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SECUREDEVICE VERSION 1.3 Copyright (C) 1994 by Max Loewenthal and Arthur Helwig - see chapter 6 May 1st 1994 1. WHAT IS IT? 2. HOW DO I USE IT? 2.1 GETTING STARTED - CREATING A VOLUME 2.2 LOGGING IN TO VOLUMES 2.3 LOGGING OUT 2.4 HOW DO I BACKUP MY FILES? 2.5 CAUTION WITH DISK-UNFRAGMENTERS! 2.6 UNFRAGMENTING VOLUMES 2.7 MULTITASKERS - Windows and DesqView/X 2.8 STACKER SUPPORT 2.9 MS-DOS SMARTDrive QUIRKS 3. FEATURES 3.1 AUTO CLOSE AFTER TIMEOUT 3.2 HOTKEY CLOSE 3.3 MODIFYING SDTSR-COLORS 4. REFERENCE - command-line parameters, usage etc. 4.1 MKVOLUME.COM 4.2 SECDEV.SYS 4.3 SDTSR.COM 4.4 LOGIN.COM 4.5 LOGOUT.COM 5. SECURITY 6. LEGAL STUFF 6.1 COPYRIGHT 6.2 COPYING 6.3 WARRANTY 6.4 CREDITS 6.4.1 IDEA 6.4.2 MD5 6.4.3 SECUREDRIVE 6.4.4 Microsoft, DesqView/X and Stacker 7. CONTACTING THE AUTHORS 1. WHAT IS IT? SecureDevice is a device-driver that will help you keep your private data private. It creates 'extra drives' on your system that are accessible just like normal disk drives, but everything you transfer to the volume will be encrypted using the IDEA encryption algorithm, and when you transfer data from the volume it will be automatically decrypted. The encryption/decryption mechanism is transparant to DOS and other application programs. 2. HOW DO I USE IT? 2.1 GETTING STARTED - CREATING A VOLUME First, you must create a file containing the data for your new drive. To do this, first run MKVOLUME <filename> <size>. Instead of <filename>, you type the name of the file that you want to use to store your data in. For <size>, type the size (in bytes) of the file. Alternatively, you could type the word 'ALL' (without the quotes) instead of the size - this will automatically use all available space on the drive. The size will be rounded down to the nearest sector (512-byte) boundary. After creating the boot sector, the FATs and the rootdirectory, whatever number of bytes remains will be available to you on the new-to-be-created drive. NOTES: - The file must be located in the root-directory of the drive - If the file is fragmented by DOS in more than 50 non-contiguous areas, you will get a 'General Failure'-error when you try to access the volume. Refer to 'UNFRAGMENTING VOLUMES' to solve this problem - You can create volumes on your hard disk as well as on floppy disks. When you create multiple volumes on floppy disks and you give the same name to the volumes on each disk, you can access the different floppies using the same logical driveletter. In addition to this, if you choose the same passphrase for the volumes on your floppies, you can swap floppies without having to enter a new passphrase. EXAMPLE: MKVOLUME C:\PRIVATE.!@# 362496 MKVOLUME A:\PRIVATE2 ALL To load SECDEV and to be able to access the newly created volume, place a line in your CONFIG.SYS-file according to the following convention: DEVICE=<Drive:\Path>SECDEV.SYS <Drive:\volumename> After you have done this, reboot your system. To use your volume, refer to 'LOGGING IN TO VOLUMES'. NOTES: - To create multiple volumes, just add them on the same line after the first <Drive:\volumename>. Up to 10 different volumes are supported. EXAMPLE: DEVICE=C:\SECDEV\SECDEV.SYS C:\PRIVATE.!@# C:\PRIVATE2.!@# 2.2 LOGGING IN TO VOLUMES There are two ways to log in to your volumes: - Load the TSR SDTSR.COM. Whenever you need to enter a passphrase, SDTSR will prompt you to enter this. - Use LOGIN.COM. If you have only 1 volume, LOGIN will automatically prompt you for a passphrase for that volume. If you have multiple volumes, give the driveletter of the volume you want to login to as a parameter to LOGIN. You can use LOGIN.COM to login to a volume on a floppy disk, even if the floppydisk containing the volume is not yet in the drive. This is the reason that LOGIN.COM will NOT tell you whether the passphrase you entered is correct or not. EXAMPLE: LOGIN D 2.3 LOGGING OUT There are three ways to log out: - Use LOGOUT.COM with the driveletter that you wish to log out, or alternatively the word ALL to log out of all drives simultaneously. - You can automatically log out of drives after a specific time of inactivity. See section 3.1. - Load the TSR SDTSR and specify a hotkey. Each time you hit the hotkey you will be logged out of the drive specified. See section 3.2. EXAMPLE: LOGOUT D LOGOUT ALL 2.4 HOW DO I BACKUP MY FILES? You can backup your files just as if you backed them up from a 'normal' drive. However, your backups may not be very secure! You could use an archive-program (such as ARJ or PKZIP) with the password-garble-option, but many questions have been raised about the security of these options. To make a totally safe backup, you can back up the volume itself rather than all files residing on the volume. EXAMPLE: COPY C:\PRIVATE.!