blob: d16b27eb12e03ba456aa65d698cafc07f057464d [file] [log] [blame]
/* dtls -- a very basic DTLS implementation
*
* Copyright (C) 2011--2012 Olaf Bergmann <bergmann@tzi.org>
* Copyright (C) 2013 Hauke Mehrtens <hauke@hauke-m.de>
*
* 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 <stdio.h>
#include "tinydtls.h"
#include "dtls_config.h"
#ifdef HAVE_ASSERT_H
#include <assert.h>
#endif
#include "global.h"
#include "debug.h"
#include "numeric.h"
#include "dtls.h"
#include "crypto.h"
#include "ccm.h"
#include "ecc/ecc.h"
#include "prng.h"
#include "netq.h"
#ifndef WITH_CONTIKI
#include <pthread.h>
#endif
#define HMAC_UPDATE_SEED(Context,Seed,Length) \
if (Seed) dtls_hmac_update(Context, (Seed), (Length))
static struct dtls_cipher_context_t cipher_context;
#ifndef WITH_CONTIKI
static pthread_mutex_t cipher_context_mutex = PTHREAD_MUTEX_INITIALIZER;
#endif
static struct dtls_cipher_context_t *dtls_cipher_context_get(void)
{
#ifndef WITH_CONTIKI
pthread_mutex_lock(&cipher_context_mutex);
#endif
return &cipher_context;
}
static void dtls_cipher_context_release(void)
{
#ifndef WITH_CONTIKI
pthread_mutex_unlock(&cipher_context_mutex);
#endif
}
#ifndef WITH_CONTIKI
void crypto_init()
{
}
static dtls_handshake_parameters_t *dtls_handshake_malloc() {
return malloc(sizeof(dtls_handshake_parameters_t));
}
static void dtls_handshake_dealloc(dtls_handshake_parameters_t *handshake) {
free(handshake);
}
static dtls_security_parameters_t *dtls_security_malloc() {
return malloc(sizeof(dtls_security_parameters_t));
}
static void dtls_security_dealloc(dtls_security_parameters_t *security) {
free(security);
}
#else /* WITH_CONTIKI */
#include "memb.h"
MEMB(handshake_storage, dtls_handshake_parameters_t, DTLS_HANDSHAKE_MAX);
MEMB(security_storage, dtls_security_parameters_t, DTLS_SECURITY_MAX);
void crypto_init() {
memb_init(&handshake_storage);
memb_init(&security_storage);
}
static dtls_handshake_parameters_t *dtls_handshake_malloc() {
return memb_alloc(&handshake_storage);
}
static void dtls_handshake_dealloc(dtls_handshake_parameters_t *handshake) {
memb_free(&handshake_storage, handshake);
}
static dtls_security_parameters_t *dtls_security_malloc() {
return memb_alloc(&security_storage);
}
static void dtls_security_dealloc(dtls_security_parameters_t *security) {
memb_free(&security_storage, security);
}
#endif /* WITH_CONTIKI */
dtls_handshake_parameters_t *dtls_handshake_new()
{
dtls_handshake_parameters_t *handshake;
handshake = dtls_handshake_malloc();
if (!handshake) {
dtls_crit("can not allocate a handshake struct\n");
return NULL;
}
memset(handshake, 0, sizeof(*handshake));
if (handshake) {
/* initialize the handshake hash wrt. the hard-coded DTLS version */
dtls_debug("DTLSv12: initialize HASH_SHA256\n");
/* TLS 1.2: PRF(secret, label, seed) = P_<hash>(secret, label + seed) */
/* FIXME: we use the default SHA256 here, might need to support other
hash functions as well */
dtls_hash_init(&handshake->hs_state.hs_hash);
}
return handshake;
}
void dtls_handshake_free(dtls_handshake_parameters_t *handshake)
{
if (!handshake)
return;
netq_delete_all(handshake->reorder_queue);
dtls_handshake_dealloc(handshake);
}
dtls_security_parameters_t *dtls_security_new()
{
dtls_security_parameters_t *security;
security = dtls_security_malloc();
if (!security) {
dtls_crit("can not allocate a security struct\n");
return NULL;
}
memset(security, 0, sizeof(*security));
