Question

I need compress library for following needs:

1) Packing directory in one file with extension of my choice ( .pack for example )

2) Work with content in this file (directory) without unpaking it

3) Mechanism for encrypting

I already know about zlib, but for me it is ugly documented and not written anywhere what features are support from it

Answer 1

Packing directory in one file with extension of my choice ( .pack for example )

Most archivers don’t require you to use a particular file extension. Regardless, one can still invoke file on a file to guess its content type.

Work with content in this file (directory) without unpaking it

It’s possible to create a file list manually and prepend any archive file with that. Often, .sh installers for Linux contain a shell script in the beginning, followed by some magic line like __ARCHIVE_START__ followed by a binary archive. Hence it is possible to read lines from a file until __ARCHIVE_START__ line has been read. The rest of the file is an archive file.

Mechanism for encrypting

One easy way is to use different libraries for archiving and encrypting:

1. Bundle the files into one .tar.
2. Archive .tar into say .tar.xz.
3. Prepend the .tar.xz with file list followed by __ARCHIVE_START__ line.
4. Encrypt the file with any encryption library you please.