Here are a couple of news items regarding TSA and their radio communications.
This item has some details about the purchase of the Icom F-50V radios as part of the efforts to equip everyone at the airport security checkpoints with radios. The article indicates that the original purchase was for 10,000 radios:
http://radioresourcemag.com/newsArticle.cfm?news_id=6260
Secondly, this item describes how the TSA is interested in adding OTAR (Over-The-Air Re-keying) of their existing radios:
https://www.fbo.gov/index?s=opportunity&mode=form&id=7ed6d706b0f60fd6c019983e9d417567&tab=core&_cview=0
If you download some of the linked documents in this page, it describes the test procedures that indicate the OTAR encryption keys will be provided by the Customs & Border Protection (CBP) Key Management Facility.
One could speculate on why the TSA needs to have OTAR. Almost none of the P-25 radios used by the TSA are using encryption, although they are all capable. Some airport locations are using encrypted communications full-time, but many are not. This request, along with a request from TSA for RF tracking devices, seem to indicate a more aggressive technical requirement that just airport security checkpoints.
