1 /* dtls -- a very basic DTLS implementation
3 * Copyright (C) 2011--2012 Olaf Bergmann <bergmann@tzi.org>
4 * Copyright (C) 2013 Hauke Mehrtens <hauke@hauke-m.de>
6 * Permission is hereby granted, free of charge, to any person
7 * obtaining a copy of this software and associated documentation
8 * files (the "Software"), to deal in the Software without
9 * restriction, including without limitation the rights to use, copy,
10 * modify, merge, publish, distribute, sublicense, and/or sell copies
11 * of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be
15 * included in all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
21 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
22 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
23 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
27 #ifndef _DTLS_CRYPTO_H_
28 #define _DTLS_CRYPTO_H_
30 #include <stdlib.h> /* for rand() and srand() */
35 #include "aes/rijndael.h"
43 /* TLS_PSK_WITH_AES_128_CCM_8 */
44 #define DTLS_MAC_KEY_LENGTH 0
45 #define DTLS_KEY_LENGTH 16 /* AES-128 */
46 #define DTLS_BLK_LENGTH 16 /* AES-128 */
47 #define DTLS_MAC_LENGTH DTLS_HMAC_DIGEST_SIZE
48 #define DTLS_IV_LENGTH 4 /* length of nonce_explicit */
51 * Maximum size of the generated keyblock. Note that MAX_KEYBLOCK_LENGTH must
52 * be large enough to hold the pre_master_secret, i.e. twice the length of the
55 #define MAX_KEYBLOCK_LENGTH \
56 (2 * DTLS_MAC_KEY_LENGTH + 2 * DTLS_KEY_LENGTH + 2 * DTLS_IV_LENGTH)
58 /** Length of DTLS master_secret */
59 #define DTLS_MASTER_SECRET_LENGTH 48
60 #define DTLS_RANDOM_LENGTH 32
62 typedef enum { AES128=0
66 DTLS_ECDH_CURVE_SECP256R1
69 /** Crypto context for TLS_PSK_WITH_AES_128_CCM_8 cipher suite. */
71 rijndael_ctx ctx; /**< AES-128 encryption context */
74 typedef struct dtls_cipher_context_t {
75 /** numeric identifier of this cipher suite in host byte order. */
76 aes128_ccm_t data; /**< The crypto context */
77 } dtls_cipher_context_t;
80 uint8 own_eph_priv[32];
81 uint8 other_eph_pub_x[32];
82 uint8 other_eph_pub_y[32];
83 uint8 other_pub_x[32];
84 uint8 other_pub_y[32];
85 } dtls_handshake_parameters_ecdsa_t;
87 /* This is the maximal supported length of the psk client identity and psk
88 * server identity hint */
89 #define DTLS_PSK_MAX_CLIENT_IDENTITY_LEN 32
91 /* This is the maximal supported length of the pre-shared key. */
92 #define DTLS_PSK_MAX_KEY_LEN 32
96 unsigned char identity[DTLS_PSK_MAX_CLIENT_IDENTITY_LEN];
97 } dtls_handshake_parameters_psk_t;
100 dtls_compression_t compression; /**< compression method */
102 dtls_cipher_t cipher; /**< cipher type */
103 uint16_t epoch; /**< counter for cipher state changes*/
104 uint64_t rseq; /**< sequence number of last record sent */
107 * The key block generated from PRF applied to client and server
108 * random bytes. The actual size is given by the selected cipher and
109 * can be calculated using dtls_kb_size(). Use \c dtls_kb_ macros to
110 * access the components of the key block.
