In this chapter, you learned how GPG can protect e-mail confidentiality. We created a
threat model for our system and showed how this analysis can help us understand the cap-
abilities and limitations of our design. At the end, we successfully built a BBB GPG co-
processor that uses a TPM to help protect the GPG keys at rest and got more practice com-
bining a microcontroller with an embedded Linux platform.
In the next chapter, we will investigate another major privacy enhancing technology that is
used to protect real-time chat. You'll learn about the unique cryptographic properties of
Off-the-Record ( OTR ) and how to use OTR over an Internet Relay Chat gateway that is
hosted by your BBB.