ac9bf1cc2a
This replaces the earlier commit 4c079dcc64 ("Increment
hmac_sha*_vector() maximum num_elem value to 25") with a smaller
increment of just one extra element since the updated FTE MIC
calculation design does not use separate elements. This reduces stack
memory need. In addition, this starts using a define value for the
maximum number of vector elements to make this easier to change and to
make the code more readable.
Signed-off-by: Jouni Malinen <quic_jouni@quicinc.com>
113 lines
2.8 KiB
C
113 lines
2.8 KiB
C
/*
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* SHA-256 hash implementation and interface functions
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* Copyright (c) 2003-2012, Jouni Malinen <j@w1.fi>
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*
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* This software may be distributed under the terms of the BSD license.
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* See README for more details.
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*/
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#include "includes.h"
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#include "common.h"
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#include "sha256.h"
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#include "crypto.h"
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/**
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* hmac_sha256_vector - HMAC-SHA256 over data vector (RFC 2104)
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* @key: Key for HMAC operations
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* @key_len: Length of the key in bytes
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* @num_elem: Number of elements in the data vector
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* @addr: Pointers to the data areas
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* @len: Lengths of the data blocks
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* @mac: Buffer for the hash (32 bytes)
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* Returns: 0 on success, -1 on failure
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*/
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int hmac_sha256_vector(const u8 *key, size_t key_len, size_t num_elem,
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const u8 *addr[], const size_t *len, u8 *mac)
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{
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unsigned char k_pad[64]; /* padding - key XORd with ipad/opad */
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unsigned char tk[32];
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const u8 *_addr[HMAC_VECTOR_MAX_ELEM + 1];
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size_t _len[HMAC_VECTOR_MAX_ELEM + 1], i;
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int ret;
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if (num_elem > HMAC_VECTOR_MAX_ELEM) {
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/*
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* Fixed limit on the number of fragments to avoid having to
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* allocate memory (which could fail).
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*/
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return -1;
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}
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/* if key is longer than 64 bytes reset it to key = SHA256(key) */
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if (key_len > 64) {
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if (sha256_vector(1, &key, &key_len, tk) < 0)
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return -1;
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key = tk;
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key_len = 32;
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}
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/* the HMAC_SHA256 transform looks like:
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*
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* SHA256(K XOR opad, SHA256(K XOR ipad, text))
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*
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* where K is an n byte key
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* ipad is the byte 0x36 repeated 64 times
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* opad is the byte 0x5c repeated 64 times
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* and text is the data being protected */
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/* start out by storing key in ipad */
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os_memset(k_pad, 0, sizeof(k_pad));
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os_memcpy(k_pad, key, key_len);
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/* XOR key with ipad values */
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for (i = 0; i < 64; i++)
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k_pad[i] ^= 0x36;
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/* perform inner SHA256 */
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_addr[0] = k_pad;
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_len[0] = 64;
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for (i = 0; i < num_elem; i++) {
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_addr[i + 1] = addr[i];
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_len[i + 1] = len[i];
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}
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ret = sha256_vector(1 + num_elem, _addr, _len, mac);
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if (ret < 0)
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goto fail;
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os_memset(k_pad, 0, sizeof(k_pad));
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os_memcpy(k_pad, key, key_len);
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/* XOR key with opad values */
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for (i = 0; i < 64; i++)
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k_pad[i] ^= 0x5c;
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/* perform outer SHA256 */
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_addr[0] = k_pad;
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_len[0] = 64;
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_addr[1] = mac;
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_len[1] = SHA256_MAC_LEN;
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ret = sha256_vector(2, _addr, _len, mac);
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fail:
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forced_memzero(k_pad, sizeof(k_pad));
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forced_memzero(tk, sizeof(tk));
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return ret;
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}
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/**
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* hmac_sha256 - HMAC-SHA256 over data buffer (RFC 2104)
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* @key: Key for HMAC operations
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* @key_len: Length of the key in bytes
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* @data: Pointers to the data area
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* @data_len: Length of the data area
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* @mac: Buffer for the hash (32 bytes)
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* Returns: 0 on success, -1 on failure
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*/
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int hmac_sha256(const u8 *key, size_t key_len, const u8 *data,
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size_t data_len, u8 *mac)
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{
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return hmac_sha256_vector(key, key_len, 1, &data, &data_len, mac);
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}
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