Механизм действия S-блоков
Преобразование, с помощью которого 48-разрядный блок преобразуется в 32-разрядный, сводится к выборке восьми тетрад из 8 таблиц (S-блоков) размером 4 ´ 16 (табл. 18.7). Из каждого S-блока выбирается одна тетрада. Для этого 48-разрядный блок делится последовательно на 8 комбинаций по 6 бит каждая. Первая комбинация (слева) является входом в первый S-блок, вторая — во второй и т.д. При этом первый и последний биты комбинации задают номер строки, а остальные 4 бита — номер столбца S-блока, на пересечении которых расположена соответствующая тетрада. Конкретные значения Si (i = 1, …, 8) представлены в табл. 18.7.
Таблица 18.7. Таблицы S -блоков для DES
| S1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | |||||||||||||||||
| 0 | 14 | 4 | 13 | 1 | 2 | 15 | 11 | 8 | 3 | 10 | 6 | 12 | 5 | 9 | 0 | 7 | |||||||||||||||||
| 1 | 0 | 15 | 7 | 4 | 14 | 2 | 13 | 1 | 10 | 6 | 12 | 11 | 9 | 5 | 3 | 8 | |||||||||||||||||
| 2 | 4 | 1 | 14 | 8 | 13 | 6 | 2 | 11 | 15 | 12 | 9 | 7 | 3 | 10 | 5 | 0 | |||||||||||||||||
| 3 | 15 | 12 | 8 | 2 | 4 | 9 | 1 | 7 | 5 | 11 | 3 | 14 | 10 | 0 | 6 | 13 | |||||||||||||||||
| S2 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | |||||||||||||||||
| 0 | 15 | 1 | 8 | 14 | 6 | 11 | 3 | 4 | 9 | 7 | 2 | 13 | 12 | 0 | 5 | 10 | |||||||||||||||||
| 1 | 3 | 13 | 4 | 7 | 15 | 2 | 8 | 14 | 12 | 0 | 1 | 10 | 6 | 9 | 11 | 5 | |||||||||||||||||
| 2 | 0 | 14 | 7 | 11 | 10 | 4 | 13 | 1 | 5 | 8 | 12 | 6 | 9 | 3 | 2 | 15 | |||||||||||||||||
| 3 | 13 | 8 | 10 | 1 | 3 | 15 | 4 | 2 | 11 | 6 | 7 | 12 | 0 | 5 | 14 | 9 | |||||||||||||||||
| S3 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | |||||||||||||||||
| 0 | 10 | 0 | 9 | 14 | 6 | 3 | 15 | 5 | 1 | 13 | 12 | 7 | 11 | 4 | 2 | 8 | |||||||||||||||||
| 1 | 13 | 7 | 0 | 9 | 3 | 4 | 6 | 10 | 2 | 8 | 5 | 14 | 12 | 11 | 15 | 1 | |||||||||||||||||
| 2 | 13 | 6 | 4 | 9 | 8 | 15 | 3 | 0 | 11 | 1 | 2 | 12 | 5 | 10 | 14 | 7 | |||||||||||||||||
| 3 | 1 | 10 | 13 | 0 | 6 | 9 | 8 | 7 | 4 | 15 | 14 | 3 | 11 | 5 | 2 | 12 | |||||||||||||||||
| S4 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | |||||||||||||||||
| 0 | 7 | 13 | 14 | 3 | 0 | 6 | 9 | 10 | 1 | 2 | 8 | 5 | 11 | 12 | 4 | 15 | |||||||||||||||||
| 1 | 13 | 8 | 11 | 5 | 6 | 15 | 0 | 3 | 4 | 7 | 2 | 12 | 1 | 10 | 14 | 9 | |||||||||||||||||
| 2 | 10 | 6 | 9 | 0 | 12 | 11 | 7 | 13 | 15 | 1 | 3 | 14 | 5 | 2 | 8 | 4 | |||||||||||||||||
| 3 | 3 | 15 | 0 | 6 | 10 | 1 | 13 | 8 | 9 | 4 | 5 | 11 | 12 | 7 | 2 | 14 | |||||||||||||||||
| S5 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | |||||||||||||||||
| 0 | 2 | 12 | 4 | 1 | 7 | 10 | 11 | 6 | 8 | 5 | 3 | 15 | 13 | 0 | 14 | 9 | |||||||||||||||||
| 1 | 14 | 11 | 2 | 12 | 4 | 7 | 13 | 1 | 5 | 0 | 15 | 10 | 3 | 9 | 8 | 6 | |||||||||||||||||
| 2 | 4 | 2 | 1 | 11 | 10 | 13 | 7 | 8 | 15 | 9 | 12 | 5 | 6 | 3 | 0 | 14 | |||||||||||||||||
| 3 | 11 | 8 | 12 | 7 | 1 | 14 | 2 | 13 | 6 | 15 | 0 | 9 | 10 | 4 | 5 | 3 | |||||||||||||||||
| S6 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | |||||||||||||||||
| 0 | 12 | 1 | 10 | 15 | 9 | 2 | 6 | 8 | 0 | 13 | 3 | 4 | 14 | 7 | 5 | 11 | |||||||||||||||||
| 1 | 10 | 15 | 4 | 2 | 7 | 12 | 9 | 5 | 6 | 1 | 13 | 14 | 0 | 11 | 3 | 8 | |||||||||||||||||
