You could have invented that Bluetooth attack

Summary: Biham and Newman found an invalid curve point attack in Bluetooth's elliptic curve Diffie-Hellman key exchange, which validated only the x coordinate of exchanged points and not the y coordinate. An attacker who replaces a point (x, y) with (x, 0) gets a 50% chance per substituted message that the shared secret becomes the point at infinity, and if both messages are replaced there is a 25% chance Alice and Bob agree on that key, letting the attacker read and insert messages.
Bottom line: The protocol required curve point validation but applied it only to the x coordinate, and that single omission went unnoticed for a decade in a protocol used widely across patch-averse IoT devices.

Read the original at Trail of Bits Blog ↗