Others have given very good overall arguments against this. But let me give one specific technical problem with your proposal. The gov't will be able to get th

Others have given very good overall arguments against this. But let me give one specific technical problem with your proposal. The gov't will be able to get the encrypted input for the device mfr, and the output decrypted from that. Given this data, they will have a huge headstart in backing out a solution to what the mfr's private key is. Even if this weren't so, it makes every major vendor a very cost-effective target for the government. They'll devote resources to either breaking their private key (as I described above), or just using straightforward human engineering techniques. This apparent extra layer of security will not last long in practice. EDIT - in my 2nd para above, it assumes that a mfr has a single private key, which is probably not the case. But generating a unique key pair for every discrete device is both an expense problem and introduces difficulties with managing the set of keys, which makes its security even more difficult.