combox

split and encrypted files between online file storage providers
git clone git://git.ricketyspace.net/combox.git
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commit 32a6631412d4289f72ee41a13850bb95c9320f4a
parent 1535a2f1200db9da8e60f05500bc8cb74fef9360
Author: Siddharth Ravikumar <sravik@bgsu.edu>
Date:   Wed,  5 Nov 2014 22:49:03 -0500

Added crypto.py: Contains function that encrypt data and decrypt ciphers using AES.

Functions defined: pad, encrypt, decrypt, encrypt_shards, decrypt_shards.

Also added: tests/test_crypto.py

Diffstat:
combox/crypto.py | 84+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
combox/tests/test_crypto.py | 52++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 136 insertions(+), 0 deletions(-)

diff --git a/combox/crypto.py b/combox/crypto.py @@ -0,0 +1,84 @@ +# Copyright (C) 2014 Combox author(s). See AUTHORS. +# +# This file is part of Combox. +# +# Combox is free software: you can redistribute it and/or modify it +# under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# Combox is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +# General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with Combox (see COPYING). If not, see +# <http://www.gnu.org/licenses/>. + +## Adapted from https://gist.github.com/sekondus/4322469 + +import base64 +import os + +from Crypto.Cipher import AES + +BLOCK_SIZE = 32 +PAD_CHAR = '#' + + +def pad(data): + """Pad data such that its length is a multiple of BLOCK_SIZE. + """ + + padding = (BLOCK_SIZE - (len(data) % BLOCK_SIZE)) * PAD_CHAR + data += padding + + return data + + +def encrypt(data, secret): + """Encrypt byestream and return cipher. + """ + aes = AES.new(pad(secret)) + cipher = base64.b64encode(aes.encrypt(pad(data))) + + return cipher + + +def decrypt(cipher, secret): + """Decrypt cipher and return data. + """ + aes = AES.new(pad(secret)) + data = aes.decrypt(base64.b64decode(cipher)).rstrip(PAD_CHAR) + + return data + +def encrypt_shards(shards, secret): + """Encrypt the shards of data and return a list of ciphers. + + shards: list of shards (string, bytes). + secret: top secret passphrase + """ + + ciphers = [] + for shard in shards: + cipher = encrypt(shard, secret) + ciphers.append(cipher) + + return ciphers + + +def decrypt_shards(ciphers, secret): + """Decrypt the ciphered shards and return a list of shards. + + shards: list of ciphered shards. + secret: top secret passphrase + """ + + shards = [] + for cipher in ciphers: + shard = decrypt(cipher, secret) + shards.append(shard) + + return shards diff --git a/combox/tests/test_crypto.py b/combox/tests/test_crypto.py @@ -0,0 +1,52 @@ +# Copyright (C) 2014 Combox author(s). See AUTHORS. +# +# This file is part of Combox. +# +# Combox is free software: you can redistribute it and/or modify it +# under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# Combox is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +# General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with Combox (see COPYING). If not, see +# <http://www.gnu.org/licenses/>. + +from os import path + +from file import (split_data, glue_data, write_file, + read_file, write_shards, read_shards) +from crypto import encrypt, decrypt, encrypt_shards, decrypt_shards + +PASS = 'topsecret' +### Read file, encrypt it to a cipher, write cipher to file, read +### encrypted file, decrypt it, write decrypted data to file. +f = path.abspath('tests/files/the-red-star.jpg') +f_content = read_file(f) +f_cipher = encrypt(f_content, PASS) +f_encrypted = path.abspath('tests/files/the-red-star.cipher') +write_file(f_encrypted, f_cipher) +f_cipher = read_file(f_encrypted) +f_content = decrypt(f_cipher, PASS) +f = path.abspath('tests/files/the-red-star-decrypted.jpg') +write_file(f, f_content) + +### Read file, split it, encrypt shards, write encrypted shards to +### file, read encrypted shards from file, decrypt the encrypted +### shards, glue the shards together, write glued data to file. +f = path.abspath('tests/files/the-red-star.jpg') +f_content = read_file(f) +f_shards = split_data(f_content, 5) +ciphered_shards = encrypt_shards(f_shards, PASS) +f_path = path.dirname(f) +f_basename = "%s.ciphered" % path.basename(f) +write_shards(ciphered_shards, f_path, f_basename) +ciphered_shards = read_shards(f_path, f_basename) +f_parts = decrypt_shards(ciphered_shards, PASS) +f_content = glue_data(f_parts) +f = path.abspath('tests/files/the-red-star-from-ciphered-shards.jpg') +write_file(f, f_content)