Bluetooth: SMP: Use TinyCrypt for AES CMAC
TinyCrypt provides implementation of AES CMAC so there is not need for internal implementation in SMP code. Change-Id: I15fe0daf8fca8c44b002636983b46502419c57a5 Signed-off-by: Szymon Janc <ext.szymon.janc@tieto.com>
This commit is contained in:
Szymon Janc
Gerrit Code Review
parent
c70c851ded
commit
3ed1a37a41
6 changed files with 27 additions and 172 deletions
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@ -29,28 +29,21 @@ if BLUETOOTH
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config BLUETOOTH_LE
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bool "Bluetooth Low Energy (LE) support"
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default n
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select TINYCRYPT
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select TINYCRYPT_AES if BLUETOOTH_SMP
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select TINYCRYPT_AES_CMAC if BLUETOOTH_SMP
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select TINYCRYPT_SHA256
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select TINYCRYPT_SHA256_HMAC
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select TINYCRYPT_SHA256_HMAC_PRNG
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help
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This option enables Bluetooth Low Energy (LE) support.
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Currently it is mandatory whenever Bluetooth support
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(CONFIG_BLUETOOTH) is enabled.
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if BLUETOOTH_LE
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config BLUETOOTH_TINYCRYPT
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bool "Use TinyCrypt library"
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default n
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select TINYCRYPT
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select TINYCRYPT_AES if BLUETOOTH_SMP
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select TINYCRYPT_SHA256
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select TINYCRYPT_SHA256_HMAC
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select TINYCRYPT_SHA256_HMAC_PRNG
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help
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If this option is set TinyCrypt library is used for Bluetooth
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cryptographic operations. If not set controller crypto is used.
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config BLUETOOTH_TINYCRYPT_ECC
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bool "Use TinyCrypt library for ECDH"
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default n
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depends on BLUETOOTH_TINYCRYPT
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select TINYCRYPT_ECC_DH
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help
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If this option is set TinyCrypt library is also used for LE Secure
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@ -37,6 +37,7 @@
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#if defined(CONFIG_TINYCRYPT_AES)
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#include <tinycrypt/aes.h>
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#include <tinycrypt/utils.h>
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#include <tinycrypt/cmac_mode.h>
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#endif
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#if defined(CONFIG_TINYCRYPT_ECC_DH)
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@ -267,17 +268,6 @@ static const char *h(const void *buf, size_t len)
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#define BT_DBG(fmt, ...)
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#endif
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typedef struct {
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uint64_t a;
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uint64_t b;
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} uint128_t;
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static void xor_128(const uint128_t *p, const uint128_t *q, uint128_t *r)
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{
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r->a = p->a ^ q->a;
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r->b = p->b ^ q->b;
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}
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/* swap octets for LE encrypt */
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static void swap_buf(uint8_t *dst, const uint8_t *src, uint16_t len)
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{
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@ -389,68 +379,6 @@ static int smp_ah(const uint8_t irk[16], const uint8_t r[3], uint8_t out[3])
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return 0;
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}
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/* 1 bit left shift */
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static void array_shift(const uint8_t *in, uint8_t *out)
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{
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uint8_t overflow = 0;
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for (int i = 15; i >= 0; i--) {
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out[i] = in[i] << 1;
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/* previous byte */
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out[i] |= overflow;
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overflow = in[i] & 0x80 ? 1 : 0;
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}
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}
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/* CMAC subkey generation algorithm */
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static int cmac_subkey(const uint8_t *key, uint8_t *k1, uint8_t *k2)
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{
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static const uint8_t rb[16] = {
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[0 ... 14] = 0x00,
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[15] = 0x87,
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};
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uint8_t l[16] = { 0 };
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int err;
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/* L := AES-128(K, const_Zero) */
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err = le_encrypt(key, l, l);
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if (err) {
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return err;
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}
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swap_in_place(l, 16);
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BT_DBG("l %s", h(l, 16));
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/* if MSB(L) == 0 K1 = L << 1 */
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if (!(l[0] & 0x80)) {
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array_shift(l, k1);
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/* else K1 = (L << 1) XOR rb */
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} else {
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array_shift(l, k1);
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xor_128((uint128_t *)k1, (uint128_t *)rb, (uint128_t *)k1);
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}
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/* if MSB(K1) == 0 K2 = K1 << 1 */
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if (!(k1[0] & 0x80)) {
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array_shift(k1, k2);
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/* else K2 = (K1 << 1) XOR rb */
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} else {
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array_shift(k1, k2);
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xor_128((uint128_t *)k2, (uint128_t *)rb, (uint128_t *)k2);
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}
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return 0;
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}
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/* padding(x) = x || 10^i where i is 128 - 8 * r - 1 */
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static void add_pad(const uint8_t *in, unsigned char *out, int len)
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{
