DATA 20, 21 ,22, 23, 16, 17, 18, 19
DATA 28, 29, 30, 31, 24, 25, 26, 27
DATA  4,  5,  6,  7,  0,  1,  2,  3
DATA 12, 13, 14, 15,  8,  9, 10 ,11

DIM cod(32)

FOR i = 0 TO 31
 READ cod(i)
NEXT i


DATA &HA5, &HA5, &HA5, &HA5, &HA1, &HA1, &HA1, &HA1, &HA5, &HA5, &HA5, &HA5, &HA1, &HA1, &HA1, &HA1
DATA &HB5, &HB5, &HB5, &HB5, &HB1, &HB1, &HB1, &HB1, &HB5, &HB5, &HB5, &HB5, &HB1, &HB1, &HB1, &HB1
DATA &HA5, &HA5, &HA5, &HA5, &HA1, &HA1, &HA1, &HA1, &HA5, &HA5, &HA5, &HA5, &HA1, &HA1, &HA1, &HA1
DATA &HB5, &HB5, &HB5, &HB5, &HB1, &HB1, &HB1, &HB1, &HB5, &HB5, &HB5, &HB5, &HB1, &HB1, &HB1, &HB1
DATA &HE5, &HE5, &HE5, &HE5, &HE1, &HE1, &HE1, &HE1, &HE5, &HE5, &HE5, &HE5, &HE1, &HE1, &HE1, &HE1
DATA &HF5, &HF5, &HF5, &HF5, &HF1, &HF1, &HF1, &HF1, &HF5, &HF5, &HF5, &HF5, &HF1, &HF1, &HF1, &HF1
DATA &HE5, &HE5, &HE5, &HE5, &HE1, &HE1, &HE1, &HE1, &HE5, &HE5, &HE5, &HE5, &HE1, &HE1, &HE1, &HE1
DATA &HF5, &HF5, &HF5, &HF5, &HF1, &HF1, &HF1, &HF1, &HF5, &HF5, &HF5, &HF5, &HF1, &HF1, &HF1, &HF1

DIM var(128)

FOR i = 0 TO 127
 READ var(i)
NEXT i


10

INPUT "Use decoding method 1 (XOR 0xA5) or 2 (128 byte key)? ", ans
IF ans = 1 GOTO 100
IF ans = 2 GOTO 200
GOTO 10

REM Normal encoding / decoding:

REM 1. xor everything with 0xA5
REM 2. in blocks of 8 bytes swap the 1st 4 bytes with the last 4 bytes
REM 3. in blocks of 32 bytes swap the 1st 16 bytes with the last 16 bytes

100

OPEN "dvdrom.bin" FOR RANDOM AS #1 LEN = 32
OPEN "_dvdrom.bin" FOR OUTPUT AS #2

FIELD #1, 32 AS block$

DIM temp$(32)


WHILE NOT EOF(1)

GET #1

 IF EOF(1) THEN GOTO 150

 FOR i = 0 TO 31
  temp$(i) = MID$(block$, i + 1, 1)
 NEXT i

 FOR i = 0 TO 31
  dat$ = CHR$(&HA5 XOR ASC(temp$(cod(i))))
  PRINT #2, dat$;
 NEXT i

150 WEND

CLOSE
END


REM But Hyundai DVX-&HB152U firmware it's different, and ditto for
REM Evertone DVX-511S / DVX-510S, Denver DVU1008MK2

REM xor everything with 128 byte key

200

idx = 0

OPEN "dvdrom.bin" FOR RANDOM AS #1 LEN = 1
OPEN "_dvdrom.bin" FOR OUTPUT AS #2

FIELD #1, 1 AS A$

WHILE NOT EOF(1)

 GET #1
 IF EOF(1) THEN GOTO 250
 PRINT #2, CHR$(var(idx) XOR ASC(A$));
 idx = (idx + 1) MOD 128

250 WEND

CLOSE
END