35 lines
619 B
C
35 lines
619 B
C
#include "os.h"
|
|
#include <mp.h>
|
|
#include <libsec.h>
|
|
|
|
static uint8_t nine[32] = {9};
|
|
|
|
void
|
|
curve25519_dh_new(uint8_t x[32], uint8_t y[32])
|
|
{
|
|
uint8_t 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(uint8_t x[32], uint8_t y[32], uint8_t z[32])
|
|
{
|
|
/* remove the random bit */
|
|
y[31] &= 0x7f;
|
|
|
|
/* calculate dhx key */
|
|
curve25519(z, x, y);
|
|
|
|
memset(x, 0, 32);
|
|
memset(y, 0, 32);
|
|
}
|