I strongly advise you to pick a high-entropy encryption key to avoid the possibility of brute-force attacks.
Install and usage
Make sure you have node
0.10.x (tip: use n) and then install the package globally with
sudo npm install -g cryptochat
Three variants of cryptochat are available depending on your use case:
Send and receive messages$ sudo cryptochat <ip> <encryption_key>
Receive messages$ sudo cryptochat server <encryption_key>
Send messages$ sudo cryptochat client <ip> <encryption_key>
Because it relies on
stdin for input, it is possible to use pipes to send data:
cat cryptochat.js | sudo cryptochat client <ip> <encryption_key>
ICMP Echo request format
|bits 0-7||bits 8-15||bits 16-31|
The message data is attached as the ICMP payload.
Messages are piped from
stdin and split into payload packages, which are encrypted and sent as ICMP Echo requests. The payload size per request is currently set to 32 bytes. The first byte is the length of the message and the rest is the message itself.
The first request contains a salt and an initialization vector needed to decrypt the payloads.
|byte 0||bytes 1-15||bytes 16-31|
An "end" request is sent in order for the receiver to know when a message is completed. The end request has the following format:
|byte 0||bytes 1-31|
When the end request is received, the full message is printed to the screen.
As always, contributions are much appreciated.