[ANN] ltn12ce - An all-in-one compression and encryption library for Lua

[Michal Kottman <k0mpjut0r@...>]

Hello,

for anyone interested (and as my birthday present from me to the community), I have just uploaded a new compression and encryption/digest library [1], which I call ltn12ce for now.

[1] https://github.com/mkottman/ltn12ce

The main motivation for creating this module was to provide all-in-one functionality in one module without any external dependencies, and with a common API. This module contains the following modules: bzip2, miniLZO, LZMA, PolarSSL (for encryption/hashing) and zlib. I translated all systems to CMake, so it should be relatively portable (Windows, Linux, Mac OS X).

The API tries to adhere to the "filter" [2] standard to be usable by LuaSocket LTN12 module [3]. The Lua side of the API is not ready yet, but all the filters are ready and usable. The existing API is object-based (a filter is an object with update() and finish() methods), and will be wrapped in a function-interface as described in [2] in the next release of the library.

[2] http://lua-users.org/wiki/FiltersSourcesAndSinks

[3] http://w3.impa.br/~diego/software/luasocket/ltn12.html

My use-case for this library is testing a custom web API that sends JSON documents, which are sent compressed and encrypted. This module is designed to be plugged in with LuaSocket, so that all I have to do in Lua to access the data is:

    local ltn12 = require 'ltn12'

    local ce = require 'ltn12ce'

    local filter = ltn12.filter.chain(ce.decrypt('aes', key), ce.decompress('zlib'))

    local result = {}

    http.request { url = "" sink = ltn12.sink.chain(filter, ltn12.sink.table(result) }

For an example of what works now: to compress and encrypt a string, you can do this:

    local core = require 'ltn12ce.core'

    function runthrough(filter, data)

    return filter:update(data) .. filter:finish()

    end

    function makekey(key, bits)

    return key .. string.rep('0', bits/8 - #key)

    end

    local compressor = core.zlib('compress', 9)

    local encrypter = core.cipher('aes-256-cbc')

    encrypter:setkey(makekey('12345678', 256), 'encrypt')

    local input = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.'

    local compressed = runthrough(compressor, input)

    local output = runthrough(encrypter, compressed)

Regarding the name of the library - I searching for a nicer name for the library than the current ltn12ce (as in "LTN12-based Compression and Encryption"), and I am really thinking about changing it. I would be grateful for any ideas - something which represents the nature of the module (I was thinking about "binary-filters"), is searchable on Google (bad example: "go" programming language) and not already used...

Also, any feedback regarding the library and it's design/usability is more than welcome.

Have a happy and productive year 2013 :)