Int 21/AX=4405h

SFS v1.00 - DRIVER CONTROL

AX = 4405h
BL = drive number (00h = default, 01h = A:, etc)
CX = number of bytes to write
DS:DX -> data to write (see #01543)

Return:
CF clear if successful
AX = number of bytes actually written
CF set on error
AX = error code (01h,05h,06h,0Dh) (see #01680 at AH=59h/BX=0000h)

Program: SFS (Secure FileSystem) is a shareware encrypting disk driver by Peter C. Gutmann

See Also: AX=4404h"SFS"



(Table 01542)
Values for SFS control function:
00h    "PACKET_SET_DISKINFO"    set disk parameters
01h    "PACKET_SET_KEYINFO"     set keying information
02h    "PACKET_SET_READONLY"    select read/write or read-only
03h    "PACKET_SET_DRIVENO"     set drive number to mount
04h    "PACKET_SET_MOUNTSTATUS" set mount status
05h    "PACKET_SET_UNMOUNT"     set/clear quick-unmount hotkey
06h    "PACKET_SET_TIMEOUT"     set/clear auto-unmount timeout

Format of SFS control data packet:

Offset  Size    Description     (Table 01543)
00h    WORD    signature 4330h ('C0')
02h    WORD    function (see #01542)
---function 00h---
04h    WORD    sector size in bytes
06h    BYTE    sectors per cluster
07h    WORD    number of boot sectors
09h    BYTE    number of copies of FAT
0Ah    WORD    size of root directory in entries
0Ch    WORD    number of sectors on disk, 16-bit
0Eh    BYTE    media descriptor byte
0Fh    WORD    sectors per FAT
11h    WORD    sectors per track
13h    WORD    number of heads
15h    DWORD   number of hidden sectors
19h    DWORD   number of sectors on disk, 32-bit
---function 01h---
04h 20 BYTEs   master IV for encrypted disk
18h 64 BYTEs   NDC/SHS keying information
---function 02h---
04h    WORD    read-only state:
00h read-only, 01h read/write
---function 03h---
04h    WORD    drive number (see #01544)
06h    DWORD   sector offset of logical volume from start of physical volume
0 if logical volume = physical volume
---function 04h---
04h    WORD    mount status (00h unmounted, 01h mounted)
---function 05h---
04h    WORD    hotkey (high byte = shift state, low byte = scan code or 00h)
(see #00006)
0000h to disable hotkey
---function 06h---
04h    WORD    timeout in minutes before automatic unmount
0000h to disable auto-unmount

Notes: The data for function 00h corresponds to a DOS BPB (see AH=53h). Functions 00h, 01h, and 03h automatically unmount the encrypted drive. Unmounting a drive with function 04h also destroys the encryption information in the driver and forces all dirty buffers to be flushed

Bitfields for SFS drive number: Bit(s) Description (Table 01544) 15-12 drive access mode. 0000 BIOS access. 0001 direct IDE access. 0010 direct SCSI access ---if BIOS access--- 11-8 unused (0) 7-0 BIOS drive number ---if IDE access--- 11-8 unused (0) 7-0 IDE drive number ---if SCSI access--- 11-8 SCSI host number 7-4 SCSI target ID 3-0 SCSI logical unit number

Category: Disk I/O Enhancements - Int 21h - S

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