[Interest] Qt, openssl and redistribution (of binary packages)

Constantin Makshin cmakshin at gmail.com
Tue Jan 24 07:14:11 CET 2017

On 01/23/2017 01:12 PM, René J. V. Bertin wrote:
> Constantin Makshin wrote:
> Thank you Constantin,
>> Qt can be redistributed under the terms of LGPL which allows linking
>> against everything so there are no license-related issues in linking Qt
>> and OpenSSL.
> The MacPorts packaging lists 3 licenses governing Qt5, the LGPL v2 and v3, but 
> also GPL3. Are you saying we shouldn't be listing the GPL3 license and that we 
> can do so without "risk"?
I'm not sure omitting licensing information is a good idea. Instead you
may specify that while Qt5 itself can be redistributed under the terms
of either GPL3 or LGPL{2|3}, MacPorts package in particular is limited
to LGPL (due to OpenSSL). But even that is not necessary if you use
OpenSSL libraries provided by the OS (I don't know whether macOS does
that) because GPL explicitly allows linking to system libraries without
any restrictions.

> Can Qt Creator be redistributed uder the LGPL too? MacPorts has that one down as 
> covered under the GPL3, which does make it incompatible with linking with 
> OpenSSL.
Qt Creator is GPL-only, but that's okay if you use system OpenSSL libraries.
I also did "fgrep -R ssl" on a directory with unpacked Qt Creator 4.2.1
sources and didn't find any signs of Qt Creator's [direct] dependency on

>> AFAIK the primary (if not the only one) reason against linking to
>> libraries like OpenSSL is that redistribution of cryptographic software
>> is forbidden in some countries. Loading these libraries at runtime is
> You may well be right, because even when built for runtime openssl loading 
> QtNetwork still includes OpenSSL headers during compilation. And I have a hunch 
> that's enough for lawyers on the war path...
> R.

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