add note about Bob mashing the "Verify" button prematurely
@@ -83,6 +83,21 @@ Step 4 is to ensure that Bob does not present a QR code claiming to be Carol's
key. Without this check, Bob will be able to trick Alice into verifying a key
under his control, and evesdropping on Alice's communications with Carol.
+The security of verifying Alice's key depends on Bob not hitting the "Verified"
+button until after Alice's device indicates success. However, users have a
+tendency to click on buttons without reading what the screen says. This might
+be addressed by:
+
+- allowing Bob to easily undo the verification if Alice's device subsequently
+ gives an error
+- posing Bob a dummy question that he cannot answer until after Alice's device
+ displays the check results. For example: "Does Alice's device show a cat or
+ a dog?" Alice's device will show one or the other after it has checked the
+ key received from Bob, forcing Bob to wait for the check to complete.
+ (Whether a cat or a dog is displayed could be keyed to, for example, a bit in
+ the transaction ID.)
+- (possibly other ways)
+
Other Issues
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