Another things that crossed my mind: Currently the FAQ states in respect to the whirpool problem, to do a header backup prior to changing the header or using reencrypt. Wouldn't it be better to make this a minimum requirement and recommend a full backup instead? Imagine for whatever reason some portion after the payload offset gets damaged/overwritten, be it by mixing up numbers or because of any unobvious bug somewhere. Regards -Sven On Sat, March 1, 2014 00:27, Arno Wagner wrote: > On Fri, Feb 28, 2014 at 23:06:30 CET, Sven Eschenberg wrote: >> On Fri, February 28, 2014 22:46, Arno Wagner wrote: >> > On Fri, Feb 28, 2014 at 22:26:03 CET, Sven Eschenberg wrote: >> >> Just out of curiosity, >> >> >> >> Isn't it possible (yet) to override header fields during luksopen? If >> >> not, >> >> wouldn't it make sense to add something like that in future versions? >> I >> >> think it could be of great help when the header is partly damaged, to >> be >> >> able to override things without using a hex editor. >> > >> > I doubt this makes much sense. From what I have seen, >> > usually the magic string at the start is gone as well, >> > and then there is a real risk that people try this with >> > the wrong data. Using a hex-editor is not that hard and >> > using a hex-dumper is basically required to get any >> > reasonable form of diagnostics. Even the keyslot- >> > checker is basically a specialized hexdump tool. >> >> Okay, that's true. I personally do use a hexeditor too, I have to admit, >> just thought it could help less experienced people. Then again, if >> people >> fail to use a hex editor chances are big they make things worse. I guess >> I >> didn't think this through long enough. > > I have a _lot_ of experience with students, some not so bright > or experienced ;-) > >> >> I am aware that one could use the non-LUKS mode to open a LUKS device >> by >> >> passing all required parameters, admitted. But a mode where one can >> use >> >> what's in the header and override single fields could be interesting. >> >> Once >> >> the correct params are determinde this way, one could maybe add an >> >> option >> >> to repair the header with the given replacements (Maybe by adding the >> >> option to reencryt?). >> >> >> >> Just some thoughts that crossed my mind. >> > >> > I doubt this really helps. Also remember that finding out what >> > actually broke the header is important, so fiddeling around >> > with an opaque header and commandline arguments to cryptsetup >> > after you have analyzed a hexdump strikes me as not that effective. >> >> That's absolutely true, indeed. >> >> > >> > I do understand that hex-editing is akward for many people, >> > but I do not think this makes it any better or clearer. >> > One thing that would help a bit is a header layout with >> > hex offsets. I think I am going to add that to the FAQ. >> >> Good point, I'd propose adding this to the luks on disk format document >> as >> well. If you cannot convert HEX<->DEC inside your head having the hex >> offsets at disposal helps alot. I admit, I used a converter when I >> edited >> my headers lately. > > Me too. For the time being, there now is a nice hex + dec table > in FAQ Item 6.12 > > Arno > -- > Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@xxxxxxxxxxx > GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D > 9718 > ---- > A good decision is based on knowledge and not on numbers. - Plato > _______________________________________________ > dm-crypt mailing list > dm-crypt@xxxxxxxx > http://www.saout.de/mailman/listinfo/dm-crypt > _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx http://www.saout.de/mailman/listinfo/dm-crypt
