Web service jwt token

Hi...,

   

Am using the below JWT Token web service used the below link nut am getting error see the below screen shot and i wil share the source, kindly check and give the solutions plz, am used the below link source code on your website soruce 

  

https://www.c-sharpcorner.com/article/wcf-service-with-jwt-token/ 

 

 

The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters. 

 

am sharing the source code kindly check as rar file