Refactor and change CMAC interface
Change the CMAC interface to match the mbedtls_md_hmac_xxxx() interface. This
changes the overall design of the CMAC interface to make it more consistent with
the existing HMAC interface, and will allow incremental updates of input data
rather than requiring all data to be presented at once, which is what the
current interface requires.
diff --git a/include/mbedtls/cmac.h b/include/mbedtls/cmac.h
index ddacb21..ceeb20a 100644
--- a/include/mbedtls/cmac.h
+++ b/include/mbedtls/cmac.h
@@ -1,9 +1,10 @@
/**
* \file cmac.h
*
- * \brief The CMAC Mode for Authentication
+ * \brief Cipher-based Message Authentication Code (CMAC) Mode for
+ * Authentication
*
- * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
+ * Copyright (C) 2015-2016, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -23,110 +24,131 @@
#ifndef MBEDTLS_CMAC_H
#define MBEDTLS_CMAC_H
-#include "cipher.h"
-
-#define MBEDTLS_ERR_CMAC_BAD_INPUT -0x0011 /**< Bad input parameters to function. */
-#define MBEDTLS_ERR_CMAC_VERIFY_FAILED -0x0013 /**< Verification failed. */
-#define MBEDTLS_ERR_CMAC_ALLOC_FAILED -0x0015 /**< Failed to allocate memory */
-
+#include "mbedtls/cipher.h"
#ifdef __cplusplus
extern "C" {
#endif
+#if defined(MBEDTLS_AES_C)
+#define MBEDTLS_CIPHER_BLKSIZE_MAX_SIZE 16 /* longest known is AES */
+#else
+#define MBEDTLS_CIPHER_BLKSIZE_MAX_SIZE 8 /* longest known is 3DES */
+#endif
+
/**
* \brief CMAC context structure
*/
-typedef struct {
- mbedtls_cipher_context_t cipher_ctx; /*!< cipher context used */
- unsigned char* K1; /*!< CMAC Subkey 1 */
- unsigned char* K2; /*!< CMAC Subkey 2 */
+typedef struct mbedtls_cmac_context_t {
+
+ /** Internal state of the CMAC algorithm */
+ unsigned char state[MBEDTLS_CIPHER_BLKSIZE_MAX_SIZE];
+
+ /** Unprocessed data - either data that was not block aligned and is still
+ * pending to be processed, or the final block */
+ unsigned char unprocessed_block[MBEDTLS_CIPHER_BLKSIZE_MAX_SIZE];
+
+ /** Length of data pending to be processed */
+ size_t unprocessed_len;
+
+ /** Flag to indicate if the last block needs padding */
+ int padding_flag;
}
-mbedtls_cmac_context;
+mbedtls_cmac_context_t;
/**
- * \brief Initialize CMAC context (just makes references valid)
- * Makes the context ready for mbedtls_cmac_setkey() or
- * mbedtls_cmac_free().
+ * \brief Set the CMAC key and prepare to authenticate the input
+ * data.
+ * Should be called with an initialised cipher context.
*
- * \param ctx CMAC context to initialize
+ * \param ctx Cipher context
+ * \param key CMAC key
+ * \param keybits length of the CMAC key in bits
+ * (must be acceptable by the cipher)
+ *
+ * \return 0 if successful, or a cipher specific error code
*/
-void mbedtls_cmac_init( mbedtls_cmac_context *ctx );
+int mbedtls_cipher_cmac_starts( mbedtls_cipher_context_t *ctx,
+ const unsigned char *key, size_t keylen );
/**
- * \brief Initialize the CMAC context
+ * \brief Generic CMAC process buffer.
+ * Called between mbedtls_cipher_cmac_starts() or
+ * mbedtls_cipher_cmac_reset() and
+ * mbedtls_cipher_cmac_finish().
+ * May be called repeatedly.
*
- * \param ctx CMAC context to be initialized
- * \param cipher cipher to use.
- Cipher block size must be 8 bytes or 16 bytes.
- * \param key encryption key
- * \param keybits encryption key size in bits (must be acceptable by the cipher)
+ * \param ctx CMAC context
+ * \param input buffer holding the data
+ * \param ilen length of the input data
*
- * \return 0 if successful, or a cipher specific error code
+ * \returns 0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ * verification fails.
