/* * 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 <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_LEN; aad = scratch + 4 * AES_BLOCK_LEN; b = scratch; s_0 = scratch + AES_BLOCK_LEN; crypto_cipher_encrypt_one(tfm, b, b_0); /* Extra Authenticate-only data (always two AES blocks) */ for (i = 0; i < AES_BLOCK_LEN; i++) aad[i] ^= b[i]; crypto_cipher_encrypt_one(tfm, b, aad); aad += AES_BLOCK_LEN; for (i = 0; i < AES_BLOCK_LEN; 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, *aad; b = scratch; s_0 = scratch + AES_BLOCK_LEN; e = scratch + 2 * AES_BLOCK_LEN; b_0 = scratch + 3 * AES_BLOCK_LEN; aad = scratch + 4 * AES_BLOCK_LEN; num_blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN); last_len = data_len % AES_BLOCK_LEN; 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_LEN; /* 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, *aad; b = scratch; s_0 = scratch + AES_BLOCK_LEN; a = scratch + 2 * AES_BLOCK_LEN; b_0 = scratch + 3 * AES_BLOCK_LEN; aad = scratch + 4 * AES_BLOCK_LEN; num_blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN); last_len = data_len % AES_BLOCK_LEN; 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_LEN; /* 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) { if (tfm) crypto_free_cipher(tfm); }