if (security) {
security->cipher = TLS_NULL_WITH_NULL_NULL;
security->compression = TLS_COMPRESSION_NULL;
}
return security;
}
void dtls_security_free(dtls_security_parameters_t *security)
{
if (!security)
return;
dtls_security_dealloc(security);
}
size_t
dtls_p_hash(dtls_hashfunc_t h,
const unsigned char *key, size_t keylen,
const unsigned char *label, size_t labellen,
const unsigned char *random1, size_t random1len,
const unsigned char *random2, size_t random2len,
unsigned char *buf, size_t buflen) {
dtls_hmac_context_t *hmac_a, *hmac_p;
unsigned char A[DTLS_HMAC_DIGEST_SIZE];
unsigned char tmp[DTLS_HMAC_DIGEST_SIZE];
size_t dlen; /* digest length */
size_t len = 0; /* result length */
hmac_a = dtls_hmac_new(key, keylen);
if (!hmac_a)
return 0;
/* calculate A(1) from A(0) == seed */
HMAC_UPDATE_SEED(hmac_a, label, labellen);
HMAC_UPDATE_SEED(hmac_a, random1, random1len);
HMAC_UPDATE_SEED(hmac_a, random2, random2len);
dlen = dtls_hmac_finalize(hmac_a, A);
hmac_p = dtls_hmac_new(key, keylen);
if (!hmac_p)
goto error;
while (len + dlen < buflen) {
/* FIXME: rewrite loop to avoid superflous call to dtls_hmac_init() */
dtls_hmac_init(hmac_p, key, keylen);
dtls_hmac_update(hmac_p, A, dlen);
HMAC_UPDATE_SEED(hmac_p, label, labellen);
HMAC_UPDATE_SEED(hmac_p, random1, random1len);
HMAC_UPDATE_SEED(hmac_p, random2, random2len);
len += dtls_hmac_finalize(hmac_p, tmp);
memcpy(buf, tmp, dlen);
buf += dlen;
/* calculate A(i+1) */
dtls_hmac_init(hmac_a, key, keylen);
dtls_hmac_update(hmac_a, A, dlen);
dtls_hmac_finalize(hmac_a, A);
}
dtls_hmac_init(hmac_p, key, keylen);
dtls_hmac_update(hmac_p, A, dlen);
HMAC_UPDATE_SEED(hmac_p, label, labellen);
HMAC_UPDATE_SEED(hmac_p, random1, random1len);
HMAC_UPDATE_SEED(hmac_p, random2, random2len);
dtls_hmac_finalize(hmac_p, tmp);
memcpy(buf, tmp, buflen - len);
error:
dtls_hmac_free(hmac_a);
dtls_hmac_free(hmac_p);
return buflen;
}
size_t
dtls_prf(const unsigned char *key, size_t keylen,
const unsigned char *label, size_t labellen,
const unsigned char *random1, size_t random1len,
const unsigned char *random2, size_t random2len,
unsigned char *buf, size_t buflen) {
/* Clear the result buffer */
memset(buf, 0, buflen);
return dtls_p_hash(HASH_SHA256,
key, keylen,
label, labellen,
random1, random1len,
random2, random2len,
buf, buflen);
}
void
dtls_mac(dtls_hmac_context_t *hmac_ctx,
const unsigned char *record,
const unsigned char *packet, size_t length,
unsigned char *buf) {
uint16 L;
dtls_int_to_uint16(L, length);
assert(hmac_ctx);
dtls_hmac_update(hmac_ctx, record +3, sizeof(uint16) + sizeof(uint48));
dtls_hmac_update(hmac_ctx, record, sizeof(uint8) + sizeof(uint16));
dtls_hmac_update(hmac_ctx, L, sizeof(uint16));
dtls_hmac_update(hmac_ctx, packet, length);
dtls_hmac_finalize(hmac_ctx, buf);
}
static size_t
dtls_ccm_encrypt(aes128_ccm_t *ccm_ctx, const unsigned char *src, size_t srclen,
unsigned char *buf,
unsigned char *nounce,
const unsigned char *aad, size_t la) {
long int len;
assert(ccm_ctx);
len = dtls_ccm_encrypt_message(&ccm_ctx->ctx, 8 /* M */,
max(2, 15 - DTLS_CCM_NONCE_SIZE),
nounce,
buf, srclen,
aad, la);
return len;
}
static size_t
dtls_ccm_decrypt(aes128_ccm_t *ccm_ctx, const unsigned char *src,
size_t srclen, unsigned char *buf,
unsigned char *nounce,
const unsigned char *aad, size_t la) {
long int len;
assert(ccm_ctx);
len = dtls_ccm_decrypt_message(&ccm_ctx->ctx, 8 /* M */,
