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Certificate Validation Differences Between HTTPS, SSL over TCP, and SOAP Security

You can use certificates in Windows Communication Foundation (WCF) with message-layer (SOAP) security in addition to transport-layer security (TLS) over HTTP (HTTPS) or TCP. This topic describes differences in the way such certificates are validated.

Validation of HTTPS Client Certificates

When using HTTPS to communicate between a client and a service, the certificate that the client uses to authenticate to the service must support chain trust. That is, it must chain to a trusted root certificate authority. If not, the HTTP layer raises a WebException with the message "The remote server returned an error: (403) Forbidden." WCF surfaces this exception as a MessageSecurityException.

Validation of HTTPS Service Certificates

When using HTTPS to communicate between a client and a service, the certificate that the server authenticates with must support chain trust by default. That is, it must chain to a trusted root certificate authority. No online check is performed to see whether the certificate has been revoked. You can override this behavior by registering a RemoteCertificateValidationCallback callback, as shown in the following code.

ServicePointManager.ServerCertificateValidationCallback +=
    new RemoteCertificateValidationCallback(ValidateServerCertificate);

where the signature for ValidateServerCertificate is as follows:

public static bool ValidateServerCertificate(
  object sender,
  X509Certificate certificate,
  X509Chain chain,
  SslPolicyErrors sslPolicyErrors)

Implementing ValidateServerCertificate can perform any checks that the client application developer deems necessary to validate the service certificate.

Validation of Client Certificates in SSL over TCP or SOAP Security

When using Secure Sockets Layer (SSL) over TCP or message (SOAP) security, client certificates are validated according to the CertificateValidationMode property value of the X509ClientCertificateAuthentication class. The property is set to one of the X509CertificateValidationMode values. Revocation checking is performed according to the values of the RevocationMode property value of the X509ClientCertificateAuthentication class. The property is set to one of the X509RevocationMode values.

myServiceHost.Credentials.ClientCertificate.Authentication.
    CertificateValidationMode=
    X509CertificateValidationMode.PeerOrChainTrust;

myServiceHost.Credentials.ClientCertificate.Authentication.
    RevocationMode=X509RevocationMode.Offline;

Validation of Service Certificate in SSL over TCP and SOAP Security

When using SSL over TCP or (SOAP) message security, service certificates are validated according to the CertificateValidationMode property value of the X509ServiceCertificateAuthentication class. The property is set to one of the X509CertificateValidationMode values.

Revocation checking is performed according to the values of the RevocationMode property value of the X509ServiceCertificateAuthentication class. The property is set to one of the X509RevocationMode values.

myClient.ClientCredentials.ServiceCertificate.
    Authentication.CertificateValidationMode=
    X509CertificateValidationMode.PeerOrChainTrust;
myClient.ClientCredentials.ServiceCertificate.Authentication.
    RevocationMode = X509RevocationMode.Offline;

See also