112 uint8 key_block[MAX_KEYBLOCK_LENGTH];
113 } dtls_security_parameters_t;
118 uint8 client[DTLS_RANDOM_LENGTH]; /**< client random gmt and bytes */
119 uint8 server[DTLS_RANDOM_LENGTH]; /**< server random gmt and bytes */
121 /** the session's master secret */
122 uint8 master_secret[DTLS_MASTER_SECRET_LENGTH];
124 LIST_STRUCT(reorder_queue); /**< the packets to reorder */
125 dtls_hs_state_t hs_state; /**< handshake protocol status */
127 dtls_compression_t compression; /**< compression method */
128 dtls_cipher_t cipher; /**< cipher type */
129 unsigned int do_client_auth:1;
132 dtls_handshake_parameters_ecdsa_t ecdsa;
133 #endif /* DTLS_ECC */
135 dtls_handshake_parameters_psk_t psk;
136 #endif /* DTLS_PSK */
138 } dtls_handshake_parameters_t;
140 /* The following macros provide access to the components of the
141 * key_block in the security parameters. */
143 #define dtls_kb_client_mac_secret(Param, Role) ((Param)->key_block)
144 #define dtls_kb_server_mac_secret(Param, Role) \
145 (dtls_kb_client_mac_secret(Param, Role) + DTLS_MAC_KEY_LENGTH)
146 #define dtls_kb_remote_mac_secret(Param, Role) \
147 ((Role) == DTLS_SERVER \
148 ? dtls_kb_client_mac_secret(Param, Role) \
149 : dtls_kb_server_mac_secret(Param, Role))
150 #define dtls_kb_local_mac_secret(Param, Role) \
151 ((Role) == DTLS_CLIENT \
152 ? dtls_kb_client_mac_secret(Param, Role) \
153 : dtls_kb_server_mac_secret(Param, Role))
154 #define dtls_kb_mac_secret_size(Param, Role) DTLS_MAC_KEY_LENGTH
155 #define dtls_kb_client_write_key(Param, Role) \
156 (dtls_kb_server_mac_secret(Param, Role) + DTLS_MAC_KEY_LENGTH)
157 #define dtls_kb_server_write_key(Param, Role) \
158 (dtls_kb_client_write_key(Param, Role) + DTLS_KEY_LENGTH)
159 #define dtls_kb_remote_write_key(Param, Role) \
160 ((Role) == DTLS_SERVER \
161 ? dtls_kb_client_write_key(Param, Role) \
162 : dtls_kb_server_write_key(Param, Role))
163 #define dtls_kb_local_write_key(Param, Role) \
164 ((Role) == DTLS_CLIENT \
165 ? dtls_kb_client_write_key(Param, Role) \
166 : dtls_kb_server_write_key(Param, Role))
167 #define dtls_kb_key_size(Param, Role) DTLS_KEY_LENGTH
168 #define dtls_kb_client_iv(Param, Role) \
169 (dtls_kb_server_write_key(Param, Role) + DTLS_KEY_LENGTH)
170 #define dtls_kb_server_iv(Param, Role) \
171 (dtls_kb_client_iv(Param, Role) + DTLS_IV_LENGTH)
172 #define dtls_kb_remote_iv(Param, Role) \
173 ((Role) == DTLS_SERVER \
174 ? dtls_kb_client_iv(Param, Role) \
175 : dtls_kb_server_iv(Param, Role))
176 #define dtls_kb_local_iv(Param, Role) \
177 ((Role) == DTLS_CLIENT \
178 ? dtls_kb_client_iv(Param, Role) \
179 : dtls_kb_server_iv(Param, Role))
180 #define dtls_kb_iv_size(Param, Role) DTLS_IV_LENGTH
182 #define dtls_kb_size(Param, Role) \
183 (2 * (dtls_kb_mac_secret_size(Param, Role) + \
184 dtls_kb_key_size(Param, Role) + dtls_kb_iv_size(Param, Role)))
186 /* just for consistency */
187 #define dtls_kb_digest_size(Param, Role) DTLS_MAC_LENGTH
190 * Expands the secret and key to a block of DTLS_HMAC_MAX
191 * size according to the algorithm specified in section 5 of
194 * \param h Identifier of the hash function to use.
195 * \param key The secret.
196 * \param keylen Length of \p key.
197 * \param seed The seed.
198 * \param seedlen Length of \p seed.
199 * \param buf Output buffer where the result is XORed into
200 * The buffe must be capable to hold at least
202 * \return The actual number of bytes written to \p buf or 0
205 size_t dtls_p_hash(dtls_hashfunc_t h,
206 const unsigned char *key, size_t keylen,
207 const unsigned char *label, size_t labellen,
208 const unsigned char *random1, size_t random1len,
209 const unsigned char *random2, size_t random2len,
210 unsigned char *buf, size_t buflen);
213 * This function implements the TLS PRF for DTLS_VERSION. For version
214 * 1.0, the PRF is P_MD5 ^ P_SHA1 while version 1.2 uses
215 * P_SHA256. Currently, the actual PRF is selected at compile time.
217 size_t dtls_prf(const unsigned char *key, size_t keylen,
218 const unsigned char *label, size_t labellen,
219 const unsigned char *random1, size_t random1len,
220 const unsigned char *random2, size_t random2len,
221 unsigned char *buf, size_t buflen);
224 * Calculates MAC for record + cleartext packet and places the result
225 * in \p buf. The given \p hmac_ctx must be initialized with the HMAC
226 * function to use and the proper secret. As the DTLS mac calculation
227 * requires data from the record header, \p record must point to a
228 * buffer of at least \c sizeof(dtls_record_header_t) bytes. Usually,
229 * the remaining packet will be encrypted, therefore, the cleartext
230 * is passed separately in \p packet.
232 * \param hmac_ctx The HMAC context to use for MAC calculation.
233 * \param record The record header.
234 * \param packet Cleartext payload to apply the MAC to.
235 * \param length Size of \p packet.