max(2, 15 - DTLS_CCM_NONCE_SIZE),
nounce,
buf, srclen,
aad, la);
return len;
}
#ifdef DTLS_PSK
int
dtls_psk_pre_master_secret(unsigned char *key, size_t keylen,
unsigned char *result, size_t result_len) {
unsigned char *p = result;
if (result_len < (2 * (sizeof(uint16) + keylen))) {
return -1;
}
dtls_int_to_uint16(p, keylen);
p += sizeof(uint16);
memset(p, 0, keylen);
p += keylen;
memcpy(p, result, sizeof(uint16));
p += sizeof(uint16);
memcpy(p, key, keylen);
return 2 * (sizeof(uint16) + keylen);
}
#endif /* DTLS_PSK */
#ifdef DTLS_ECC
static void dtls_ec_key_to_uint32(const unsigned char *key, size_t key_size,
uint32_t *result) {
int i;
for (i = (key_size / sizeof(uint32_t)) - 1; i >= 0 ; i--) {
*result = dtls_uint32_to_int(&key[i * sizeof(uint32_t)]);
result++;
}
}
static void dtls_ec_key_from_uint32(const uint32_t *key, size_t key_size,
unsigned char *result) {
int i;
for (i = (key_size / sizeof(uint32_t)) - 1; i >= 0 ; i--) {
dtls_int_to_uint32(result, key[i]);
result += 4;
}
}
int dtls_ec_key_from_uint32_asn1(const uint32_t *key, size_t key_size,
unsigned char *buf) {
int i;
unsigned char *buf_orig = buf;
int first = 1;
for (i = (key_size / sizeof(uint32_t)) - 1; i >= 0 ; i--) {
if (key[i] == 0)
continue;
/* the first bit has to be set to zero, to indicate a poritive integer */
if (first && key[i] & 0x80000000) {
*buf = 0;
buf++;
dtls_int_to_uint32(buf, key[i]);
buf += 4;
} else if (first && !(key[i] & 0xFF800000)) {
buf[0] = (key[i] >> 16) & 0xff;
buf[1] = (key[i] >> 8) & 0xff;
buf[2] = key[i] & 0xff;
buf += 3;
} else if (first && !(key[i] & 0xFFFF8000)) {
buf[0] = (key[i] >> 8) & 0xff;
buf[1] = key[i] & 0xff;
buf += 2;
} else if (first && !(key[i] & 0xFFFFFF80)) {
buf[0] = key[i] & 0xff;
buf += 1;
} else {
dtls_int_to_uint32(buf, key[i]);
buf += 4;
}
first = 0;
}
return buf - buf_orig;
}
int dtls_ecdh_pre_master_secret(unsigned char *priv_key,
unsigned char *pub_key_x,
unsigned char *pub_key_y,
size_t key_size,
unsigned char *result,
size_t result_len) {
uint32_t priv[8];
uint32_t pub_x[8];
uint32_t pub_y[8];
uint32_t result_x[8];
uint32_t result_y[8];
if (result_len < key_size) {
return -1;
}
dtls_ec_key_to_uint32(priv_key, key_size, priv);
dtls_ec_key_to_uint32(pub_key_x, key_size, pub_x);
dtls_ec_key_to_uint32(pub_key_y, key_size, pub_y);
ecc_ecdh(pub_x, pub_y, priv, result_x, result_y);
dtls_ec_key_from_uint32(result_x, key_size, result);
return key_size;
}
void
dtls_ecdsa_generate_key(unsigned char *priv_key,
unsigned char *pub_key_x,
unsigned char *pub_key_y,
size_t key_size) {
uint32_t priv[8];
uint32_t pub_x[8];
uint32_t pub_y[8];
do {
dtls_prng((unsigned char *)priv, key_size);
} while (!ecc_is_valid_key(priv));
ecc_gen_pub_key(priv, pub_x, pub_y);
dtls_ec_key_from_uint32(priv, key_size, priv_key);
dtls_ec_key_from_uint32(pub_x, key_size, pub_key_x);
dtls_ec_key_from_uint32(pub_y, key_size, pub_key_y);
}
/* rfc4492#section-5.4 */
void
dtls_ecdsa_create_sig_hash(const unsigned char *priv_key, size_t key_size,
const unsigned char *sign_hash, size_t sign_hash_size,
uint32_t point_r[9], uint32_t point_s[9]) {
int ret;
uint32_t priv[8];
uint32_t hash[8];
uint32_t rand[8];
dtls_ec_key_to_uint32(priv_key, key_size, priv);
dtls_ec_key_to_uint32(sign_hash, sign_hash_size, hash);
do {
dtls_prng((unsigned char *)rand, key_size);
ret = ecc_ecdsa_sign(priv, hash, rand, point_r, point_s);
} while (ret);
}
void
