Ahodges/documentation/doc158

@WatsonEmily please share with PMs who have worked through this process with data czars before... I'd love to get their feedback on level of detail and completeness.
@rocha and @stroilova , please let me know if this information is accurate (or designate others in Analytics).
@mhoeber and @srpearce , your feedback always welcome.

Reorg:

To assure the security of data packages, the edX Analytics team encrypts all files before transferring them to a partner institution. As a result, when you receive a data package (or any other file from the edX Analytics team), you must decrypt the data before it can be used in any way. 

The encryption and decryption process requires two keys: a private key that you use in decrypting files from edX and the unique public key that you send to edX and that edX then uses to in encrypting your data packages and files. Each data czar creates his or her own private and public key pair to use with edX files. 

 To create the keys needed for this encryption and decryption process, you use GNU Privacy Guard (GnuPG or GPG). Essentially, you install a cryptographic application on your local computer and supply your email address and a secret passphrase (a password). The application uses this information to create both the private key and the public key.