int
dh_gm_compute_key(PACE_CTX * ctx, const BUF_MEM * s, const BUF_MEM * in,
BN_CTX *bn_ctx)
{
int ret = 0;
BUF_MEM * mem_h = NULL;
BIGNUM * bn_s = NULL, *bn_h = NULL, *bn_g = NULL;
DH *static_key = NULL, *ephemeral_key = NULL;
check(ctx && ctx->static_key && s && ctx->ka_ctx, "Invalid arguments");
BN_CTX_start(bn_ctx);
static_key = EVP_PKEY_get1_DH(ctx->static_key);
if (!static_key)
goto err;
/* Convert nonce to BIGNUM */
bn_s = BN_bin2bn((unsigned char *) s->data, s->length, bn_s);
if (!bn_s)
goto err;
/* complete the DH and convert the result to a BIGNUM */
mem_h = dh_compute_key(ctx->static_key, in, bn_ctx);
if (!mem_h)
goto err;
bn_h = BN_bin2bn((unsigned char *) mem_h->data, mem_h->length, bn_h);
if (!bn_h)
goto err;
/* Initialize ephemeral parameters with parameters from the static key */
ephemeral_key = DHparams_dup_with_q(static_key);
if (!ephemeral_key)
goto err;
/* map to new generator */
bn_g = BN_CTX_get(bn_ctx);
if (!bn_g ||
/* bn_g = g^s mod p */
!BN_mod_exp(bn_g, static_key->g, bn_s, static_key->p, bn_ctx) ||
/* ephemeral_key->g = bn_g * h mod p = g^s * h mod p */
!BN_mod_mul(ephemeral_key->g, bn_g, bn_h, static_key->p, bn_ctx))
goto err;
/* Copy ephemeral key to context structure */
if (!EVP_PKEY_set1_DH(ctx->ka_ctx->key, ephemeral_key))
goto err;
ret = 1;
err:
if (mem_h) {
OPENSSL_cleanse(mem_h->data, mem_h->max);
BUF_MEM_free(mem_h);
}
if (bn_h)
BN_clear_free(bn_h);
if (bn_s)
BN_clear_free(bn_s);
/* Decrement reference count, keys are still available via PACE_CTX */
if (static_key)
DH_free(static_key);
if (ephemeral_key)
DH_free(ephemeral_key);
BN_CTX_end(bn_ctx);
return ret;
}
EVP_PKEY *
EVP_PKEY_dup(EVP_PKEY *key)
{
EVP_PKEY *out = NULL;
DH *dh_in = NULL, *dh_out = NULL;
EC_KEY *ec_in = NULL, *ec_out = NULL;
RSA *rsa_in = NULL, *rsa_out = NULL;
check(key, "Invalid arguments");
out = EVP_PKEY_new();
if (!out)
goto err;
switch (EVP_PKEY_base_id(key)) {
case EVP_PKEY_DH:
dh_in = EVP_PKEY_get1_DH(key);
if (!dh_in)
goto err;
dh_out = DHparams_dup_with_q(dh_in);
if (!dh_out)
goto err;
EVP_PKEY_set1_DH(out, dh_out);
DH_free(dh_out);
DH_free(dh_in);
break;
case EVP_PKEY_EC:
ec_in = EVP_PKEY_get1_EC_KEY(key);
if (!ec_in)
goto err;
ec_out = EC_KEY_dup(ec_in);
if (!ec_out)
goto err;
EVP_PKEY_set1_EC_KEY(out, ec_out);
EC_KEY_free(ec_out);
EC_KEY_free(ec_in);
break;
case EVP_PKEY_RSA:
rsa_in = EVP_PKEY_get1_RSA(key);
if (!rsa_in)
goto err;
rsa_out = RSAPrivateKey_dup(rsa_in);
if (!rsa_out)
goto err;
EVP_PKEY_set1_RSA(out, rsa_out);
RSA_free(rsa_out);
RSA_free(rsa_in);
break;
default:
log_err("Unknown protocol");
goto err;
}
return out;
err:
if (dh_in)
DH_free(dh_in);
if (ec_in)
EC_KEY_free(ec_in);
if (rsa_in)
RSA_free(rsa_in);
return NULL;
}
int
dh_im_compute_key(PACE_CTX * ctx, const BUF_MEM * s, const BUF_MEM * in,
BN_CTX *bn_ctx)
{
int ret = 0;
BUF_MEM * x_mem = NULL;
BIGNUM * x_bn = NULL, *a = NULL, *p_1 = NULL, *q = NULL;
DH *static_key = NULL, *ephemeral_key = NULL;
check((ctx && in && ctx->ka_ctx), "Invalid arguments");
if (in->length < (size_t) EVP_CIPHER_key_length(ctx->ka_ctx->cipher)
|| !ctx->static_key)
goto err;
BN_CTX_start(bn_ctx);
static_key = EVP_PKEY_get1_DH(ctx->static_key);
if (!static_key)
goto err;
/* Initialize ephemeral parameters with parameters from the static key */
ephemeral_key = DHparams_dup_with_q(static_key);
if (!ephemeral_key)
goto err;
/* Perform the actual mapping */
x_mem = cipher_no_pad(ctx->ka_ctx, NULL, in, s, 1);
if (!x_mem)
goto err;
x_bn = BN_bin2bn((unsigned char *) x_mem->data, x_mem->length, x_bn);
a = BN_CTX_get(bn_ctx);
q = DH_get_q(static_key, bn_ctx);
p_1 = BN_dup(static_key->p);
if (!x_bn || !a || !q || !p_1 ||
/* p_1 = p-1 */
!BN_sub_word(p_1, 1) ||
/* a = p-1 / q */
!BN_div(a, NULL, p_1, q, bn_ctx) ||
/* g~ = x^a mod p */
!BN_mod_exp(ephemeral_key->g, x_bn, a, static_key->p, bn_ctx))
goto err;
/* check if g~ != 1 */
check((!BN_is_one(ephemeral_key->g)), "Bad DH generator");
/* Copy ephemeral key to context structure */
if (!EVP_PKEY_set1_DH(ctx->ka_ctx->key, ephemeral_key))
goto err;
ret = 1;
err:
if (q)
BN_clear_free(q);
if (p_1)
BN_clear_free(p_1);
if (x_bn)
BN_clear_free(x_bn);
if (x_mem)
BUF_MEM_free(x_mem);
/* Decrement reference count, keys are still available via PACE_CTX */
if (static_key)
DH_free(static_key);
if (ephemeral_key)
DH_free(ephemeral_key);
BN_CTX_end(bn_ctx);
return ret;
}
