = config["Vault:Secret"] ?? "";

        Console.WriteLine($"Loading certificate '{certificateName}' from Azure Key Vault");

        var credentials = new ClientSecretCredential(tenantId: tenantId, clientId: clientId, clientSecret: secret);
        var certClient = new CertificateClient(new Uri(vaultUrl), credentials);
        var secretClient = new SecretClient(new Uri(vaultUrl), credentials);

        var cert = GetCertificateAsync(certClient, secretClient, certificateName);

        Console.WriteLine("Certificate loaded");
        return cert;
    }


    /// <summary>
    /// Helper method to get a certificate
    /// 
    /// Source https://github.com/heaths/azsdk-sample-getcert/blob/master/Program.cs
    /// </summary>
    /// <param name="certificateClient"></param>
    /// <param name="secretClient"></param>
    /// <param name="certificateName"></param>
    /// <returns></returns>
    private static X509Certificate2 GetCertificateAsync(CertificateClient certificateClient,
                                                            SecretClient secretClient,
                                                            string certificateName)
    {

        KeyVaultCertificateWithPolicy certificate = certificateClient.GetCertificate(certificateName);

        // Return a certificate with only the public key if the private key is not exportable.
        if (certificate.Policy?.Exportable != true)
        {
            return new X509Certificate2(certificate.Cer);
        }

        // Parse the secret ID and version to retrieve the private key.
        string[] segments = certificate.SecretId.AbsolutePath.Split('/', StringSplitOptions.RemoveEmptyEntries);
        if (segments.Length != 3)
        {
            throw new InvalidOperationException($"Number of segments is incorrect: {segments.Length}, URI: {certificate.SecretId}");
        }

        string secretName = segments[1];
        string secretVersion = segments[2];

        KeyVaultSecret secret = secretClient.GetSecret(secretName, secretVersion);

        // For PEM, you'll need to extract the base64-encoded message body.
        // .NET 5.0 preview introduces the System.Security.Cryptography.PemEncoding class to make this easier.
        if ("application/x-pkcs12".Equals(secret.Properties.ContentType, StringComparison.InvariantCultureIgnoreCase))
        {
            byte[] pfx = Convert.FromBase64String(secret.Value);
            return new X509Certificate2(pfx);
        }

        throw new NotSupportedException($"Only PKCS#12 is supported. Found Content-Type: {secret.Properties.ContentType}");
    }
}

//
///从Azure密钥库加载证书（带私钥）
///
///获取带有私钥的证书有点困难，但下面的代码解决了这一问题。
/// 
///获取密钥库证书的私钥
/// https://github.com/heaths/azsdk-sample-getcert
/// 
///另请参见以下GitHub问题：
/// https://github.com/Azure/azure-sdk-for-net/issues/12742
/// https://github.com/Azure/azure-sdk-for-net/issues/12083
/// 
/// 
/// 
/// 
公共静态X509Certificate2加载证书（IConfiguration配置，字符串certificateName）
{
字符串vaultUrl=config[“Vault:Url”]？？“”；
字符串clientId=config[“Vault:clientId”]；
字符串tenantId=config[“Vault:tenantId”]；
字符串secret=config[“Vault:secret”]；
WriteLine（$“正在从Azure密钥库加载证书“{certificateName}”）；
var-credentials=new-ClientSecretCredential（tenantId:tenantId，clientId:clientId，clientSecret:secret）；
var certClient=new CertificateClient（新Uri（Vault URL）、凭据）；
var secretClient=新secretClient（新Uri（Vault URL）、凭据）；
var cert=GetCertificateAsync（certClient、secretClient、certificateName）；
Console.WriteLine（“已加载证书”）；
返回证书；
}
/// 
///获取证书的助手方法
/// 
///来源https://github.com/heaths/azsdk-sample-getcert/blob/master/Program.cs
/// 
/// 
/// 
/// 
/// 
专用静态X509Certificate2 GetCertificateAsync（CertificateClient CertificateClient，
SecretClient SecretClient，
字符串（名称）
{
KeyVault CertificateWithPolicy certificate=certificateClient.GetCertificate（certificateName）；
//如果私钥不可导出，则返回仅包含公钥的证书。
if（certificate.Policy？.Exportable！=true）
{
返回新的X509Certificate2（certificate.Cer）；
}
//解析机密ID和版本以检索私钥。
string[]segments=certificate.SecretId.AbsolutePath.Split（“/”，StringSplitOptions.RemoveEmptyEntries）；
如果（segments.Length！=3）
{
抛出新的InvalidOperationException（$“段数不正确：{segments.Length}，URI:{certificate.SecretId}”）；
}
字符串secretName=段[1]；
字符串secretVersion=段[2]；
KeyVaultSecret-secret=secretClient.GetSecret（secretName，secretVersion）；
//对于PEM，您需要提取base64编码的消息体。
//.NET 5.0预览版引入了System.Security.Cryptography.PemEncoding类以简化此操作。
if（“application/x-pkcs12”.Equals（secret.Properties.ContentType、StringComparison.InvariantCultureInogoreCase））
{
字节[]pfx=Convert.FromBase64String（secret.Value）；
返回新的X509Certificate2（pfx）；
}
抛出新的NotSupportedException（$“仅支持PKCS#12。找到的内容类型：{secret.Properties.ContentType}”）；
}
}