From 05d6054cec16a5f5647d86ad825fcf4ffa22a170 Mon Sep 17 00:00:00 2001 From: Jouni Malinen Date: Sun, 9 Sep 2012 18:00:14 +0300 Subject: [PATCH] wlantest: Move generic AES-CCM into separate functions This part of the implementation is not specific to CCMP and could be used for other purposes, too. Signed-hostap: Jouni Malinen --- wlantest/ccmp.c | 409 +++++++++++++++++++++++++----------------------- 1 file changed, 217 insertions(+), 192 deletions(-) diff --git a/wlantest/ccmp.c b/wlantest/ccmp.c index 6292ee0b8..af580628e 100644 --- a/wlantest/ccmp.c +++ b/wlantest/ccmp.c @@ -1,6 +1,6 @@ /* * CTR with CBC-MAC Protocol (CCMP) - * Copyright (c) 2010, Jouni Malinen + * Copyright (c) 2010-2012, Jouni Malinen * * This software may be distributed under the terms of the BSD license. * See README for more details. @@ -14,6 +14,204 @@ #include "wlantest.h" +static void xor_aes_block(u8 *dst, const u8 *src) +{ + u32 *d = (u32 *) dst; + u32 *s = (u32 *) src; + *d++ ^= *s++; + *d++ ^= *s++; + *d++ ^= *s++; + *d++ ^= *s++; +} + + +static void aes_ccm_auth_start(void *aes, size_t M, size_t L, const u8 *nonce, + const u8 *aad, size_t aad_len, size_t plain_len, + u8 *x) +{ + u8 aad_buf[2 * AES_BLOCK_SIZE]; + u8 b[AES_BLOCK_SIZE]; + + /* Authentication */ + /* B_0: Flags | Nonce N | l(m) */ + b[0] = aad_len ? 0x40 : 0 /* Adata */; + b[0] |= (((M - 2) / 2) /* M' */ << 3); + b[0] |= (L - 1) /* L' */; + os_memcpy(&b[1], nonce, 15 - L); + WPA_PUT_BE16(&b[AES_BLOCK_SIZE - L], plain_len); + + wpa_hexdump_key(MSG_EXCESSIVE, "CCM B_0", b, AES_BLOCK_SIZE); + aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */ + + if (!aad_len) + return; + + WPA_PUT_BE16(aad_buf, aad_len); + os_memcpy(aad_buf + 2, aad, aad_len); + os_memset(aad_buf + 2 + aad_len, 0, sizeof(aad_buf) - 2 - aad_len); + + xor_aes_block(aad_buf, x); + aes_encrypt(aes, aad_buf, x); /* X_2 = E(K, X_1 XOR B_1) */ + + if (aad_len > AES_BLOCK_SIZE - 2) { + xor_aes_block(&aad_buf[AES_BLOCK_SIZE], x); + /* X_3 = E(K, X_2 XOR B_2) */ + aes_encrypt(aes, &aad_buf[AES_BLOCK_SIZE], x); + } +} + + +static void aes_ccm_auth(void *aes, const u8 *data, size_t len, u8 *x) +{ + size_t last = len % AES_BLOCK_SIZE; + size_t i; + + for (i = 0; i < len / AES_BLOCK_SIZE; i++) { + /* X_i+1 = E(K, X_i XOR B_i) */ + xor_aes_block(x, data); + data += AES_BLOCK_SIZE; + aes_encrypt(aes, x, x); + } + if (last) { + /* XOR zero-padded last block */ + for (i = 0; i < last; i++) + x[i] ^= *data++; + aes_encrypt(aes, x, x); + } +} + + +static void aes_ccm_encr_start(size_t L, const u8 *nonce, u8 *a) +{ + /* A_i = Flags | Nonce N | Counter i */ + a[0] = L - 1; /* Flags = L' */ + os_memcpy(&a[1], nonce, 15 - L); +} + + +static void aes_ccm_encr(void *aes, size_t L, const u8 *in, size_t len, u8 *out, + u8 *a) +{ + size_t last = len % AES_BLOCK_SIZE; + size_t i; + + /* crypt = msg XOR (S_1 | S_2 | ... | S_n) */ + for (i = 1; i <= len / AES_BLOCK_SIZE; i++) { + WPA_PUT_BE16(&a[AES_BLOCK_SIZE - 2], i); + /* S_i = E(K, A_i) */ + aes_encrypt(aes, a, out); + xor_aes_block(out, in); + out += AES_BLOCK_SIZE; + in += AES_BLOCK_SIZE; + } + if (last) { + WPA_PUT_BE16(&a[AES_BLOCK_SIZE - 2], i); + aes_encrypt(aes, a, out); + /* XOR zero-padded last block */ + for (i = 0; i < last; i++) + *out++ ^= *in++; + } +} + + +static void aes_ccm_encr_auth(void *aes, size_t