Subversion Repositories planix.SVN

#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);
}