I think that's exactly it. (16) means the 16 already arrested (not yet identified to us). 19 is these 16 plus 3 former/present #1 and #2 agency heads.
Thanks for finding the typo. Corrected.
Tested by whom, and in what manner?
Companies who make chips consider their chips trade secrets and/or the masks protected by copyright. Letting an outsider into the chip foundry is anathema to them (but there could be some way to force the inspection).
Testing how? How do you test a chip for backdoors?
People in the software testing industry know that testing 100% of the paths through software is impossible. The best that can be done is probabilistic fuzz testing with random inputs to reduce the error rate to something acceptable small, stated as number of errors per line of code. They know it is mathematically impossible to actually catch 100% of all bugs. The more complex the software or chip, the more impossible to guarantee 100% free of bugs/errors. Same applies to backdoors.
Also chip industry does not want some government inspector come in, take a randomly selected chip off the production line, then take it away to subject it to tests in their lab for an indeterminate length of time. During that time, they are scared competitors will get trade secret info about their latest chip. Scared of corrupt inspector selling trade secrets. A reasonable fear! A threat to competition.
I predict there is no way this idea would fly.
There has to be some other way to prevent backdoors, but random testing by an authority isn't one of them.
Testing of finished product by an industry group (without direct inspection of the chip mask) with published reports might work.
Consumers would decide if they like a product based on published test reports. But this idea too has flaws. How do you know industry group is competent, unbiased, and not corrupt?
We all probably thought the Electronic Frontier Foundation was trustworthy … until we found out probable CIA links going way back.
Really this is a thorny problem with no good solutions in sight.