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Diffstat (limited to 'package/ead/src/ead-crypt.c')
| -rw-r--r-- | package/ead/src/ead-crypt.c | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/package/ead/src/ead-crypt.c b/package/ead/src/ead-crypt.c new file mode 100644 index 0000000000..03721721d9 --- /dev/null +++ b/package/ead/src/ead-crypt.c @@ -0,0 +1,179 @@ +/* + * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org> + * + * 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 + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <stddef.h> +#include <stdint.h> +#include <stdlib.h> +#include <stdbool.h> +#include <string.h> +#include <unistd.h> +#include <stdio.h> +#include "ead.h" + +#include "sha1.c" +#include "aes.c" + +#if EAD_DEBUGLEVEL >= 1 +#define DEBUG(n, format, ...) do { \ + if (EAD_DEBUGLEVEL >= n) \ + fprintf(stderr, format, ##__VA_ARGS__); \ +} while (0); + +#else +#define DEBUG(n, format, ...) do {} while(0) +#endif + + +static uint32_t aes_enc_ctx[AES_PRIV_SIZE]; +static uint32_t aes_dec_ctx[AES_PRIV_SIZE]; +static uint32_t ead_rx_iv; +static uint32_t ead_tx_iv; +static uint32_t ivofs_vec; +static unsigned int ivofs_idx = 0; +static uint32_t W[80]; /* work space for sha1 */ + +#define EAD_ENC_PAD 64 + +void +ead_set_key(unsigned char *skey) +{ + uint32_t *ivp = (uint32_t *)skey; + + memset(aes_enc_ctx, 0, sizeof(aes_enc_ctx)); + memset(aes_dec_ctx, 0, sizeof(aes_dec_ctx)); + + /* first 32 bytes of skey are used as aes key for + * encryption and decryption */ + rijndaelKeySetupEnc(aes_enc_ctx, skey); + rijndaelKeySetupDec(aes_dec_ctx, skey); + + /* the following bytes are used as initialization vector for messages + * (highest byte cleared to avoid overflow) */ + ivp += 8; + ead_rx_iv = ntohl(*ivp) & 0x00ffffff; + ead_tx_iv = ead_rx_iv; + + /* the last bytes are used to feed the random iv increment */ + ivp++; + ivofs_vec = *ivp; +} + + +static bool +ead_check_rx_iv(uint32_t iv) +{ + if (iv <= ead_rx_iv) + return false; + + if (iv > ead_rx_iv + EAD_MAX_IV_INCR) + return false; + + ead_rx_iv = iv; + return true; +} + + +static uint32_t +ead_get_tx_iv(void) +{ + unsigned int ofs; + + ofs = 1 + ((ivofs_vec >> 2 * ivofs_idx) & 0x3); + ivofs_idx = (ivofs_idx + 1) % 16; + ead_tx_iv += ofs; + + return ead_tx_iv; +} + +static void +ead_hash_message(struct ead_msg_encrypted *enc, uint32_t *hash, int len) +{ + unsigned char *data = (unsigned char *) enc; + + /* hash the packet with the stored hash part initialized to zero */ + sha_init(hash); + memset(enc->hash, 0, sizeof(enc->hash)); + while (len > 0) { + sha_transform(hash, data, W); + len -= 64; + data += 64; + } +} + +void +ead_encrypt_message(struct ead_msg *msg, unsigned int len) +{ + struct ead_msg_encrypted *enc = EAD_DATA(msg, enc); + unsigned char *data = (unsigned char *) enc; + uint32_t hash[5]; + int enclen, i; + + len += sizeof(struct ead_msg_encrypted); + enc->pad = (EAD_ENC_PAD - (len % EAD_ENC_PAD)) % EAD_ENC_PAD; + enclen = len + enc->pad; + msg->len = htonl(enclen); + enc->iv = htonl(ead_get_tx_iv()); + + ead_hash_message(enc, hash, enclen); + for (i = 0; i < 5; i++) + enc->hash[i] = htonl(hash[i]); + DEBUG(2, "SHA1 generate (0x%08x), len=%d\n", enc->hash[0], enclen); + + while (enclen > 0) { + rijndaelEncrypt(aes_enc_ctx, data, data); + data += 16; + enclen -= 16; + } +} + +int +ead_decrypt_message(struct ead_msg *msg) +{ + struct ead_msg_encrypted *enc = EAD_DATA(msg, enc); + unsigned char *data = (unsigned char *) enc; + uint32_t hash_old[5], hash_new[5]; + int len = ntohl(msg->len); + int i, enclen = len; + + if (!len || (len % EAD_ENC_PAD > 0)) + return 0; + + while (len > 0) { + rijndaelDecrypt(aes_dec_ctx, data, data); + data += 16; + len -= 16; + } + + data = (unsigned char *) enc; + + if (enc->pad >= EAD_ENC_PAD) { + DEBUG(2, "Invalid padding length\n"); + return 0; + } + + if (!ead_check_rx_iv(ntohl(enc->iv))) { + DEBUG(2, "RX IV mismatch (0x%08x <> 0x%08x)\n", ead_rx_iv, ntohl(enc->iv)); + return 0; + } + + for (i = 0; i < 5; i++) + hash_old[i] = ntohl(enc->hash[i]); + ead_hash_message(enc, hash_new, enclen); + if (memcmp(hash_old, hash_new, sizeof(hash_old)) != 0) { + DEBUG(2, "SHA1 mismatch (0x%08x != 0x%08x), len=%d\n", hash_old[0], hash_new[0], enclen); + return 0; + } + + enclen -= enc->pad + sizeof(struct ead_msg_encrypted); + return enclen; +} |