Linked by Thom Holwerda on Fri 23rd Sep 2011 22:22 UTC, submitted by kragil
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RE[2]: Bootloader anyone ?
by matthewp131 on Sun 25th Sep 2011 18:58
in reply to "RE: Bootloader anyone ?"
RE[2]: Bootloader anyone ?
by lemur2 on Sun 25th Sep 2011 23:51
in reply to "RE: Bootloader anyone ?"
DVDs on the other hand are not cryptographically sound because the encryption keys used must be accessible on the end user device (otherwise the DVD would not play).
Correct. Linux, for example, does not use DeCSS software to play DVDs, it uses libdvdcss.
DeCSS used a "stolen" player key, it was stolen from the Xing software player I believe. This strategy is arguably illegal.
libdvdcss does not use a stolen player key, but rather it reads information from the DVD it is attempting to play, and from that data it calculates a list of possible keys. All of the possible keys are tried until one which works for that DVD is found.
The situation with UEFI secure boot is that the keys will be stored in secure storage on the motherboard, and they will not be accessible to the boot loader.
In order to boot the boot loader must in effect know one of the signing keys, because no method similar to that used by libdvdcss will be possible. Any work-around will have to be similar to DeCSS, which is to say it must use "stolen" keys. This will probably be in violation of the DMCA, and therefore illegal.
RE[3]: Bootloader anyone ?
by Alfman on Mon 26th Sep 2011 03:22
in reply to "RE[2]: Bootloader anyone ?"
lemur2,
"The situation with UEFI secure boot is that the keys will be stored in secure storage on the motherboard, and they will not be accessible to the boot loader."
One slight clarification here. Only the *public key* will be on the motherboard, the private key will be with MS/OEM and cannot be leaked/cracked by analyzing the motherboard.
"In order to boot the boot loader must in effect know one of the signing keys, because no method similar to that used by libdvdcss will be possible."
I don't think the DVD analogy fits very well, though I know you were just continuing with benayed's example.
Edited 2011-09-26 03:40 UTC





Member since:
2011-01-28
benayed,
"Grub or LILO bases boot loaders would allow regular non signed kernels to boot. This is after getting the keys through reverse engineering and all more or less in a similar fashion like the DVD scene played out through DeCSS."
This is a misunderstanding of the public key cryptography involved. Reverse engineering may reveal bugs in the bios which might be exploited, however all the keys present in the firmware are public knowledge. Even if the firmware is completely open source, it would not help break the private keys.
DVDs on the other hand are not cryptographically sound because the encryption keys used must be accessible on the end user device (otherwise the DVD would not play).
"2) legally through the anti-trust process."
Maybe someone with a legal background can provide some legal insight?
"On my side, personally, I would refrain from purchasing any PC motherboard or laptop that does not allow disabling this feature."
Same here, but we'd be such a minority that the large OEMs may not take notice. The key is to get the major media to pick it up.