@# A:\ Note that your volume by default will be stored as a hidden file, which means you can't copy it with the standard DOS COPY-command. You can a) unhide it (ATTRIB -R <volumename>) and then copy it with DOS's COPY, rehiding the file if you are done, or b) you can use a file-management program (such as the Norton Commander or PCTools) to copy it. Since this file is encrypted, you will get very low if any result by using an archive-program to try to compress the volume. 2.5 CAUTION WITH DISK-UNFRAGMENTERS! If you have a volume which resides, for example, on your C-drive, use harddisk-unfragmenters with caution! Although the volumes are by default marked as Hidden, System and Read-Only, and most disk-unfragmenters will not touch these files, it's better to be safe than sorry. Use the following procedure to safely unfragment any host drive: - Log out from any volumes that physically reside on the drive that you're about to compress - You can now safely unfragment the drive 2.6 UNFRAGMENTING VOLUMES If you get a 'General Failure'-error when you try to access a volume, it's possible that the volume is just too fragmented (more than 50 non-contiguous areas). You can check this with special utility programs, like PCTOOLS or Norton's DiskEdit. To unfragment volumes, you have to remove the Hidden, System and Read-Only attributes. To do this, issue the following DOS-command: ATTRIB -R -H -S <volumename> For example: ATTRIB -R -H -S C:\PRIVATE.!@# Now, unfragment your drive. When this is done, set the Hidden, System and Read-Only attributes again. Use the following DOS-command: ATTRIB +R +H +S <volumename> For example: ATTRIB +R +H +S C:\PRIVATE.!@# 2.7 MULTITASKERS - Windows and DesqView/X You can use SecureDevice volumes with multitaskers such as MicroSoft Windows or DesqView/X. However, SDTSR.COM won't function if you load it before you start the multitasker. SDTSR will notice if you start Windows or DesqView/X and will deactivate itself when one of these 2 programs is running. If you try another multitasker, chances are pretty good that your system will crash whenever SDTSR tries to pop-up. You can, however, load a seperate copy of SDTSR in every DOS-window that you open. Then, SDTSR will operate normally, but only in the window where it is loaded. 2.8 STACKER SUPPORT Creating SecureDevice-volumes on a Stacker volume will not give you much result - you are very likely to get an 1.0 compression ratio. You can do it if you want to, though (but read section 2.9). However, you CAN create Stacker volumes on your SecureDevice volumes! But, because your SecureDevice volumes won't be accessible at boot time (you have to login first to use them), you'll have to mount the Stacker volumes by hand (using STACKER.COM) after you've logged in to your SecureDevice volume. 2.9 MS-DOS SMARTDrive QUIRKS You may encounter a few quirks when using SecureDevice in combination with MS-DOS SMARTDrive. - When creating SecureDevice volumes on a Stacker volume, you'll get weird errors if you let SMARTDrive cache your SecureDevice volume. In our test case, disabling the cache for the SecureDevice volume was enough to solve this problem. - Under Windows, if you open a (windowed) DOS-window and load SDTSR in that window, you won't see the pop-up window. It seems that SMARTDrive has its own ideas about non-standard device drivers. You have the following options: a) Learn to live with it, or b) Use another disk-caching program ;-) 3. FEATURES 3.1 AUTO CLOSE AFTER TIMEOUT You can configure SecureDevice to automatically close volumes after a certain time of inactivity. To do this, specify /Tn on the SECDEV.SYS-commandline, where n is the number of minutes of inactivity after which the volumes are to be closed. EXAMPLE: DEVICE=C:\SECDEV\SECDEV.SYS C:\PRIVATE.!