Check if Certificate Expired

How to check to see if a digital certificate is expired.

Download Chilkat .NET for 2.0 Framework

Download Chilkat .NET for 1.0 / 1.1 Framework

Chilkat.Cert cert = new Chilkat.Cert();
bool isExpired;

//  The LoadByCommonName method searches the registry-based
//  Windows Current User Certificate Store and Local Machine Certificate
//  Store for a certificate whose common name (CN) matches
//  the argument:
bool success;
success = cert.LoadByCommonName("Chilkat Software, Inc.");
if (success == false) {
    MessageBox.Show("Failed to find certificate!");
}
else {

    //  Display the certificate's distinguished name:
    textBox1.Text += cert.SubjectDN + "\r\n";

    isExpired = cert.Expired;
    if (isExpired == true) {
        textBox1.Text += "Certificate is expired." + "\r\n";
    }
    else {
        textBox1.Text += "Certificate is NOT expired." + "\r\n";
    }

}

//  Alternatively, load a Certificate from a .cer file.
//  (Certs may also be loaded from other types of files, such as PEM, DER, PFX, etc.)
success = cert.LoadFromFile("myCert.cer");
if (success == false) {
    MessageBox.Show("Failed to load certificate!");
}
else {

    //  Display the certificate's distinguished name:
    textBox1.Text += cert.SubjectDN + "\r\n";

    isExpired = cert.Expired;
    if (isExpired == true) {
        textBox1.Text += "Certificate is expired." + "\r\n";
    }
    else {
        textBox1.Text += "Certificate is NOT expired." + "\r\n";
    }

}

//  The Chilkat Certificate, Certificate Store, Private Key,
//  Public Key, and Key Container classes / objects are freeware.

//  They are used by and included with the Chilkat Email,
//  Crypt, S/MIME, and other commercial Chilkat components.