decrypt a Twofish encrypted file

[m4rtin]

I have a 50MiB encrypted file which was created with Sentry 2020(version 2.8) for Windows Mobile. This 50MiB file is a virtual volume which appears as a directory in Windows Mobile root directory once the correct password is provided and volume is mounted. Along with the 50MiB encrypted file, there is a 760 byte key-file:

Code:

root@T60:~# hexdump -C /media/0C64-8931/encrypted2.key
00000000  00 00 00 00 00 00 00 00  10 00 00 00 00 00 00 00  |................|
00000010  01 00 00 00 00 00 00 00  18 00 00 00 00 00 00 00  |................|
00000020  00 00 00 00 41 00 00 00  00 1a 71 18 02 00 00 00  |....A.....q.....|
00000030  00 00 00 00 5e f8 cf 93  02 00 00 00 0a 00 00 00  |....^...........|
00000040  98 00 00 00 00 00 00 00  45 df 28 34 dd 14 bf 6d  |........E.(4...n|
00000050  5b 5b c5 a2 78 68 e4 ab  f8 13 2d 0d 07 ab 1e fd  |[[..xh....-.....|
00000060  b8 66 41 ea 43 51 49 9c  c5 8a 9b 52 2d 2b e8 6c  |.fA.CQI....R-+.l|
00000070  2d 7e 1d 7f 40 66 a6 77  2a 1a 80 33 2e 14 71 16  |-~..@f.w*..3..q.|
00000080  3f 26 84 91 ff 03 80 03  40 9f 63 8e 93 45 b0 b2  |?&......@.c..E..|
00000090  a4 e9 17 60 e5 62 d3 e0  5d 0d 06 14 c2 b0 a1 69  |...`.b..]......i|
000000a0  9c 0f 94 fd dc 52 58 0f  c6 9c 46 3f c1 b9 92 df  |.....RX...F?....|
000000b0  6e 4e 1d c0 9a bc 77 75  c8 71 7c 73 a4 23 da 0a  |nN....wu.q|s.#..|
000000c0  b3 c6 cc 2a 70 c8 9f 8a  32 d0 6b c5 2d 6c 18 df  |...*p...2.k.-l..|
000000d0  4d ce 48 01 e9 4f 06 c3  7b 8f 84 34 f7 eb 53 01  |M.H..O..{..4..S.|
000000e0  03 00 00 00 02 00 00 00  08 02 00 00 00 00 00 00  |................|
000000f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000002f8
root@T60:~#

According to security details of Sentry 2020, this 50MiB file is encrypted using a randomly generated key, which itself is encrypted using a user supplied password. The randomly generated key is stored in a 760 byte key file, encrypted with a user supplied password and a randomly generated "salt" value stored in the same file. This means that once I have decrypted the 760 byte key file I could access the content of the 50MiB file? Is there a way to tell which encryption method is used for a key file? For 50MiB file I chose Twofish encryption with 256 byte key. I would guess that the key file is encrypted with the same method.

Is there a way to brute-force this key-file using hashcat? I guess not as this key-file is probably encrypted with Twofish which is not supported by hashcat. What tool should I use here? In addition, it's important to mention that while my password was ~15 characters long, I *think* I remember the characters and order of character to large extent in the password so number of variations is few thousands.

[m4rtin]

I solved this in a way that I created a password file with maskprocessor. It contained less than 200k passwords all separated by carriage return and line feed. Then I made a Windows batch script which read those passwords line by line from the password file:

Code:

FOR /F "usebackq delims=" %a in ("C:\Users\winuser\Desktop\passfile.txt") do SentryCommand.exe mount /file test-volume.key /password %a /drive A /timeout 10 /volume encrypted-file

..and used those in Sentry 2020 command line interface:

Code:

Sentry.exe supports following command line options:
mount [/volume] file.raw [/key file.key] [/password 12345]
dismount [/volume] file.raw

[atom]

Cool, thanks for letting us now