| 1 | /*
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| 2 | * SHA-256 hash implementation and interface functions
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| 3 | * Copyright (c) 2003-2012, Jouni Malinen <j@w1.fi>
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| 4 | *
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| 5 | * This software may be distributed under the terms of the BSD license.
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| 6 | * See README for more details.
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| 7 | */
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| 8 |
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| 9 | #include "includes.h"
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| 10 |
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| 11 | #include "common.h"
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| 12 | #include "sha256.h"
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| 13 | #include "crypto.h"
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| 14 |
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| 15 |
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| 16 | /**
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| 17 | * hmac_sha256_vector - HMAC-SHA256 over data vector (RFC 2104)
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| 18 | * @key: Key for HMAC operations
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| 19 | * @key_len: Length of the key in bytes
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| 20 | * @num_elem: Number of elements in the data vector
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| 21 | * @addr: Pointers to the data areas
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| 22 | * @len: Lengths of the data blocks
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| 23 | * @mac: Buffer for the hash (32 bytes)
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| 24 | * Returns: 0 on success, -1 on failure
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| 25 | */
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| 26 | int hmac_sha256_vector(const u8 *key, size_t key_len, size_t num_elem,
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| 27 | const u8 *addr[], const size_t *len, u8 *mac)
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| 28 | {
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| 29 | unsigned char k_pad[64]; /* padding - key XORd with ipad/opad */
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| 30 | unsigned char tk[32];
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| 31 | const u8 *_addr[6];
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| 32 | size_t _len[6], i;
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| 33 |
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| 34 | if (num_elem > 5) {
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| 35 | /*
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| 36 | * Fixed limit on the number of fragments to avoid having to
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| 37 | * allocate memory (which could fail).
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| 38 | */
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| 39 | return -1;
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| 40 | }
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| 41 |
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| 42 | /* if key is longer than 64 bytes reset it to key = SHA256(key) */
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| 43 | if (key_len > 64) {
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| 44 | if (sha256_vector(1, &key, &key_len, tk) < 0)
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| 45 | return -1;
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| 46 | key = tk;
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| 47 | key_len = 32;
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| 48 | }
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| 49 |
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| 50 | /* the HMAC_SHA256 transform looks like:
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| 51 | *
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| 52 | * SHA256(K XOR opad, SHA256(K XOR ipad, text))
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| 53 | *
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| 54 | * where K is an n byte key
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| 55 | * ipad is the byte 0x36 repeated 64 times
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| 56 | * opad is the byte 0x5c repeated 64 times
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| 57 | * and text is the data being protected */
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| 58 |
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| 59 | /* start out by storing key in ipad */
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| 60 | os_memset(k_pad, 0, sizeof(k_pad));
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| 61 | os_memcpy(k_pad, key, key_len);
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| 62 | /* XOR key with ipad values */
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| 63 | for (i = 0; i < 64; i++)
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| 64 | k_pad[i] ^= 0x36;
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| 65 |
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| 66 | /* perform inner SHA256 */
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| 67 | _addr[0] = k_pad;
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| 68 | _len[0] = 64;
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| 69 | for (i = 0; i < num_elem; i++) {
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| 70 | _addr[i + 1] = addr[i];
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| 71 | _len[i + 1] = len[i];
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| 72 | }
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| 73 | if (sha256_vector(1 + num_elem, _addr, _len, mac) < 0)
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| 74 | return -1;
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| 75 |
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| 76 | os_memset(k_pad, 0, sizeof(k_pad));
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| 77 | os_memcpy(k_pad, key, key_len);
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| 78 | /* XOR key with opad values */
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| 79 | for (i = 0; i < 64; i++)
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| 80 | k_pad[i] ^= 0x5c;
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| 81 |
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| 82 | /* perform outer SHA256 */
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| 83 | _addr[0] = k_pad;
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| 84 | _len[0] = 64;
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| 85 | _addr[1] = mac;
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| 86 | _len[1] = SHA256_MAC_LEN;
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| 87 | return sha256_vector(2, _addr, _len, mac);
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| 88 | }
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| 89 |
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| 90 |
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| 91 | /**
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| 92 | * hmac_sha256 - HMAC-SHA256 over data buffer (RFC 2104)
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| 93 | * @key: Key for HMAC operations
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| 94 | * @key_len: Length of the key in bytes
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| 95 | * @data: Pointers to the data area
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| 96 | * @data_len: Length of the data area
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| 97 | * @mac: Buffer for the hash (32 bytes)
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| 98 | * Returns: 0 on success, -1 on failure
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| 99 | */
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| 100 | int hmac_sha256(const u8 *key, size_t key_len, const u8 *data,
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| 101 | size_t data_len, u8 *mac)
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| 102 | {
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| 103 | return hmac_sha256_vector(key, key_len, 1, &data, &data_len, mac);
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| 104 | }
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