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It was a serious design flaw to move away from physical write-enable protection. Physical interlocks for rare-but-important events such as upgrading firmware sh
by pdkl95 12y ago
It was a serious design flaw to move away from physical write-enable protection. Physical interlocks for rare-but-important events such as upgrading firmware should exist in almost all situations.
Look back at floppy disks: while many people were caught by the write-protect tab/switch while they were still learning, it was an easy concept for people to understand once taught. I knew many non-technical people that quickly adopted habits that utilized write-protection.
The physical interlock is something that can be taught a lot easier than how to use crypto without screwing up. If you require proactive checking or fancy technique, it will be forgotten and skipped. On the other hand, if you fail the update with a message "did you forget to flip the write-protect switch? [picture of switch]", a lot of people will figure it out.
There are similarities to Schneier's (et al) recommendation to make good (long, random) passwords, but write them down and keep them someplace safe. (i.e. leverage the physical security knowledge that people already have)
- tehwalrus 12y agoI still use write protection on SD cards, since I had a buggy Mac that reformatted one to be unusable by my camera. I just got into the habit of flipping the switch whenever plugging a card into a machine, and it works fine (and is slightly safer).
- jnbiche 12y agoYeah, as you suggest by your "slightly safer" parenthetical, the mechanical write protection on most SD cards is just a suggestion that the card reader is free to ignore (though obviously most don't). It's actually specified in the SD spec [1], which says on p. 38 that the mechanical protect switch is "Host responsibility only" and that the "The position of the write protect switch is unknown to the internal circuitry of the card." 1. https://www.sdcard.org/downloads/pls/simplified_specs/part1_410.pdf https://www.sdcard.org/downloads/pls/simplified_specs/part1_... [pdf file]
- tehwalrus 12y agoI did read that somewhere, but I'd forgotten.. Good catch! Hardware write protection is harder to find than you think..
- semi-extrinsic 12y agoThe popular CHDK custom firmware for Canon compact cameras subverts the write-protect tab on the SD card to be a CHDK on/off switch. So it's widely known that software may ignore this switch.
- TeMPOraL 12y agoI keep wondering why create a feature only to not implement it? What was the reasoning behind this soft write protection mechanism?