47 lines
1.1 KiB
C
47 lines
1.1 KiB
C
#include <stdint.h>
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#include "scramble.h"
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void scramble(uint8_t *in, uint8_t *out, const int size)
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{
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/* table extracted from bootrom */
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static const uint8_t key[] = {
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0x7C, 0x4E, 0x03, 0x04,
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0x55, 0x05, 0x09, 0x07,
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0x2D, 0x2C, 0x7B, 0x38,
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0x17, 0x0D, 0x17, 0x11
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};
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int i, i3, x, val, idx;
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uint8_t key1[0x100];
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uint8_t key2[0x100];
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for (i=0; i<0x100; i++) {
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key1[i] = i;
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key2[i] = key[i&0xf];
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}
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i3 = 0;
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for (i=0; i<0x100; i++) {
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x = key1[i];
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i3 = key1[i] + i3;
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i3 += key2[i];
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i3 &= 0xff;
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key1[i] = key1[i3];
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key1[i3] = x;
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}
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idx = 0;
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for (i=0; i<size; i++) {
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x = key1[(i+1) & 0xff];
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val = x;
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idx = (x + idx) & 0xff;
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key1[(i+1) & 0xff] = key1[idx];
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key1[idx] = (x & 0xff);
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val = (key1[(i+1)&0xff] + x) & 0xff;
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val = key1[val];
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out[i] = val ^ in[i];
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}
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}
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