BEFORE
SIGN: OLD
CONSUMER CHECKS OLD
OVERLAP
SIGN: OLD + NEW
CONSUMER SWITCHES
AFTER
SIGN: NEW
OLD KEY RETIRED
HEADER DURING THE OVERLAP
v1,g0hM9SsE+OTPJTGt/tmIK v1,bm9ldHUjKzFob2VudXRo
ANY ONE MATCHING SIGNATURE IS ENOUGH TO PASS