Diff: tinydtls/hmac.h

Revision:

0:6ae42a2aff75

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tinydtls/hmac.h	Wed Oct 09 14:48:52 2013 +0000
@@ -0,0 +1,149 @@
+/* dtls -- a very basic DTLS implementation
+ *
+ * Copyright (C) 2011--2012 Olaf Bergmann <bergmann@tzi.org>
+ *
+ * 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 _HMAC_H_
+#define _HMAC_H_
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
+#include "global.h"
+
+#ifdef WITH_SHA256
+/** Aaron D. Gifford's implementation of SHA256
+ *  see http://www.aarongifford.com/ */
+#include "sha2/sha2.h"
+
+typedef SHA256_CTX dtls_hash_ctx;
+typedef dtls_hash_ctx *dtls_hash_t;
+#define DTLS_HASH_CTX_SIZE sizeof(SHA256_CTX)
+
+static inline void
+dtls_hash_init(dtls_hash_t ctx) {
+  SHA256_Init((SHA256_CTX *)ctx);
+}
+
+static inline void 
+dtls_hash_update(dtls_hash_t ctx, const unsigned char *input, size_t len) {
+  SHA256_Update((SHA256_CTX *)ctx, input, len);
+}
+
+static inline size_t
+dtls_hash_finalize(unsigned char *buf, dtls_hash_t ctx) {
+  SHA256_Final(buf, (SHA256_CTX *)ctx);
+  return SHA256_DIGEST_LENGTH;
+}
+#endif /* WITH_SHA256 */
+
+/**
+ * \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 /* _HMAC_H_ */