| 2 | 9 | 14 | 15 | 5 | 2 | 8 | 12 | 3 | 7 | 0 | 4 | 10 | 1 | 13 | 11 | 6 | |||||||||||||||||
| 3 | 4 | 3 | 2 | 12 | 9 | 5 | 15 | 10 | 11 | 14 | 1 | 7 | 6 | 0 | 8 | 13 |
Окончание таблицы 18.7
|
S7 |
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
14 |
15 |
|
0 |
4 |
11 |
2 |
14 |
15 |
0 |
8 |
13 |
3 |
32 |
9 |
7 |
5 |
10 |
6 |
1 |
|
1 |
13 |
0 |
11 |
7 |
4 |
9 |
1 |
10 |
14 |
3 |
5 |
12 |
2 |
15 |
8 |
6 |
|
2 |
1 |
4 |
11 |
13 |
12 |
3 |
7 |
14 |
10 |
15 |
6 |
8 |
0 |
5 |
9 |
2 |
|
3 |
6 |
11 |
13 |
8 |
1 |
4 |
10 |
7 |
9 |
5 |
0 |
15 |
14 |
2 |
3 |
12 |
|
S8 |
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
14 |
15 |
|
0 |
13 |
2 |
8 |
4 |
6 |
15 |
11 |
1 |
10 |
9 |
3 |
14 |
5 |
0 |
12 |
7 |
|
1 |
1 |
15 |
13 |
8 |
10 |
3 |
7 |
4 |
12 |
5 |
6 |
11 |
0 |
14 |
9 |
2 |
|
2 |
7 |
11 |
4 |
1 |
9 |
12 |
14 |
2 |
0 |
6 |
10 |
13 |
15 |
3 |
5 |
8 |
|
3 |
2 |
1 |
14 |
7 |
4 |
10 |
8 |
13 |
15 |
12 |
9 |
0 |
3 |
5 |
6 |
11 |
Листинг 18.3. Пример реализации
алгоритма DES на языке Basic для шифрования файлов
$CPU 80386
$FLOAT NPX
$OPTIMIZE SPEED
$LIB ALL-
$OPTION CNTLBREAK ON
DECLARE FUNCTION MYBIN$ (n%)
DECLARE FUNCTION desalg$ (a$)
DECLARE SUB f (i%, a%(), x%())
DECLARE SUB transpose (datax%(), T%(), n%)
DECLARE SUB mrotate (keyx%())
DECLARE SUB stob (a$, mbits%())
DECLARE SUB btos (mbits%(), a$)
DECLARE SUB letbe (target%(), source%(), LAST%)
DECLARE SUB init (x() AS INTEGER, n%)
DECLARE SUB sboxinit (b() AS INTEGER)
DECLARE SUB xtob (a$, mbits%())
DIM s(1 TO 8, 1 TO 64) AS shared INTEGER
Продолжение листинга 18.3
' Инициализация
RESTORE InitialTrl
DIM InitialTr(1 TO 64) AS shared INTEGER
init InitialTr(), 64
RESTORE FinalTrl
DIM FinalTr( 1 TO 64) AS shared INTEGER
init FinalTr(), 64
RESTORE swappyl
DIM swappy(1 TO 64) AS shared INTEGER
init swappy(), 64
RESTORE KeyTr1l
DIM KeyTr1(1 TO 56) AS shared INTEGER
init KeyTr1(), 56
RESTORE KeyTr2l
DIM KeyTr2(1 TO 48) AS shared INTEGER
init KeyTr2(), 48
RESTORE etrl
DIM etr(1 TO 48) AS shared INTEGER
init etr(), 48
RESTORE ptrl
DIM ptr(1 TO 32) AS shared INTEGER
init ptr(), 32
sboxinit s()
RESTORE rotsl
DIM rots(1 TO 16) AS shared INTEGER
init rots(), 16
DIM XR(1 TO 56) AS shared INTEGER
DIM EF(1 TO 64) AS shared INTEGER
DIM ikeyf(1 TO 64) AS shared INTEGER
DIM yf(1 TO 64) AS shared INTEGER
Продолжение листинга 18.3
DIM ades(1 TO 64) AS shared INTEGER
DIM bdes(1 TO 64) AS shared INTEGER
DIM xdes(1 TO 64) AS shared INTEGER
DIM XT(1 TO 64) AS shared INTEGER
DIM P2(1 TO 64) AS shared INTEGER
' Главная программа
main:
CLS
parm$ = ltrim$(rtrim$(COMMAND$))+" "
IF LEN(parm$) > 1 THEN
Plainf$ = LTRIM$(RTRIM$(LEFT$(parm$, INSTR(parm$, " "))))
PRINT "Исходный файл : "; Plainf$
ELSE
INPUT "Исходный файл : ", plainf$
END IF
if len(plainf$)=0 then
print : print "СБОЙ: введите имя файла!"
system
end if
OPEN plainf$ FOR RANDOM AS 1
lof1& = LOF(1)
IF lof1& = 0 THEN
CLOSE #1
KILL plainf$
PRINT : PRINT "Файл не найден!";
SYSTEM
ELSE
IF lof1& > 9999999 THEN PRINT : PRINT "Исходный файл слишком велик!": SYSTEM
CLOSE #1
OPEN plainf$ for binary access read as #1
END IF
cipherf$ = ""
sp0% = 0: sp% = 0
DO
sp0% = sp%
sp% = INSTR(sp% + 1, plainf$, "\")
Продолжение листинга 18.3
LOOP WHILE sp% > 0
bplainf$ = RIGHT$(plainf$, LEN(plainf$) - (sp0%))
PRINT "Сохраняемое имя файла: "; bplainf$
pp% = INSTR(sp0% + 1, plainf$, ".")