*/
-int mbedtls_cmac_setkey( mbedtls_cmac_context *ctx,
- mbedtls_cipher_id_t cipher,
- const unsigned char *key,
- unsigned int keybits );
+int mbedtls_cipher_cmac_update( mbedtls_cipher_context_t *ctx,
+ const unsigned char *input, size_t ilen );
/**
- * \brief Free a CMAC context and underlying cipher sub-context
- * Securely wipes sub keys and other sensitive data.
+ * \brief Output CMAC.
+ * Called after mbedtls_cipher_cmac_update().
+ * Usually followed by mbedtls_cipher_cmac_reset(), then
+ * mbedtls_cipher_cmac_starts(), or mbedtls_cipher_free().
*
- * \param ctx CMAC context to free
+ * \param ctx CMAC context
+ * \param output Generic CMAC checksum result
+ *
+ * \returns 0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ * verification fails.
*/
-void mbedtls_cmac_free( mbedtls_cmac_context *ctx );
+int mbedtls_cipher_cmac_finish( mbedtls_cipher_context_t *ctx,
+ unsigned char *output );
/**
- * \brief Generate a CMAC tag.
+ * \brief Prepare to authenticate a new message with the same key.
+ * Called after mbedtls_cipher_cmac_finish() and before
+ * mbedtls_cipher_cmac_update().
*
- * \param ctx CMAC context
- * \param input buffer holding the input data
- * \param in_len length of the input data in bytes
- * \param tag buffer for holding the generated tag
- * \param tag_len length of the tag to generate in bytes
- * Must be 2, 4, 6, 8 if cipher block size is 8
- * Must be 2, 4, 6, 8, 10, 12, 14 or 16 if cipher block size is 16
+ * \param ctx CMAC context to be reset
*
- * \return 0 if successful
+ * \returns 0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ * verification fails.
*/
-int mbedtls_cmac_generate( mbedtls_cmac_context *ctx,
- const unsigned char *input, size_t in_len,
- unsigned char *tag, size_t tag_len );
+int mbedtls_cipher_cmac_reset( mbedtls_cipher_context_t *ctx );
/**
- * \brief Verify a CMAC tag.
+ * \brief Output = Generic_CMAC( hmac key, input buffer )
*
- * \param ctx CMAC context
- * \param input buffer holding the input data
- * \param in_len length of the input data in bytes
- * \param tag buffer holding the tag to verify
- * \param tag_len length of the tag to verify in bytes
- * Must be 2, 4, 6, 8 if cipher block size is 8
- * Must be 2, 4, 6, 8, 10, 12, 14 or 16 if cipher block size is 16
- * \return 0 if successful and authenticated
- * MBEDTLS_ERR_CMAC_VERIFY_FAILED if tag does not match
+ * \param cipher_info message digest info
+ * \param key CMAC key
+ * \param keylen length of the CMAC key in bits
+ * \param input buffer holding the data
+ * \param ilen length of the input data
+ * \param output Generic CMAC-result
+ *
+ * \returns 0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ * verification fails.
*/
-int mbedtls_cmac_verify( mbedtls_cmac_context *ctx,
- const unsigned char *input, size_t in_len,
- const unsigned char *tag, size_t tag_len );
+int mbedtls_cipher_cmac( const mbedtls_cipher_info_t *cipher_info,
+ const unsigned char *key, size_t keylen,
+ const unsigned char *input, size_t ilen,
+ unsigned char *output );
#ifdef MBEDTLS_AES_C
/**
* \brief AES-CMAC-128-PRF
- * See RFC 4615 for details
+ * Implementation of (AES-CMAC-PRF-128), as defined in RFC 4615
*
* \param key PRF key
- * \param key_len PRF key length
+ * \param key_len PRF key length in bytes
* \param input buffer holding the input data
* \param in_len length of the input data in bytes
- * \param tag buffer holding the generated pseudorandom output (16 bytes)
+ * \param output buffer holding the generated pseudorandom output (16 bytes)
*
* \return 0 if successful
*/
int mbedtls_aes_cmac_prf_128( const unsigned char *key, size_t key_len,
const unsigned char *input, size_t in_len,
- unsigned char tag[16] );
+ unsigned char output[16] );
#endif /* MBEDTLS_AES_C */
#if defined(MBEDTLS_SELF_TEST) && ( defined(MBEDTLS_AES_C) || defined(MBEDTLS_DES_C) )