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bacnet-stack/ports/linux/bacsec_linux.c

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/**************************************************************************
*
* Copyright (C) 2015 Nikola Jelic <nikola.jelic@euroicc.com>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*********************************************************************/
#include "bacsec.h"
#include <string.h>
#include <time.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#define TMP_BUF_LEN 2048
/* structures for keys - we use existing structures */
BACNET_KEY_ENTRY master_key;
BACNET_UPDATE_DISTRIBUTION_KEY distribution_key;
BACNET_UPDATE_KEY_SET key_sets;
static bool rand_set = false;
static HMAC_CTX hmac_ctx;
static EVP_CIPHER_CTX evp_ctx;
static uint8_t tmp_buf[TMP_BUF_LEN];
static uint16_t next_mult_of_16(uint16_t arg)
{
if ((arg & 0xF) == 0)
return arg;
else
return ((arg >> 4) + 1) << 4;
}
/* signing/verification and encryption/decryption - port specific */
int key_sign_msg(BACNET_KEY_ENTRY * key,
uint8_t * msg,
uint32_t msg_len,
uint8_t * signature)
{
uint8_t full_signature[32]; /* longest case */
HMAC_CTX_init(&hmac_ctx);
switch (key_algorithm(key->key_identifier)) {
case KIA_AES_MD5:
HMAC_Init_ex(&hmac_ctx, &key->key[16], 16, EVP_md5(), NULL);
break;
case KIA_AES_SHA256:
HMAC_Init_ex(&hmac_ctx, &key->key[16], 32, EVP_sha256(), NULL);
break;
default:
return -1;
}
HMAC_Update(&hmac_ctx, msg, msg_len);
HMAC_Final(&hmac_ctx, full_signature, NULL); /* we ignore the signature size */
HMAC_CTX_cleanup(&hmac_ctx);
memcpy(signature, full_signature, SIGNATURE_LEN);
return 0;
}
bool key_verify_sign_msg(BACNET_KEY_ENTRY * key,
uint8_t * msg,
uint32_t msg_len,
uint8_t * signature)
{
uint8_t full_signature[32]; /* longest case */
HMAC_CTX_init(&hmac_ctx);
switch (key_algorithm(key->key_identifier)) {
case KIA_AES_MD5:
HMAC_Init_ex(&hmac_ctx, &key->key[16], 16, EVP_md5(), NULL);
break;
case KIA_AES_SHA256:
HMAC_Init_ex(&hmac_ctx, &key->key[16], 32, EVP_sha256(), NULL);
break;
default:
return false;
}
HMAC_Update(&hmac_ctx, msg, msg_len);
HMAC_Final(&hmac_ctx, full_signature, NULL); /* we ignore the signature size */
HMAC_CTX_cleanup(&hmac_ctx);
return (memcmp(signature, full_signature,
SIGNATURE_LEN) == 0 ? true : false);
}
int key_encrypt_msg(BACNET_KEY_ENTRY * key,
uint8_t * msg,
uint32_t msg_len,
uint8_t * signature)
{
int outlen, outlen2;
switch (key_algorithm(key->key_identifier)) {
case KIA_AES_MD5:
case KIA_AES_SHA256:
EVP_EncryptInit_ex(&evp_ctx, EVP_aes_128_cbc(), NULL, key->key,
signature);
break;
default:
return -1;
}
EVP_EncryptUpdate(&evp_ctx, tmp_buf, &outlen, msg, msg_len);
EVP_EncryptFinal(&evp_ctx, &msg[outlen], &outlen2);
EVP_CIPHER_CTX_cleanup(&evp_ctx);
if (outlen2 != 0)
return -1;
memcpy(msg, tmp_buf, msg_len);
return 0;
}
bool key_decrypt_msg(BACNET_KEY_ENTRY * key,
uint8_t * msg,
uint32_t msg_len,
uint8_t * signature)
{
int outlen, outlen2;
switch (key_algorithm(key->key_identifier)) {
case KIA_AES_MD5:
case KIA_AES_SHA256:
EVP_DecryptInit_ex(&evp_ctx, EVP_aes_128_cbc(), NULL, key->key,
signature);
break;
default:
return false;
}
if (EVP_DecryptUpdate(&evp_ctx, tmp_buf, &outlen, msg, msg_len) == 0)
return false;
if (EVP_DecryptFinal(&evp_ctx, &msg[outlen], &outlen2) == 0)
return false;
EVP_CIPHER_CTX_cleanup(&evp_ctx);
if (outlen2 != 0)
return false;
memcpy(msg, tmp_buf, msg_len);
return true;
}
void key_set_padding(BACNET_KEY_ENTRY * key,
int enc_len,
uint16_t * padding_len,
uint8_t * padding)
{
/* in the future, we should check for the block size, but for now it is always 16 */
int i;
