1/* 2 * Copyright 2003-2004, Instant802 Networks, Inc. 3 * Copyright 2005-2006, Devicescape Software, Inc. 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 */ 9 10#include <linux/types.h> 11#include <linux/crypto.h> 12#include <linux/err.h> 13#include <asm/scatterlist.h> 14 15#include <net/mac80211.h> 16#include "ieee80211_key.h" 17#include "aes_ccm.h" 18 19 20static void ieee80211_aes_encrypt(struct crypto_cipher *tfm, 21 const u8 pt[16], u8 ct[16]) 22{ 23 crypto_cipher_encrypt_one(tfm, ct, pt); 24} 25 26 27static inline void aes_ccm_prepare(struct crypto_cipher *tfm, u8 *b_0, u8 *aad, 28 u8 *b, u8 *s_0, u8 *a) 29{ 30 int i; 31 32 ieee80211_aes_encrypt(tfm, b_0, b); 33 34 /* Extra Authenticate-only data (always two AES blocks) */ 35 for (i = 0; i < AES_BLOCK_LEN; i++) 36 aad[i] ^= b[i]; 37 ieee80211_aes_encrypt(tfm, aad, b); 38 39 aad += AES_BLOCK_LEN; 40 41 for (i = 0; i < AES_BLOCK_LEN; i++) 42 aad[i] ^= b[i]; 43 ieee80211_aes_encrypt(tfm, aad, a); 44 45 /* Mask out bits from auth-only-b_0 */ 46 b_0[0] &= 0x07; 47 48 /* S_0 is used to encrypt T (= MIC) */ 49 b_0[14] = 0; 50 b_0[15] = 0; 51 ieee80211_aes_encrypt(tfm, b_0, s_0); 52} 53 54 55void ieee80211_aes_ccm_encrypt(struct crypto_cipher *tfm, u8 *scratch, 56 u8 *b_0, u8 *aad, u8 *data, size_t data_len, 57 u8 *cdata, u8 *mic) 58{ 59 int i, j, last_len, num_blocks; 60 u8 *pos, *cpos, *b, *s_0, *e; 61 62 b = scratch; 63 s_0 = scratch + AES_BLOCK_LEN; 64 e = scratch + 2 * AES_BLOCK_LEN; 65 66 num_blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN; 67 last_len = data_len % AES_BLOCK_LEN; 68 aes_ccm_prepare(tfm, b_0, aad, b, s_0, b); 69 70 /* Process payload blocks */ 71 pos = data; 72 cpos = cdata; 73 for (j = 1; j <= num_blocks; j++) { 74 int blen = (j == num_blocks && last_len) ? 75 last_len : AES_BLOCK_LEN; 76 77 /* Authentication followed by encryption */ 78 for (i = 0; i < blen; i++) 79 b[i] ^= pos[i]; 80 ieee80211_aes_encrypt(tfm, b, b); 81 82 b_0[14] = (j >> 8) & 0xff; 83 b_0[15] = j & 0xff; 84 ieee80211_aes_encrypt(tfm, b_0, e); 85 for (i = 0; i < blen; i++) 86 *cpos++ = *pos++ ^ e[i]; 87 } 88 89 for (i = 0; i < CCMP_MIC_LEN; i++) 90 mic[i] = b[i] ^ s_0[i]; 91} 92 93 94int ieee80211_aes_ccm_decrypt(struct crypto_cipher *tfm, u8 *scratch, 95 u8 *b_0, u8 *aad, u8 *cdata, size_t data_len, 96 u8 *mic, u8 *data) 97{ 98 int i, j, last_len, num_blocks; 99 u8 *pos, *cpos, *b, *s_0, *a; 100 101 b = scratch; 102 s_0 = scratch + AES_BLOCK_LEN; 103 a = scratch + 2 * AES_BLOCK_LEN; 104 105 num_blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN; 106 last_len = data_len % AES_BLOCK_LEN; 107 aes_ccm_prepare(tfm, b_0, aad, b, s_0, a); 108 109 /* Process payload blocks */ 110 cpos = cdata; 111 pos = data; 112 for (j = 1; j <= num_blocks; j++) { 113 int blen = (j == num_blocks && last_len) ? 114 last_len : AES_BLOCK_LEN; 115 116 /* Decryption followed by authentication */ 117 b_0[14] = (j >> 8) & 0xff; 118 b_0[15] = j & 0xff; 119 ieee80211_aes_encrypt(tfm, b_0, b); 120 for (i = 0; i < blen; i++) { 121 *pos = *cpos++ ^ b[i]; 122 a[i] ^= *pos++; 123 } 124 125 ieee80211_aes_encrypt(tfm, a, a); 126 } 127 128 for (i = 0; i < CCMP_MIC_LEN; i++) { 129 if ((mic[i] ^ s_0[i]) != a[i]) 130 return -1; 131 } 132 133 return 0; 134} 135 136 137struct crypto_cipher * ieee80211_aes_key_setup_encrypt(const u8 key[]) 138{ 139 struct crypto_cipher *tfm; 140 141 tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC); 142 if (IS_ERR(tfm)) 143 return NULL; 144 145 crypto_cipher_setkey(tfm, key, ALG_CCMP_KEY_LEN); 146 147 return tfm; 148} 149 150 151void ieee80211_aes_key_free(struct crypto_cipher *tfm) 152{ 153 if (tfm) 154 crypto_free_cipher(tfm); 155} 156