136 lines
2.7 KiB
C
136 lines
2.7 KiB
C
/*
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* AES-128-CMAC with TLen 16 for IEEE 802.11w BIP
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* Copyright 2008, Jouni Malinen <j@w1.fi>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/crypto.h>
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#include <linux/err.h>
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#include <net/mac80211.h>
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#include "key.h"
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#include "aes_cmac.h"
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#define AES_BLOCK_SIZE 16
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#define AES_CMAC_KEY_LEN 16
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#define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */
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#define AAD_LEN 20
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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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static void aes_128_cmac_vector(struct crypto_cipher *tfm, u8 *scratch,
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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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u8 *cbc, *pad;
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const u8 *pos, *end;
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size_t i, e, left, total_len;
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cbc = scratch;
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pad = scratch + AES_BLOCK_SIZE;
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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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crypto_cipher_encrypt_one(tfm, cbc, cbc);
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left -= AES_BLOCK_SIZE;
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}
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memset(pad, 0, AES_BLOCK_SIZE);
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crypto_cipher_encrypt_one(tfm, 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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crypto_cipher_encrypt_one(tfm, pad, pad);
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memcpy(mac, pad, CMAC_TLEN);
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}
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void ieee80211_aes_cmac(struct crypto_cipher *tfm, u8 *scratch, const u8 *aad,
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const u8 *data, size_t data_len, u8 *mic)
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{
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const u8 *addr[3];
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size_t len[3];
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u8 zero[CMAC_TLEN];
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memset(zero, 0, CMAC_TLEN);
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addr[0] = aad;
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len[0] = AAD_LEN;
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addr[1] = data;
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len[1] = data_len - CMAC_TLEN;
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addr[2] = zero;
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len[2] = CMAC_TLEN;
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aes_128_cmac_vector(tfm, scratch, 3, addr, len, mic);
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}
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struct crypto_cipher * ieee80211_aes_cmac_key_setup(const u8 key[])
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{
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struct crypto_cipher *tfm;
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tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
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if (IS_ERR(tfm))
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return NULL;
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crypto_cipher_setkey(tfm, key, AES_CMAC_KEY_LEN);
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return tfm;
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}
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void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm)
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{
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if (tfm)
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crypto_free_cipher(tfm);
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}
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