Closed source applications like WhatsApp can be and in fact are reverse engineered by researchers who want to verify the end-to-end encryption claim. For exampl

Closed source applications like WhatsApp can be and in fact are reverse engineered by researchers who want to verify the end-to-end encryption claim. For example, see this BlackHat talk: https://i.blackhat.com/USA-19/Wednesday/us-19-Zaikin-Reverse-Engineering-WhatsApp-Encryption-For-Chat-Manipulation-And-More.pdf https://i.blackhat.com/USA-19/Wednesday/us-19-Zaikin-Reverse...