This are raw notes, they might not be complete and/or too cryptic.

• mail is base on search
• 3 ways of encidx:
  • 1- dec as you go in your storage
  • 2- index the dec message (index is secure)
  • 3- PIR server side enc queries
• 2 is the only viable
• How to handle the index:
  • trusted machine
  • enc container
    • separated indx for enc mail

• you even if the query is secure, but retrieving the emails the server could guess it
  • mixed enc search result retrieval leak
  • all encrypted search result retrieval leak, too
  • if you have the whole set of emails locally is fixed
  • it can solve by fetching more than what you want

• index could be big, we can accept it
  • full text index = the size of the mail store
  • bandwidth is a problem for big syncs

• 3 is expensive in CPU and bandwidth, it can be more leaky to reduce that
  • in the long term the server could guess the content of the encrypted index by the relations of emails that are retrieved
  • we could put the encryted emails in the index, it's not doable

• single mail
• lables (tags)
• free search

• For a lot of results I don't need to see them, but the MUA loads them for when you see it

• Each client can build the index, less bandwidth more CPU

• make a bloomfilter for each word, too much computation time

• the 90s technology solves everything (do anything in the client)
  • does that work in the smartphone?

• usability: unlock the secret keys/storage for the whole session
  • it index when things are fetched

• We don't need to index encrypted emails, that could be a choice of the user

• clients to think on how to sync and store email storage and index in a secure manor

• the case of separated indx for enc email don't gain much, too hard to explain to the user to choose

local model

• store everything in the client side
• store the entire message archive
• protect the index
• pruning strategies (index and messages)
• protect archive
• lookaside metadata associated per message, you could store the session key of the message so you can decrypt it if you don't have the key anymore