read_mpbin(&a, secret, secretlen);
- mpz_powm(&b, &st->g, &a, &st->p);
+ mpz_powm_sec(&b, &st->g, &a, &st->p);
r=write_mpstring(&b);
return r;
}
+static void write_mpbin_anomalous(MP_INT *a, uint8_t *buffer,
+ int32_t buflen)
+ /* If the BN is smaller than buflen, pads it *at the wrong end* */
+{
+ char *hb = write_mpstring(a);
+ int32_t len;
+ hex_decode(buffer, buflen, &len, hb, True);
+ if (len<buflen)
+ memset(buffer+len,0,buflen-len);
+ free(hb);
+}
+
static dh_makeshared_fn dh_makeshared;
static void dh_makeshared(void *sst, uint8_t *secret, int32_t secretlen,
cstring_t rempublic, uint8_t *sharedsecret,
read_mpbin(&a, secret, secretlen);
mpz_set_str(&b, rempublic, 16);
- mpz_powm(&c, &b, &a, &st->p);
+ mpz_powm_sec(&c, &b, &a, &st->p);
- write_mpbin(&c,sharedsecret,buflen);
+ write_mpbin_anomalous(&c,sharedsecret,buflen);
mpz_clear(&a);
mpz_clear(&b);