#include <libsec.h>

#include "os.h"
#include <libsec.h>

void
setupRC4state(RC4state *key, uchar *start, int n)
{
int t;
int index2;
uchar *state;
uchar *p, *e, *sp, *se;

state = key->state;
se = &state[256];
for(sp = state; sp < se; sp++)
*sp = sp - state;

key->x = 0;
key->y = 0;
index2 = 0;
e = start + n;
p = start;
for(sp = state; sp < se; sp++)
{
t = *sp;
index2 = (*p + t + index2) & 255;
*sp = state[index2];
state[index2] = t;
if(++p >= e)
p = start;
}
}

void
rc4(RC4state *key, uchar *p, int len)
{
int tx, ty;
int x, y;
uchar *state;
uchar *e;

x = key->x;
y = key->y;
state = &key->state[0];
for(e = p + len; p < e; p++)
{
x = (x+1)&255;
tx = state[x];
y = (y+tx)&255;
ty = state[y];
state[x] = ty;
state[y] = tx;
*p ^= state[(tx+ty)&255];
}
key->x = x;
key->y = y;
}

void
rc4skip(RC4state *key, int len)
{
int tx, ty;
int x, y;
uchar *state;
int i;

x = key->x;
y = key->y;
state = &key->state[0];
for(i=0; i<len; i++)
{
x = (x+1)&255;
tx = state[x];
y = (y+tx)&255;
ty = state[y];
state[x] = ty;
state[y] = tx;
}
key->x = x;
key->y = y;
}

void
rc4back(RC4state *key, int len)
{
int tx, ty;
int x, y;
uchar *state;
int i;

x = key->x;
y = key->y;
state = &key->state[0];
for(i=0; i<len; i++)
{
ty = state[x];
tx = state[y];
state[y] = ty;
state[x] = tx;
y = (y-tx)&255;
x = (x-1)&255;
}
key->x = x;
key->y = y;
}