Improved LBC

A pure-Python implementation of LBC with supporting updates of ciphertext based on byte-level modifications of plaintext.

Installation

Use git clone to install our project.

git clone git@github.com:ssu-csec/improved-lbc.git

Usage

Use Improved LBC(Mode of Operation of AES)

If you just want to use Improbed LBC, one of the modes of operation of AES, you can move the file crypto/aes.py and crypto/core.py to your project folder.

Then, insert the code below at the first part of your code.

import aes
import core

For encrypting your data, you need the functions below:

encrypt(input string, enc_key, f_iv, b_iv)
gen_global(str_len)
global_enc(input_str, enc_key)

After encrypt your data and metadata, you can generate Data object with the output. It is the input type of decrypt function.

For decrypting your ciphertext, you need the function below:

decrypt(input_data, dec_key)

The output of the function above is string type.

Use Improved LBC Protocol

If you need the protocol - safe server and clients - you can utilize crypto/protocol.py for your code.

import core
import protocol

You can use Server and Client classes in protocol.py.

server = protocol.Server(port number, file name)
client - protocol.Client(socket, key, input queue)

Server class has two inputs: port number and file name. When you execute a server with server.main(), it opens the port specified by the input and waits clients to share contents of the file with the name provided as an input.

After executing server.main(), you can connect clients to the server by executing client.main(ip_address, port number). The input input queue of the constructor of Client functions as a channel through which the modifications made to the externally received data can be accessed and utilized within the functions of client object.

You can push modification information to input_queue and the information should contain category of modification(Insert/Delete), the location of the modification(index) and the length(deletion) or inserted data(insertion).

Test

For testing, we made test_s.py(server) and test_c.py(client).

The sequence for testing is as follows:

1. Create the file to be shared upon running the server program (it can be an empty file).
2. Run the server program and enter the port number and the name of the file to be shared(the file created in step 1).
3. Run the client program while providing the server's IP address and port number as inputs.
4. Upon running the client program, enter the data into the activated editor program.
5. Run additional instances of the client program to verify real-time sharing of the data.