IF pp% = 0 THEN
dcipherf$ = plainf$ + ".DES"
ELSE
dcipherf$ = LEFT$(plainf$, pp% - 1) + ".DES"
END IF
PRINT " По умолчанию : "; dcipherf$
INPUT "Выходной файл : ", cipherf$
IF cipherf$ = "" THEN cipherf$ = dcipherf$
OPEN cipherf$ FOR RANDOM AS 2
IF LOF(2) > 0 THEN
CLOSE #2
PRINT : PRINT "Выходной файл уже существует!"
SYSTEM
ELSE
CLOSE #2
OPEN cipherf$ FOR binary AS 2
END IF
PW$ = ""
LOCATE 9, 1
INPUT ; " Пароль : ", PW$
IF (LEN(PW$) < 8) THEN PW$ = PW$ + STRING$(8 - LEN(PW$), 0)
IF len(pw$) = 16 then
LOCATE 9, 8: PRINT "Пароль : "; STRING$(16, 15); STRING$(10, " ")
PW$ = ucase$(PW$)
xtob PW$, P2()
ELSE
LOCATE 9, 8: PRINT "Пароль : "; STRING$(8, 15); STRING$(10, " ")
PW$ = LEFT$(PW$, 8)
stob PW$, P2()
end IF
Продолжение листинга 18.3
transpose P2(), KeyTr1(), 56
ciphertekst$ = ""
blocks& = lof1& \ 256
w = RND(-INT(TIMER))
anything$ = ""
FOR i% = 1 TO 12
anything$ = anything$ + CHR$(128 + INT(127 * RND(1)))
NEXT i%
header$ = "#" + LTRIM$(STR$(lof1&))
header$ = "DES" + LEFT$(anything$, 8 - LEN(header$)) + header$
header$ = header$ + RIGHT$(anything$, 12 - LEN(bplainf$)) +
"#" + bplainf$
cheader$=desalg$(left$(header$,8))+desalg$(MID$(header$,9,8))+desalg$(right$(header$,8))
put$ #2, cheader$
LOCATE 10, 8: PRINT ; "Шифрование: 0 %";
inblock$=space$(256)
FOR n& = 1 TO blocks&
get$ #1,256,inblock$
outblock$=""
for b%=1 to 256 step 8
outblock$ = outblock$+desalg$(mid$(inblock$,b%,8))
next
Put$ #2, outblock$
LOCATE 10, 19: PRINT ; USING "###"; (n& / blocks&) * 100;
NEXT n&
rest1 = lof1& MOD 256
rest2 = lof1& MOD 8
rest = rest1-rest2
IF rest1 > 0 THEN
outblock$=""
get$ #1,rest1,inblock$
Продолжение листинга 18.3
if rest2 > 0 then
inblock$=inblock$+left$(anything$,(8-rest2))
end if
for b%=1 to len(inblock$) step 8
outblock$ = outblock$+desalg$(mid$(inblock$,b%,8))
next
Put$ #2, outblock$
END IF
CLOSE
LOCATE 10, 19: PRINT "100 % завершено"
PRINT : PRINT "Шифрование по алгоритму DES завершено."
SYSTEM
' Данные и функции
InitialTrl:
DATA 58,50,42,34,26,18,10,02,60,52,44,36,28,20,12,04
DATA 62,54,46,38,30,22,14,06,64,56,48,40,32,24,16,08
DATA 57,49,41,33,25,17,09,01,59,51,43,35,27,19,11,03
DATA 61,53,45,37,29,21,13,05,63,55,47,39,31,23,15,07
FinalTrl:
DATA 40,08,48,16,56,24,64,32,39,07,47,15,55,23,63,31
DATA 38,06,46,14,54,22,62,30,37,05,45,13,53,21,61,29
DATA 36,04,44,12,52,20,60,28,35,03,43,11,51,19,59,27
DATA 34,02,42,10,50,18,58,26,33,01,41,09,49,17,57,25
swappyl:
DATA 33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48
DATA 49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64
DATA 01,02,03,04,05,06,07,08,09,10,11,12,13,14,15,16
DATA 17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32
KeyTr1l:
DATA 57,49,41,33,25,17,09,01,58,50,42,34,26,18,10,02
DATA 59,51,43,35,27,19,11,03,60,52,44,36
DATA 63,55,47,39,31,23,15,07,62,54,46,38,30,22,14,06
DATA 61,53,45,37,29,21,13,05,28,20,12,04
Продолжение листинга 18.3
KeyTr2l:
DATA 14,17,11,24,01,05,03,28,15,06,21,10,23,19,12,04
DATA 26,08,16,07,27,20,13,02,41,52,31,37,47,55,30,40
DATA 51,45,33,48,44,49,39,56,34,53,46,42,50,36,29,32
etrl:
DATA 32,01,02,03,04,05,04,05,06,07,08,09,08,09,10,11
DATA 12,13,12,13,14,15,16,17,16,17,18,19,20,21,20,21
DATA 22,23,24,25,24,25,26,27,28,29,28,29,30,31,32,01
ptrl:
DATA 16,07,20,21,29,12,28,17,01,15,23,26,05,18,31,10
DATA 02,08,24,14,32,27,03,09,19,13,30,06,22,11,04,25
