How Can I Override SSL Certificate Validation in C# HTTPS Requests?

Bypassing SSL Certificate Validation in C# HTTPS Requests

This article details how to suppress SSL certificate validation when making HTTPS requests in C#. This is achieved using the ServicePointManager.ServerCertificateValidationCallback delegate, allowing custom handling of SSL certificate errors.

Understanding ServicePointManager.ServerCertificateValidationCallback

The ServicePointManager.ServerCertificateValidationCallback delegate is triggered during HTTPS connection establishment. It receives four arguments:

• sender: The originating HttpWebRequest object.
• certificate: The server's presented X.509 certificate.
• chain: The server's X.509 certificate chain.
• errors: SSL policy errors encountered during validation.

How ServicePointManager.ServerCertificateValidationCallback Works

This delegate executes before the TLS handshake and certificate validation. Its return value determines whether the connection proceeds.

Correct Placement of the Override

The override should be implemented before any HTTPS requests are made. This ensures it's active when connections are initiated.

Lambda Expression Example

A concise method uses a lambda expression:

<code class="language-csharp">ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, errors) => {
    return true; // Accept all certificates
};</code>

Important Considerations

• The lambda expression above returns true, effectively ignoring all certificate errors. This is generally not recommended for production environments due to significant security risks.
• Setting HttpWebRequest.PreAuthenticate to true is usually unnecessary for certificate validation.
• While a global override (affecting all requests) is possible, it's best practice to handle certificate validation individually for each request to minimize security vulnerabilities. Only use global overrides in very controlled and understood circumstances.

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