C# GetExpirationDateString() returning data in short date format creating issue

Question

I have to check and ensure a certificate is not expired using the below code:

if (DateTime.Parse(cert.GetExpirationDateString()) <= DateTime.Now)
{
     _logger.Log(LogLevel.Error, "Chain Certificate is Expired");
     return false;
} 

cert is a instance of X509Certificate class of .net.

Issue that am facing is GetExpirationDateString function gives the date of expiry in string format(which depends upon the short date format of the current culture)

If the short date format of my machine is DD-MM-YY it returns expiry date 21-12-2030 as 21-12-30, DateTime.Parse function converts 30 to 1930 (if the expiry year is >30).

Is there a way by which I can get the certificate expiry always in dd/mm/yyyy format in order to avoid this issue?

Answer 1

The string representation year 30 will always be converted by default to 1930 and never to 2030 when parsing a DateTime no matter how you try it. Your best bet is to do as @Glorin suggested and use X509Certificate2. This type has a constructor that takes an instance of X509Certificate. Alternatively you can generate using one of the other constructors. Here is a code sample based on what you provided:

var cert2 = new X509Certificate2(cert);
if(cert2.NotAfter <= DateTime.Now)
{
     _logger.Log(LogLevel.Error, "Chain Certificate is Expired");
     return false;
}