sboxesl:
DATA 14,04,13,01,02,15,11,08,03,10,06,12,05,09,00,07
DATA 00,15,07,04,14,02,13,01,10,06,12,11,09,05,03,08
DATA 04,01,14,08,13,06,02,11,15,12,09,07,03,10,05,00
DATA 15,12,08,02,04,09,01,07,05,11,03,14,10,00,06,13
DATA 15,01,08,14,06,11,03,04,09,07,02,13,12,00,05,10
DATA 03,13,04,07,15,02,08,14,12,00,01,10,06,09,11,05
DATA 00,14,07,11,10,04,13,01,05,08,12,06,09,03,02,15
DATA 13,08,10,01,03,15,04,02,11,06,07,12,00,05,14,09
DATA 10,00,09,14,06,03,15,05,01,13,12,07,11,04,02,08
DATA 13,07,00,09,03,04,06,10,02,08,05,14,12,11,15,01
DATA 13,06,04,09,08,15,03,00,11,01,02,12,05,10,14,07
DATA 01,10,13,00,06,09,08,07,04,15,14,03,11,05,02,12
DATA 07,13,14,03,00,06,09,10,01,02,08,05,11,12,04,15
DATA 13,08,11,05,06,15,00,03,04,07,02,12,01,10,14,09
DATA 10,06,09,00,12,11,07,13,15,01,03,14,05,02,08,04
DATA 03,15,00,06,10,01,13,08,09,04,05,11,12,07,02,14
DATA 02,12,04,01,07,10,11,06,08,05,03,15,13,00,14,09
DATA 14,11,02,12,04,07,13,01,05,00,15,10,03,09,08,06
DATA 04,02,01,11,10,13,07,08,15,09,12,05,06,03,00,14
DATA 11,08,12,07,01,14,02,13,06,15,00,09,10,04,05,03
Продолжение листинга 18.3
DATA 12,01,10,15,09,02,06,08,00,13,03,04,14,07,05,11
DATA 10,15,04,02,07,12,09,05,06,01,13,14,00,11,03,08
DATA 09,14,15,05,02,08,12,03,07,00,04,10,01,13,11,06
DATA 04,03,02,12,09,05,15,10,11,14,01,07,06,00,08,13
DATA 04,11,02,14,15,00,08,13,03,12,09,07,05,10,06,01
DATA 13,00,11,07,04,09,01,10,14,03,05,12,02,15,08,06
DATA 01,04,11,13,12,03,07,14,10,15,06,08,00,05,09,02
DATA 06,11,13,08,01,04,10,07,09,05,00,15,14,02,03,12
DATA 13,02,08,04,06,15,11,01,10,09,03,14,05,00,12,07
DATA 01,15,13,08,10,03,07,04,12,05,06,11,00,14,09,02
DATA 07,11,04,01,09,12,14,02,00,06,10,13,15,03,05,08
DATA 02,01,14,07,04,10,08,13,15,12,09,00,03,05,06,11
rotsl:
DATA 1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1
SUB btos (mbits() AS INTEGER, a$)
a$ = ""
FOR i% = 1 TO 8
w% = 0
FOR j% = 1 TO 8
w% = w% + ((mbits(((i% - 1) * 8) + j%)) * (2 ^ (8 - j%)))
NEXT j%
a$ = a$ + CHR$(w%)
NEXT i%
END SUB
FUNCTION desalg$ (a$)
temp$ = ""
stob a$, ades()
transpose ades(), InitialTr(), 64
FOR i% = 1 TO 16
letbe bdes(), ades(), 64
FOR j% = 1 TO 32
ades(j%) = bdes(j% + 32)
NEXT j%
f i%, ades(), xdes()
FOR j% = 1 TO 32
ades(j% + 32) = (bdes(j%) + xdes(j%)) MOD 2
Продолжение листинга 18.3
NEXT j%
NEXT i%
transpose ades(), swappy(), 64
transpose ades(), FinalTr(), 64
btos ades(), temp$
desalg$ = temp$
END FUNCTION
SUB f (i%, a() AS INTEGER, x() AS INTEGER)
h% = i%: letbe EF(), a(), 64
transpose EF(), etr(), 48
FOR j% = 1 TO rots(h%)
mrotate P2()
NEXT j%
letbe ikeyf(), P2(), 64: transpose ikeyf(), KeyTr2(), 48
FOR j% = 1 TO 48
yf(j%) = (EF(j%) + ikeyf(j%)) MOD 2
NEXT j%
FOR k% = 1 TO 8
k6% = 6 * k%: k4% = 4 * k%
r% = (32 * yf(k6% - 5)) + (16 * yf(k6%)) + (8 * yf(k6% - 4)) + (4 * yf(k6% - 3)) + (2 * yf(k6% - 2)) + yf(k6% - 1) + 1
x(k4% - 3) = (s(k%, r%) \ 8) MOD 2: x(k4% - 2) = (s(k%, r%) \ 4) MOD 2
x(k4% - 1) = (s(k%, r%) \ 2) MOD 2: x(k4%) = s(k%, r%) MOD 2
NEXT k%
transpose x(), ptr(), 32
END SUB
SUB init (x() AS INTEGER, n%)
FOR i% = 1 TO n%
READ x(i%)
NEXT i%
END SUB
SUB letbe (target() AS INTEGER, source() AS INTEGER, LAST%)
FOR i% = 1 TO LAST%
target(i%) = source(i%)
NEXT i%
END SUB
Продолжение листинга 18.3
FUNCTION MYBIN$ (n%)
LOCAL ST$
p% = n%
ST$=""
FOR i% = 1 TO 8
