Last week I criticized Richard Posner for saying that labeling content and adding filtering to P2P apps would do much to reduce infringement on P2P net. In responding to comments, Judge Posner unfortunately makes a very similar mistake:
Several pointed out correctly that tags on software files, indicating that the file is copyrighted, can probably be removed; and this suggests that only encryption, preventing copying, is likely to be effective in protecting the intellectual property rights of the owner of the copyright.
The error is rooted in the phrase “encryption, preventing copying”. Encryption does nothing to prevent copying – nor is it intended to. Encrypted data can be readily copied. Once decrypted, the plaintext data can again be readily copied. Encryption prevents one and only one thing – decryption without knowledge of the secret key.
It’s easy to see, then, why encryption has so little value in preventing infringement. You can ship content to customers in encrypted form, and the content won’t be decrypted in transit. But if you want to play the content, you have to decrypt it. And this means two things. First, the decrypted content will exist on the customer’s premises, where it can be readily copied. Second, the decryption key (and any other knowledge needed to decrypt) will exist on the customer’s premises, where it can be reverse-engineered. Either of these facts by itself would allow decrypted content to leak onto the Internet. So it’s not surprising that every significant encryption-based anticopying scheme has failed.
We need to recognize that these are not failures of implementation. Nor do they follow from the (incorrect) claim that every code can be broken. The problem is more fundamental: encryption does not stop copying.
Why do copyright owners keep building encryption-based systems? The answer is not technical but legal and economic. Encryption does not prevent infringement, but it does provide a basis for legal strategems. If content is encrypted, then anyone who wants to build a content-player device needs to know the decryption key. If you make the decryption key a trade secret, you can control entry to the market for players, by giving the key only to acceptable parties who will agree to your licensing terms. This ought to raise antitrust concerns in some cases, but the antitrust authorities have not shown much interest in scrutinizing such arrangements.
To his credit, Judge Posner recognizes the problems that result from anticompetitive use of encryption technology.
But this in turn presents the spectre of overprotection of [copyright owners'] rights. Copyright is limited in term and, more important (given the length of the term), is limited in other ways as well, such as by the right to make one copy for personal use and, in particular, the right of “fair use,” which permits a significant degree of unauthorized copying. To the extent that encryption creates an impenetrable wall to copying, it eliminates these limitations on copyright. In addition, encryption efforts generate countervailing circumvention efforts, touching off an arms race that may create more costs than benefits.
Once we recognize this landscape, we can get down to the hard work of defining a sensible policy.