TSA “Travel Sentry” luggage locks contain a disclosed backdoor which is similar in spirit to what Director Comey desires for encrypted phones. In theory, only the Transportation Security Agency or other screeners should be able to open a TSA lock using one of their master keys. All others, notably baggage handlers and hotel staff, should be unable to surreptitiously open these locks.
Unfortunately for everyone, a TSA agent and the Washington Post revealed the secret. All it takes to duplicate a physical key is a photograph, since it is the pattern of the teeth, not the key itself, that tells you how to open the lock. So by simply including a pretty picture of the complete spread of TSA keys in the Washington Post’s paean to the TSA, the Washington Post enabled anyone to make their own TSA keys.
Telephone systems also have a backdoor thanks to CALEA (the Communications Assistance to Law Enforcement Act). Although CALEA doesn’t mandate any particular technology, it mandates that switches support wiretapping, so any phone switch sold in the US must include the ability to efficiently tap a large number of calls. And since the US represents such a major market, this means virtually every phone switch sold worldwide contains “lawful intercept” functionality. Yet this capability doesn’t just find use in law enforcement.
The final backdoor, Dual_EC_DRBG, was surreptitiously developed by the NSA. This trap-doored pseudo-“random” number generator enables the NSA (or anyone who knows a secret number) to efficiently decrypt communication. Yet as many cryptographers were suspicious of both Dual_EC’s poor performance and “backdoor-capable” nature, the NSA also needed to use its market power to encourage adoption, including reportedly bribing RSA Data Security $10M to make it the default pRNG.