IF (p% MOD 2) THEN
ST$ = "1" + ST$
ELSE
ST$ = "0" + ST$
END IF
p% = p% \ 2
NEXT i%
MYBIN$ = ST$
END FUNCTION
SUB mrotate (keyr() AS INTEGER)
letbe XR(), keyr(), 56
FOR i% = 1 TO 55
XR(i%) = XR(i% + 1)
NEXT i%
XR(28) = keyr(1): XR(56) = keyr(29)
letbe keyr(), XR(), 56
END SUB
SUB sboxinit (b() AS INTEGER)
RESTORE sboxesl
FOR i% = 1 TO 8
FOR j% = 1 TO 64
READ b(i%, j%)
NEXT j%
NEXT i%
END SUB
SUB stob (a$, mbits() AS INTEGER)
FOR i% = 1 TO 8
b$ = MYBIN$(ASC(MID$(a$, i%, 1)))
FOR j% = 1 TO 8
mbits(((i% - 1) * 8) + j%) = ASC(MID$(b$, j%, 1)) - 48
NEXT j%
NEXT i%
END SUB
Продолжение листинга 18.3
SUB transpose (datax() AS INTEGER, T() AS INTEGER, n%)
letbe XT(), datax(), 64
FOR i% = 1 TO n%
datax(i%) = XT(T(i%))
NEXT i%
END SUB
SUB xtob (a$, mbits() AS INTEGER)
LOCAL X$,NIBBLE$
FOR i% = 1 to 16
X$ = MID$(a$,i%,1)
SELECT CASE X$
CASE "0"
NIBBLE$ = "0000"
CASE "1"
NIBBLE$ = "0001"
CASE "2"
NIBBLE$ = "0010"
CASE "3"
NIBBLE$ = "0011"
CASE "4"
NIBBLE$ = "0100"
CASE "5"
NIBBLE$ = "0101"
CASE "6"
NIBBLE$ = "0110"
CASE "7"
NIBBLE$ = "0111"
CASE "8"
NIBBLE$ = "1000"
CASE "9"
NIBBLE$ = "1001"
CASE "A"
NIBBLE$ = "1010"
CASE "B"
NIBBLE$ = "1011"
CASE "C"
NIBBLE$ = "1100"
CASE "D"
NIBBLE$ = "1101"
CASE "E"
Окончание листинга 18.3
NIBBLE$ = "1110"
CASE "F"
NIBBLE$ = "1111"
CASE ELSE
Print "Не является 16-ричным значением!"
SYSTEM
END SELECT
FOR j% = 1 to 4
mbits(((i% - 1) * 4) + j%) = ASC(MID$(NIBBLE$, j%, 1)) - 48
NEXT j%
NEXT i%
END SUB
Листинг 18.4. Пример реализации алгоритма
DES на языке Basic для расшифровывания файлов
$CPU 80386
$FLOAT NPX
$OPTIMIZE SPEED
$LIB ALL-
$OPTION CNTLBREAK ON
DECLARE FUNCTION MYBIN$ (n%)
DECLARE FUNCTION desalg$ (a$)
DECLARE SUB f (i%, a%(), x%())
DECLARE SUB transpose (datax%(), T%(), n%)
DECLARE SUB mrotate (keyx%())
DECLARE SUB stob (a$, mbits%())
DECLARE SUB btos (mbits%(), a$)
DECLARE SUB letbe (target%(), source%(), last%)
DECLARE SUB init (x() AS INTEGER, n%)
DECLARE SUB sboxinit (b() AS INTEGER)
DECLARE SUB xtob (a$, mbits%())
DIM s(1 TO 8, 1 TO 64) AS shared INTEGER
' Инициализация
RESTORE InitialTrl
Продолжение листинга 18.4
DIM InitialTr(1 TO 64) AS shared INTEGER
init InitialTr(), 64
RESTORE FinalTrl
DIM FinalTr(1 TO 64) AS shared INTEGER
init FinalTr(), 64
RESTORE swappyl
DIM swappy(1 TO 64) AS shared INTEGER
init swappy(), 64
RESTORE KeyTr1l
DIM KeyTr1(1 TO 56) AS shared INTEGER
init KeyTr1(), 56
RESTORE KeyTr2l
DIM KeyTr2(1 TO 48) AS shared INTEGER
init KeyTr2(), 48
RESTORE etrl
DIM etr(1 TO 48) AS shared INTEGER
init etr(), 48
RESTORE ptrl
DIM ptr(1 TO 32) AS shared INTEGER
init ptr(), 32
sboxinit s()
RESTORE rotsl
DIM rots(1 TO 16) AS shared INTEGER
init rots(), 16
DIM XR(1 TO 56) AS shared INTEGER
DIM EF(1 TO 64) AS shared INTEGER
DIM ikeyf(1 TO 64) AS shared INTEGER
DIM yf(1 TO 64) AS shared INTEGER
DIM ades(1 TO 64) AS shared INTEGER
DIM bdes(1 TO 64) AS shared INTEGER
Продолжение листинга 18.4
DIM xdes(1 TO 64) AS shared INTEGER
DIM XT(1 TO 64) AS shared INTEGER
DIM P2(1 TO 64) AS shared INTEGER
main:
CLS
parm$ = ltrim$(rtrim$(COMMAND$))+" "
IF LEN(parm$) > 1 THEN
cipherf$ = LTRIM$(RTRIM$(LEFT$(parm$, INSTR(parm$, " "))))
PRINT "Имя зашифрованного файла : "; cipherf$
ELSE
INPUT "Имя расшифрованного файла : ", cipherf$
END IF
if len(cipherf$)=0 then
print : print "СБОЙ: введите имя файла!"
