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146 lines
3.0 KiB
146 lines
3.0 KiB
/* |
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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/export.h> |
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#include <linux/err.h> |
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#include <crypto/aes.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_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, 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[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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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, 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, 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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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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crypto_free_cipher(tfm); |
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} |
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void ieee80211_aes_cmac_calculate_k1_k2(struct ieee80211_key_conf *keyconf, |
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u8 *k1, u8 *k2) |
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{ |
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u8 l[AES_BLOCK_SIZE] = {}; |
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struct ieee80211_key *key = |
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container_of(keyconf, struct ieee80211_key, conf); |
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crypto_cipher_encrypt_one(key->u.aes_cmac.tfm, l, l); |
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memcpy(k1, l, AES_BLOCK_SIZE); |
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gf_mulx(k1); |
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memcpy(k2, k1, AES_BLOCK_SIZE); |
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gf_mulx(k2); |
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} |
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EXPORT_SYMBOL(ieee80211_aes_cmac_calculate_k1_k2);
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