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ZX Review #7-8-9-10
08 ноября 1997 |
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Studies - Set of protective boot.
(C) DeathSOFT, pos.Lebyazhe
Ca. Ed.: Our correspondent, did not disclose his name,
offers to your Court set all sorts of "protection to your
boot." These procedures are quite simple and do not require a
separate comment, but they are very indicative for the beginner
Hacker programmer or because Procedure this class should be
compact, fast and well designed.
140.
LD HL, START
LD BC, LENGTH
LOOP LD A, (HL)
XOR B
LD (HL), A
INC HL
DEC BC
LD A, B
OR C
JR NZ, LOOP
LD HL, START
LD DE, LENGTH
LOOP LD A, (HL)
CPL
LD (HL), A
INC HL
DEC DE
LD A, E
OR D
JR NZ, LOOP
LD HL, START
LD BC, LENGTH
LD HL, START
LD BC, LENGTH
LD A, # 33
LD R, A
LOOP LD A, R
XOR (HL)
LD (HL), A
INC HL
DEC BC
LD A, B
OR C
JR NZ, LOOP
LD HL, START
LD DE, START1
LD BC, LENGTH
LD A, # 33
LD R, A
LOOP LD A, (HL)
XOR D
XOR H
XOR E
LD C, A
LD A, R
XOR C
LD (HL), A
LD (DE), A
INC HL; \
INC DE; LDI
DEC BC; /
LD A, B
OR C
JR NZ, LOOP
LD SP, START
LD DE, LENGTH
DI
XOR A
DEC A
DAA
LD R, A
LD HL, START1
LD DE, START1 +1
LD BC, LENGTH1
LD (HL), L
LDIR
LOOP LD A, R
POP HL
XOR L
LD L, A
PUSH HL
INC SP
DEC DE
LD A, D
OR E
JR NZ, LOOP
LD IX, START
LD DE, LENGTH
LOOP LD A, (IX +0)
CPL
XOR E
XOR D
LD (IX +0), A
INC IX
DEC DE
LD A, D
OR E
JR NZ, LOOP
LD HL, START
LD BC, LENGTH
LOOP LD A, (HL)
CPL
LD (HL), A
INC HL
DJNZ LOOP
XOR A
LD HL, START
LD BC, LENGTH
LD R, A
LOOP POP HL
LD A, R
XOR (HL)
XOR C
XOR B
LD (HL), A
INC HL
DEC BC
PUSH HL
LD A, B
OR C
JR NZ, LOOP
2
CORR.: Then I would suggest a more complex code. Procedure
(CP). A procedure containing the insert:
140.
LD HL, START
LD DE, START1
LD BC, LENGTH
LD (HL), L
LDIR
2
the monitor debugger can not
be untwisted. Because, if the KP
substitute for the address - 23925, and
registers Record these values: HL, 24100; DE, 24101; BC,
41100, then after the KP with
addresses 24100 and 65200 to the entire memory will be scored
by byte from the register of L, ie automatically be spoiled
debugger.
Ca. Ed.: For beginners: what the author calls the KP is
nothing like ordinary and pleasant to the ear "ksorkoy.
As for the non-disclosure of such protection,
There has long been the means to cope with such powerful
algorithms, as the score of memory usage register
R, and other methods of protection. But we
carried away ...
140.
DI
LD HL, START
LD BC, LENGTH
IM 2
LD A, R
LD IY, START1
LD IX, START1 +1
LD DE, LENGTH1
LOOP LD (IY +0), E
INC IX
INC IY
DEC DE
LD A, D
OR E
JR NZ, LOOP
LOOP1 POP HL
LD R, A
XOR (HL)
XOR C
XOR B
LD (HL), A
CPL
PUSH HL
LD A, B
OR C
JR NZ, LOOP1
LD IX, START
LD A, 51
LD R, A
LD HL, START1
LD DE, START1 +1
LD BC, LENGTH
LOOP POP HL
LD A, R
XOR (HL)
XOR E
XOR D
LD (IX +0), A
INC IX
DEC BC
PUSH HL
LD A, B
OR C
JR NZ, LOOP
DI
LD A, 78
LD R, A
XOR A
LD IXh, NN; START
LD IXl, NN;
PUSH IX
POP HL
LD IXh, 1964
LD IXl, 255
LD A, IXl
CPL
LD IXl, A
PUSH IX
POP DE
LD BC, LENGTH
LD IXh, 255
LD IXl, 253
CALL 13251
LD A, 0
LD L, A
SET 5, A
LD H, A
RES 2, H
RES 5, H
SET 6, H
LD DE, LENGTH
LD BC, START
LOOP LD A, R
XOR (HL)
CPL
XOR H
XOR L
XOR B
XOR C
XOR D
XOR E
XOR IXh
XOR IXl
XOR IYl
XOR IYh
PUSH HL
POP IX
LD (IX +0), A
LD (BC), A
INC BC
INC HL
DEC DE
LD A, D
OR E
JR NZ, LOOP
LD HL, START
LD BC, LENGTH
DI
LD A, 51
LD I, A
LOOP LD R, A
LD A, I
LD A, R
XOR (HL)
CPL
XOR B
XOR H
XOR L
XOR C
LD (HL), A
CPI
LD A, B
OR C
JR NZ, LOOP
2
*
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