236 * \param buf A result buffer that is large enough to hold
237 * the generated digest.
239 void dtls_mac(dtls_hmac_context_t *hmac_ctx,
240 const unsigned char *record,
241 const unsigned char *packet, size_t length,
245 * Encrypts the specified \p src of given \p length, writing the
246 * result to \p buf. The cipher implementation may add more data to
247 * the result buffer such as an initialization vector or padding
248 * (e.g. for block cipers in CBC mode). The caller therefore must
249 * ensure that \p buf provides sufficient storage to hold the result.
250 * Usually this means ( 2 + \p length / blocksize ) * blocksize. The
251 * function returns a value less than zero on error or otherwise the
252 * number of bytes written.
254 * \param ctx The cipher context to use.
255 * \param src The data to encrypt.
256 * \param length The actual size of of \p src.
257 * \param buf The result buffer. \p src and \p buf must not
259 * \param aad additional data for AEAD ciphers
260 * \param aad_length actual size of @p aad
261 * \return The number of encrypted bytes on success, less than zero
264 int dtls_encrypt(const unsigned char *src, size_t length,
266 unsigned char *nounce,
267 unsigned char *key, size_t keylen,
268 const unsigned char *aad, size_t aad_length);
271 * Decrypts the given buffer \p src of given \p length, writing the
272 * result to \p buf. The function returns \c -1 in case of an error,
273 * or the number of bytes written. Note that for block ciphers, \p
274 * length must be a multiple of the cipher's block size. A return
275 * value between \c 0 and the actual length indicates that only \c n-1
276 * block have been processed. Unlike dtls_encrypt(), the source
277 * and destination of dtls_decrypt() may overlap.
279 * \param ctx The cipher context to use.
280 * \param src The buffer to decrypt.
281 * \param length The length of the input buffer.
282 * \param buf The result buffer.
283 * \param aad additional authentication data for AEAD ciphers
284 * \param aad_length actual size of @p aad
285 * \return Less than zero on error, the number of decrypted bytes
288 int dtls_decrypt(const unsigned char *src, size_t length,
290 unsigned char *nounce,
291 unsigned char *key, size_t keylen,
292 const unsigned char *a_data, size_t a_data_length);
294 /* helper functions */
297 * Generates pre_master_sercet from given PSK and fills the result
298 * according to the "plain PSK" case in section 2 of RFC 4279.
299 * Diffie-Hellman and RSA key exchange are currently not supported.
301 * @param key The shared key.
302 * @param keylen Length of @p key in bytes.
303 * @param result The derived pre master secret.
304 * @return The actual length of @p result.
306 int dtls_psk_pre_master_secret(unsigned char *key, size_t keylen,
307 unsigned char *result, size_t result_len);
309 #define DTLS_EC_KEY_SIZE 32
311 int dtls_ecdh_pre_master_secret(unsigned char *priv_key,
312 unsigned char *pub_key_x,
313 unsigned char *pub_key_y,
315 unsigned char *result,
318 void dtls_ecdsa_generate_key(unsigned char *priv_key,
319 unsigned char *pub_key_x,
320 unsigned char *pub_key_y,
323 void dtls_ecdsa_create_sig_hash(const unsigned char *priv_key, size_t key_size,
324 const unsigned char *sign_hash, size_t sign_hash_size,
325 uint32_t point_r[9], uint32_t point_s[9]);
327 void dtls_ecdsa_create_sig(const unsigned char *priv_key, size_t key_size,
328 const unsigned char *client_random, size_t client_random_size,
329 const unsigned char *server_random, size_t server_random_size,
330 const unsigned char *keyx_params, size_t keyx_params_size,
331 uint32_t point_r[9], uint32_t point_s[9]);
333 int dtls_ecdsa_verify_sig_hash(const unsigned char *pub_key_x,
334 const unsigned char *pub_key_y, size_t key_size,
335 const unsigned char *sign_hash, size_t sign_hash_size,
336 unsigned char *result_r, unsigned char *result_s);
338 int dtls_ecdsa_verify_sig(const unsigned char *pub_key_x,
339 const unsigned char *pub_key_y, size_t key_size,
340 const unsigned char *client_random, size_t client_random_size,
341 const unsigned char *server_random, size_t server_random_size,
342 const unsigned char *keyx_params, size_t keyx_params_size,
343 unsigned char *result_r, unsigned char *result_s);
345 int dtls_ec_key_from_uint32_asn1(const uint32_t *key, size_t key_size,
349 dtls_handshake_parameters_t *dtls_handshake_new();
351 void dtls_handshake_free(dtls_handshake_parameters_t *handshake);
353 dtls_security_parameters_t *dtls_security_new();
355 void dtls_security_free(dtls_security_parameters_t *security);
358 #endif /* _DTLS_CRYPTO_H_ */