system
end if
OPEN cipherf$ FOR RANDOM AS 1
lof1& = LOF(1)
IF lof1& = 0 THEN
CLOSE #1
KILL cipherf$
PRINT : PRINT "Файл не найден!";
SYSTEM
ELSE
CLOSE #1
OPEN cipherf$ for binary access read as #1
END IF
PW$ = ""
LOCATE 6, 1
INPUT " Пароль : ", PW$
IF (LEN(PW$) < 8) THEN PW$ = PW$ + STRING$(8 - LEN(PW$), 0)
IF len(pw$) = 16 then
LOCATE 6, 1: PRINT " Пароль : ";
STRING$(16, 15); STRING$(10, " ")
Продолжение листинга 18.4
PW$ = ucase$(PW$)
xtob PW$, P2()
ELSE
LOCATE 6, 1: PRINT " Пароль : ";
STRING$(8, 15); STRING$(10, " ")
PW$ = LEFT$(PW$, 8)
stob PW$, P2()
END IF
PRINT " Проверка пароля : ";
transpose P2(), KeyTr1(), 56
get$ #1,24,cheader$
header$ = desalg$(LEFT$(cheader$, 8))
IF NOT (LEFT$(header$, 3) = "DES") THEN
PRINT "Неверен!": PRINT : PRINT "Неправильный пароль или ";
cipherf$; " не является зашифрованным файлом!"
SYSTEM
ELSE
PRINT "Верен!"
END IF
PRINT " Проверка длины файла :";
header$ = header$ + desalg$(MID$(cheader$, 9, 8))
header$ = header$ + desalg$(RIGHT$(cheader$, 8))
pl% = INSTR(header$, "#")
le$ = MID$(header$, pl% + 1, (11 - pl%))
lf& = VAL(le$)
ev& = lf& + 24
IF (ev& MOD 8) THEN ev& = ev& + 8 - (ev& MOD 8)
rescue% = 0
IF (ev& <> lof1&) THEN
PRINT "Неверна!! (возможна потеря данных)"
PRINT " Длина исходного файла :"; lf&
PRINT " Длина указанного файла :"; lof1&
PRINT " Длина файла должна быть :"; ev&
INPUT ; "Попытаться восстановить? (y/n) : ", q$:
IF (INSTR(q$, "N") OR (INSTR(q$, "n"))) THEN SYSTEM
rescue% = 4: PRINT
ELSE
PRINT lf&; ", Верна!"
END IF
Продолжение листинга 18.4
pl% = INSTR(12, header$, "#")
oldplainf$ = RIGHT$(header$, 24 - pl%)
PRINT " Имя исходного файла : "; oldplainf$;
OPEN oldplainf$ FOR RANDOM AS 2
IF INSTR(oldplainf$, ".") THEN
PRINT " ([*.*] ";
ELSE
PRINT " ([*] ";
END IF
IF LOF(2) > 0 THEN PRINT "уже есть в каталоге";
PRINT ")"
CLOSE #2
plainf$ = ""
INPUT " Имя выходного файла : ", plainf$
IF plainf$ = "" THEN plainf$ = oldplainf$
plainf$ = RTRIM$(LTRIM$(plainf$))
IF INSTR(plainf$, "*.") THEN
IF INSTR(oldplainf$, ".") THEN
plainf$ = LEFT$(plainf$, INSTR(plainf$, "*.") - 1) + LEFT$(oldplainf$, INSTR(oldplainf$, ".")) + RIGHT$(plainf$, LEN(plainf$) - INSTR(plainf$, "*.") - 1)
ELSE
plainf$ = LEFT$(plainf$, INSTR(plainf$, "*.") - 1) + oldplainf$ + RIGHT$(plainf$, LEN(plainf$) - INSTR(plainf$, "*."))
END IF
END IF
IF (RIGHT$(plainf$, 1) = "*") THEN
IF plainf$ = "*" THEN
plainf$ = oldplainf$
ELSE
IF (MID$(plainf$, LEN(plainf$) - 1, 1) = ".") THEN
plainf$ = LEFT$(plainf$, INSTR(plainf$, ".") - 1) +
RIGHT$(oldplainf$, LEN(oldplainf$) -
INSTR(oldplainf$, ".") + 1)
ELSE
plainf$ = LEFT$(plainf$, LEN(plainf$) - 1) + oldplainf$
END IF
END IF
END IF
IF RIGHT$(plainf$, 1) = "\" THEN plainf$ = plainf$ + oldplainf$
Продолжение листинга 18.4
OPEN plainf$ FOR RANDOM AS 2
IF LOF(2) > 0 THEN
CLOSE #2
PRINT : PRINT "Уже есть файл с таким именем!"
SYSTEM
ELSE
CLOSE #2
OPEN plainf$ FOR BINARY AS 2
END IF
plaintekst$ = ""
blocks& = (LOF(1) \ 8) - 3
LOCATE rescue% + 11, 21: PRINT ; "Расшифровывание : 0 %";
bigblocks&=(blocks&-1) \ 32
large$=space$(256)
FOR m& = 1 TO bigblocks&
outblock$=""
get$ #1,256,large$
for o%=1 to 256 step 8
outblock$=outblock$+desalg$(mid$(large$,o%,8))
next
put$ #2,outblock$
LOCATE rescue% + 11, 32: PRINT ; USING "###"; (m& / (bigblocks&+1)) * 100;
next
FOR n& = (bigblocks&*32)+1 TO blocks& - 1
GET$ #1,8,ciphertekst$
plaintekst$ = desalg$(ciphertekst$)
PUT$ #2, plaintekst$
LOCATE rescue% + 11, 32: PRINT ; USING "###"; (n& / blocks&) * 100;
NEXT n&
get$ #1,8,ciphertekst$
if len(ciphertekst$) > 0 then
plaintekst$ = desalg$(ciphertekst$)
IF rescue% THEN
last$ = plaintekst$
ELSE
Продолжение листинга 18.4
last$ = LEFT$(plaintekst$, lf& + 32 - LOF(1))
END IF
IF LEN(last$) > 0 THEN
PUT$ #2, last$
END IF
end if
CLOSE
LOCATE 11 + rescue%, 32: PRINT "100 % готово": PRINT
IF rescue% THEN
PRINT " Попытайтесь другим способом расшифровать этот файл."
