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 <j@w1.fi>
This commit is contained in:
Jouni Malinen 2012-09-09 18:00:14 +03:00
parent 071c6164ab
commit 05d6054cec

View file

@ -1,6 +1,6 @@
/* /*
* CTR with CBC-MAC Protocol (CCMP) * CTR with CBC-MAC Protocol (CCMP)
* Copyright (c) 2010, Jouni Malinen <j@w1.fi> * Copyright (c) 2010-2012, Jouni Malinen <j@w1.fi>
* *
* This software may be distributed under the terms of the BSD license. * This software may be distributed under the terms of the BSD license.
* See README for more details. * See README for more details.
@ -14,6 +14,204 @@
#include "wlantest.h" #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, static void ccmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data,
u8 *aad, size_t *aad_len, u8 *nonce) 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, u8 * ccmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
const u8 *data, size_t data_len, size_t *decrypted_len) 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; size_t aad_len;
u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE]; size_t mlen;
void *aes; u8 *plain;
const u8 *m, *mpos, *mic;
size_t mlen, last;
int i;
u8 *plain, *ppos;
u8 t[8];
if (data_len < 8 + 8) if (data_len < 8 + 8)
return NULL; return NULL;
@ -107,95 +289,15 @@ u8 * ccmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
if (plain == NULL) if (plain == NULL)
return 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; mlen = data_len - 8 - 8;
last = mlen % AES_BLOCK_SIZE;
os_memset(aad, 0, sizeof(aad)); os_memset(aad, 0, sizeof(aad));
ccmp_aad_nonce(hdr, data, &aad[2], &aad_len, nonce); ccmp_aad_nonce(hdr, data, aad, &aad_len, nonce);
WPA_PUT_BE16(aad, aad_len); wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", aad, aad_len);
wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len);
wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13); wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13);
/* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */ if (aes_ccm_ad(tk, 16, nonce, 8, data + 8, mlen, aad, aad_len,
data + 8 + mlen, plain) < 0) {
/* 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) {
u16 seq_ctrl = le_to_host16(hdr->seq_ctrl); u16 seq_ctrl = le_to_host16(hdr->seq_ctrl);
wpa_printf(MSG_INFO, "Invalid CCMP MIC in frame: A1=" MACSTR wpa_printf(MSG_INFO, "Invalid CCMP MIC in frame: A1=" MACSTR
" A2=" MACSTR " A3=" MACSTR " seq=%u frag=%u", " 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), MAC2STR(hdr->addr3),
WLAN_GET_SEQ_SEQ(seq_ctrl), WLAN_GET_SEQ_SEQ(seq_ctrl),
WLAN_GET_SEQ_FRAG(seq_ctrl)); WLAN_GET_SEQ_FRAG(seq_ctrl));
wpa_hexdump(MSG_DEBUG, "CCMP decrypted", plain, mlen);
os_free(plain); os_free(plain);
return NULL; return NULL;
} }
wpa_hexdump(MSG_EXCESSIVE, "CCMP decrypted", plain, mlen);
*decrypted_len = mlen; *decrypted_len = mlen;
return plain; 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 * ccmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
u8 *pn, int keyid, size_t *encrypted_len) u8 *pn, int keyid, size_t *encrypted_len)
{ {
u8 aad[2 + 30], nonce[13]; u8 aad[30], nonce[13];
size_t aad_len; size_t aad_len, plen;
u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE]; u8 *crypt, *pos;
void *aes;
u8 *crypt, *pos, *ppos, *mpos;
size_t plen, last;
struct ieee80211_hdr *hdr; struct ieee80211_hdr *hdr;
int i;
if (len < hdrlen || hdrlen < 24) if (len < hdrlen || hdrlen < 24)
return NULL; return NULL;
plen = len - hdrlen; plen = len - hdrlen;
last = plen % AES_BLOCK_SIZE;
crypt = os_malloc(hdrlen + 8 + plen + 8 + AES_BLOCK_SIZE); crypt = os_malloc(hdrlen + 8 + plen + 8 + AES_BLOCK_SIZE);
if (crypt == NULL) 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[1]; /* PN4 */
*pos++ = pn[0]; /* PN5 */ *pos++ = pn[0]; /* PN5 */
aes = aes_encrypt_init(tk, 16); os_memset(aad, 0, sizeof(aad));
if (aes == NULL) { 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); os_free(crypt);
return NULL; 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); wpa_hexdump(MSG_EXCESSIVE, "CCMP encrypted", crypt + hdrlen + 8, plen);
aes_encrypt_deinit(aes);
*encrypted_len = hdrlen + 8 + plen + 8; *encrypted_len = hdrlen + 8 + plen + 8;
return crypt; return crypt;