M, u8 *x, u8 *a, u8 *auth) +{ + size_t i; + u8 tmp[AES_BLOCK_SIZE]; + + wpa_hexdump_key(MSG_EXCESSIVE, "CCM T", x, M); + /* U = T XOR S_0; S_0 = E(K, A_0) */ + WPA_PUT_BE16(&a[AES_BLOCK_SIZE - 2], 0); + aes_encrypt(aes, a, tmp); + for (i = 0; i < M; i++) + auth[i] = x[i] ^ tmp[i]; + wpa_hexdump_key(MSG_EXCESSIVE, "CCM U", auth, M); +} + + +static void aes_ccm_decr_auth(void *aes, size_t M, u8 *a, const u8 *auth, u8 *t) +{ + size_t i; + u8 tmp[AES_BLOCK_SIZE]; + + wpa_hexdump_key(MSG_EXCESSIVE, "CCM U", auth, M); + /* U = T XOR S_0; S_0 = E(K, A_0) */ + WPA_PUT_BE16(&a[AES_BLOCK_SIZE - 2], 0); + aes_encrypt(aes, a, tmp); + for (i = 0; i < M; i++) + t[i] = auth[i] ^ tmp[i]; + wpa_hexdump_key(MSG_EXCESSIVE, "CCM T", t, M); +} + + +/* AES-CCM with fixed L=2 and aad_len <= 30 assumption */ +static int aes_ccm_ae(const u8 *key, size_t key_len, const u8 *nonce, + size_t M, const u8 *plain, size_t plain_len, + const u8 *aad, size_t aad_len, u8 *crypt, u8 *auth) +{ + const size_t L = 2; + void *aes; + u8 x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE]; + + if (aad_len > 30 || M > AES_BLOCK_SIZE) + return -1; + + aes = aes_encrypt_init(key, key_len); + if (aes == NULL) + return -1; + + aes_ccm_auth_start(aes, M, L, nonce, aad, aad_len, plain_len, x); + aes_ccm_auth(aes, plain, plain_len, x); + + /* Encryption */ + aes_ccm_encr_start(L, nonce, a); + aes_ccm_encr(aes, L, plain, plain_len, crypt, a); + aes_ccm_encr_auth(aes, M, x, a, auth); + + aes_encrypt_deinit(aes); + + return 0; +} + + +/* AES-CCM with fixed L=2 and aad_len <= 30 assumption */ +static int aes_ccm_ad(const u8 *key, size_t key_len, const u8 *nonce, + size_t M, const u8 *crypt, size_t crypt_len, + const u8 *aad, size_t aad_len, const u8 *auth, u8 *plain) +{ + const size_t L = 2; + void *aes; + u8 x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE]; + u8 t[AES_BLOCK_SIZE]; + + if (aad_len > 30 || M > AES_BLOCK_SIZE) + return -1; + + aes = aes_encrypt_init(key, key_len); + if (aes == NULL) + return -1; + + /* Decryption */ + aes_ccm_encr_start(L, nonce, a); + aes_ccm_decr_auth(aes, M, a, auth, t); + + /* plaintext = msg XOR (S_1 | S_2 | ... | S_n) */ + aes_ccm_encr(aes, L, crypt, crypt_len, plain, a); + + aes_ccm_auth_start(aes, M, L, nonce, aad, aad_len, crypt_len, x); + aes_ccm_auth(aes, plain, crypt_len, x); + + aes_encrypt_deinit(aes); + + if (os_memcmp(x, t, M) != 0) { + wpa_printf(MSG_EXCESSIVE, "CCM: Auth mismatch"); + return -1; + } + + return 0; +} + + static void ccmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data, u8 *aad, size_t *aad_len, u8 *nonce) { @@ -76,29 +274,13 @@ static void ccmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data, } -static void xor_aes_block(u8 *dst, const u8 *src) -{ - u32 *d = (u32 *) dst; - u32 *s = (u32 *) src; - *d++ ^= *s++; - *d++ ^= *s++; - *d++ ^= *s++; - *d++ ^= *s++; -} - - u8 * ccmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr, const u8 *data, size_t data_len, size_t *decrypted_len) { - u8 aad[2 + 30], nonce[13]; + u8 aad[30], nonce[13]; size_t aad_len; - u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE]; - void *aes; - const u8 *m, *mpos, *mic; - size_t mlen, last; - int i; - u8 *plain, *ppos; - u8 t[8]; + size_t mlen; + u8 *plain; if (data_len < 8 + 8) return NULL; @@ -107,95 +289,15 @@ u8 * ccmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr, if (plain == NULL) return NULL; - aes = aes_encrypt_init(tk, 16); - if (aes == NULL) { - os_free(plain); - return NULL; - } - - m = data + 8; mlen = data_len - 8 - 8; - last = mlen % AES_BLOCK_SIZE; os_memset(aad, 0, sizeof(aad)); - ccmp_aad_nonce(hdr, data, &aad[2], &aad_len, nonce); - WPA_PUT_BE16(aad, aad_len); - wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len); + ccmp_aad_nonce(hdr, data, aad, &aad_len, nonce); + wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", aad, aad_len); wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13); - /* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */ - - /* A_i = Flags | Nonce N | Counter i */ - a[0] = 0x01; /* Flags = L' */ - os_memcpy(&a[1], nonce, 13); - - /* Decryption */ - - mic = data + data_len - 8; - wpa_hexdump(MSG_EXCESSIVE, "CCMP U", mic, 8); - /* U = T XOR S_0; S_0 = E(K, A_0) */ - WPA_PUT_BE16(&a[14], 0); - aes_encrypt(aes, a, x); - for (i = 0; i < 8; i++) - t[i] = mic[i] ^ x[i]; - wpa_hexdump(MSG_EXCESSIVE, "CCMP T", t, 8); - - /* plaintext = msg XOR (S_1 | S_2 | ... | S_n) */ - ppos = plain; - mpos = m; - for (i = 1; i <= mlen / AES_BLOCK_SIZE; i++) { - WPA_PUT_BE16(&a[14], i); - /* S_i = E(K, A_i) */ - aes_encrypt(aes, a, ppos); - xor_aes_block(ppos, mpos); - ppos += AES_BLOCK_SIZE; - mpos += AES_BLOCK_SIZE; - } - if (last) { - WPA_PUT_BE16(&a[14], i); - aes_encrypt(aes, a, ppos); - /* XOR zero-padded last block */ - for (i = 0; i < last; i++) - *ppos++ ^= *mpos++; - } - wpa_hexdump(MSG_EXCESSIVE, "CCMP decrypted", plain, mlen); - - /* Authentication */ - /* B_0: Flags | Nonce N | l(m) */ - b[0] = 0x40 /* Adata */ | (3 /* M' */ << 3) | 1 /* L' */; - os_memcpy(&b[1], nonce, 13); - WPA_PUT_BE16(&b[14], mlen); - - wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE); - aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */ - - wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE); - xor_aes_block(aad, x); - aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */ - - wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE], - AES_BLOCK_SIZE); - xor_aes_block(&aad[AES_BLOCK_SIZE], x); - aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2) - */ - - ppos = plain; - for (i = 0; i < mlen / AES_BLOCK_SIZE; i++) { - /* X_i+1 = E(K, X_i XOR B_i) */ - xor_aes_block(x, ppos); - ppos += AES_BLOCK_SIZE; - aes_encrypt(aes, x, x); - } - if (last) { - /* XOR zero-padded last block */ - for (i = 0; i < last; i++) - x[i] ^= *ppos++; - aes_encrypt(aes, x, x); - } - - aes_encrypt_deinit(aes); - - if (os_memcmp(x, t, 8) != 0) { + if (aes_ccm_ad(tk, 16, nonce, 8, data + 8, mlen, aad, aad_len, + data + 8 + mlen, plain) < 0) { u16 seq_ctrl = le_to_host16(hdr->seq_ctrl); wpa_printf(MSG_INFO, "Invalid CCMP MIC in frame: A1=" MACSTR " A2=" MACSTR " A3=" MACSTR " seq=%u frag=%u", @@ -203,10 +305,10 @@ u8 * ccmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr, MAC2STR(hdr->addr3), WLAN_GET_SEQ_SEQ(seq_ctrl), WLAN_GET_SEQ_FRAG(seq_ctrl)); - wpa_hexdump(MSG_DEBUG, "CCMP decrypted", plain, mlen); os_free(plain); return NULL; } + wpa_hexdump(MSG_EXCESSIVE, "CCMP decrypted", plain, mlen); *decrypted_len = mlen; return plain; @@ -227,19 +329,14 @@ void ccmp_get_pn(u8 *pn, const u8 *data) u8 * ccmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos, u8 *pn, int keyid, size_t *encrypted_len) { - u8 aad[2 + 30], nonce[13]; - size_t aad_len; - u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE]; - void *aes; - u8 *crypt, *pos, *ppos, *mpos; - size_t plen, last; + u8 aad[30], nonce[13]; + size_t aad_len, plen; + u8 *crypt, *pos; struct ieee80211_hdr *hdr; - int i; if (len < hdrlen || hdrlen < 24) return NULL; plen = len - hdrlen; - last = plen % AES_BLOCK_SIZE; crypt = os_malloc(hdrlen + 8 + plen + 8 + AES_BLOCK_SIZE); if (crypt == NULL) @@ -258,91 +355,19 @@ u8 * ccmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos, *pos++ = pn[1]; /* PN4 */ *pos++ = pn[0]; /* PN5 */ - aes = aes_encrypt_init(tk, 16); - if (aes == NULL) { + os_memset(aad, 0, sizeof(aad)); + ccmp_aad_nonce(hdr, crypt + hdrlen, aad, &aad_len, nonce); + wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", aad, aad_len); + wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13); + + if (aes_ccm_ae(tk, 16, nonce, 8, frame + hdrlen, plen, aad, aad_len, + pos, pos + plen) < 0) { os_free(crypt); return NULL; } - os_memset(aad, 0, sizeof(aad)); - ccmp_aad_nonce(hdr, crypt + hdrlen, &aad[2], &aad_len, nonce); - WPA_PUT_BE16(aad, aad_len); - wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len); - wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13); - - /* Authentication */ - /* B_0: Flags | Nonce N | l(m) */ - b[0] = 0x40 /* Adata */ | (3 /* M' */ << 3) | 1 /* L' */; - os_memcpy(&b[1], nonce, 13); - WPA_PUT_BE16(&b[14], plen); - - wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE); - aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */ - - wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE); - xor_aes_block(aad, x); - aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */ - - wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE], - AES_BLOCK_SIZE); - xor_aes_block(&aad[AES_BLOCK_SIZE], x); - aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2) - */ - - ppos = frame + hdrlen; - for (i = 0; i < plen / AES_BLOCK_SIZE; i++) { - /* X_i+1 = E(K, X_i XOR B_i) */ - xor_aes_block(x, ppos); - ppos += AES_BLOCK_SIZE; - aes_encrypt(aes, x, x); - } - if (last) { - /* XOR zero-padded last block */ - for (i = 0; i < last; i++) - x[i] ^= *ppos++; - aes_encrypt(aes, x, x); - } - - /* Encryption */ - - /* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */ - - /* A_i = Flags | Nonce N | Counter i */ - a[0] = 0x01; /* Flags = L' */ - os_memcpy(&a[1], nonce, 13); - - ppos = crypt + hdrlen + 8; - - /* crypt = msg XOR (S_1 | S_2 | ... | S_n) */ - mpos = frame + hdrlen; - for (i = 1; i <= plen / AES_BLOCK_SIZE; i++) { - WPA_PUT_BE16(&a[14], i); - /* S_i = E(K, A_i) */ - aes_encrypt(aes, a, ppos); - xor_aes_block(ppos, mpos); - ppos += AES_BLOCK_SIZE; - mpos += AES_BLOCK_SIZE; - } - if (last) { - WPA_PUT_BE16(&a[14], i); - aes_encrypt(aes, a, ppos); - /* XOR zero-padded last block */ - for (i = 0; i < last; i++) - *ppos++ ^= *mpos++; - } - - wpa_hexdump(MSG_EXCESSIVE, "CCMP T", x, 8); - /* U = T XOR S_0; S_0 = E(K, A_0) */ - WPA_PUT_BE16(&a[14], 0); - aes_encrypt(aes, a, b); - for (i = 0; i < 8; i++) - ppos[i] = x[i] ^ b[i]; - wpa_hexdump(MSG_EXCESSIVE, "CCMP U", ppos, 8); - wpa_hexdump(MSG_EXCESSIVE, "CCMP encrypted", crypt + hdrlen + 8, plen); - aes_encrypt_deinit(aes); - *encrypted_len = hdrlen + 8 + plen + 8; return crypt;