Permission to read private key IIS Server

You need the permission to read private key for IIS Server.

   1.Go to this path:  C:\ProgramData\Microsoft\Crypto\RSA\MachineKeys[File Name]

2. Go to that path and open file properties
3. Go to security tab
4. Click on "Edit" then "Add"
5. Add  users "Network Service" and "IIS_IUSRS" and give Full controll Permitions.

or add  IIS AppPool\[your application pool name]