mirror of
https://github.com/vanhoefm/fragattacks.git
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0f3d578efc
Remove the GPL notification text from the files that were initially contributed by myself. Signed-hostap: Jouni Malinen <j@w1.fi>
119 lines
2.8 KiB
C
119 lines
2.8 KiB
C
/*
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* One-key CBC MAC (OMAC1) hash with AES-128
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*
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* Copyright (c) 2003-2007, 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 "aes.h"
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#include "aes_wrap.h"
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static void gf_mulx(u8 *pad)
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{
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int i, carry;
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carry = pad[0] & 0x80;
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for (i = 0; i < AES_BLOCK_SIZE - 1; i++)
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pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
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pad[AES_BLOCK_SIZE - 1] <<= 1;
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if (carry)
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pad[AES_BLOCK_SIZE - 1] ^= 0x87;
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}
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/**
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* omac1_aes_128_vector - One-Key CBC MAC (OMAC1) hash with AES-128
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* @key: 128-bit key for the hash operation
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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 MAC (128 bits, i.e., 16 bytes)
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* Returns: 0 on success, -1 on failure
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*
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* This is a mode for using block cipher (AES in this case) for authentication.
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* OMAC1 was standardized with the name CMAC by NIST in a Special Publication
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* (SP) 800-38B.
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*/
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int omac1_aes_128_vector(const u8 *key, 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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void *ctx;
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u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE];
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const u8 *pos, *end;
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size_t i, e, left, total_len;
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ctx = aes_encrypt_init(key, 16);
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if (ctx == NULL)
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return -1;
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os_memset(cbc, 0, AES_BLOCK_SIZE);
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total_len = 0;
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for (e = 0; e < num_elem; e++)
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total_len += len[e];
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left = total_len;
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e = 0;
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pos = addr[0];
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end = pos + len[0];
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while (left >= AES_BLOCK_SIZE) {
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for (i = 0; i < AES_BLOCK_SIZE; i++) {
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cbc[i] ^= *pos++;
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if (pos >= end) {
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e++;
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pos = addr[e];
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end = pos + len[e];
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}
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}
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if (left > AES_BLOCK_SIZE)
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aes_encrypt(ctx, cbc, cbc);
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left -= AES_BLOCK_SIZE;
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}
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os_memset(pad, 0, AES_BLOCK_SIZE);
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aes_encrypt(ctx, pad, pad);
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gf_mulx(pad);
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if (left || total_len == 0) {
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for (i = 0; i < left; i++) {
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cbc[i] ^= *pos++;
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if (pos >= end) {
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e++;
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pos = addr[e];
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end = pos + len[e];
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}
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}
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cbc[left] ^= 0x80;
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gf_mulx(pad);
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}
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for (i = 0; i < AES_BLOCK_SIZE; i++)
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pad[i] ^= cbc[i];
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aes_encrypt(ctx, pad, mac);
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aes_encrypt_deinit(ctx);
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return 0;
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}
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/**
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* omac1_aes_128 - One-Key CBC MAC (OMAC1) hash with AES-128 (aka AES-CMAC)
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* @key: 128-bit key for the hash operation
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* @data: Data buffer for which a MAC is determined
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* @data_len: Length of data buffer in bytes
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* @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
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* Returns: 0 on success, -1 on failure
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*
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* This is a mode for using block cipher (AES in this case) for authentication.
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* OMAC1 was standardized with the name CMAC by NIST in a Special Publication
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* (SP) 800-38B.
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*/
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int omac1_aes_128(const u8 *key, const u8 *data, size_t data_len, u8 *mac)
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{
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return omac1_aes_128_vector(key, 1, &data, &data_len, mac);
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}
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