/* dtls -- a very basic DTLS implementation * * Copyright (C) 2011--2012 Olaf Bergmann * Copyright (C) 2013 Hauke Mehrtens * * 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. */ #ifndef _DTLS_CRYPTO_H_ #define _DTLS_CRYPTO_H_ #include /* for rand() and srand() */ #include #include "t_list.h" #include "aes/rijndael.h" #include "global.h" #include "state.h" #include "numeric.h" #include "hmac.h" #include "ccm.h" /* TLS_PSK_WITH_AES_128_CCM_8 */ #define DTLS_MAC_KEY_LENGTH 0 #define DTLS_KEY_LENGTH 16 /* AES-128 */ #define DTLS_BLK_LENGTH 16 /* AES-128 */ #define DTLS_MAC_LENGTH DTLS_HMAC_DIGEST_SIZE #define DTLS_IV_LENGTH 4 /* length of nonce_explicit */ /** * Maximum size of the generated keyblock. Note that MAX_KEYBLOCK_LENGTH must * be large enough to hold the pre_master_secret, i.e. twice the length of the * pre-shared key + 1. */ #define MAX_KEYBLOCK_LENGTH \ (2 * DTLS_MAC_KEY_LENGTH + 2 * DTLS_KEY_LENGTH + 2 * DTLS_IV_LENGTH) /** Length of DTLS master_secret */ #define DTLS_MASTER_SECRET_LENGTH 48 #define DTLS_RANDOM_LENGTH 32 typedef enum { AES128=0 } dtls_crypto_alg; typedef enum { DTLS_ECDH_CURVE_SECP256R1 } dtls_ecdh_curve; /** Crypto context for TLS_PSK_WITH_AES_128_CCM_8 cipher suite. */ typedef struct { rijndael_ctx ctx; /**< AES-128 encryption context */ } aes128_ccm_t; typedef struct dtls_cipher_context_t { /** numeric identifier of this cipher suite in host byte order. */ aes128_ccm_t data; /**< The crypto context */ } dtls_cipher_context_t; typedef struct { uint8 own_eph_priv[32]; uint8 other_eph_pub_x[32]; uint8 other_eph_pub_y[32]; uint8 other_pub_x[32]; uint8 other_pub_y[32]; } dtls_handshake_parameters_ecdsa_t; /* This is the maximal supported length of the psk client identity and psk * server identity hint */ #define DTLS_PSK_MAX_CLIENT_IDENTITY_LEN 32 /* This is the maximal supported length of the pre-shared key. */ #define DTLS_PSK_MAX_KEY_LEN 32 typedef struct { uint16_t id_length; unsigned char identity[DTLS_PSK_MAX_CLIENT_IDENTITY_LEN]; } dtls_handshake_parameters_psk_t; typedef struct { dtls_compression_t compression; /**< compression method */ dtls_cipher_t cipher; /**< cipher type */ uint16_t epoch; /**< counter for cipher state changes*/ uint64_t rseq; /**< sequence number of last record sent */ /** * The key block generated from PRF applied to client and server * random bytes. The actual size is given by the selected cipher and * can be calculated using dtls_kb_size(). Use \c dtls_kb_ macros to * access the components of the key block. */ uint8 key_block[MAX_KEYBLOCK_LENGTH]; } dtls_security_parameters_t; typedef struct { union { struct random_t { uint8 client[DTLS_RANDOM_LENGTH]; /**< client random gmt and bytes */ uint8 server[DTLS_RANDOM_LENGTH]; /**< server random gmt and bytes */ } random; /** the session's master secret */ uint8 master_secret[DTLS_MASTER_SECRET_LENGTH]; } tmp; LIST_STRUCT(reorder_queue); /**< the packets to reorder */ dtls_hs_state_t hs_state; /**< handshake protocol status */ dtls_compression_t compression; /**< compression method */ dtls_cipher_t cipher; /**< cipher type */ unsigned int do_client_auth:1; union { #ifdef DTLS_ECC dtls_handshake_parameters_ecdsa_t ecdsa; #endif /* DTLS_ECC */ #ifdef DTLS_PSK dtls_handshake_parameters_psk_t psk; #endif /* DTLS_PSK */ } keyx; } dtls_handshake_parameters_t; /* The following macros provide access to the components of the * key_block in the security parameters. */ #define dtls_kb_client_mac_secret(Param, Role) ((Param)->key_block) #define dtls_kb_server_mac_secret(Param, Role) \ (dtls_kb_client_mac_secret(Param, Role) + DTLS_MAC_KEY_LENGTH) #define dtls_kb_remote_mac_secret(Param, Role) \ ((Role) == DTLS_SERVER \ ? dtls_kb_client_mac_secret(Param, Role) \ : dtls_kb_server_mac_secret(Param, Role)) #define dtls_kb_local_mac_secret(Param, Role) \ ((Role) == DTLS_CLIENT \ ? dtls_kb_client_mac_secret(Param, Role) \ : dtls_kb_server_mac_secret(Param, Role)) #define dtls_kb_mac_secret_size(Param, Role) DTLS_MAC_KEY_LENGTH #define dtls_kb_client_write_key(Param, Role) \ (dtls_kb_server_mac_secret(Param, Role) + DTLS_MAC_KEY_LENGTH) #define dtls_kb_server_write_key(Param, Role) \ (dtls_kb_client_write_key(Param, Role) + DTLS_KEY_LENGTH) #define dtls_kb_remote_write_key(Param, Role) \ ((Role) == DTLS_SERVER \ ? dtls_kb_client_write_key(Param, Role) \ : dtls_kb_server_write_key(Param, Role)) #define dtls_kb_local_write_key(Param, Role) \ ((Role) == DTLS_CLIENT \ ? dtls_kb_client_write_key(Param, Role) \ : dtls_kb_server_write_key(Param, Role)) #define dtls_kb_key_size(Param, Role) DTLS_KEY_LENGTH #define dtls_kb_client_iv(Param, Role) \ (dtls_kb_server_write_key(Param, Role) + DTLS_KEY_LENGTH) #define dtls_kb_server_iv(Param, Role) \ (dtls_kb_client_iv(Param, Role) + DTLS_IV_LENGTH) #define dtls_kb_remote_iv(Param, Role) \ ((Role) == DTLS_SERVER \ ? dtls_kb_client_iv(Param, Role) \ : dtls_kb_server_iv(Param, Role)) #define dtls_kb_local_iv(Param, Role) \ ((Role) == DTLS_CLIENT \ ? dtls_kb_client_iv(Param, Role) \ : dtls_kb_server_iv(Param, Role)) #define