@# C:\PRIVATE2.!@# /T5 This sets the auto-closure timeout value to 5 minutes. N.B.: The inactivity-timer is monitored individually for each volume. So, in the previous example, C:\PRIVATE.!@# will be automatically closed after 5 minutes of inactivity regardless of the usage of C:\PRIVATE2.!@# and vice versa. 3.2 HOTKEY CLOSE If you've loaded SDTSR.COM, you can specify hot-keys to close specific or all volumes. To do this, load SDTSR.COM with the /Kdxxxxyy parameter. If you've previously loaded SDTSR, just run SDTSR.COM again with the proper /K-switch - the hotkeys will be updated in memory. The /Kdxxxxyy parameter is interpreted as follows: d represents the driveletter to which the auto-close applies (or, the @ sign for all drives at once), xxxx represents the CTRL-ALT-SHIFT-states and yy is the scancode of any other key on your keyboard (or leave it set at 00 to just trigger on Shift/Alt/Ctrl states). Ok - so it is sortof complicated, it is _flexible_! You can specify one hotkey for each volume. In addition to this, you can specify one extra hotkey that closes all volumes simultaneously. EXAMPLE 1: SDTSR /KD000C2E This quickly closes drive D every time you hit CTRL-ALT-C. EXAMPLE 2: SDTSR /K@000E00 This quickly closes all your SecureDevice-drives every time you hit CTRL-ALT-LEFTSHIFT. Table of the xxxx - values: 0000 No Ctrl, Shift of Alt-keys 0001 Right Shift 0002 Left Shift 0004 Any Ctrl 0008 Any Alt 1000 Scroll Lock depressed 2000 Num Lock depressed 4000 Caps Lock depressed 8000 SysReq depressed 0104 Left Ctrl (if you have 2 Ctrl's) 0208 Left Alt (if you have 2 Alt's) 0404 Right Ctrl (if you have 2 Ctrl's) 0808 Right Alt (if you have 2 Alt's) To specify a combination of shift, alt and ctrl-keys, just OR the values given in the above table. You can use the bottom 8 values only if you have a 101- or 102-key keyboard. Table of the yy - values (These are just the hex-scancodes) ' 28 | , 33 | - 0C | . 34 | / 35 0 0B | 1 02 | 2 03 | 3 04 | 4 05 5 06 | 6 07 | 7 08 | 8 09 | 9 0A ; 27 | = 0D | A 1E | B 30 | C 2E D 20 | E 12 | F 21 | G 22 | H 23 I 17 | J 24 | K 25 | L 26 | M 32 N 31 | O 18 | P 19 | Q 10 | R 13 S 1F | T 14 | U 16 | V 2F | W 11 X 2D | Y 15 | Z 2C | [ 1A | \ 2B ] 1B | ` 29 F1 3B | F2 3C | F3 3D | F4 3E | F5 3F F6 40 | F7 41 | F8 42 | F9 43 | F10 44 F11 57 | F12 58 Backspace 0E Keypad 0 (Ins) 52 Enter 1C Keypad 1 (End) 4F Esc 01 Keypad 2 (Down arrow) 50 Space 39 Keypad 3 (PgDn) 51 Sys Req (AT) 54 Keypad 4 (Left arrow) 4B Tab 0F Keypad 5 4C Keypad 6 (Right arrow) 4D Keypad 7 (Home) 47 Keypad 8 (Up arrow) 48 Keypad 9 (PgUp) 49 Keypad . (Del) 53 Keypad * (PrtSc) 37 Keypad - 4A Keypad + 4E 3.3 MODIFYING SDTSR-COLORS You can modify the colors of the pop-up windows of SDTSR by running SDTSR with the /Caabbccddee parameter. The values for aa,bb,cc,dd and ee are the hexadecimal values of the color attributes for: aa) the Box for the 'Enter'-window bb) the Box for a 'Wrong password!'-window cc) the text of the 'Enter'-message dd) the text of the 'Wrong password!'-text ee) the password you type A color attribute is composed as follows: Hi nibble: Lo nibble: 0 - Black background 0 - Black foreground 1 - Blue background 1 - Blue foreground 2 - Green background 2 - Green foreground 3 - Cyan background 3 - Cyan foreground 4 - Red background 4 - Red foreground 5 - Magenta background 5 - Magenta foreground 6 - Brown background 6 - Brown foreground 7 - White background 7 - White foreground 8-F: Same as 0-7, but blinking 8-F: Same as 0-7, but intensified EXAMPLE 1: The default settings are equivalent to /C1F4E1E4F0F (EnterBox: Intensified White on Blue, Wrong Password Box: Intensified Brown (Yellow) on Red etc.) EXAMPLE 2: In a MDA video-mode, you might want to use: /C0F0F070770. This only uses (intensified) White and Black. 4. REFERENCE - command-line parameters, usage etc. 4.1 MKVOLUME.COM Usage: MKVOLUME <filename> <size>|ALL 4.2 SECDEV.SYS In CONFIG.SYS: DEVICE=<path>SECDEV.SYS <Drive:\file1> [<Drive:\file2> ...] [/Tn] /Tn defines an automatic closure after n minutes of inactivity. 