static int dss_pubkey_bits(void *blob, int len)
{
struct dss_key *dss;
int ret;
dss = dss_newkey((char *) blob, len);
ret = bignum_bitcount(dss->p);
dss_freekey(dss);
return ret;
}
static void *dss_createkey(unsigned char *pub_blob, int pub_len, unsigned char *priv_blob, int priv_len)
{
dss_key *dss;
char *pb = (char *) priv_blob;
char *hash;
int hashlen;
SHA_State s;
unsigned char digest[20];
Bignum ytest;
dss = dss_newkey((char *) pub_blob, pub_len);
if (!dss)
return NULL;
dss->x = getmp(&pb, &priv_len);
if (!dss->x) {
dss_freekey(dss);
return NULL;
}
/*
* Check the obsolete hash in the old DSS key format.
*/
hashlen = -1;
getstring(&pb, &priv_len, &hash, &hashlen);
if (hashlen == 20)
{
SHA_Init(&s);
sha_mpint(&s, dss->p);
sha_mpint(&s, dss->q);
sha_mpint(&s, dss->g);
SHA_Final(&s, digest);
if (0 != memcmp(hash, digest, 20))
{
dss_freekey(dss);
return NULL;
}
}
/*
* Now ensure g^x mod p really is y.
*/
ytest = modpow(dss->g, dss->x, dss->p);
if (0 != bignum_cmp(ytest, dss->y))
{
dss_freekey(dss);
freebn(ytest);
return NULL;
}
freebn(ytest);
return dss;
}