ELSE
PRINT "Расшифровывание по алгоритму DES завершено."
END IF
SYSTEM
' Данные и функции
InitialTrl:
DATA 58,50,42,34,26,18,10,02,60,52,44,36,28,20,12,04
DATA 62,54,46,38,30,22,14,06,64,56,48,40,32,24,16,08
DATA 57,49,41,33,25,17,09,01,59,51,43,35,27,19,11,03
DATA 61,53,45,37,29,21,13,05,63,55,47,39,31,23,15,07
FinalTrl:
DATA 40,08,48,16,56,24,64,32,39,07,47,15,55,23,63,31
DATA 38,06,46,14,54,22,62,30,37,05,45,13,53,21,61,29
DATA 36,04,44,12,52,20,60,28,35,03,43,11,51,19,59,27
DATA 34,02,42,10,50,18,58,26,33,01,41,09,49,17,57,25
swappyl:
DATA 33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48
DATA 49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64
DATA 01,02,03,04,05,06,07,08,09,10,11,12,13,14,15,16
DATA 17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32
KeyTr1l:
DATA 57,49,41,33,25,17,09,01,58,50,42,34,26,18,10,02
DATA 59,51,43,35,27,19,11,03,60,52,44,36
DATA 63,55,47,39,31,23,15,07,62,54,46,38,30,22,14,06
DATA 61,53,45,37,29,21,13,05,28,20,12,04
Продолжение листинга 18.4
KeyTr2l:
DATA 14,17,11,24,01,05,03,28,15,06,21,10,23,19,12,04
DATA 26,08,16,07,27,20,13,02,41,52,31,37,47,55,30,40
DATA 51,45,33,48,44,49,39,56,34,53,46,42,50,36,29,32
etrl:
DATA 32,01,02,03,04,05,04,05,06,07,08,09,08,09,10,11
DATA 12,13,12,13,14,15,16,17,16,17,18,19,20,21,20,21
DATA 22,23,24,25,24,25,26,27,28,29,28,29,30,31,32,01
ptrl:
DATA 16,07,20,21,29,12,28,17,01,15,23,26,05,18,31,10
DATA 02,08,24,14,32,27,03,09,19,13,30,06,22,11,04,25
sboxesl:
DATA 14,04,13,01,02,15,11,08,03,10,06,12,05,09,00,07
DATA 00,15,07,04,14,02,13,01,10,06,12,11,09,05,03,08
DATA 04,01,14,08,13,06,02,11,15,12,09,07,03,10,05,00
DATA 15,12,08,02,04,09,01,07,05,11,03,14,10,00,06,13
DATA 15,01,08,14,06,11,03,04,09,07,02,13,12,00,05,10
DATA 03,13,04,07,15,02,08,14,12,00,01,10,06,09,11,05
DATA 00,14,07,11,10,04,13,01,05,08,12,06,09,03,02,15
DATA 13,08,10,01,03,15,04,02,11,06,07,12,00,05,14,09
DATA 10,00,09,14,06,03,15,05,01,13,12,07,11,04,02,08
DATA 13,07,00,09,03,04,06,10,02,08,05,14,12,11,15,01
DATA 13,06,04,09,08,15,03,00,11,01,02,12,05,10,14,07
DATA 01,10,13,00,06,09,08,07,04,15,14,03,11,05,02,12
DATA 07,13,14,03,00,06,09,10,01,02,08,05,11,12,04,15
DATA 13,08,11,05,06,15,00,03,04,07,02,12,01,10,14,09
DATA 10,06,09,00,12,11,07,13,15,01,03,14,05,02,08,04
DATA 03,15,00,06,10,01,13,08,09,04,05,11,12,07,02,14
DATA 02,12,04,01,07,10,11,06,08,05,03,15,13,00,14,09
DATA 14,11,02,12,04,07,13,01,05,00,15,10,03,09,08,06
DATA 04,02,01,11,10,13,07,08,15,09,12,05,06,03,00,14
DATA 11,08,12,07,01,14,02,13,06,15,00,09,10,04,05,03
Продолжение листинга 18.4
DATA 12,01,10,15,09,02,06,08,00,13,03,04,14,07,05,11
DATA 10,15,04,02,07,12,09,05,06,01,13,14,00,11,03,08
DATA 09,14,15,05,02,08,12,03,07,00,04,10,01,13,11,06
DATA 04,03,02,12,09,05,15,10,11,14,01,07,06,00,08,13
DATA 04,11,02,14,15,00,08,13,03,12,09,07,05,10,06,01
DATA 13,00,11,07,04,09,01,10,14,03,05,12,02,15,08,06
DATA 01,04,11,13,12,03,07,14,10,15,06,08,00,05,09,02
DATA 06,11,13,08,01,04,10,07,09,05,00,15,14,02,03,12
DATA 13,02,08,04,06,15,11,01,10,09,03,14,05,00,12,07
DATA 01,15,13,08,10,03,07,04,12,05,06,11,00,14,09,02
