120 lines
2.7 KiB
C
120 lines
2.7 KiB
C
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/*
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* Copyright 2003-2004, Instant802 Networks, Inc.
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* Copyright 2005, Devicescape Software, Inc.
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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/types.h>
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#include <linux/netdevice.h>
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#include <net/ieee80211.h>
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#include "ieee80211_key.h"
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#include "aes_ccm.h"
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#include "aes.c"
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static inline void aes_ccm_prepare(u32 *rk, u8 *b_0, u8 *aad, u8 *b,
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u8 *s_0, u8 *a)
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{
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int i;
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ieee80211_aes_encrypt(rk, b_0, b);
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/* Extra Authenticate-only data (always two AES blocks) */
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for (i = 0; i < AES_BLOCK_LEN; i++)
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aad[i] ^= b[i];
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ieee80211_aes_encrypt(rk, aad, b);
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aad += AES_BLOCK_LEN;
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for (i = 0; i < AES_BLOCK_LEN; i++)
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aad[i] ^= b[i];
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ieee80211_aes_encrypt(rk, aad, a);
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/* Mask out bits from auth-only-b_0 */
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b_0[0] &= 0x07;
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/* S_0 is used to encrypt T (= MIC) */
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b_0[14] = 0;
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b_0[15] = 0;
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ieee80211_aes_encrypt(rk, b_0, s_0);
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}
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void ieee80211_aes_ccm_encrypt(u32 *rk, u8 *b_0, u8 *aad, u8 *data,
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size_t data_len, u8 *cdata, u8 *mic)
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{
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int i, j, last_len, num_blocks;
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u8 *pos, *cpos;
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u8 b[AES_BLOCK_LEN], s_0[AES_BLOCK_LEN], e[AES_BLOCK_LEN];
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num_blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
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last_len = data_len % AES_BLOCK_LEN;
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aes_ccm_prepare(rk, b_0, aad, b, s_0, b);
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/* Process payload blocks */
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pos = data;
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cpos = cdata;
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for (j = 1; j <= num_blocks; j++) {
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int blen = (j == num_blocks && last_len) ?
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last_len : AES_BLOCK_LEN;
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/* Authentication followed by encryption */
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for (i = 0; i < blen; i++)
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b[i] ^= pos[i];
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ieee80211_aes_encrypt(rk, b, b);
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b_0[14] = (j >> 8) & 0xff;
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b_0[15] = j & 0xff;
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ieee80211_aes_encrypt(rk, b_0, e);
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for (i = 0; i < blen; i++)
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*cpos++ = *pos++ ^ e[i];
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}
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for (i = 0; i < CCMP_MIC_LEN; i++)
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mic[i] = b[i] ^ s_0[i];
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}
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int ieee80211_aes_ccm_decrypt(u32 *rk, u8 *b_0, u8 *aad, u8 *cdata,
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size_t data_len, u8 *mic, u8 *data)
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{
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int i, j, last_len, num_blocks;
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u8 *pos, *cpos;
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u8 b[AES_BLOCK_LEN], s_0[AES_BLOCK_LEN], a[AES_BLOCK_LEN];
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num_blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
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last_len = data_len % AES_BLOCK_LEN;
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aes_ccm_prepare(rk, b_0, aad, b, s_0, a);
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/* Process payload blocks */
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cpos = cdata;
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pos = data;
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for (j = 1; j <= num_blocks; j++) {
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int blen = (j == num_blocks && last_len) ?
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last_len : AES_BLOCK_LEN;
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/* Decryption followed by authentication */
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b_0[14] = (j >> 8) & 0xff;
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b_0[15] = j & 0xff;
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ieee80211_aes_encrypt(rk, b_0, b);
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for (i = 0; i < blen; i++) {
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*pos = *cpos++ ^ b[i];
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a[i] ^= *pos++;
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}
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ieee80211_aes_encrypt(rk, a, a);
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}
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for (i = 0; i < CCMP_MIC_LEN; i++) {
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if ((mic[i] ^ s_0[i]) != a[i])
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return -1;
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}
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return 0;
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}
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