diff options
Diffstat (limited to 'utils/rk27utils/rk27load/scramble.c')
-rw-r--r-- | utils/rk27utils/rk27load/scramble.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/utils/rk27utils/rk27load/scramble.c b/utils/rk27utils/rk27load/scramble.c new file mode 100644 index 0000000000..7e5b1518d7 --- /dev/null +++ b/utils/rk27utils/rk27load/scramble.c | |||
@@ -0,0 +1,46 @@ | |||
1 | #include <stdint.h> | ||
2 | #include "scramble.h" | ||
3 | |||
4 | void scramble(uint8_t *in, uint8_t *out, const int size) | ||
5 | { | ||
6 | /* table extracted from bootrom */ | ||
7 | static const uint8_t key[] = { | ||
8 | 0x7C, 0x4E, 0x03, 0x04, | ||
9 | 0x55, 0x05, 0x09, 0x07, | ||
10 | 0x2D, 0x2C, 0x7B, 0x38, | ||
11 | 0x17, 0x0D, 0x17, 0x11 | ||
12 | }; | ||
13 | |||
14 | int i, i3, x, val, idx; | ||
15 | |||
16 | uint8_t key1[0x100]; | ||
17 | uint8_t key2[0x100]; | ||
18 | |||
19 | for (i=0; i<0x100; i++) { | ||
20 | key1[i] = i; | ||
21 | key2[i] = key[i&0xf]; | ||
22 | } | ||
23 | |||
24 | i3 = 0; | ||
25 | for (i=0; i<0x100; i++) { | ||
26 | x = key1[i]; | ||
27 | i3 = key1[i] + i3; | ||
28 | i3 += key2[i]; | ||
29 | i3 &= 0xff; | ||
30 | key1[i] = key1[i3]; | ||
31 | key1[i3] = x; | ||
32 | } | ||
33 | |||
34 | idx = 0; | ||
35 | for (i=0; i<size; i++) { | ||
36 | x = key1[(i+1) & 0xff]; | ||
37 | val = x; | ||
38 | idx = (x + idx) & 0xff; | ||
39 | key1[(i+1) & 0xff] = key1[idx]; | ||
40 | key1[idx] = (x & 0xff); | ||
41 | val = (key1[(i+1)&0xff] + x) & 0xff; | ||
42 | val = key1[val]; | ||
43 | out[i] = val ^ in[i]; | ||
44 | } | ||
45 | } | ||
46 | |||