dtls_ecdsa_create_sig(const unsigned char *priv_key, size_t key_size,
const unsigned char *client_random, size_t client_random_size,
const unsigned char *server_random, size_t server_random_size,
const unsigned char *keyx_params, size_t keyx_params_size,
uint32_t point_r[9], uint32_t point_s[9]) {
dtls_hash_ctx data;
unsigned char sha256hash[DTLS_HMAC_DIGEST_SIZE];
dtls_hash_init(&data);
dtls_hash_update(&data, client_random, client_random_size);
dtls_hash_update(&data, server_random, server_random_size);
dtls_hash_update(&data, keyx_params, keyx_params_size);
dtls_hash_finalize(sha256hash, &data);
dtls_ecdsa_create_sig_hash(priv_key, key_size, sha256hash,
sizeof(sha256hash), point_r, point_s);
}
/* rfc4492#section-5.4 */
int
dtls_ecdsa_verify_sig_hash(const unsigned char *pub_key_x,
const unsigned char *pub_key_y, size_t key_size,
const unsigned char *sign_hash, size_t sign_hash_size,
unsigned char *result_r, unsigned char *result_s) {
uint32_t pub_x[8];
uint32_t pub_y[8];
uint32_t hash[8];
uint32_t point_r[8];
uint32_t point_s[8];
dtls_ec_key_to_uint32(pub_key_x, key_size, pub_x);
dtls_ec_key_to_uint32(pub_key_y, key_size, pub_y);
dtls_ec_key_to_uint32(result_r, key_size, point_r);
dtls_ec_key_to_uint32(result_s, key_size, point_s);
dtls_ec_key_to_uint32(sign_hash, sign_hash_size, hash);
return ecc_ecdsa_validate(pub_x, pub_y, hash, point_r, point_s);
}
int
dtls_ecdsa_verify_sig(const unsigned char *pub_key_x,
const unsigned char *pub_key_y, size_t key_size,
const unsigned char *client_random, size_t client_random_size,
const unsigned char *server_random, size_t server_random_size,
const unsigned char *keyx_params, size_t keyx_params_size,
unsigned char *result_r, unsigned char *result_s) {
dtls_hash_ctx data;
unsigned char sha256hash[DTLS_HMAC_DIGEST_SIZE];
dtls_hash_init(&data);
dtls_hash_update(&data, client_random, client_random_size);
dtls_hash_update(&data, server_random, server_random_size);
dtls_hash_update(&data, keyx_params, keyx_params_size);
dtls_hash_finalize(sha256hash, &data);
return dtls_ecdsa_verify_sig_hash(pub_key_x, pub_key_y, key_size, sha256hash,
sizeof(sha256hash), result_r, result_s);
}
#endif /* DTLS_ECC */
int
dtls_encrypt(const unsigned char *src, size_t length,
unsigned char *buf,
unsigned char *nounce,
unsigned char *key, size_t keylen,
const unsigned char *aad, size_t la)
{
int ret;
struct dtls_cipher_context_t *ctx = dtls_cipher_context_get();
ret = rijndael_set_key_enc_only(&ctx->data.ctx, key, 8 * keylen);
if (ret < 0) {
/* cleanup everything in case the key has the wrong size */
dtls_warn("cannot set rijndael key\n");
goto error;
}
if (src != buf)
memmove(buf, src, length);
ret = dtls_ccm_encrypt(&ctx->data, src, length, buf, nounce, aad, la);
error:
dtls_cipher_context_release();
return ret;
}
int
dtls_decrypt(const unsigned char *src, size_t length,
unsigned char *buf,
unsigned char *nounce,
unsigned char *key, size_t keylen,
const unsigned char *aad, size_t la)
{
int ret;
struct dtls_cipher_context_t *ctx = dtls_cipher_context_get();
ret = rijndael_set_key_enc_only(&ctx->data.ctx, key, 8 * keylen);
if (ret < 0) {
/* cleanup everything in case the key has the wrong size */
dtls_warn("cannot set rijndael key\n");
goto error;
}
if (src != buf)
memmove(buf, src, length);
ret = dtls_ccm_decrypt(&ctx->data, src, length, buf, nounce, aad, la);
error:
dtls_cipher_context_release();
return ret;
}