How To Authenticate The Gklocalplayer On My Node.js Server

In Apple's Doc, generateIdentityVerificationSignatureWithCompletionHandler, you are to concatenate into a data buffer 4 parameters, one of which being 'The timestamp parameter in B

Solution 1:

The easier way is to use ref

varref = require('ref');

var buf = ref.alloc('uint64');
ref.writeUInt64BE(buf, 0, '1401893400733');

after that you could use the buffer to update the verifier.