155 lines
5.0 KiB
C
155 lines
5.0 KiB
C
/* dtls -- a very basic DTLS implementation
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*
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* Copyright (C) 2011--2012 Olaf Bergmann <bergmann@tzi.org>
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy,
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* modify, merge, publish, distribute, sublicense, and/or sell copies
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* of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef _DTLS_HMAC_H_
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#define _DTLS_HMAC_H_
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#include <sys/types.h>
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#include "global.h"
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#ifdef WITH_SHA256
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/** Aaron D. Gifford's implementation of SHA256
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* see http://www.aarongifford.com/ */
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#include "sha2/sha2.h"
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typedef SHA256_CTX dtls_hash_ctx;
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typedef dtls_hash_ctx *dtls_hash_t;
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#define DTLS_HASH_CTX_SIZE sizeof(SHA256_CTX)
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static inline void
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dtls_hash_init(dtls_hash_t ctx) {
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SHA256_Init((SHA256_CTX *)ctx);
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}
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static inline void
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dtls_hash_update(dtls_hash_t ctx, const unsigned char *input, size_t len) {
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SHA256_Update((SHA256_CTX *)ctx, input, len);
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}
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static inline size_t
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dtls_hash_finalize(unsigned char *buf, dtls_hash_t ctx) {
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SHA256_Final(buf, (SHA256_CTX *)ctx);
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return SHA256_DIGEST_LENGTH;
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}
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#endif /* WITH_SHA256 */
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#ifndef WITH_CONTIKI
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static inline void dtls_hmac_storage_init()
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{ }
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#else
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void dtls_hmac_storage_init();
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#endif
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/**
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* \defgroup HMAC Keyed-Hash Message Authentication Code (HMAC)
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* NIST Standard FIPS 198 describes the Keyed-Hash Message Authentication
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* Code (HMAC) which is used as hash function for the DTLS PRF.
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* @{
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*/
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#define DTLS_HMAC_BLOCKSIZE 64 /**< size of hmac blocks */
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#define DTLS_HMAC_DIGEST_SIZE 32 /**< digest size (for SHA-256) */
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#define DTLS_HMAC_MAX 64 /**< max number of bytes in digest */
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/**
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* List of known hash functions for use in dtls_hmac_init(). The
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* identifiers are the same as the HashAlgorithm defined in
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* <a href="http://tools.ietf.org/html/rfc5246#section-7.4.1.4.1"
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* >Section 7.4.1.4.1 of RFC 5246</a>.
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*/
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typedef enum {
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HASH_NONE=0, HASH_MD5=1, HASH_SHA1=2, HASH_SHA224=3,
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HASH_SHA256=4, HASH_SHA384=5, HASH_SHA512=6
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} dtls_hashfunc_t;
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/**
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* Context for HMAC generation. This object is initialized with
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* dtls_hmac_init() and must be passed to dtls_hmac_update() and
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* dtls_hmac_finalize(). Once, finalized, the component \c H is
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* invalid and must be initialized again with dtls_hmac_init() before
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* the structure can be used again.
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*/
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typedef struct {
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unsigned char pad[DTLS_HMAC_BLOCKSIZE]; /**< ipad and opad storage */
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dtls_hash_ctx data; /**< context for hash function */
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} dtls_hmac_context_t;
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/**
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* Initializes an existing HMAC context.
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*
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* @param ctx The HMAC context to initialize.
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* @param key The secret key.
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* @param klen The length of @p key.
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*/
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void dtls_hmac_init(dtls_hmac_context_t *ctx, const unsigned char *key, size_t klen);
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/**
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* Allocates a new HMAC context \p ctx with the given secret key.
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* This function returns \c 1 if \c ctx has been set correctly, or \c
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* 0 or \c -1 otherwise. Note that this function allocates new storage
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* that must be released by dtls_hmac_free().
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*
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* \param key The secret key.
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* \param klen The length of \p key.
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* \return A new dtls_hmac_context_t object or @c NULL on error
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*/
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dtls_hmac_context_t *dtls_hmac_new(const unsigned char *key, size_t klen);
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/**
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* Releases the storage for @p ctx that has been allocated by
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* dtls_hmac_new().
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*
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* @param ctx The dtls_hmac_context_t to free.
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*/
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void dtls_hmac_free(dtls_hmac_context_t *ctx);
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/**
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* Updates the HMAC context with data from \p input.
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*
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* \param ctx The HMAC context.
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* \param input The input data.
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* \param ilen Size of \p input.
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*/
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void dtls_hmac_update(dtls_hmac_context_t *ctx,
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const unsigned char *input, size_t ilen);
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/**
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* Completes the HMAC generation and writes the result to the given
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* output parameter \c result. The buffer must be large enough to hold
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* the message digest created by the actual hash function. If in
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* doubt, use \c DTLS_HMAC_MAX. The function returns the number of
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* bytes written to \c result.
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*
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* \param ctx The HMAC context.
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* \param result Output parameter where the MAC is written to.
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* \return Length of the MAC written to \p result.
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*/
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int dtls_hmac_finalize(dtls_hmac_context_t *ctx, unsigned char *result);
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/**@}*/
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#endif /* _DTLS_HMAC_H_ */
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