Blizzard v bnetd – or, why the TPM exceptions should be protected from exclusion by contract

Blizzard make several popular games, including Warcraft, Diablo and Starcraft. Online multiplayer in these games is limited to using Blizzard's Battle.net service. Battle.net provides a mechanism for users to create and join multi-player games, to meet and chat with other users, and to record statistics and participate in tournaments. Battle.net functionality is built into the games. Blizzard's Battle.net servers check the validity of users' cd-keys when a user connects to the service from within the game. This validation is known as the “secret handshake” which allows only users with valid cd-keys to continue connecting to Battle.net.

The Eight Circuit Court of Appeals has determined that an open source replacement to Blizzard's Battle.net violates the DMCA by bypassing this 'secret handshake'.

Blizzard's End User License Agreements on the games themselves state that a user may not “in whole or in part, copy, photocopy, reproduce, translate, reverse engineer, derive source code, modify, disassemble, decompile, create derivative works based on the Program, or remove any proprietary notices or labels on the program without the prior consent, in writing, of Blizzard”1)

Blizzard's Terms of Use on Battle.net state that a player may not

(ii) copy, photocopy, reproduce, translate, reverse engineer, modify, disassemble, or de-compile in whole or in part any Battle.net software;
(iii) create derivative works based on Battle.net;
(iv) host or provide matchmaking services for any Blizzard software programs or emulate or redirect the communication protocols used by Blizzard as part of Battle.net, through protocol emulation, tunneling, modifying, or adding components to the Program, use of a utility program, or any other technique now known or hereafter developed for any purpose, including, but not limited to, network play over the Internet, network play utilizing commercial or non-commercial gaming networks, or as part of content aggregation networks […]
(v) use any third-party software to modify Battle.net to change game play, including, but not limited to cheats and/or hacks;
(vi) use Blizzard's intellectual property rights contained in Battle.net to create or provide any other means through which Blizzard entertainment software products […] may be played by others, including, not limited to, server emulators.2)


The defendants were frustrated by the poor performance of Blizzard's Battle.net service, as well as cheating and otherwise offensive players. They subsequently began free development of bnetd, which would act as a replacement server for Battle.net which gave users more control over the games they played online. To create bnetd, the defendants had to reverse engineer the protocol spoken by Battle.net and the Blizzard games, and they also developed a small utility which was used to modify the Blizzard games so they could connect to other multiplayer servers. Notably, the defendants had no way of enforcing the cd-key validity check, and were forced to treat any cd-key presented as valid.

The district court granted summary judgment to Blizzard, holding that fair-use reverse engineering could be excluded by terms in shrink-wrap or click-wrap contracts, and that the reverse-engineering exceptions in the DMCA do not protect reverse-engineering in order to create fully functional alternative products, or where the program is distributed for free.3)

The Eight Circuit Court of Appeals affirmed the decision. Blizzard's EULA and ToS were enforceable contracts, and the defendants had waived any fair-use defence they may have had.4) The 'secret-handshake' constituted an effective Technological Protection Measure (TPM), and bnetd circumvented that TPM by allowing all clients to connect. The 'interoperability' exception did not apply, on the basis that the bnetd emulator allowed unauthorised copies of the Blizzard games to be played on the bnetd.org servers. The court considered that this constituted infringement of copyright, and as such, the interoperability defence could not apply. The Court did not consider whether bnetd was a dual use technology which could have both infringing and non-infringing uses, or whether the playing of an infringing copy of a game on an internet server constituted copyright infringement at all.

The Australian position


In Australia, reverse engineering to make interoperable products is protected as an exception to copyright by Copyright Act 1968 (Cth) s 47D. Section 47H provides that section 47D, which was inserted by the Digital Agenda amendments, can not be excluded by contract. In Australia, Blizzard could not require that its users refrain from reverse engineering.

Reverse engineering for interoperability is also an exception to circumvention of a technological protection measure, in s 116A(3), where a 'qualified person' is permitted to circumvent a TPM for a permitted purpose, which includes interoperability from s 47D. A qualified person in this case would mean the owner or licensee of the copy of the game. Section 116A(4)(b) provides a similar exception for supplying a circumvention device.

There is nothing in the text of the anti-circumvention law that prevents the right to reverse engineer for interoperability from being excluded by contract. The exceptions to infringement in s 116A are not protected in the same way as s 47D protects ss 47B(3), 47C, 47D, 47E and 47F.

This case shows that this gap in Australian anti-circumvention law can have real consequences for Australian developers. Reverse engineering for interoperability is an important exception to the exclusive rights of the copyright owner, in that it provides developers with a mechanism to make competing products, or to adapt a technology product to work in new environments.


These exceptions are important – they concern not the piracy of games, but the right of players to make use of their lawfully acquired games in the way they want. A player who purchases a game which doesn't work satisfactorily with another product, like an internet game server, should not be precluded from seeking to play the game on another interoperable server. The right to use a game is a fundamental right of a purchaser of a copy of that game, and if the game must be reverse engineered in order to enable its use, then that reverse engineering should be permissible.


Both the Copyright Law Review Committee Copyright and Contract report and the Philips Fox Digital Agenda Review recommended that the Copyright Act be amended so that the permitted purpose exceptions in s 116A(3) cannot be excluded by contract.5) If these recommendations are not followed, there is a significant risk that the ability to create interoperable software in Australia will be crippled, and producers of computer games will be able to require that purchasers of their games are tied to their other software products and services in order to make use of the games.

2)
Ibid, p 6 (at footnote 5); Blizzard, Battle.net Terms of Use.
4)
Davidson & Associates v Jung 422 F.3d 630 (8th Cir. 2005).
5)
Copyright Law Review Committee, Copyright and Contract (2002) [7.50]; Philips Fox, Digital Agenda Review (2004) p 113.