Update Readme to clarify some security aspects

* Clarify that HTTPS is essential
* Clarify how/when user data is protected in case of a server breach, fixes https://github.com/sebsauvage/ZeroBin/issues/45
* Clarify the password-strength matters when you post the URL publicly
* some rewording

README.md

@@ -5,9 +5,11 @@ knowledge of pasted data.
 
 Data is encrypted/decrypted in the browser using 256 bit AES.
 
-This fork of ZeroBin refactored the source code to allow easier and cleaner 
-extensions. It is still fully compatible to the original ZeroBin 0.19 data 
-storage scheme. Therefore such installations can be upgraded to this fork 
+This is a fork of ZeroBin, originally developed by
+[Sébastien Sauvage](https://github.com/sebsauvage/ZeroBin). It was refactored
+code to allow easier and cleaner extensions and has now much more features than
+the original. It is however still fully compatible to the original ZeroBin 0.19 
+data storage scheme. Therefore such installations can be upgraded to this fork 
 without loosing any data.
 
 ## What ZeroBin provides
@@ -19,7 +21,7 @@ without loosing any data.
 
 + Pastebin-like system to store text documents, code samples, etc.
 
-+ Encryption of data sent to server, even if it does not provide HTTPS.
++ Encryption of data sent to server.
 
 + Possibility to set a password which is required to read the paste. It further 
   protects a paste and prevents people stumbling upon your paste's link
@@ -27,26 +29,35 @@ without loosing any data.
 
 ## What it doesn't provide
 
-- As a user you have to trust the server administrator, your internet provider 
+- As a user you have to trust the server administrator. If the server you use does
+  not use HTTPS (which is *not* recommend!) you also have to trust your internet provider 
   and any country the traffic passes not to inject any malicious javascript code.
-  Ideally, the ZeroBin installation used would provide HTTPS, secured by 
+  All ZeroBin installation should use HTTPS. Ideally secured by 
   [HSTS](https://en.wikipedia.org/wiki/HTTP_Strict_Transport_Security) and
   [HPKP](https://en.wikipedia.org/wiki/HTTP_Public_Key_Pinning) using a 
-  certificate either validated by a trusted third party (check the certificate 
-  when first using a new ZeroBin instance) or self-signed by the server operator,
-  validated using a
+  certificate either validated by a trusted third party (in most cases Certificate
+  Authorities) or self-signed by the server operator, validated using a
   [DNSSEC](https://en.wikipedia.org/wiki/Domain_Name_System_Security_Extensions) protected
   [DANE](https://en.wikipedia.org/wiki/DNS-based_Authentication_of_Named_Entities)
   record.
 
 - The "key" used to encrypt the paste is part of the URL. If you publicly post
   the URL of a paste that is not password-protected, everybody can read it.
-  Use a password if you want your paste to be private.
+  Use a password if you want your paste to be private. In this case make sure to
+  use a strong password and do only share it privatly and end-to-end-encrypted.
 
 - A server admin might be forced to hand over access logs to the authorities.
   ZeroBin encrypts your text and the discussion contents, but who accessed it
   first might still be disclosed via such access logs.
 
+- In case of a server breach your data is secure as it is only stored encrypted on
+  the server. However the server could be misused or the server admin could be legally
+  forced into sending malicious JavaScript to all web users, which grabs the decryption key
+  and send it to the server when a user accesses a ZeroBin.  
+  Therefore do not access any ZeroBin instance if you think it has been compromised. As long
+  as no user accesses this instance with a previously generated URL, the content cannot be
+  decrypted.
+
 ## Options
 
 Some features are optional and can be enabled or disabled in the [configuration