sphinx: a password Store that Perfectly Hides from Itself (No Xaggeration)

pwdsphinx is python wrapper around libsphinx - a cryptographic password storage as described in https://eprint.iacr.org/2015/1099

Dependencies

You need libsphinx.

You need also to install pysodium using either your OS package manager or pip.

If you want to use also the websphinx browser extension you need to install also an X11 variant of pinentry from the gnupg project:

• either apt-get install pinentry-qt
• or apt-get install pinentry-gtk2
• or apt-get install pinentry-gnome3
• or apt-get install pinentry-fltk

(or anything equivalent to apt-get install on your OS)

Installation

pip3 install pwdsphinx should get you started.

API

sphinxlib is a ctypes-based python wrapper around libsphinx, so you can build whatever you fancy immediately in python. The interface exposed wraps the 3 sphinx functions from the library like this:

def challenge(pwd)

returns bfac and chal

def respond(chal, secret)

return the response

def finish(pwd, bfac, resp)

returns the raw 32 byte password.

The functions for the PAKE (OPAQUE) protocol are not yet exposed.

Server/Client

Since the sphinx protocol only makes sense if the "device" is somewhere else than where you type your password, pitchforked sphinx comes with a server implemented in py3 which you can host off-site from your usual desktop/smartphone. Also a client is supplied which is able to communicate with the server and manage passwords.

Both the client and the server can be configured by any of the following files:

• /etc/sphinx/config
• ~/.sphinxrc
• ~/.config/sphinx/config
• ./sphinx.cfg

Files are parsed in this order, this means global settings can be overridden by per-user and per-directory settings.

oracle - the server

The server can be "configured" by changing the variables in the [server] section of the config file.

The address is the IP address on which the server is listening, default is localhost - you might want to change that.

The port where the server is listening is by default 2355.

datadir specifies the data directory where all the device "secrets" are stored, this defaults to "data/" in the current directory. You might want to back up this directory from time to time to an encrypted medium.

verbose enables logging to standard output.

keydir is the directory where the server stores its secret key, that is used to sign messages to the clients.

Change these settings to fit your needs. Starting the server can be done simply by:

./oracle.py

sphinx - the client

This is the client that connects to the oracle to manage passwords using the sphinx protocol.

Client Configuration

Like the server, the client can be configured changing the settings in the [client] section of the config file. The host and port should match what you set in the server.

The datadir (default: ~/.sphinx) variable holds the location for your client parameters. Particularly it contains a salt (by default ~/.sphinx/salt) which is used to calculate the ids for secrets on the server, and more importantly it also contains a secret key (default: ~/.sphinx/key) that is used to sign every message sent to the server to authorize the operations on your passwords. Both the salt and the key is generated automatically if not available. You might want to back up and encrypt both the salt and the key.

Authorization

All operations are authenticated by your (default: ~/.sphinx/key) file which is used to sign all operations. You should protect this file, so that only you can operate on your passwords.

Operations

The client provides the following operations: Create, Get, Change, Delete. Note there is no command to list "records", as the server does not contain any textual information about what it stores. All operations need a username and a site this password belongs to.

Create password

Creating a new password for a site is easy, pass your "master" password on standard input to the client, and provide parameters like in this example:

echo 'my master password' | ./sphinx.py create username https://example.com ulsd 0

The parameters to the client are create for the operation, then username for the username on the site https://example.com then a combination of the letters ulsd and the 0 for the size of the final password. The letters ulsd stand in order for the following character classes: u upper-case letters, l lower-case letters, s symbols and d for digits.

Note, you can actually use different "master" passwords for different user/site combinations.

Get password

Getting a password from the sphinx oracle works by running the following command:

echo 'my master password' | ./sphinx.py get username https://example.com

Here again you supply your master password on standard input, provide the get operation as the first parameter, your username as the 2nd and the site as the 3rd parameter. The resulting password is returned on standard output.

Change password

You might want to (be forced to regularly) change your password, this is easy while you can keep your master password the unchanged (or you can change it too, if you want). The command is this:

echo 'my master password' | ./sphinx.py change username https://example.com

Here again you supply your master password on standard input. This master password can be the same, but can also be a new password if you want to change also the master password. You provide the change operation as the first parameter to the client, your username as the 2nd and the site as the 3rd parameter. Your new new password is returned on standard output.

After changing the password, you will get back the old password, until you commit the changes with

echo 'my master password' | ./sphinx.py commit username https://example.com

Deleting passwords

In case you want to delete a password, you can do using the following command:

./sphinx.py delete username https://example.com

You provide the delete operation as the first parameter to the client, your username as the 2nd and the site as the 3rd parameter. This command does not need anything on standard input, nor does it provide anything on standard output in case everything goes well.