See EHR Dashboard.
This is a completely useless EHR feature which nobody will ever use. The only reason it exists is that we were required, for EHR certification, to prove that Open Dental was capable of producing a encryption and decryption using AES-128. The code that we wrote for this window will become part of some security features in the next round of EHR certification in 2013.
In the EHR Dashboard, click the Encryption button at the right.