More README

.gitignore

@@ -1,4 +1,4 @@
 notes/
-./run.sh
+run.sh
 ./dethnote
 ./dethnote.exe

README.md

@@ -138,3 +138,55 @@ ever in the application's working memory.
 
 Only when access has been fully granted to decrypt the message will the
 `message.bin` file be opened.
+
+## Zero Admin Visibility
+
+The admin of the web server has zero visibility into any of the data in
+the service.
+
+* The filesystem is just full of hexadecimal path names leading to
+  files encrypted with AES-256.
+* No e-mail addresses are visible to the admin, because those are stored
+  _inside_ those encrypted files.
+* The admin can't snoop on other peoples messages because they are _very_
+  heavily encrypted:
+    * Strong Diceware pass phrases that would resist brute force attacks
+      for millions of years even with a fast hashing algorithm.
+    * Dethnote uses the bcrypt hashing algorithm with a slow iteration
+      count making brute forcing all the harder.
+* The admin can't enumerate what passwords _even exist_. All he can see
+  is the hexadecimal data paths, but doesn't know what the passwords are,
+  and can't even tell _whose_ files belong to _who_. And brute forcing
+  random Diceware passwords is practically impossible.
+
+## Robustness and "Offline Mode"
+
+This service relies heavily on a reliable e-mail server for sending out
+verification e-mails, Decryption Routine warning e-mails, and so-on.
+
+But this is the real world and web servers aren't always reliable.
+
+On the web, the service will naturally self-test the e-mail system:
+before you can decrypt a note, you have to verify an e-mail address.
+This ensures that the e-mail system is working, so that when the
+Decryption Routine begins, it will be able to send an e-mail to the
+note owner.
+
+But I mainly wrote this service for myself, and so it has an "Offline
+Mode" that works in absence of a running web server or e-mail configuration.
+
+My web server backs up to my desktop PC at home, and so there will always
+be a copy of _this application_ and its database of encrypted notes there.
+The command line interface of the program allows you to immediately decrypt
+and open a note _that you have a password for_. Example:
+
+```bash
+# Open a note with this password:
+% dethnote -open "viewable require broom taunt spoiled"
+Here is the contents of the note!
+```
+
+Note that this doesn't change any of the security considerations of the
+service. The passwords are still just as hard to brute force. All this
+"offline mode" does is bypass the need for e-mail validation and
+minimum timeouts before opening notes.