After some reading and samples I've been trying to use libsodium in an Azure website. 
Since I read that sodium would be part of the php core since 7.2 and php site shows
no additional configuration is needed
tried Windows with fastcgi and Linux
phpinfo() shows sodium in both of them yet i cannot use it , as exampled in https://paragonie.com/book/pecl-libsodium/read/08-advanced.md#crypto-aead-aes256gcm because all i get is
Fatal error: Uncaught Error: Call to undefined function sodium_crypto_aead_aes256gcm_is_available()
my phpinfo -> 
PHP Version 7.2.1  
System  Linux 737d7217d54e 4.4.0-119-generic #143-Ubuntu SMP Mon Apr 2 16:08:24 UTC 2018 x86_64  
Server API  Apache 2.0 Handler  
PHP API 20170718  
PHP Extension   20170718  
Zend Extension  320170718  
Zend Extension Build    API320170718,NTS  
PHP Extension Build API20170718,NTS  
....  
Sodium  Frank Denis  
....
thank you all for the help
 
     
     
    