#include <arc4.h>

#define I s[256]
#define J s[257]

void arc4_init(ARC4_STATE *a __attribute__((__unused__)))
{
}

void arc4_setkey(ARC4_STATE *a, const void *key, unsigned int keylen, unsigned int n_discard)
{
 unsigned char *s;
 int i;
 int j;
 int k;
 unsigned char t;

 j = 0;
 k = 0;
 s = &a->s[0];
 for (i=0;i<256;i++) s[i] = i;
 for (i=0;i<256;i++)
  { if (k >= keylen) k = 0;
    j = (j + s[i] + ((const unsigned char *)key)[k++]) & 0xff;
    t = s[i];
    s[i] = s[j];
    s[j] = t;
  }
 i = 0;
 j = 0;
 for (k=n_discard;k>0;k--)
  { i = (i + 1) & 0xff;
    t = s[i];
    j = (j + t) & 0xff;
    if (i != j)
     { s[i] = s[j];
       s[j] = t;
     }
  }
 I = i;
 J = j;
}

void arc4_crypt(ARC4_STATE *a, const void *in, unsigned int len, void *out)
{
 const unsigned char *ip;
 unsigned char *op;
 unsigned char *s;
 unsigned char t1;
 unsigned char t2;
 int i;
 int j;

 ip = in;
 op = out;
 s = a->s;
 i = I;
 j = J;
 while (len > 0)
  { for (;len>0;len--)
     { i = (i + 1) & 0xff;
       t1 = s[i];
       j = (j + t1) & 0xff;
       t2 = s[j];
       s[i] = t2;
       s[j] = t1;
       *op++ = *ip++ ^ s[(t1+t2)&0xff];
     }
  }
 I = i;
 J = j;
}