uint16_t padlen = next_mult_of_16(enc_len + 2);
(void) key;
(void) padding_len;
if (!rand_set) {
srand(time(NULL));
rand_set = true;
}
if (padlen > 2)
for (i = 0; i < padlen - 2; i++)
padding[i] = rand();
}
BACNET_SECURITY_RESPONSE_CODE bacnet_master_key_set(BACNET_SET_MASTER_KEY *
key)
{
memcpy(&master_key, &key->key, sizeof(BACNET_KEY_ENTRY));
return SEC_RESP_SUCCESS;
}
BACNET_SECURITY_RESPONSE_CODE
bacnet_distribution_key_update(BACNET_UPDATE_DISTRIBUTION_KEY * key)
{
memcpy(&distribution_key, key, sizeof(BACNET_KEY_ENTRY));
return SEC_RESP_SUCCESS;
}
BACNET_SECURITY_RESPONSE_CODE bacnet_key_set_update(BACNET_UPDATE_KEY_SET *
update_key_sets)
{
int i, j, k, l;
bool found;
for (i = 0; i < 2; i++) {
if (update_key_sets->set_rae[i]) {
found = false;
/* try with a valid set */
for (j = 0; j < 2; j++)
if ((key_sets.set_key_revision[j] ==
update_key_sets->set_key_revision[i]) &&
key_sets.set_rae[j]) {
found = true;
break;
}
/* try with an empty set */
if (!found) {
for (j = 0; j < 2; j++)
if (!key_sets.set_rae[j]) {
found = true;
break;
}
}
/* failure */
if (!found)
return -SEC_RESP_UNKNOWN_KEY_REVISION;
/* just in case we're writing over an empty set */
key_sets.set_key_revision[j] =
update_key_sets->set_key_revision[i];
/* update revision activation and expiration time */
key_sets.set_activation_time[j] =
update_key_sets->set_activation_time[i];
key_sets.set_expiration_time[j] =
update_key_sets->set_expiration_time[i];
/* should we clear the key set? */
if (update_key_sets->set_clr[i]) {
key_sets.set_key_count[j] = 0;
}
for (k = 0; k < update_key_sets->set_key_count[i]; k++) {
found = false;
for (l = 0; l < key_sets.set_key_count[j]; l++)
if (update_key_sets->set_keys[i][k].key_identifier ==
key_sets.set_keys[j][l].key_identifier) {
found = true;
break;
}
if (!found) {
if (!update_key_sets->remove) { /* add key */
/* check for available space */
if (key_sets.set_key_count[j] == MAX_UPDATE_KEY_COUNT)
return -SEC_RESP_TOO_MANY_KEYS;
memcpy(&key_sets.set_keys[j][key_sets.
set_key_count[j]],
&update_key_sets->set_keys[i][k],
sizeof(BACNET_KEY_ENTRY));
key_sets.set_key_count[j]++;
} /* else do nothing, successfuly */
} else {
if (!update_key_sets->remove) { /* update key */
memcpy(&key_sets.set_keys[j][l],
&update_key_sets->set_keys[i][k],
sizeof(BACNET_KEY_ENTRY));
} else { /* remove key */
memmove(&key_sets.set_keys[j][l],
&key_sets.set_keys[j][l + 1],
sizeof(BACNET_KEY_ENTRY) *
(key_sets.set_key_count[j] - l));
key_sets.set_key_count[j]--;
}
}
}
}
}
return SEC_RESP_SUCCESS;
}
BACNET_SECURITY_RESPONSE_CODE bacnet_find_key(uint8_t revision,
BACNET_KEY_ENTRY * key)
{
int i, j;
unsigned int current_time = time(NULL);
switch (key_number(key->key_identifier)) {
case KIKN_DEVICE_MASTER:
if (revision != 0)
return -SEC_RESP_UNKNOWN_KEY_REVISION;
else
memcpy(key, &master_key, sizeof(BACNET_KEY_ENTRY));
break;
case KIKN_DISTRIBUTION:
if (revision != distribution_key.key_revision)
return -SEC_RESP_UNKNOWN_KEY_REVISION;
else
memcpy(key, &distribution_key.key, sizeof(BACNET_KEY_ENTRY));
break;
default: /* all other keys must be in a key set */
for (i = 0; i < 2; i++) {
if ((revision == key_sets.set_key_revision[i]) &&
(key_sets.set_activation_time[i] <= current_time) &&
(current_time <= key_sets.set_expiration_time[i])) {
for (j = 0; j < key_sets.set_key_count[i]; j++)
if (key->key_identifier ==
key_sets.set_keys[i][j].key_identifier) {
memcpy(key,
&key_sets.set_keys[i][j].key_identifier,
sizeof(BACNET_KEY_ENTRY));
return SEC_RESP_SUCCESS;
}
}
}
return -SEC_RESP_UNKNOWN_KEY_REVISION;
}
return SEC_RESP_SUCCESS;
}
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