DATA 07,11,04,01,09,12,14,02,00,06,10,13,15,03,05,08
DATA 02,01,14,07,04,10,08,13,15,12,09,00,03,05,06,11
rotsl:
DATA 1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1
SUB btos (mbits() AS INTEGER, a$)
a$ = ""
FOR i% = 1 TO 8
w% = 0
FOR j% = 1 TO 8
w% = w% + ((mbits(((i% - 1) * 8) + j%)) * (2 ^ (8 - j%)))
NEXT j%
a$ = a$ + CHR$(w%)
NEXT i%
END SUB
FUNCTION desalg$ (a$)
temp$ = "": stob a$, ades()
transpose ades(), InitialTr(), 64
transpose ades(), swappy(), 64
FOR i% = 16 TO 1 STEP -1
letbe bdes(), ades(), 64
f i%, bdes(), xdes()
FOR j% = 1 TO 32
ades(j%) = (bdes(j% + 32) + xdes(j%)) MOD 2
NEXT j%
FOR j% = 33 TO 64
ades(j%) = bdes(j% - 32)
Продолжение листинга 18.4
NEXT j%
NEXT i%
transpose ades(), FinalTr(), 64
btos ades(), temp$
desalg$ = temp$
END FUNCTION
SUB f (i%, a() AS INTEGER, x() AS INTEGER)
h% = i%: letbe EF(), a(), 64
transpose EF(), etr(), 48
letbe ikeyf(), P2(), 64
transpose ikeyf(), KeyTr2(), 48
FOR j% = 1 TO rots(h%)
mrotate P2()
NEXT j%
FOR j% = 1 TO 48
yf(j%) = (EF(j%) + ikeyf(j%)) MOD 2
NEXT j%
FOR k% = 1 TO 8
k6% = 6 * k%: k4% = 4 * k%
r% = (32 * yf(k6% - 5)) + (16 * yf(k6%)) + (8 * yf(k6% - 4)) + (4 * yf(k6% - 3)) + (2 * yf(k6% - 2)) + yf(k6% - 1) + 1
x(k4% - 3) = (s(k%, r%) \ 8) MOD 2: x(k4% - 2) = (s(k%, r%) \ 4) MOD 2
x(k4% - 1) = (s(k%, r%) \ 2) MOD 2: x(k4%) = s(k%, r%) MOD 2
NEXT k%
transpose x(), ptr(), 32
END SUB
SUB init (x() AS INTEGER, n%)
FOR i% = 1 TO n%
READ x(i%)
NEXT i%
END SUB
SUB letbe (target() AS INTEGER, source() AS INTEGER, last%)
FOR il% = 1 TO last%
target(il%) = source(il%)
NEXT il%
END SUB
Продолжение листинга 18.4
FUNCTION MYBIN$ (n%)
STS$ = ""
p% = n%
FOR i% = 1 TO 8
IF (p% MOD 2) THEN
ST$ = "1" + ST$
ELSE
ST$ = "0" + ST$
END IF
p% = p% \ 2
NEXT i%
MYBIN$ = ST$
END FUNCTION
SUB mrotate (keyr() AS INTEGER)
letbe XR(), keyr(), 56
FOR ir% = 56 TO 2 STEP -1
XR(ir%) = XR(ir% - 1)
NEXT ir%
XR(1) = keyr(28): XR(29) = keyr(56)
letbe keyr(), XR(), 56
END SUB
SUB sboxinit (b() AS INTEGER)
RESTORE sboxesl
FOR i% = 1 TO 8
FOR j% = 1 TO 64
READ b(i%, j%)
NEXT j%
NEXT i%
END SUB
SUB stob (a$, mbits() AS INTEGER)
FOR i% = 1 TO 8
b$ = MYBIN$(ASC(MID$(a$, i%, 1)))
FOR j% = 1 TO 8
mbits(((i% - 1) * 8) + j%) = ASC(MID$(b$, j%, 1)) - 48
NEXT j%
NEXT i%
END SUB
Продолжение листинга 18.4
SUB transpose (datax() AS INTEGER, T() AS INTEGER, nt%)
letbe XT(), datax(), 64
FOR i% = 1 TO nt%
datax(i%) = XT(T(i%))
NEXT i%
END SUB
SUB xtob (a$, mbits() AS INTEGER)
LOCAL X$,NIBBLE$
FOR i% = 1 to 16
X$ = MID$(a$,i%,1)
SELECT CASE X$
CASE "0"
NIBBLE$ = "0000"
CASE "1"
NIBBLE$ = "0001"
CASE "2"
NIBBLE$ = "0010"
CASE "3"
NIBBLE$ = "0011"
CASE "4"
NIBBLE$ = "0100"
CASE "5"
NIBBLE$ = "0101"
CASE "6"
NIBBLE$ = "0110"
CASE "7"
NIBBLE$ = "0111"
CASE "8"
NIBBLE$ = "1000"
CASE "9"
NIBBLE$ = "1001"
CASE "A"
NIBBLE$ = "1010"
CASE "B"
NIBBLE$ = "1011"
CASE "C"
NIBBLE$ = "1100"
CASE "D"
NIBBLE$ = "1101"
CASE "E"
Окончание листинга 18.4
NIBBLE$ = "1110"
CASE "F"
NIBBLE$ = "1111"
CASE ELSE
Print "Не является 16-ричным значением!"
SYSTEM
END SELECT
FOR j% = 1 to 4
mbits(((i% - 1) * 4) + j%) = ASC(MID$(NIBBLE$, j%, 1)) - 48
NEXT j%
NEXT i%
END SUB
