diff options
Diffstat (limited to 'drivers/mxc/security/rng/shw_hmac.c')
| -rw-r--r-- | drivers/mxc/security/rng/shw_hmac.c | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/drivers/mxc/security/rng/shw_hmac.c b/drivers/mxc/security/rng/shw_hmac.c new file mode 100644 index 000000000000..57c086405a49 --- /dev/null +++ b/drivers/mxc/security/rng/shw_hmac.c @@ -0,0 +1,145 @@ +/* + * Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved. + */ + +/* + * The code contained herein is licensed under the GNU General Public + * License. You may obtain a copy of the GNU General Public License + * Version 2 or later at the following locations: + * + * http://www.opensource.org/licenses/gpl-license.html + * http://www.gnu.org/copyleft/gpl.html + */ + +/*! + * @file shw_hmac.c + * + * This file contains implementations for use of the (internal) SHW HMAC + * software computation. It defines the usual three steps: + * + * - #shw_hmac_init() + * - #shw_hmac_update() + * - #shw_hmac_final() + * + * + */ + +#include "shw_driver.h" +#include "shw_hmac.h" + +#ifndef __KERNEL__ +#include <asm/types.h> +#include <linux/byteorder/little_endian.h> /* or whichever is proper for target arch */ +#define printk printf +#endif + +/*! XOR value for HMAC inner key */ +#define INNER_HASH_CONSTANT 0x36 + +/*! XOR value for HMAC outer key */ +#define OUTER_HASH_CONSTANT 0x5C + +/*! + * Initialize the HMAC state structure with the HMAC key + * + * @param state Address of HMAC state structure + * @param key Address of the key to be used for the HMAC. + * @param key_len Number of bytes of @c key. + * + * Convert the key into its equivalent inner and outer hash state objects. + * + * @return FSL_RETURN_OK_S if all went well, otherwise an error code. + */ +fsl_shw_return_t shw_hmac_init(shw_hmac_state_t * state, + const uint8_t * key, unsigned int key_len) +{ + fsl_shw_return_t code = FSL_RETURN_ERROR_S; + uint8_t first_block[SHW_HASH_BLOCK_LEN]; + unsigned int i; + + /* Don't bother handling the pre-hash. */ + if (key_len > SHW_HASH_BLOCK_LEN) { + code = FSL_RETURN_BAD_KEY_LENGTH_S; + goto out; + } + + /* Prepare inner hash */ + for (i = 0; i < SHW_HASH_BLOCK_LEN; i++) { + if (i < key_len) { + first_block[i] = key[i] ^ INNER_HASH_CONSTANT; + } else { + first_block[i] = INNER_HASH_CONSTANT; + } + } + code = shw_hash_init(&state->inner_hash, FSL_HASH_ALG_SHA256); + if (code != FSL_RETURN_OK_S) { + goto out; + } + shw_hash_update(&state->inner_hash, first_block, SHW_HASH_BLOCK_LEN); + + /* Prepare outer hash */ + for (i = 0; i < SHW_HASH_BLOCK_LEN; i++) { + if (i < key_len) { + first_block[i] = key[i] ^ OUTER_HASH_CONSTANT; + } else { + first_block[i] = OUTER_HASH_CONSTANT; + } + } + code = shw_hash_init(&state->outer_hash, FSL_HASH_ALG_SHA256); + if (code != FSL_RETURN_OK_S) { + goto out; + } + shw_hash_update(&state->outer_hash, first_block, SHW_HASH_BLOCK_LEN); + + /* Wipe evidence of key */ + memset(first_block, 0, SHW_HASH_BLOCK_LEN); + + out: + return code; +} + +/*! + * Put data into the HMAC calculation + * + * Send the msg data inner inner hash's update function. + * + * @param state Address of HMAC state structure. + * @param msg Address of the message data for the HMAC. + * @param msg_len Number of bytes of @c msg. + * + * @return FSL_RETURN_OK_S if all went well, otherwise an error code. + */ +fsl_shw_return_t shw_hmac_update(shw_hmac_state_t * state, + const uint8_t * msg, unsigned int msg_len) +{ + shw_hash_update(&state->inner_hash, msg, msg_len); + + return FSL_RETURN_OK_S; +} + +/*! + * Calculate the final HMAC + * + * @param state Address of HMAC state structure. + * @param hmac Address of location to store the HMAC. + * @param hmac_len Number of bytes of @c mac to be stored. Probably best if + * this value is no greater than #SHW_HASH_LEN. + * + * This function finalizes the internal hash, and uses that result as + * data for the outer hash. As many bytes of that result are passed + * to the user as desired. + * + * @return FSL_RETURN_OK_S if all went well, otherwise an error code. + */ +fsl_shw_return_t shw_hmac_final(shw_hmac_state_t * state, + uint8_t * hmac, unsigned int hmac_len) +{ + uint8_t hash_result[SHW_HASH_LEN]; + + shw_hash_final(&state->inner_hash, hash_result, sizeof(hash_result)); + shw_hash_update(&state->outer_hash, hash_result, SHW_HASH_LEN); + + shw_hash_final(&state->outer_hash, hmac, hmac_len); + + return FSL_RETURN_OK_S; +} |