diff options
Diffstat (limited to 'net/mac80211/aes_ccm.c')
| -rw-r--r-- | net/mac80211/aes_ccm.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/net/mac80211/aes_ccm.c b/net/mac80211/aes_ccm.c new file mode 100644 index 00000000..0785e95c --- /dev/null +++ b/net/mac80211/aes_ccm.c @@ -0,0 +1,150 @@ +/* + * Copyright 2003-2004, Instant802 Networks, Inc. + * Copyright 2005-2006, Devicescape Software, Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/crypto.h> +#include <linux/err.h> +#include <crypto/aes.h> + +#include <net/mac80211.h> +#include "key.h" +#include "aes_ccm.h" + +static void aes_ccm_prepare(struct crypto_cipher *tfm, u8 *scratch, u8 *a) +{ + int i; + u8 *b_0, *aad, *b, *s_0; + + b_0 = scratch + 3 * AES_BLOCK_SIZE; + aad = scratch + 4 * AES_BLOCK_SIZE; + b = scratch; + s_0 = scratch + AES_BLOCK_SIZE; + + crypto_cipher_encrypt_one(tfm, b, b_0); + + /* Extra Authenticate-only data (always two AES blocks) */ + for (i = 0; i < AES_BLOCK_SIZE; i++) + aad[i] ^= b[i]; + crypto_cipher_encrypt_one(tfm, b, aad); + + aad += AES_BLOCK_SIZE; + + for (i = 0; i < AES_BLOCK_SIZE; i++) + aad[i] ^= b[i]; + crypto_cipher_encrypt_one(tfm, a, aad); + + /* Mask out bits from auth-only-b_0 */ + b_0[0] &= 0x07; + + /* S_0 is used to encrypt T (= MIC) */ + b_0[14] = 0; + b_0[15] = 0; + crypto_cipher_encrypt_one(tfm, s_0, b_0); +} + + +void ieee80211_aes_ccm_encrypt(struct crypto_cipher *tfm, u8 *scratch, + u8 *data, size_t data_len, + u8 *cdata, u8 *mic) +{ + int i, j, last_len, num_blocks; + u8 *pos, *cpos, *b, *s_0, *e, *b_0; + + b = scratch; + s_0 = scratch + AES_BLOCK_SIZE; + e = scratch + 2 * AES_BLOCK_SIZE; + b_0 = scratch + 3 * AES_BLOCK_SIZE; + + num_blocks = DIV_ROUND_UP(data_len, AES_BLOCK_SIZE); + last_len = data_len % AES_BLOCK_SIZE; + aes_ccm_prepare(tfm, scratch, b); + + /* Process payload blocks */ + pos = data; + cpos = cdata; + for (j = 1; j <= num_blocks; j++) { + int blen = (j == num_blocks && last_len) ? + last_len : AES_BLOCK_SIZE; + + /* Authentication followed by encryption */ + for (i = 0; i < blen; i++) + b[i] ^= pos[i]; + crypto_cipher_encrypt_one(tfm, b, b); + + b_0[14] = (j >> 8) & 0xff; + b_0[15] = j & 0xff; + crypto_cipher_encrypt_one(tfm, e, b_0); + for (i = 0; i < blen; i++) + *cpos++ = *pos++ ^ e[i]; + } + + for (i = 0; i < CCMP_MIC_LEN; i++) + mic[i] = b[i] ^ s_0[i]; +} + + +int ieee80211_aes_ccm_decrypt(struct crypto_cipher *tfm, u8 *scratch, + u8 *cdata, size_t data_len, u8 *mic, u8 *data) +{ + int i, j, last_len, num_blocks; + u8 *pos, *cpos, *b, *s_0, *a, *b_0; + + b = scratch; + s_0 = scratch + AES_BLOCK_SIZE; + a = scratch + 2 * AES_BLOCK_SIZE; + b_0 = scratch + 3 * AES_BLOCK_SIZE; + + num_blocks = DIV_ROUND_UP(data_len, AES_BLOCK_SIZE); + last_len = data_len % AES_BLOCK_SIZE; + aes_ccm_prepare(tfm, scratch, a); + + /* Process payload blocks */ + cpos = cdata; + pos = data; + for (j = 1; j <= num_blocks; j++) { + int blen = (j == num_blocks && last_len) ? + last_len : AES_BLOCK_SIZE; + + /* Decryption followed by authentication */ + b_0[14] = (j >> 8) & 0xff; + b_0[15] = j & 0xff; + crypto_cipher_encrypt_one(tfm, b, b_0); + for (i = 0; i < blen; i++) { + *pos = *cpos++ ^ b[i]; + a[i] ^= *pos++; + } + crypto_cipher_encrypt_one(tfm, a, a); + } + + for (i = 0; i < CCMP_MIC_LEN; i++) { + if ((mic[i] ^ s_0[i]) != a[i]) + return -1; + } + + return 0; +} + + +struct crypto_cipher *ieee80211_aes_key_setup_encrypt(const u8 key[]) +{ + struct crypto_cipher *tfm; + + tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC); + if (!IS_ERR(tfm)) + crypto_cipher_setkey(tfm, key, ALG_CCMP_KEY_LEN); + + return tfm; +} + + +void ieee80211_aes_key_free(struct crypto_cipher *tfm) +{ + crypto_free_cipher(tfm); +} |