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/** @mainpage SafeChat
SafeChat runs on:
https://safechat.ch
SafeChat development is on:
https://dev.marc.waeckerlin.org/redmine/projects/safechat
Implementation Details: @ref security, @ref api, @ref protocol,
@ref database
SafeChat is a chat program designed to protect your privacy. It is
designed to be:
-# extremely easy to use
-# zero installation
-# simple registration, within seconds
-# web 2.0 - works in any modern browser
-# user does not have to care about keys, security, encryption
-# all cool features
-# pseudonym accounts, no phone number, no email,nothing required
-# send images and other attachments
-# build groups
-# no need to be online, receive messages on next login
-# central user directory
-# absolutely secure
-# tap-proof
-# no metadata available
-# all messages are sent to all users, only the authorized users can decrypt it
-# server can be untrusted
-# thin server, rich client
-# all encryption is done in the client
-# server only stores minimal user data (name, public key) and encrypted messages
-# no access to plain data, not even through server confiscation
-# double secured internet transport
-# messages are encrypted for the recipents only
-# server connection is SSL secured in addition
-# private data fully in the user's hand
-# password is stored in the user's brain only
-# private key is password encrypted
-# private key is stored in the user's local machine only
-# two factor security, access needs two tokens
-# the password in the user's brain
-# the private key in the user's browser memory
-# fully open source
@section why Why I Created SafeChat
The Swiss parliament has decided to increase the power of police
(BÜPF: Bundesgesetz zur Überwachung des Post- und
Fernmeldeverkehrs) and secret service (NDG:
Nachrichtendienstgesetz). This increases global enforced data
preservation without any suspicion. This even allows the police to
run a trojan in computers of suspicious persons.
That was the point, when I started to think about secure
communication that defeats these attacks against our
privacy. Noone should be able to read what's not for his eyes,
even if he controls the server. There should be no metadata,
i.e. no one should know, who is communicating to each other.
There are secure means of communication, i.e. Jabber/OTR and
PGP-Mail (but with unprotected metadata). But these are too
complicated for the avarage user. He has to take care about keys
and their distribution. In some chat programs, there is no offline
message store, so you can only send a message, if the receiver is
online. Some chat programs require to identify you, they ask your
phone number and some even steal your address book
(i.e. WhatsApp). Not here! Use any pseudonym. No special knowledge
needed. User is guided as much as possible, the interface is as
simple as possible. Data is only collected, if it is necessary.
So I present here the safe chat program for dummies
@page design Design
Safechat is designed to provide a safe chat program for
dummies. Everything is simple to use, everything is strong
enrcrypted, everything is open source. You can chat and you can
write encrypted e-mails from the same address.
<a ahref="https://www.eff.org/de/node/82654">SafeChat provides</a>:
- Encrypted in transit ✓
- Encrypted so the provider can't read it ✓
- You can verify contacts' identities ✓
- Past communications are secure if your key is stolen ✓
- Code is open to independent review ✓
- Security design is properly documented ✓
- Audit not yet done, we invite you to audit our code ✗
@dot
@enddot
@msc
user, browser, "safechat.ch", keyserver;
|||
--- [label="load homepage"];
user => browser [label="load https://safechat.ch"];
browser => "safechat.ch" [label="GET /"];
"safechat.ch" >> browser [label="index.html"];
browser => "safechat.ch" [label="GET /safechat.js"];
"safechat.ch" >> browser [label="safechat.js"];
...;
browser -> browser [label="run safechat.js"];
--- [label="Create Account"];
browser => user [label="show create account"];
user >> browser [label="username, password"];
browser -> browser [label="create openpgp key pair"];
browser -> browser [label="locally store encrypted keys"];
browser -> browser [label="msg=encrypt(datetime)"];
browser -> "safechat.ch" [label="logon(username, pubkey, msg)"];
"safechat.ch" -> "safechat.ch" [label="datetime=decrypt(msg)"];
"safechat.ch" -> "safechat.ch" [label="verify datetime"];
"safechat.ch" => keyserver [label="lookup(username)"];
keyserver >> "safechat.ch" [label="not found"];
"safechat.ch" -> keyserver [label="upload(pubkey)"];
"safechat.ch" -> browser [label="logon success"];
browser -> user [label="ready to chat"];
@endmsc
@page security Password and Secrets Concept
Neither the password nor the private key are sent to the
server. They remain under the user's control and in the user's
property. Only the user name and the public key are sent to the
server.
- The password is only kept in the browser's transient memory.
- The private key is kept in encrypted form in the browser's
persistent local storage.
- The public key is stored on server, so that other users can
lookup for a user's public key.
There are two secret security tokens: The password, that is in the
user's mind and the private key, which is in the user's device, in
the local storage of his browser. Messages can only be sent or
read with access to both security tokens.
@page protocol SafeChat Protocol
@tableofcontents
@section newuser Create New User
If no credentials exist in the browser's local storage, the
browser asks the user for a user name and a password and creates a
private key that is encrypted with the password.
In the login(), the browser sends the user's name and public key
to the server. The server creates a new user, if the user does not
exist yet. Then the server returns, whether user name and public
key match to what he has in his table.
@msc
user, browser, server;
user -> browser [label="https://safechat.ch"];
browser -> server [label="index.html"];
browser <- server [label="safechat.js",URL="\ref safechat.js"];
user <- browser [label="register new user"];
user -> browser [label="username / password"];
browser -> browser [label="create openpgp-public/private keys"];
browser -> server [label="login.php(username, public-key)"];
server -> server [label="if user name does not exist:\nstore username/public-key"];
server -> browser [label="success"];
@endmsc
*/
/** @page api Server API Calls
@tableofcontents
List of server REST API calls. SafeChat server implement s REST
API, so that all API calls are in the following form, where
parameters and values are url encoded:
@code
https://safechat.ch/api-call.php?param1=value1¶m2=value2[...]
@endcode
So for method get() a valid call could be:
@code
https://safechat.ch/get.php?start=100
@endcode
*/
