Update BQP adversary model: adversary sees QR codes.

protocols/BQP.md

@@ -12,7 +12,7 @@ Each peer derives a shared secret from its own private key and the received publ
 
 ### 1.2 Adversary Model 
 
-We assume the adversary can read, modify, delete and insert traffic on all transports at will.
+We assume the adversary can read, modify, delete and insert traffic on all transports at will. Anything displayed on a screen (specifically QR codes) is assumed to be seen by the adversary.
 
 ### 1.3 Man-in-the-Middle Attacks