2 * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2
6 * as published by the Free Software Foundation
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
26 #if EAD_DEBUGLEVEL >= 1
27 #define DEBUG(n, format, ...) do { \
28 if (EAD_DEBUGLEVEL >= n) \
29 fprintf(stderr, format, ##__VA_ARGS__); \
33 #define DEBUG(n, format, ...) do {} while(0)
37 static uint32_t aes_enc_ctx[AES_PRIV_SIZE];
38 static uint32_t aes_dec_ctx[AES_PRIV_SIZE];
39 static uint32_t ead_rx_iv;
40 static uint32_t ead_tx_iv;
41 static uint32_t ivofs_vec;
42 static unsigned int ivofs_idx = 0;
43 static uint32_t W[80]; /* work space for sha1 */
45 #define EAD_ENC_PAD 64
48 ead_set_key(unsigned char *skey)
50 uint32_t *ivp = (uint32_t *)skey;
52 memset(aes_enc_ctx, 0, sizeof(aes_enc_ctx));
53 memset(aes_dec_ctx, 0, sizeof(aes_dec_ctx));
55 /* first 32 bytes of skey are used as aes key for
56 * encryption and decryption */
57 rijndaelKeySetupEnc(aes_enc_ctx, skey);
58 rijndaelKeySetupDec(aes_dec_ctx, skey);
60 /* the following bytes are used as initialization vector for messages
61 * (highest byte cleared to avoid overflow) */
63 ead_rx_iv = ntohl(*ivp) & 0x00ffffff;
64 ead_tx_iv = ead_rx_iv;
66 /* the last bytes are used to feed the random iv increment */
73 ead_check_rx_iv(uint32_t iv)
78 if (iv > ead_rx_iv + EAD_MAX_IV_INCR)
91 ofs = 1 + ((ivofs_vec >> 2 * ivofs_idx) & 0x3);
92 ivofs_idx = (ivofs_idx + 1) % 16;
99 ead_hash_message(struct ead_msg_encrypted *enc, uint32_t *hash, int len)
101 unsigned char *data = (unsigned char *) enc;
103 /* hash the packet with the stored hash part initialized to zero */
105 memset(enc->hash, 0, sizeof(enc->hash));
107 sha_transform(hash, data, W);
114 ead_encrypt_message(struct ead_msg *msg, unsigned int len)
116 struct ead_msg_encrypted *enc = EAD_DATA(msg, enc);
117 unsigned char *data = (unsigned char *) enc;
121 len += sizeof(struct ead_msg_encrypted);
122 enc->pad = (EAD_ENC_PAD - (len % EAD_ENC_PAD)) % EAD_ENC_PAD;
123 enclen = len + enc->pad;
124 msg->len = htonl(enclen);
125 enc->iv = htonl(ead_get_tx_iv());
127 ead_hash_message(enc, hash, enclen);
128 for (i = 0; i < 5; i++)
129 enc->hash[i] = htonl(hash[i]);
130 DEBUG(2, "SHA1 generate (0x%08x), len=%d\n", enc->hash[0], enclen);
133 rijndaelEncrypt(aes_enc_ctx, data, data);
140 ead_decrypt_message(struct ead_msg *msg)
142 struct ead_msg_encrypted *enc = EAD_DATA(msg, enc);
143 unsigned char *data = (unsigned char *) enc;
144 uint32_t hash_old[5], hash_new[5];
145 int len = ntohl(msg->len);
148 if (!len || (len % EAD_ENC_PAD > 0))
152 rijndaelDecrypt(aes_dec_ctx, data, data);
157 data = (unsigned char *) enc;
159 if (enc->pad >= EAD_ENC_PAD) {
160 DEBUG(2, "Invalid padding length\n");
164 if (!ead_check_rx_iv(ntohl(enc->iv))) {
165 DEBUG(2, "RX IV mismatch (0x%08x <> 0x%08x)\n", ead_rx_iv, ntohl(enc->iv));
169 for (i = 0; i < 5; i++)
170 hash_old[i] = ntohl(enc->hash[i]);
171 ead_hash_message(enc, hash_new, enclen);
172 if (memcmp(hash_old, hash_new, sizeof(hash_old)) != 0) {
173 DEBUG(2, "SHA1 mismatch (0x%08x != 0x%08x), len=%d\n", hash_old[0], hash_new[0], enclen);
177 enclen -= enc->pad + sizeof(struct ead_msg_encrypted);