Tivo and point 4 [LWN.net]

Tivo and point 4

Posted Oct 5, 2006 22:15 UTC (Thu) by zlynx (subscriber, #2285)
In reply to: 4 points by coriordan
Parent article: Similar in spirit?

Quick note on your point 4:
The keys are not required for the work to run. Take Tivo for example: a Tivo binary should execute just fine on some other non-Tivo PowerPC based system.

So what the keys do is prevent executing a binary on a particular piece of hardware, not prevent executing it at all. At least, in the Tivo case. An encrypted binary, rather than a signed one, would be a different situation.

So it seems the key is a part of the hardware, not the software, and thus a separate work.

It's just like having a Linux or HURD (since Linux is staying GPLv2) kernel executing from a virtual machine. If I restrict the execute permissions of the kernel's VM image to a single user, is that user's login password suddenly a "part of the work" required to run the kernel? Ridiculous.

A better example yet, say I build a HURD kernel just the way I like it and take it's SHA1 key. I customize a copy of QEMU to only run if the boot image matches that SHA1 key. Your copy of my image isn't affected. You just can't run a modified version on my QEMU.

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Tivo and point 4

Posted Oct 6, 2006 10:57 UTC (Fri) by nim-nim (subscriber, #34454) [Link]

> So what the keys do is prevent executing a binary on a particular piece of
> hardware, not prevent executing it at all.

That's assuming availability of non-DRMed hardware. This is not a safe bet, especially if the existing software pool can be DRMed at will.

Tivo and point 4

Posted Oct 6, 2006 16:10 UTC (Fri) by man_ls (subscriber, #15091) [Link]

Take Tivo for example: a Tivo binary should execute just fine on some other non-Tivo PowerPC based system.

If I had purchased a Tivo and it had some serious flaw which the company did not want to fix, it would not help much to know that I could execute it on some other piece of hardware.

The keys are part of the particular software distribution, which is contained in the Tivo. You could have another type of hardware, another distribution

So it seems the key is a part of the hardware, not the software, and thus a separate work.

Hardly. I could make the same argument about a particular driver: my Linux kernel might run just fine without the driver, on a different hardware configuration. Therefore the driver is part of the hardware.

The key is just a magic number. It is required to install and run the software on a particular piece of hardware. Providing source code but not the magic number is cheating IMHO.