I'd support an encryption backdoors if they implement it similar to the backdoors in the existing telephony system. They must get a warrant to tap your telephone line and by law, the telecom company must comply. That's why all telephony switch have these "features" that can "copy/record" telephony packets for law enforcement purposes. If people don't have a problem with the existing system, I don't see why they would have a problem with data encryption backdoors.