The NSA (National Security Agency) has developed an Android phone that meets "Top Secret" criteria using off-the-shelf components. Dubbed the fishbowl phone, 100 units were built and deployed by IAD (Information Assurance Directorate) and division head Margaret Salter says that anyone can recreate the phones using the specs published at the NSA website.
The plan was to buy commercial components, layer them together and get a secure solution. It uses solely commercial infrastructure to protect classified data.
-- IAD Department head Margaret Salter
The new phones, which even have their own secure enterprise application store, mean that users no longer have to speak in code when talking about government secrets. Using IPSEC VPNs, and having voice sessions use Datagram Transport Layer Security and the Secure Real-time Transport Protocol means that calls are safe from prying eyes, and this was published because Salter thinks the voice application security specification would be useful to everyone. Voice calls are encrypted twice, and all go through the NSA enterprise servers to maintain control and keep communications safe between only the parties involved.
It appears that choosing the components was a bit difficult, and Salter urges her colleagues to "demand vendors improve unified communications interoperability". The parts weren't chosen by brand, and instead were chosen for the way they supported the required functionality. This means that a part from one vendor had to work well with a part from another vendor, which proved difficult. None of the compromises that had to be made reduced the security of the phone. In addition, a "police app" was designed to monitor all operations of the device in case any portion was compromised.
'Droid does top secret.