Maybe not the NSA, but the US census bureau certainly has: http://www.scientificamerican.com/article/confirmed-the-us-census-b/ http://www.scientificamerican.co

Maybe not the NSA, but the US census bureau certainly has: http://www.scientificamerican.com/article/confirmed-the-us-census-b/ http://www.scientificamerican.com/article/confirmed-the-us-c...