For open source messengers, you can check whether they actually encrypt your messages and whether the server has access to your encryption keys but what about WhatsApp? Since it's not open source, you can't be sure that the encryption keys aren't sent to the server, right? Has there been a case where a government was able to access WhatsApp chats without reading them from the phone itself?
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Group chats are also end-to-end encrypted in WhatsApp (so any monitoring would need to be done in cooperation with one of the participants' devices before encryption or after decryption)
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Source please.
How do they get the keys?
Who is "they"?
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