Added HMAC code from TLS project

src/crypto/hmac.c

@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/**
+ * @file
+ *
+ * Keyed-Hashing for Message Authentication
+ */
+
+#include <string.h>
+#include <assert.h>
+#include <gpxe/crypto.h>
+#include <gpxe/hmac.h>
+
+/**
+ * Reduce HMAC key length
+ *
+ * @v digest		Digest algorithm to use
+ * @v digest_ctx	Digest context
+ * @v key		Key
+ * @v key_len		Length of key
+ */
+static void hmac_reduce_key ( struct crypto_algorithm *digest,
+			      void *key, size_t *key_len ) {
+	uint8_t digest_ctx[digest->ctxsize];
+
+	digest_init ( digest, digest_ctx );
+	digest_update ( digest, digest_ctx, key, *key_len );
+	digest_final ( digest, digest_ctx, key );
+	*key_len = digest->digestsize;
+}
+
+/**
+ * Initialise HMAC
+ *
+ * @v digest		Digest algorithm to use
+ * @v digest_ctx	Digest context
+ * @v key		Key
+ * @v key_len		Length of key
+ *
+ * The length of the key should be less than the block size of the
+ * digest algorithm being used.  (If the key length is greater, it
+ * will be replaced with its own digest, and key_len will be updated
+ * accordingly).
+ */
+void hmac_init ( struct crypto_algorithm *digest, void *digest_ctx,
+		 void *key, size_t *key_len ) {
+	unsigned char k_ipad[digest->blocksize];
+	unsigned int i;
+
+	/* Reduce key if necessary */
+	if ( *key_len > sizeof ( k_ipad ) )
+		hmac_reduce_key ( digest, key, key_len );
+
+	/* Construct input pad */
+	memset ( k_ipad, 0, sizeof ( k_ipad ) );
+	memcpy ( k_ipad, key, *key_len );
+	for ( i = 0 ; i < sizeof ( k_ipad ) ; i++ ) {
+		k_ipad[i] ^= 0x36;
+	}
+	
+	/* Start inner hash */
+	digest_init ( digest, digest_ctx );
+	digest_update ( digest, digest_ctx, k_ipad, sizeof ( k_ipad ) );
+}
+
+/**
+ * Finalise HMAC
+ *
+ * @v digest		Digest algorithm to use
+ * @v digest_ctx	Digest context
+ * @v key		Key
+ * @v key_len		Length of key
+ * @v hmac		HMAC digest to fill in
+ *
+ * The length of the key should be less than the block size of the
+ * digest algorithm being used.  (If the key length is greater, it
+ * will be replaced with its own digest, and key_len will be updated
+ * accordingly).
+ */
+void hmac_final ( struct crypto_algorithm *digest, void *digest_ctx,
+		  void *key, size_t *key_len, void *hmac ) {
+	unsigned char k_opad[digest->blocksize];
+	unsigned int i;
+
+	/* Reduce key if necessary */
+	if ( *key_len > sizeof ( k_opad ) )
+		hmac_reduce_key ( digest, key, key_len );
+
+	/* Construct output pad */
+	memset ( k_opad, 0, sizeof ( k_opad ) );
+	memcpy ( k_opad, key, *key_len );
+	for ( i = 0 ; i < sizeof ( k_opad ) ; i++ ) {
+		k_opad[i] ^= 0x5c;
+	}
+	
+	/* Finish inner hash */
+	digest_final ( digest, digest_ctx, hmac );
+
+	/* Perform outer hash */
+	digest_init ( digest, digest_ctx );
+	digest_update ( digest, digest_ctx, k_opad, sizeof ( k_opad ) );
+	digest_update ( digest, digest_ctx, hmac, digest->digestsize );
+	digest_final ( digest, digest_ctx, hmac );
+}

src/include/gpxe/hmac.h

@@ -0,0 +1,30 @@
+#ifndef _GPXE_HMAC_H
+#define _GPXE_HMAC_H
+
+/** @file
+ *
+ * Keyed-Hashing for Message Authentication
+ */
+
+#include <gpxe/crypto.h>
+
+/**
+ * Update HMAC
+ *
+ * @v digest		Digest algorithm to use
+ * @v digest_ctx	Digest context
+ * @v data		Data
+ * @v len		Length of data
+ */
+static inline void hmac_update ( struct crypto_algorithm *digest,
+				 void *digest_ctx, const void *data,
+				 size_t len ) {
+	digest_update ( digest, digest_ctx, data, len );
+}
+
+extern void hmac_init ( struct crypto_algorithm *digest, void *digest_ctx,
+			void *key, size_t *key_len );
+extern void hmac_final ( struct crypto_algorithm *digest, void *digest_ctx,
+			 void *key, size_t *key_len, void *hmac );
+
+#endif /* _GPXE_HMAC_H */