How to connect key.p12 for Google Analytics via gapi-google-analytics-php-interface.class?

Question

Google Analytics

On May 25, Google switched to OAuth2. There is a wonderful class https://github.com/erebusnz/gapi-google-analytics-...
The description describes in detail about the connection with the steps:
1) The project was created,
2) API Analytics allowed,
3) Full access for [email protected] .com,
4) key.p12 generated and loaded in binary mode.
And the result is an error.

Fatal error: Uncaught exception 'Exception' with message 'GAPI: Failed load key file "key.p12". 
Check if correct p12 format.' in YYY.php:603 
Stack trace: 
#0 YYY.php(126): gapiOAuth2->fetchToken('[email protected]', 'YYY.php', NULL) 
#1 YYY.php(788): gapi->__construct('[email protected]', 'YYY.php') 
#2 {main} thrown in YYY.php on line 603

Tried for 2 different sites with different accounts on PHP 5.3.3.
Regenerated, recreated and reloaded several times.
Any ideas?