[SQL] Replication and Field Level Encryption - Mailing list pgsql-sql

I really need some assistance to see if I'm heading in the right direction and get a second opinion.  Also to see if there is anything I may need to reconsider.

I'm building a database design and application from the ground up.  The database is going to be synced in three locations using BDR.  The local office will use the instance closest to them.  Each location will also have an additional "BI/Reporting" instance with data being updated once a day.

I need to be able to do field level encryption, with both 2-way encryption and 1-way hashing (ie: passwords, PII, PHI data).  I believe I want to use PGCrypto and keep as much programming logic on the SQL server.  Right now, there will be a desktop, mobile and web application; plus additional web services to support the applications.  Even though the data will be encrypted and decrypted on the server, data transport security will rely upon SSL/TLS between the client and server.  I'd like to keep the client applications as "dumb" as possible so if we decide to change encryption methods, keys, etc.  We don't have to rollout entirely new applications just for key changes or if we have to re-hash/re-salt the database.

The things I keep going back and forth on are:

1. Should the encryption and decryption be at the client or server? 
   
   1. Advantage to the client
      1. Data is secured end-to-end
   2. Disadvantage
      1. Managing application changes during security key changes.
   3. Advantage to the server
      1. Consolidates programming logic and reduces the encryption process on the client
   4. Disadvantage to the server
      1. Data relies on communications SSL/TLS for encryption
2. Is BDR ready for multi-master in the production world?  Or should I use a master/hot-standby at the main facility?  I'm mainly the two of the locations are in rural areas and want to make sure if their internet connection goes down, they can still operate?  Yes, I'm aware there are commercial packages out there.  We are weighing those, but need to show that if we did it without the use of commercial software/support/services, there is risk/reward.

Any thoughts or items I should also consider?

-JA-