dtls_kb_iv_size(Param, Role) DTLS_IV_LENGTH #define dtls_kb_size(Param, Role) \ (2 * (dtls_kb_mac_secret_size(Param, Role) + \ dtls_kb_key_size(Param, Role) + dtls_kb_iv_size(Param, Role))) /* just for consistency */ #define dtls_kb_digest_size(Param, Role) DTLS_MAC_LENGTH /** * Expands the secret and key to a block of DTLS_HMAC_MAX * size according to the algorithm specified in section 5 of * RFC 4346. * * \param h Identifier of the hash function to use. * \param key The secret. * \param keylen Length of \p key. * \param seed The seed. * \param seedlen Length of \p seed. * \param buf Output buffer where the result is XORed into * The buffe must be capable to hold at least * \p buflen bytes. * \return The actual number of bytes written to \p buf or 0 * on error. */ 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); /** * This function implements the TLS PRF for DTLS_VERSION. For version * 1.0, the PRF is P_MD5 ^ P_SHA1 while version 1.2 uses * P_SHA256. Currently, the actual PRF is selected at compile time. */ 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); /** * Calculates MAC for record + cleartext packet and places the result * in \p buf. The given \p hmac_ctx must be initialized with the HMAC * function to use and the proper secret. As the DTLS mac calculation * requires data from the record header, \p record must point to a * buffer of at least \c sizeof(dtls_record_header_t) bytes. Usually, * the remaining packet will be encrypted, therefore, the cleartext * is passed separately in \p packet. * * \param hmac_ctx The HMAC context to use for MAC calculation. * \param record The record header. * \param packet Cleartext payload to apply the MAC to. * \param length Size of \p packet. * \param buf A result buffer that is large enough to hold * the generated digest. */ void dtls_mac(dtls_hmac_context_t *hmac_ctx, const unsigned char *record, const unsigned char *packet, size_t length, unsigned char *buf); /** * Encrypts the specified \p src of given \p length, writing the * result to \p buf. The cipher implementation may add more data to * the result buffer such as an initialization vector or padding * (e.g. for block cipers in CBC mode). The caller therefore must * ensure that \p buf provides sufficient storage to hold the result. * Usually this means ( 2 + \p length / blocksize ) * blocksize. The * function returns a value less than zero on error or otherwise the * number of bytes written. * * \param ctx The cipher context to use. * \param src The data to encrypt. * \param length The actual size of of \p src. * \param buf The result buffer. \p src and \p buf must not * overlap. * \param aad additional data for AEAD ciphers * \param aad_length actual size of @p aad * \return The number of encrypted bytes on success, less than zero * otherwise. */ 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 aad_length); /** * Decrypts the given buffer \p src of given \p length, writing the * result to \p buf. The function returns \c -1 in case of an error, * or the number of bytes written. Note that for block ciphers, \p * length must be a multiple of the cipher's block size. A return * value between \c 0 and the actual length indicates that only \c n-1 * block have been processed. Unlike dtls_encrypt(), the source * and destination of dtls_decrypt() may overlap. * * \param ctx The cipher context to use. * \param src The buffer to decrypt. * \param length The length of the input buffer. * \param buf The result buffer. * \param aad additional authentication data for AEAD ciphers * \param aad_length actual size of @p aad * \return Less than zero on error, the number of decrypted bytes * otherwise. */ 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 *a_data, size_t a_data_length); /* helper functions */ /** * Generates pre_master_sercet from given PSK and fills the result * according to the "plain PSK" case in section 2 of RFC 4279. * Diffie-Hellman and RSA key exchange are currently not supported. * * @param key The shared key. * @param keylen Length of @p key in bytes. * @param result The derived pre master secret. * @return The actual length of @p result. */ int dtls_psk_pre_master_secret(unsigned char *key, size_t keylen, unsigned char *result, size_t result_len); #define DTLS_EC_KEY_SIZE 32 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); void dtls_ecdsa_generate_key(unsigned char *priv_key, unsigned char *pub_key_x, unsigned char *pub_key_y, size_t key_size); 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]); 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]); 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); 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); int dtls_ec_key_from_uint32_asn1(const uint32_t *key, size_t key_size, unsigned char *buf); dtls_handshake_parameters_t *dtls_handshake_new(); void dtls_handshake_free(dtls_handshake_parameters_t *handshake); dtls_security_parameters_t *dtls_security_new(); void dtls_security_free(dtls_security_parameters_t *security); void crypto_init(); #endif /* _DTLS_CRYPTO_H_ */