4.3 SDTSR.COM Usage: SDTSR [/Kdxxxxyy] [/Caabbccddee] [/Q] With the /K parameter you can specify a hotkey to close drive d (enter a @ for d to specify a hotkey to close all volumes simultaneously). xxxx represents the shift-states; yy is the scancode of the hotkey you want to use. See section 3.2 for tables for xxxx and yy. The /C parameters lets you modify the colors of the pop-up windows. aa,bb,cc,dd and ee represent color-attributes for the windows and texts that SDTSR will display. See section 3.3 for tables for aa,bb,cc,dd and ee. /Q: Quiet mode. By default, if SDTSR can't pop up a window asking you for a passphrase (e.g., when in a graphics mode), you'll hear a beep. Further, different beeps are given if you enter the correct or a wrong password. If you run SDTSR with /Q, you won't hear any beeps. Please note that if you're in a graphics mode and SDTSR is in quiet mode, your system will wait without any warning or announcement for you to enter a passphrase, if needed. 4.4 LOGIN.COM Usage: LOGIN [<driveletter>] [passphrase] If you run LOGIN without parameters, you'll be prompted for a passphrase for your first volume. CAUTION! Normally, you shouldn't enter the passphrase on the commandline. Just leave it empty; LOGIN will prompt you and you can enter your passphrase without echoing to the screen. 4.5 LOGOUT.COM Usage: LOGOUT <driveletter>|ALL 5. SECURITY The question is always: how secure is a certain method of encryption? Any method of encryption is as strong as the weakest link in the chain. The encryption scheme used by SecureDevice is briefly described below. The main encryption algorithm used is IDEA. Encryption takes place on a per-sector basis. Each sector on a volume is encrypted seperately with a different IV. We take the plain MD5-hash of the user's password as a key for the IDEA-algorithm. A different IV is used for each volume created. Each sector is encrypted with a different IV. To achieve this, we take the 'master' IV for the volume and XOR both the low 32 bits and the high 32 bits of this 'master' IV with the 32-bit sector number. WEAKNESS: When a sector is changed, it is written back in the data file using the same IV as it had before. If an intruder could monitor your volumes for a long period of time, he/she could get different ciphertexts encrypted with the same IV and same key. This is a possible weakness in SecureDevice. The alternative to this would be to generate a new, random IV for each sector written. However, you'd have to keep a table with all IV's for all sectors in the volume, and you'd have to update this table each time a sector is written. Further, if this table would be destroyed for some reason, there would be absolutely no way to recover your data. We're not exactly sure how severe this 'hole' in the security is. Feedback, hints, tips or solutions are welcomed. 6. CREDITS 6.1 COPYRIGHT SecureDevice 1.0 is Copyright (C) 1994 by Max Loewenthal and Arthur Helwig. 6.2 COPYING Distributing and copying is permitted under the GNU General Public License. See the file COPYING for details. 6.3 WARRANTY SecureDevice is provided with NO WARRANTY. Use at your own risk. See the file COPYING for details. 6.4.1 IDEA The IDEA(tm) block cipher is covered by a patent held by ETH and a Swiss company called Ascom-Tech AG. The Swiss patent number is PCT/CH91/00117. International patents are pending. IDEA(tm) is a trademark of Ascom-Tech AG. There is no license fee required for noncommercial use. Commercial users may obtain licensing details from: Dieter Profos, Ascom Tech AG, Solothurn Lab, Postfach 151, 4502 Solothurn, Switzerland, Tel +41 65 242885, Fax +41 65 235761. 6.4.2 MD5 All references to MD5 refer to: RSA Data Security, Inc. MD5 Message-Digest Algorithm (C) 1990, RSA Data Security, Inc. 6.4.3 SECUREDRIVE Parts of the source of SecureDevice 1.0 are based on the sources of SecureDrive 1.0 by Mike Ingle. 6.4.4 Microsoft, DesqView/X and Stacker Microsoft is a trademark of Microsoft Corporation DesqView/X is a trademark of Quarterdeck Office Stacker is a trademark of Stac Electronics 7. CONTACTING THE AUTHORS We welcome your feedback! Send all your bugs, comments, requests and/or fanmail to: Arthur Helwig: E-Mail: A.W.S.Helwig@ET.TUDelft.NL Fido Netmail: 2:512/56.2 Max Loewenthal: Fido Netmail: 2:512/56.10 2:512/56 is a BBS called Fata Morgana located in Delft, The Netherlands. Telephone number: +31-15-568396 (As of october 10th 1995, this will change into +31-15-2568396). You can call this BBS and leave a message for either Max Loewenthal or Arthur Helwig.