2 * One-key CBC MAC (OMAC1) hash with AES-128
4 * Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * Alternatively, this software may be distributed under the terms of BSD
13 * See README and COPYING for more details.
22 static void gf_mulx(u8 *pad)
26 carry = pad[0] & 0x80;
27 for (i = 0; i < AES_BLOCK_SIZE - 1; i++)
28 pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
29 pad[AES_BLOCK_SIZE - 1] <<= 1;
31 pad[AES_BLOCK_SIZE - 1] ^= 0x87;
36 * omac1_aes_128_vector - One-Key CBC MAC (OMAC1) hash with AES-128
37 * @key: 128-bit key for the hash operation
38 * @num_elem: Number of elements in the data vector
39 * @addr: Pointers to the data areas
40 * @len: Lengths of the data blocks
41 * @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
42 * Returns: 0 on success, -1 on failure
44 * This is a mode for using block cipher (AES in this case) for authentication.
45 * OMAC1 was standardized with the name CMAC by NIST in a Special Publication
48 int omac1_aes_128_vector(const u8 *key, size_t num_elem,
49 const u8 *addr[], const size_t *len, u8 *mac)
52 u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE];
54 size_t i, e, left, total_len;
56 ctx = aes_encrypt_init(key, 16);
59 os_memset(cbc, 0, AES_BLOCK_SIZE);
62 for (e = 0; e < num_elem; e++)
70 while (left >= AES_BLOCK_SIZE) {
71 for (i = 0; i < AES_BLOCK_SIZE; i++) {
79 if (left > AES_BLOCK_SIZE)
80 aes_encrypt(ctx, cbc, cbc);
81 left -= AES_BLOCK_SIZE;
84 os_memset(pad, 0, AES_BLOCK_SIZE);
85 aes_encrypt(ctx, pad, pad);
88 if (left || total_len == 0) {
89 for (i = 0; i < left; i++) {
101 for (i = 0; i < AES_BLOCK_SIZE; i++)
103 aes_encrypt(ctx, pad, mac);
104 aes_encrypt_deinit(ctx);
110 * omac1_aes_128 - One-Key CBC MAC (OMAC1) hash with AES-128 (aka AES-CMAC)
111 * @key: 128-bit key for the hash operation
112 * @data: Data buffer for which a MAC is determined
113 * @data_len: Length of data buffer in bytes
114 * @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
115 * Returns: 0 on success, -1 on failure
117 * This is a mode for using block cipher (AES in this case) for authentication.
118 * OMAC1 was standardized with the name CMAC by NIST in a Special Publication
121 int omac1_aes_128(const u8 *key, const u8 *data, size_t data_len, u8 *mac)
123 return omac1_aes_128_vector(key, 1, &data, &data_len, mac);