A Microsoft researcher has suggested tattooing passwords on patients with pacemakers and other implanted, medical devices to ensure the remotely controlled gadgets can be accessed during emergencies. The proposal is the latest to grapple with the security of implanted, medical devices equipped with radio transmitters that can be controlled without the need for surgery. Besides pacemakers, other types of potentially vulnerable devices include insulin pumps and cardiac defibrillators. In 2008, researchers demonstrated that heart monitors were susceptible to wireless hacks that caused pacemakers to shut off or leak personal information. But equally devastating are scenarios where physicians are unable to provide emergency care because they don’t have the access codes needed to control the devices. In a paper published last week and reported in the Register of Great Britain, the researcher proposed permitting access to such devices to be controlled with encryption similar to what’s used on wifi networks. Access keys would then be tattooed on patients using ink that’s invisible under most conditions.