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/******
GameSpy / GameMaster Utility Code
Copyright 1998 Critical Mass Communications, LLC.
Suite E-204
2900 Bristol Street
Costa Mesa, CA 92626
(714)549-7689
Fax(714)549-0757
see gsutils.h for documentation
******/
typedef unsigned char uchar;
static void swap_byte(uchar* a, uchar* b)
{
uchar swapByte;
swapByte = *a;
*a = *b;
*b = swapByte;
}
static uchar encode_ct(uchar c)
{
if (c < 26) return (uchar)('A' + c);
if (c < 52) return (uchar)('a' + c - 26);
if (c < 62) return (uchar)('0' + c - 52);
if (c == 62) return (uchar)('+');
if (c == 63) return (uchar)('/');
return 0;
}
void gs_encode(uchar* ins, int size, uchar* result)
{
int i, pos;
uchar trip[3];
uchar kwart[4];
i = 0;
while (i < size)
{
for (pos = 0; pos <= 2; pos++, i++)
if (i < size) trip[pos] = *ins++;
else trip[pos] = '\0';
kwart[0] = (unsigned char)((trip[0]) >> 2);
kwart[1] = (unsigned char)((((trip[0]) & 3) << 4) + ((trip[1]) >> 4));
kwart[2] = (unsigned char)((((trip[1]) & 15) << 2) + ((trip[2]) >> 6));
kwart[3] = (unsigned char)((trip[2]) & 63);
for (pos = 0; pos <= 3; pos++) *result++ = encode_ct(kwart[pos]);
}
*result = '\0';
}
void gs_encrypt(uchar* key, int key_len, uchar* buffer_ptr, int buffer_len)
{
int counter;
uchar x, y, xorIndex;
uchar state[256];
for (counter = 0; counter < 256; counter++) state[counter] = (uchar)counter;
x = 0; y = 0;
for (counter = 0; counter < 256; counter++)
{
y = (uchar)((key[x] + state[counter] + y) % 256);
x = (uchar)((x + 1) % key_len);
swap_byte(&state[counter], &state[y]);
}
x = 0; y = 0;
for (counter = 0; counter < buffer_len; counter++)
{
x = (uchar)((x + buffer_ptr[counter] + 1) % 256);
y = (uchar)((state[x] + y) % 256);
swap_byte(&state[x], &state[y]);
xorIndex = (uchar)((state[x] + state[y]) % 256);
buffer_ptr[counter] ^= state[xorIndex];
}
}
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