How to get "exp" from jwt token and compare with it current time to check if token is expired

Question

I am using System.IdentityModel.Tokens.Jwt package and the below code decoding the jwt token, but it won't give exp value?

 var handler = new JwtSecurityTokenHandler();
 var decodedValue = handler.ReadJwtToken("token");

How to get exp and compare it with the current DateTime to calculate token is expired or not?

Update:

I am using Azure.Core.AccessToken where I have the below property,

public DateTimeOffset ExpiresOn
    {
        get;
    }

Answer 1

Glad that you found your solution Posting the complete answer for helping community member when they will encounter the same problem.

For Reproducing the issue, I have generated an Access token using Ouath2.0 with client credential with shared secret.

C# Code for converting Unix timestamps into DateTimes

using System;

public class HelloWorld
{
    
    public static DateTime ConvertFromUnixTimestamp(int timestamp)
{
    DateTime origin = new DateTime(1970, 1, 1, 0, 0, 0, 0);
    return origin.AddSeconds(timestamp); //
}
    
    public static void Main(string[] args)
    {
        Console.WriteLine ("Hello Mono World");
        int timestamp=1643438945;
        DateTime date=ConvertFromUnixTimestamp(timestamp);
        Console.WriteLine("Token Expire time "+date);
        if (date>DateTimeOffset.UtcNow)
        {
            Console.WriteLine ("Token is not expire");
        }
        else {
            Console.WriteLine ("Token has expired");
        }
    }
}

Output--