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hmac.h
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hmac.h
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/*******************************************************************************
*
* Copyright (c) 2011, 2012, 2013, 2014, 2015 Olaf Bergmann (TZI) and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
*
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Olaf Bergmann - initial API and implementation
* Hauke Mehrtens - memory optimization, ECC integration
*
*******************************************************************************/
#ifndef _DTLS_HMAC_H_
#define _DTLS_HMAC_H_
#include <sys/types.h>
#include "tinydtls.h"
#include "global.h"
#ifdef WITH_SHA256
#ifdef RIOT_VERSION
#include "hashes/sha256.h"
typedef sha256_context_t dtls_hash_ctx;
typedef sha256_context_t dtls_sha256_ctx;
#define DTLS_HASH_CTX_SIZE sizeof(sha256_context_t)
#define DTLS_SHA256_DIGEST_LENGTH (SHA256_DIGEST_LENGTH)
#define dtls_sha256_init(Ctx) sha256_init((Ctx))
#define dtls_sha256_update(Ctx,Input,Len) sha256_update((Ctx), (Input), (Len))
#define dtls_sha256_final(Buf,Ctx) sha256_final((Ctx), (Buf))
#else /* RIOT_VERSION */
/** Aaron D. Gifford's implementation of SHA256
* see http://www.aarongifford.com/ */
#include "sha2/sha2.h"
typedef dtls_sha256_ctx dtls_hash_ctx;
#define DTLS_HASH_CTX_SIZE sizeof(dtls_sha256_ctx)
#endif /* RIOT_VERSION */
typedef dtls_hash_ctx *dtls_hash_t;
static inline void
dtls_hash_init(dtls_hash_t ctx) {
dtls_sha256_init((dtls_sha256_ctx *)ctx);
}
static inline void
dtls_hash_update(dtls_hash_t ctx, const unsigned char *input, size_t len) {
dtls_sha256_update((dtls_sha256_ctx *)ctx, input, len);
}
static inline size_t
dtls_hash_finalize(unsigned char *buf, dtls_hash_t ctx) {
dtls_sha256_final(buf, (dtls_sha256_ctx *)ctx);
return DTLS_SHA256_DIGEST_LENGTH;
}
#endif /* WITH_SHA256 */
void dtls_hmac_storage_init(void);
/**
* \defgroup HMAC Keyed-Hash Message Authentication Code (HMAC)
* NIST Standard FIPS 198 describes the Keyed-Hash Message Authentication
* Code (HMAC) which is used as hash function for the DTLS PRF.
* @{
*/
#define DTLS_HMAC_BLOCKSIZE 64 /**< size of hmac blocks */
#define DTLS_HMAC_DIGEST_SIZE 32 /**< digest size (for SHA-256) */
#define DTLS_HMAC_MAX 64 /**< max number of bytes in digest */
/**
* List of known hash functions for use in dtls_hmac_init(). The
* identifiers are the same as the HashAlgorithm defined in
* <a href="http://tools.ietf.org/html/rfc5246#section-7.4.1.4.1"
* >Section 7.4.1.4.1 of RFC 5246</a>.
*/
typedef enum {
HASH_NONE=0, HASH_MD5=1, HASH_SHA1=2, HASH_SHA224=3,
HASH_SHA256=4, HASH_SHA384=5, HASH_SHA512=6
} dtls_hashfunc_t;
/**
* Context for HMAC generation. This object is initialized with
* dtls_hmac_init() and must be passed to dtls_hmac_update() and
* dtls_hmac_finalize(). Once, finalized, the component \c H is
* invalid and must be initialized again with dtls_hmac_init() before
* the structure can be used again.
*/
typedef struct {
unsigned char pad[DTLS_HMAC_BLOCKSIZE]; /**< ipad and opad storage */
dtls_hash_ctx data; /**< context for hash function */
} dtls_hmac_context_t;
/**
* Initializes an existing HMAC context.
*
* @param ctx The HMAC context to initialize.
* @param key The secret key.
* @param klen The length of @p key.
*/
void dtls_hmac_init(dtls_hmac_context_t *ctx, const unsigned char *key, size_t klen);
/**
* Allocates a new HMAC context \p ctx with the given secret key.
* This function returns \c 1 if \c ctx has been set correctly, or \c
* 0 or \c -1 otherwise. Note that this function allocates new storage
* that must be released by dtls_hmac_free().
*
* \param key The secret key.
* \param klen The length of \p key.
* \return A new dtls_hmac_context_t object or @c NULL on error
*/
dtls_hmac_context_t *dtls_hmac_new(const unsigned char *key, size_t klen);
/**
* Releases the storage for @p ctx that has been allocated by
* dtls_hmac_new().
*
* @param ctx The dtls_hmac_context_t to free.
*/
void dtls_hmac_free(dtls_hmac_context_t *ctx);
/**
* Updates the HMAC context with data from \p input.
*
* \param ctx The HMAC context.
* \param input The input data.
* \param ilen Size of \p input.
*/
void dtls_hmac_update(dtls_hmac_context_t *ctx,
const unsigned char *input, size_t ilen);
/**
* Completes the HMAC generation and writes the result to the given
* output parameter \c result. The buffer must be large enough to hold
* the message digest created by the actual hash function. If in
* doubt, use \c DTLS_HMAC_MAX. The function returns the number of
* bytes written to \c result.
*
* \param ctx The HMAC context.
* \param result Output parameter where the MAC is written to.
* \return Length of the MAC written to \p result.
*/
int dtls_hmac_finalize(dtls_hmac_context_t *ctx, unsigned char *result);
/**@}*/
#endif /* _DTLS_HMAC_H_ */