Subject: Re: [bitcoin-dev] Bitcoin Assistance

From: Cory Fields <[email-masked]>
Date: Wed, 27 Sep 2017 17:20:26 -0400

Hi Mark

Thank you very much for posting the findings. I took a look through our
repository and I think I can provide a bit of context.

I'll go through each one, annotating what I've found.

> Apache License 2.0

This is used by a few java files in the libsecp256k1 project. That library
(which lives here: https://github.com/bitcoin-core/secp256k1) is a
sub-module created and maintained by Bitcoin Core developers. The files in
question are bindings that allow other applications to use libsecp256k1
from Java. Bitcoin Core makes no use of them.

> Boost Software License 1.0

This comes from tinyformat.h. Bitcoin Core indeed uses it.

> BSD 2-clause "Simplified" License

I'm unable to find any 2-clause BSD licensed files.

> BSD 3-clause "New" or "Revised" License

This comes from leveldb, which is database software used by Bitcoin Core.
Because database software version inconsistencies can cause accidental
forks (this actually happened in 2013), we include these files in our
repository and use them rather than linking to arbitrary versions at
runtime.

There are a few non-upstream files we use in our leveldb tree to provide
windows support. Quoting from src/leveldb/util/env_win.cc:
  This file contains source that originates from:

http://code.google.com/p/leveldbwin/source/browse/trunk/win32_impl_src/env_win32.h

http://code.google.com/p/leveldbwin/source/browse/trunk/win32_impl_src/port_win32.cc
  Those files don't have any explicit license headers but the
  project (http://code.google.com/p/leveldbwin/) lists the 'New BSD License'

> Creative Commons Attribution Share Alike 3.0

I didn't manage to find any CC-licensed files. The match probably comes
from our gui svg icons, which contain an xml tag with a link to
creativecommons.org. This seems to be the default behavior of inkscape,
which was used to create those icons. Any icons that we have not created
ourselves are listed in contrib/debian/copyright (they're all expat/public
domain).

> Expat License

See MIT.

> GNU General Public License v2.0 or later

The debian folder, which holds the files used to create debian/ubuntu
packages is licensed gplv2+. These are packaging resources only,
unnecessary for use of the code.

Additionally, some gplv2 m4 macros are used to bootstrap the code that is
used to build the Bitcoin code. These contain the additional exception:

   As a special exception, the respective Autoconf Macro's copyright owner
   gives unlimited permission to copy, distribute and modify the configure
   scripts that are the output of Autoconf when processing the Macro. You
   need not follow the terms of the GNU General Public License when using
   or distributing such scripts, even though portions of the text of the
   Macro appear in them. The GNU General Public License (GPL) does govern
   all other use of the material that constitutes the Autoconf Macro.

> GNU General Public License v3.0 or later

The macdeploy script, useful for creating DMG files for macOS is gplv3. It
is not necessary for any other platform, and is only used during the build
process. Additionally, it is not the only way to create DMG files (apple's
native tools can be used as well).

Additionally, config.guess and config.sub are gplv3 scripts used to build
our buildsystem.

> GNU Lesser General Public License v2.1 or later

authproxy.py, A python script used in our test suite is licensed lgpl
v2.1+. It is only necessary for running optional tests during development.

> License for A fast alternative to the modulo reduction

This references a comment cuckoocache.h. No code from the site is used. The
link to the site was added after the code, as the site provides a helpful
explanation for the technique used.

> License for atomic by Timm Kosse

Another m4 file. As explained with the others above, this is a macro which
builds code which builds code. It is used in the build process only.

> MIT License

The primary and default license for all contributions.

> Public Domain

> University of Illinois/NCSA Open Source License

clang-format-diff.py, a python script optionally used by developers to
clean up code changes.

tl;dr: Best I can tell, all source files that comprise Bitcoin Core
binaries are licensed (excluding the public domain ones) as MIT, BSD, or
Boost.

It's also worth repeating Omar's point that many of the files in the
Bitcoin Core repository are used for optional programs/libraries. None of
the artwork, for example, is needed for the primary bitcoin daemon.

Hope that helps!

Regards,
Cory