On Sat, Nov 08, 2008 at 04:02:23PM +0100, Arno Wagner wrote: > On Sat, Nov 08, 2008 at 06:10:27PM +1300, Roscoe wrote: > > > 2048 bytes looks like it would be enough if he used a 128 bit key, but > > > if he used a 256 bit key you might not get all of the last keyslot > > > (judging by observed payload offsets of 2056 bytes). > > > > Woops....Offsets are measured in sectors not bytes! > > Ups. So he would have to look into what is actually in the > keyslots. The key-material is stored on disk directly > after the header and before the bulk data. > > Ok, revised: Look at offset 104 in the header. It lists > where the bulk data starts (in sectors). Backup everything > before. > Here is an update: I just created an 1GB luks partition via loop-device and luks-format. The keyslot seems to be 64000 bytes long, with the offfsets in the keyslots placinf them every 65536 bytes. The Filesystem seems to start at offset 0x81000 (lots of zeros before that, which I take for the 7 unused keyslots). The header at offset 104 (0x68) says 00 00 04 08, which would be 1032 and 1032 * 512 = 528384 = 0x81000. Seems that a liks header + keys material with everything as default is 516kB in size. Incidentially, below is a hexdump (via "hex") on what a good LUKS looks like. Arno 0x00000000: 4c 55 4b 53 ba be 00 01 - 61 65 73 00 00 00 00 00 LUKS<BA><BE>..aes. 0x00000010: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ................ 0x00000020: 00 00 00 00 00 00 00 00 - 63 62 63 2d 65 73 73 69 ........cbc-essi 0x00000030: 76 3a 73 68 61 32 35 36 - 00 00 00 00 00 00 00 00 v:sha256........ 0x00000040: 00 00 00 00 00 00 00 00 - 73 68 61 31 00 00 00 00 ........sha1.... 0x00000050: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ................ 0x00000060: 00 00 00 00 00 00 00 00 - 00 00 04 08 00 00 00 10 ................ 0x00000070: 14 dd 4f b8 1f 42 a1 02 - 9a 93 ec ae bf 26 8d 7c ..O..B....<EC><AE> 0x00000080: 40 2e 6d 5c 4c ba 21 d8 - 31 94 dc 00 2c 0d 43 39 @.m\L.!.1...,.C9 0x00000090: bb 03 24 95 4f fe 97 97 - a0 2c 75 63 ea 92 cb a5 ..$.O....,uc..<CB> 0x000000a0: 4d aa a0 1c 00 00 00 0a - 31 35 31 61 37 30 34 64 M.......151a704d 0x000000b0: 2d 34 36 33 36 2d 34 61 - 38 30 2d 39 34 61 66 2d -4636-4a80-94af- 0x000000c0: 63 32 61 34 65 61 62 66 - 36 38 31 63 00 00 00 00 c2a4eabf681c.... 0x000000d0: 00 ac 71 f3 00 02 af 20 - ea d9 3c b9 b5 14 85 49 ..q.... <EA><D9>< 0x000000e0: 3c 7c 57 1a c8 8c 92 9a - 61 80 de 9d 2c fd 9b 85 <|W.....a...,... 0x000000f0: ff d4 2f 72 64 81 6f 12 - 00 00 00 08 00 00 0f a0 ../rd.o......... 0x00000100: 00 00 de ad 00 00 00 00 - 00 00 00 00 00 00 00 00 ..<DE><AD>........ 0x00000110: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ................ 0x00000120: 00 00 00 00 00 00 00 00 - 00 00 00 88 00 00 0f a0 ................ 0x00000130: 00 00 de ad 00 00 00 00 - 00 00 00 00 00 00 00 00 ..<DE><AD>........ 0x00000140: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ................ 0x00000150: 00 00 00 00 00 00 00 00 - 00 00 01 08 00 00 0f a0 ................ 0x00000160: 00 00 de ad 00 00 00 00 - 00 00 00 00 00 00 00 00 ..<DE><AD>........ 0x00000170: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ................ 0x00000180: 00 00 00 00 00 00 00 00 - 00 00 01 88 00 00 0f a0 ................ 0x00000190: 00 00 de ad 00 00 00 00 - 00 00 00 00 00 00 00 00 ..<DE><AD>........ 0x000001a0: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ................ 0x000001b0: 00 00 00 00 00 00 00 00 - 00 00 02 08 00 00 0f a0 ................ 0x000001c0: 00 00 de ad 00 00 00 00 - 00 00 00 00 00 00 00 00 ..<DE><AD>........ 0x000001d0: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ................ 0x000001e0: 00 00 00 00 00 00 00 00 - 00 00 02 88 00 00 0f a0 ................ 0x000001f0: 00 00 de ad 00 00 00 00 - 00 00 00 00 00 00 00 00 ..<DE><AD>........ 0x00000200: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ................ 0x00000210: 00 00 00 00 00 00 00 00 - 00 00 03 08 00 00 0f a0 ................ 0x00000220: 00 00 de ad 00 00 00 00 - 00 00 00 00 00 00 00 00 ..<DE><AD>........ 0x00000230: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ................ 0x00000240: 00 00 00 00 00 00 00 00 - 00 00 03 88 00 00 0f a0 ................ 0x00000250: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00 00 00 ................ -- Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@xxxxxxxxxxx GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F ---- Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans If it's in the news, don't worry about it. The very definition of "news" is "something that hardly ever happens." -- Bruce Schneier --------------------------------------------------------------------- dm-crypt mailing list - http://www.saout.de/misc/dm-crypt/ To unsubscribe, e-mail: dm-crypt-unsubscribe@xxxxxxxx For additional commands, e-mail: dm-crypt-help@xxxxxxxx
