Copyright notice for Tiger implementations

I and Jacek began a while back discussing the Tiger implementation in DC++. The implementation is a C++ port of the original C code available on the official Tiger website;

What was noticable about the C code was that there was no license attached; this means that the implementation fall under default copyright laws (in this case, US laws). As such, any type of modification or derivative (which the C++ implementation might be considered as) is most likely not directly allowed.

I sent an e-mail to the authors to rectify the situation and make sure there is sound lawful ground for DC++, other derivatives and users of the C++ code.

The following is what I sent to Eli Biham, one of the authors;

Under what license is your C implementation of the Tiger ( algorithm? The source code doesn’t state any license explicitly, nor does the Tiger main page. As it stands now, it is not possible to use your implementation, as is, in an application without getting explicit permission from you.

Biham responded;

Dear Fredrik,

I hereby allow you to use it, provided it will compute Tiger, and state
the names of the authors in it.

Clearly, the usual disclaimers hold, e.g., that it’s use will be legal,
and that it will not be exported to countries banned by law, that the
authors will not be responsible for the code, your software, nor
anything else.



In an effort to create a cleaner phrasing that would suit source code, I rephrased and added the following to the DC++ source (in TigerHash.cpp/h, in DC++ 0.780);

* The Tiger algorithm was written by Eli Biham and Ross Anderson and
* is available on the official Tiger algorithm page .
* The below Tiger implementation is a C++ version of their original C code.
* Permission was granted by Eli Biham to use with the following conditions;
* a) This note must be retained.
* b) The algorithm must correctly compute Tiger.
* c) The algorithm’s use must be legal.
* d) The algorithm may not be exported to countries banned by law.
* e) The authors of the C code are not responsible of this use of the code,
* the software or anything else.

If you are using the C implementation or a derivate (including DC++’s implementation), you must include a similar notice.

Feel free to use my phrasing or write your own (adherring to Biham’s restrictions).

Don’t forget that you can make topic suggestions for blog posts in our “Blog Topic Suggestion Box!”

Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: