[randaouser]

1) Can you clarify which users? The government issuing the search query is unable to decrypt the messages. If they flag it, they can order a warrant against the individual to decrypt the message.

2) A random salt is used so only exact keywords will match (I have a fuzzy matching implementation using jaccard similarity and minhashing but that is an extension). To answer your question technically yes, but what you describe would require many interactions with the data source as the content producer must apply the encrypted queries against their encrypted data.

Again, I am trying to provide a solution that is beyond just giving someone the ability to read your private messages without your consent. No doubt it will require work from sidechannel attacks so appreciate any feedback