gpg-bash-lib - gpg file verification bash library - first public release announcement - 0.5-1

[Patrick Schleizer]

gpg-bash-lib is a gpg file verification bash library, addresses
comprehensive threat model, that covers file name tampering, indefinite
freeze, rollback, endless data attacks, etc.

https://github.com/Whonix/gpg-bash-lib

Why?

Writing bash scripts that do file verification using gpg that really is
secure and passes a comprehensive threat model, that covers indefinite
freeze, rollback, endless data attacks, etc. is hard.

gpg-bash-lib's goal is to provide a bash library that we can
collaboratively develop, audit and abstract the hard work into reuseable
functions.

Checking gpg exit codes only is insufficient. Quote Werner Koch [1]
(gnupg lead developer):

    "there is no clear distinction between the codes and for proper
error reporting you are advised to use the --status-fd messages."

(For a definition of these attacks, see TUF [2] (The Update Framework)'s
[3] threat model [4] [5].)

Mini Demo:
After installation, if you would run the following command.

/usr/share/gpg-bash-lib/examples/one

You would see the following output.

your_script_begin: ...
verification: BEGIN
verification: END
your_script_output: BEGIN
gpg_bash_lib_output_failure_status: false
gpg_bash_lib_output_gpg_verify_exit_code: 0
gpg_bash_lib_output_goodsig_status: true
gpg_bash_lib_output_validsig_status: true
gpg_bash_lib_output_fingerprint_in_hex:
5E08605EBEA0FE88695DCB88FD0A8B4171DFE4E4
gpg_bash_lib_output_signed_on_unixtime: 1422049448
gpg_bash_lib_output_signed_on_date: March 01 13:56:27 UTC 2015
gpg_bash_lib_output_notation[$file at name]: test-file
gpg_bash_lib_output_file_name_tampering: false
gpg_bash_lib_output_freshness_status: true
gpg_bash_lib_output_freshness_detail: current
gpg_bash_lib_output_freshness_msg:
- Freshness: Signature is current.
- valid-max: Signatures are valid up to 30 days.
- Signature Creation Date: March 01 13:56:27 UTC 2015
- Current System Date    : March 02 16:0:55 UTC 2015
- Local System Clock: Your clock seems okay.
- Relative Signature Creation Time: According to your system clock,
signature was created 2 days 26 minutes 3 seconds ago.
gpg_bash_lib_output_alright_status: true
your_script_output: END

All information (Signature Creation Date, etc.) are easily accessible
through separate variables, which are all documented.

Documentation:
https://github.com/Whonix/gpg-bash-lib/blob/master/README.mediawiki

Usage examples:
https://github.com/Whonix/gpg-bash-lib/tree/master/usr/share/gpg-bash-lib/examples

Main code file:
https://github.com/Whonix/gpg-bash-lib/blob/master/usr/lib/gpg-bash-lib/modules.d/50_common

Specifically, does the status-fd parsing code look sane?
https://github.com/Whonix/gpg-bash-lib/blob/d6cff902f40135c3e100a5bb13a6fe8275a41828/usr/lib/gpg-bash-lib/modules.d/50_common#L350

Could you leave some feedback please?

Anyone else interested to contribute?

Cheers,
Patrick

[1] http://lists.gnupg.org/pipermail/gnupg-devel/2005-December/022559.html
[2] https://www.updateframework.com/
[3] https://github.com/theupdateframework/tuf
[4] https://github.com/theupdateframework/tuf/blob/develop/SECURITY.md
[5] http://www.webcitation.org/6F7Io2ncN