SilcBool silc_mp_modinv(SilcMPInt *inv, SilcMPInt *a, SilcMPInt *n)
{
int i;
SilcMPInt y;
SilcMPInt x;
ModInv g[3];
ModInv v[3];
/* init MP vars */
silc_mp_init(&y);
silc_mp_init(&x);
silc_mp_init(&v[0].x);
silc_mp_init(&v[1].x);
silc_mp_set_ui(&v[0].x, 0L); /* v(0) = 0 */
silc_mp_set_ui(&v[1].x, 1L); /* v(1) = 1 */
silc_mp_init(&v[2].x);
silc_mp_init(&g[0].x);
silc_mp_init(&g[1].x);
silc_mp_set(&g[0].x, n); /* g(0) = n */
silc_mp_set(&g[1].x, a); /* g(1) = a */
silc_mp_init(&g[2].x);
i = 1;
while(silc_mp_cmp_ui(&g[i].x, 0) != 0) {
silc_mp_div(&y, &g[minus1].x, &g[i].x); /* y = n / a */
silc_mp_mod(&g[plus1].x, &g[minus1].x, &g[i].x); /* remainder */
silc_mp_mul(&x, &y, &v[i].x);
silc_mp_set(&v[plus1].x, &v[minus1].x);
silc_mp_sub(&v[plus1].x, &v[plus1].x, &x);
i = plus1;
}
/* set the inverse */
silc_mp_set(inv, &v[minus1].x);
/* if inverse is negative, add n to inverse */
if (silc_mp_cmp_ui(inv, 0) < 0)
silc_mp_add(inv, inv, n);
/* clear the vars */
memset(&g, 0, sizeof(g));
memset(&v, 0, sizeof(v));
silc_mp_uninit(&y);
silc_mp_uninit(&x);
silc_mp_uninit(&g[0].x);
silc_mp_uninit(&g[1].x);
silc_mp_uninit(&g[2].x);
silc_mp_uninit(&v[0].x);
silc_mp_uninit(&v[1].x);
silc_mp_uninit(&v[2].x);
return TRUE;
}
void *silc_pkcs1_public_key_copy(void *public_key)
{
RsaPublicKey *key = public_key, *new_key;
new_key = silc_calloc(1, sizeof(*new_key));
if (!new_key)
return NULL;
silc_mp_init(&new_key->n);
silc_mp_init(&new_key->e);
silc_mp_set(&new_key->n, &key->n);
silc_mp_set(&new_key->e, &key->e);
new_key->bits = key->bits;
return new_key;
}
SilcBool silc_pkcs1_generate_key(SilcUInt32 keylen,
SilcRng rng,
void **ret_public_key,
void **ret_private_key)
{
SilcUInt32 prime_bits = keylen / 2;
SilcMPInt p, q;
SilcBool found = FALSE;
if (keylen < 768 || keylen > 16384)
return FALSE;
silc_mp_init(&p);
silc_mp_init(&q);
/* Find p and q */
while (!found) {
silc_math_gen_prime(&p, prime_bits, FALSE, rng);
silc_math_gen_prime(&q, prime_bits, FALSE, rng);
if ((silc_mp_cmp(&p, &q)) != 0)
found = TRUE;
}
/* If p is smaller than q, switch them */
if ((silc_mp_cmp(&p, &q)) > 0) {
SilcMPInt hlp;
silc_mp_init(&hlp);
silc_mp_set(&hlp, &p);
silc_mp_set(&p, &q);
silc_mp_set(&q, &hlp);
silc_mp_uninit(&hlp);
}
/* Generate the actual keys */
if (!silc_rsa_generate_keys(keylen, &p, &q, ret_public_key, ret_private_key))
return FALSE;
silc_mp_uninit(&p);
silc_mp_uninit(&q);
return TRUE;
}
void silc_mp_mp2bin_noalloc(SilcMPInt *val, unsigned char *dst,
SilcUInt32 dst_len)
{
int i;
SilcUInt32 size = dst_len;
SilcMPInt tmp;
silc_mp_init(&tmp);
silc_mp_set(&tmp, val);
for (i = size; i > 0; i--) {
dst[i - 1] = (unsigned char)(silc_mp_get_ui(&tmp) & 0xff);
silc_mp_div_2exp(&tmp, &tmp, 8);
}
silc_mp_uninit(&tmp);
}
SilcBool silc_rsa_generate_keys(SilcUInt32 bits, SilcMPInt *p, SilcMPInt *q,
void **ret_public_key, void **ret_private_key)
{
RsaPublicKey *pubkey;
RsaPrivateKey *privkey;
SilcMPInt phi, hlp;
SilcMPInt div, lcm;
SilcMPInt pm1, qm1;
*ret_public_key = pubkey = silc_calloc(1, sizeof(*pubkey));
if (!pubkey)
return FALSE;
*ret_private_key = privkey = silc_calloc(1, sizeof(*privkey));
if (!privkey)
return FALSE;
/* Default hash shall be sha1 */
silc_hash_alloc("sha1", &pubkey->hash);
silc_hash_alloc("sha1", &privkey->hash);
/* Initialize variables */
silc_mp_init(&privkey->n);
silc_mp_init(&privkey->e);
silc_mp_init(&privkey->d);
silc_mp_init(&privkey->dP);
silc_mp_init(&privkey->dQ);
silc_mp_init(&privkey->qP);
silc_mp_init(&phi);
silc_mp_init(&hlp);
silc_mp_init(&div);
silc_mp_init(&lcm);
silc_mp_init(&pm1);
silc_mp_init(&qm1);
/* Set modulus length */
privkey->bits = bits;
/* Compute modulus, n = p * q */
silc_mp_mul(&privkey->n, p, q);
/* phi = (p - 1) * (q - 1) */
silc_mp_sub_ui(&pm1, p, 1);
silc_mp_sub_ui(&qm1, q, 1);
silc_mp_mul(&phi, &pm1, &qm1);
/* Set e, the public exponent. We try to use same public exponent
for all keys. Also, to make encryption faster we use small
number. */
silc_mp_set_ui(&privkey->e, 65533);
retry_e:
/* See if e is relatively prime to phi. gcd == greates common divisor,
if gcd equals 1 they are relatively prime. */
silc_mp_gcd(&hlp, &privkey->e, &phi);
if ((silc_mp_cmp_ui(&hlp, 1)) > 0) {
silc_mp_add_ui(&privkey->e, &privkey->e, 2);
goto retry_e;
}
/* Find d, the private exponent, e ^ -1 mod lcm(phi). */
silc_mp_gcd(&div, &pm1, &qm1);
silc_mp_div(&lcm, &phi, &div);
silc_mp_modinv(&privkey->d, &privkey->e, &lcm);
/* Optimize d with CRT. */
silc_mp_mod(&privkey->dP, &privkey->d, &pm1);
silc_mp_mod(&privkey->dQ, &privkey->d, &qm1);
silc_mp_modinv(&privkey->qP, q, p);
silc_mp_set(&privkey->p, p);
silc_mp_set(&privkey->q, q);
silc_mp_uninit(&phi);
silc_mp_uninit(&hlp);
silc_mp_uninit(&div);
silc_mp_uninit(&lcm);
silc_mp_uninit(&pm1);
silc_mp_uninit(&qm1);
/* Set public key */
silc_mp_init(&pubkey->n);
silc_mp_init(&pubkey->e);
pubkey->bits = privkey->bits;
silc_mp_set(&pubkey->n, &privkey->n);
silc_mp_set(&pubkey->e, &privkey->e);
return TRUE;
}
