AMPK

AMbit PacKage

A simple archive format containing blobs of data with various pieces of meta data relating to the entry.

Format

Each block starts with a 4 letter word describing it's content

First block (length: 0) AMPK

... 0 or more entries ...

Last block (length: 0) ENDS

An entry is one of format:

HEADER (4 bytes) LENGTH (0 byte terminated) DATA (N bytes)

HEADER is one of NAME - data is filename of next DATA entry DLEN - data is original length of DATA entry (not including compression, etc) SIGN - data is signature of data (signed using private key) FILT - data describes data content - "C" => enCrypted (ie. encrypted using private key), "Z" => Zlib compressed. TYPE - data is mimetype of next DATA entry ENCD - data is encoding of next DATA entry DATA - data is the original payload (potentially compressed/encrypted)

Basic usage

To create an archive

require 'ampk/crypto'
require 'ampk/writer'

key = Crypto::Key.from_file("private_key.rsa", "my-secret-word")
AmpkWriter.new("output.ampk", key) do |writer|
  writer.add_entry('file1', File.read('file1'), :type => 'text/plain', :sign => true)
  writer.add_entry('large-file', File.read('file2'), :compress => true, :type => 'text/plain')
  writer.add_entry('secret-file', File.read('secret-words'), :encrypt => true)
end

To read an archive

require 'ampk/crypto'
require 'ampk/reader'

key = Crypto::Key.from_file("public_key.rsa", "my-secret-word")
reader = AmpkReader.new("output.ampk", key)
puts reader.entities
puts "Was secret-file encrypted? #{ reader.entity_encrypted?('secret-file') }"
puts "Secret contents: #{ reader.read_entity('secret-file') }"