actually we want to authenticate user depends on client certificate.
here is the process,
We will issue a client certificate for each device.(it will be a selfSign certificate)
We would like to enable Server with client certificate authentication.
only users who attempt to connect from clients loaded with the right client certificates will succeed. Even if a legitimate user attempts to connect with the right username and password, if that user isn't on a client application loaded with the right client certificate, that user will not be granted access.
We would like to identify\authenticate each device\user with a unqiue certificate.
This feature doesn’t appear to be supported by App Engine. There is currently a request filed for this feature to allow authentication with App Engine using SSL certificates based on user device and you can view updates here.