In a nutshell, the document details how all communications companies will be forced to break their encryption and be legally required to create a backdoor so authorities can read all communications.
Companies like WhatsApp could be forced to “modify” their products to enable intercept and metadata collection.
“The regulations would make the demands that [Home Secretary] Amber Rudd made to attack end-to-end encryption a reality. But if the powers are exercised, this will be done in secret.”
A company has to comply with the law…. it may be more difficult to force an open source project to do the same though as they often don’t have any corporate company registration.
See http://mashable.com/2017/05/05/whatsapp-encryption-uk-government-snoopers-charter/ 
How the government can force WhatsApp to break its encryption
The true extent of the government’s intrusion into your data.