如何使Go接受TLS客户端身份验证的自签名证书？

Question

我正在使用AWS API网关和一个后端。为了确保所有的连接都通过API网关，我需要使用TLS客户端身份验证（又名双向身份验证，相互身份验证）。

原则上，这与以下内容一起工作：

func enableClientAuth(server *http.Server, clientCertFile string) error {
    clientCert, err := ioutil.ReadFile(clientCertFile)
    if err != nil {
        return err
    }
    caCertPool := x509.NewCertPool()
    caCertPool.AppendCertsFromPEM(clientCert)

    tlsConfig := &tls.Config{
        ClientAuth: tls.RequireAndVerifyClientCert,
        ClientCAs:  caCertPool,
    }
    tlsConfig.BuildNameToCertificate()
    server.TLSConfig = tlsConfig
    return nil
}

我遇到的问题是这个错误：

TLS：无法验证客户端的证书:X509:由未知授权机构签署的证书（可能是因为在尝试验证候选授权机构证书“Apigateway”时“X509:签名无效：父证书无法签署此类证书”）

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Answer 1

@johnweldon的评论让我找到了解决方案，那就是我需要在加载客户端证书结构之后修改它。这需要解码PEM并解析出证书。对于API网关客户端证书，我必须将basicconstraintsvalid和isca设置为true，将keyusage设置为keyusagecertsign；对于本地生成的证书，我只需要后两个。在我的问题中修改enableClientAuth()函数：

func enableClientAuth(server *http.Server, clientCertFile string) error {
    pemBytes, err := ioutil.ReadFile(clientCertFile)
    if err != nil {
        return err
    }

    pemBlock, _ := pem.Decode(pemBytes)
    clientCert, err := x509.ParseCertificate(pemBlock.Bytes)
    if err != nil {
        return err
    }

    clientCert.BasicConstraintsValid = true
    clientCert.IsCA = true
    clientCert.KeyUsage = x509.KeyUsageCertSign

    caCertPool := x509.NewCertPool()
    caCertPool.AddCert(clientCert)

    tlsConfig := &tls.Config{
        ClientAuth: tls.RequireAndVerifyClientCert,
        ClientCAs:  caCertPool,
    }
    tlsConfig.BuildNameToCertificate()
    server.TLSConfig = tlsConfig
    return nil
}