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

static uchar nine[32] = {9};

void
curve25519_dh_new(uchar x[32], uchar y[32])
{
       uchar b;

       /* new public/private key pair */
       genrandom(x, 32);
       b = x[31];
       x[0] &= ~7;                     /* clear bit 0,1,2 */
       x[31] = 0x40 | (b & 0x7f);      /* set bit 254, clear bit 255 */
       curve25519(y, x, nine);

       /* bit 255 is always 0, so make it random */
       y[31] |= b & 0x80;
}

void
curve25519_dh_finish(uchar x[32], uchar y[32], uchar z[32])
{
       /* remove the random bit */
       y[31] &= 0x7f;

       /* calculate dhx key */
       curve25519(z, x, y);

       memset(x, 0, 32);
       memset(y, 0, 32);
}