HKExSh
--

'hkexsh' (HerraduraKEx shell) is a golang implementation of drop-in replacements for golang's
standard golang/pkg/net facilities (net.Dial(), net.Listen(), net.Accept() and the net.Conn type),
which automatically negotiate keying material for 'secure' sockets using the experimental
HerraduraKEx key exchange algorithm first released at [Omar Elejandro Herrera Reyna's HerraduraKEx project](http://github.com/Caume/HerraduraKEx).

One can simply replace calls to net.Dial() with hkex.Dial(), and likewise
net.Listen() with hkex.Listen(), to obtain connections (hkex.Conn) conforming
to the basic net.Conn interface. Upon Dial(), the HerraduraKEx key exchange
is initiated (whereby client and server independently derive the same
keying material).

Above this layer, demo apps in this repository (demo/server/server.go and demo/client/client.go)
then negotiate session settings (cipher/hmac algorithms, etc.) to be used for further communication.

NOTE: Due to the experimental nature of the HerraduraKEx algorithm used to
derive crypto keying material on each end, this algorithm and the
demonstration remote shell client/server programs should be used with caution.
As of this time (Jan 2018) no verdict by acknowledged 'crypto experts' as to
the level of security of the HerraduraKEx algorithm for purposes of session key
exchange over an insecure channel has been rendered.
It is hoped that such experts in the field will analyze the algorithm and
determine if it is indeed a suitable one for use in situations where
Diffie-Hellman and other key exchange algorithms are currently utilized.

Within the demo/ tree are client and servers implementing a simplified,
ssh-like secure shell facility and a password-setting utility using its
own user/password file separate from the system /etc/passwd, which is
used by the server to authenticate clients.

Dependencies:
--
* Recent version of go (tested with go-1.9)
* [github.com/mattn/go-isatty](http://github.com/mattn/go-isatty) //terminal tty detection
* [github.com/kr/pty](http://github.com/kr/pty) //unix pty control (server pty connections)
* [github.com/jameskeane/bcrypt](http://github.com/jameskeane/bcrypt) //password storage/auth

Get source code
--
* $ go get -u github.com/Russtopia/hkexsh
* $ go get github.com/mattn/go-isatty  ## only used by demos, not picked up by above go get -u?

To build
--
* $ cd $GOPATH/src/github.com/Russtopia/hkexsh
* $ go install .
* $ go build demo/client/client.go && go build demo/server/server.go
* $ go build demo/hkexpasswd/hkexpasswd.go

To set accounts & passwords:
--
* $ sudo echo "joebloggs:*:*:*" >/etc/hkexsh.passwd
* $ sudo ./hkexpasswd -u joebloggs
* $ <enter a password, enter again to confirm>

Running Clent and Server. In separate shells:
--
* [A]$ sudo ./server &
* [B]$ ./client -u joebloggs