README

Intent is to offer a tool for using GPG and other common tools to permit 
collection and local storage of data such that the data is only recoverable
to the holder of the private key corresponding to the public key used to
encrypt the original data.

Use case:
 - Collect data in a public place with low-cost hardware, while protecting
   the bulk of the data collected.
 - Collect sensitive data with lower concern that the data will be accessible
   to unintended recipients.

Caveats:
 - Until the encrypted file is closed and the corresponding key is erased from
   memory, the data in the current file is at risk.  Choose file cycle times
   with this in mind.
 - If the private key is lost, the data is lost.
 - Many protections intended for GPG keys that are held by persons are
   bypassed as not relevant.  Examples: revocation, email addresses, etc.

Future planned work:
 - Add ability to encrypt to multiple private keys.
 - Add ability to encrypt such that decryption only possible with a quorum of
   private keys.

Architecture:
 - Tool to create private key and set up for data collection.
   * setup.sh
     + prompts for a passphrase.
     + generates a .privkey and .pubkey pair.
 - Tool to snarf data (stdin or filename on commandline) into an encrypted
   store (series of files).  Intended for repeated, periodic use.
   * encrypt.sh
     + Requires access to .pubkey file only, and generates an encrypted output
       that cannot be accessed without the .privkey and passphrase.
 - Tool to decrypt store using private key.
   * decrypt.sh
     + Requires access to a .privkey file, and prompts for the passphrase used
       in the setup stage.


Options to retrieve data from the Pi:
 - HTTP? (can even use non-SSL because the data is all encrypted).
   * Offer a lighttpd conf file for this purpose.
   * Run as a private user by disabling (sudo systemctl disable lighttpd.servce
     and then stopping sudo sytemctl stop lighttpd.service before running it
     as the pi user)
 - Write to an external USB stick?
   * Sound recording should already stop immediately and fail to start at next
     interval if no mic.
   * Need to auto-mount and copy out current batch of audio files to a USB
     stick if plugged in, then unmount+sync.  How to signal when that is done?
   * Auto mount can happen with usbmount package.  Needs additional config:
     & If grep "PrivateMounts=yes" && echo [service]\nPrivateMounts=no |
systemctl show --property=PrivateMounts
systemctl set-property <unit> PrivateMounts=no
   * Requires this to be set by editint due to bug: systemctl edit ...?
   * requires 'zip' package
   * Requires autoExport shell script.