Messages, documents or media files sent by WhatsApp users encrypted by end-to-end encryption, will only be able to be read or viewed by the intended recipients only (not even by WhatsApp), and once messages, documents and media files are delivered to the recipients, WhatsApp will remove them from their servers. But, even if WhatsApp was storing messages, documents or media files on their servers, they wouldn't be able to decrypt the messages, documents or media files themselves, even if they are compelled by law enforcement.
This security update by WhatsApp, will make it impossible for law enforcement (the government) to subpoena WhatsApp users’ messages, documents and media files. Therefore, if the government wants WhatsApp users’ information, they will have to get it directly from the users’ mobile devices. Also, WhatsApp users will not have to worry about WhatsApp’s servers being hacked by cybercriminals, because there will be no information for the cybercriminals to steal, or even if they are able steal any information, they would not be able to decrypt, read or view it, so it would be just useless to them.
WhatsApp encryption works by securing messages, documents or media files with a lock, which only the recipients and senders have special keys needed to unlock, read or view them. Every message sent will have its own unique lock and private key, and at no time will WhatsApp server have access to any of the WhatsApp users' private keys.
WhatsApp says that encryption is one of the most important tools governments, companies, and individuals have to promote safety and security in the new digital age, and they are aware of discussion about encrypted services and the work of law enforcement (the battle between Apple and the U.S government about a terrorist’s IPhone that the F.B.I wants access to, but Apple won’t help). But, WhatsApp says while they recognize the important work of law enforcement in keeping people safe, efforts to weaken encryption risk exposing people's information to abuse by cybercriminals, hackers, and rogue states.