硬盘加密--解析三
上一篇文章解析了硬盘上有两个分区的加密过程，下面的程序将允许有N个分区的加密过程:
Source Codes:
data segment
FQB DB 512 dup(0);a buffer that will be used to store partition-table
FIRSTP DB 40 dup(0);storing the first partition information
SECONDP DB 00,01,00,00
DB 512 dup(0)
INFO1 DB "My Computer has the following drives:!$"
INFO2 DB 0DH,0AH,"Please enter the drive needed to be locked!$"
INFO3 DB 0DH,0AH,"Invalid Enter!$"
ERROR DB 0DH,0AH,"Harddisk I/O error!$"
data ends
code segment
assume cs:code,ds:data
START:
MOV AX,1000H
MOV DS,AX
MOV SI,OFFSET SECONDP;
MOV DI,OFFSET FIRSTP;
SUB DI,4
READP:
MOV AX,0201
MOV BX,OFFSET FQB
MOV CX,WORD PTR [SI+1]
MOV DX,0080
INT 13
JB ERROR
ADD SI,4
ADD DI,4
;The first partition
ADD BX,1BE
MOV AX,WORD PTR [BX+1]
MOV [DI],AX
MOV AX,WORD PTR [BX+3]
MOV [DI+2],AX
;The second partition
ADD BX,10H
MOV AX,WORD PTR [BX+1]
MOV [SI],AX
MOV AX,WORD PTR [BX+3]
MOV [SI+2],AX
CMP WORD PTR [SI+1],0;Determine whether the header,sector is 0 or not
JNZ READP
LEA DX,INFO1
MOV AH,9
INT 21H
MOV DL,43H
MOV DI,OFFSET FIRSTP
DISP:
CMP WORD PTR [DI+1],0
JZ ENCRYPT
MOV AH,02
INT 21H
MOV CL,DL
CMP BYTE PTR [DI+3],0
JNZ NLOCK
JMP ENCRYPT
NLOCK:
MOV DL,','
INT 21
MOV DL,CL
INC DL
ADD DI,4
JMP DISP
ENCRYPT:
MOV AH,9
LEA DX,INFO2
INT 21
MOV AH,1
INT 21
CMP AL,'A'
JB ERROR1
CMP AL,'Z'
JA ERROR1
SUB AL,43H
XOR AH,AH;AH=0
SHL AX,1
SHL AX,1
MOV SI,OFFSET SECONDP
ADD SI,AX
MOV AX,0201
MOV BX,OFFSET FQB
MOV CX,[SI+1];Sector,Cylinder
MOV DH,[SI];Header
MOV DL,80H;The first harddisk:80,the second:81
INT 13
JB ERROR
ADD BX,1C1H
MOV AX,[BX]
XCHG [BX-20],AX
MOV [BX],AX
MOV AX,0301
MOV BX,OFFSET FQB
MOV CX,[SI+1]
MOV DH,[SI]
MOV DL,80H
INT 13
JB ERROR
MOV AX,0040
MOV DS,AX
MOV SI,0072
MOV AX,1234
MOV [SI],AX
JMP FFFF:0
INT 20H
ERROR1:
LEA DX,INFO3
MOV AH,9
INT 21H
JMP EXIT
ERROR:
LEA DX,INFO2
MOV AH,9
INT 21
EXIT:
MOV AH,4CH
INT 21H
code ends
end start