IDEA License

[David Smith]

On 03/25/13 20:05, Jan Chaloupecky wrote:
> On Monday, March 25, 2013 at 8:36 PM, Werner Koch wrote:
>> On Mon, 25 Mar 2013 16:00, chaljan at gmail.com
>>> so the question is .. can I ship the idea shared object with my software?
>>> The idea.c contains the following comments. So if I understand it
>>
>> You need to provide the full source code and including that file.
> 
> ok so idea is GPL.

Not quite.  Werner's implementation of IDEA (as included in GnuPG) is
copyrighted but released under the terms of the GPL, and therefore, if
you take his source code directly and copy it (or any part of it) into
your code, then you are restricted by the terms of the GPL.

The algorithm itself cannot be copyrighted, but can be patented (and
was).  The patent covered /any/ implementation (whoever coded it).
However, the patent(s) have now expired, so now anyone is free to code
their own version of the algorithm under any license they like, provided
they write their own version of the code, rather than just copying
someone else's.

Disclaimer: IANAL, you should get your own proper legal advice from a
real lawyer, etc.