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memset(out, 0, 16);
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memcpy(out, in, len);
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out[len] = 0x80;
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}
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/* Cypher based Message Authentication Code (CMAC) with AES 128 bit
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*
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* Input : key ( 128-bit key )
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@ -461,95 +389,22 @@ static void add_pad(const uint8_t *in, unsigned char *out, int len)
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static int bt_smp_aes_cmac(const uint8_t *key, const uint8_t *in, size_t len,
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uint8_t *out)
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{
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uint8_t k1[16], k2[16], last_block[16], *pad_block = last_block;
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uint8_t key_s[16];
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uint8_t *x, *y;
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uint8_t n, flag;
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int err;
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struct tc_aes_key_sched_struct sched;
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struct tc_cmac_struct state;
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swap_buf(key_s, key, 16);
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/* (K1,K2) = Generate_Subkey(K) */
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err = cmac_subkey(key_s, k1, k2);
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if (err) {
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BT_ERR("SMAC subkey generation failed");
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return err;
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if (tc_cmac_setup(&state, key, &sched) == TC_FAIL) {
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return -EIO;
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}
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BT_DBG("key %s subkeys k1 %s k2 %s", h(key, 16), h(k1, 16),
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h(k2, 16));
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/* the number of blocks, n, is calculated, the block length is 16 bytes
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* n = ceil(len/const_Bsize)
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*/
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n = (len + 15) / 16;
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/* check input length, flag indicate completed blocks */
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if (n == 0) {
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/* if length is 0, the number of blocks to be processed shall
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* be 1,and the flag shall be marked as not-complete-block
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* false
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*/
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n = 1;
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flag = 0;
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} else {
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if ((len % 16) == 0) {
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/* complete blocks */
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flag = 1;
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} else {
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/* last block is not complete */
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flag = 0;
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}
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if (tc_cmac_update(&state, in, len) == TC_FAIL) {
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return -EIO;
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}
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BT_DBG("len %u n %u flag %u", len, n, flag);
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/* if flag is true then M_last = M_n XOR K1 */
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if (flag) {
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xor_128((uint128_t *)&in[16 * (n - 1)], (uint128_t *)k1,
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(uint128_t *)last_block);
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/* else M_last = padding(M_n) XOR K2 */
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} else {
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add_pad(&in[16 * (n - 1)], pad_block, len % 16);
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xor_128((uint128_t *)pad_block, (uint128_t *)k2,
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(uint128_t *)last_block);
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if (tc_cmac_final(out, &state) == TC_FAIL) {
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return -EIO;
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}
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/* Reuse k1 and k2 buffers */
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x = k1;
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y = k2;
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/* Zeroing x */
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memset(x, 0, 16);
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/* the basic CBC-MAC is applied to M_1,...,M_{n-1},M_last */
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for (int i = 0; i < n - 1; i++) {
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/* Y = X XOR M_i */
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xor_128((uint128_t *)x, (uint128_t *)&in[i * 16],
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(uint128_t *)y);
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swap_in_place(y, 16);
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/* X = AES-128(K,Y) */
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err = le_encrypt(key_s, y, x);
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if (err) {
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return err;
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}
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swap_in_place(x, 16);
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}
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/* Y = M_last XOR X */
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xor_128((uint128_t *)x, (uint128_t *)last_block, (uint128_t *)y);
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swap_in_place(y, 16);
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/* T = AES-128(K,Y) */
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err = le_encrypt(key_s, y, out);
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swap_in_place(out, 16);
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return err;
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return 0;
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}
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static int smp_f4(const uint8_t *u, const uint8_t *v, const uint8_t *x,
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@ -863,6 +718,17 @@ static uint8_t get_encryption_key_size(struct bt_smp *smp)
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}
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#if !defined(CONFIG_BLUETOOTH_SMP_SC_ONLY)
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typedef struct {
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uint64_t a;
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uint64_t b;
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} uint128_t;
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static void xor_128(const uint128_t *p, const uint128_t *q, uint128_t *r)
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{
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r->a = p->a ^ q->a;
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r->b = p->b ^ q->b;
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}
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static int smp_c1(const uint8_t k[16], const uint8_t r[16],
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const uint8_t preq[7], const uint8_t pres[7],
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const bt_addr_le_t *ia, const bt_addr_le_t *ra,
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@ -3,7 +3,6 @@ CONFIG_BLUETOOTH_LE=y
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CONFIG_BLUETOOTH_DEBUG=y
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CONFIG_BLUETOOTH_SMP=y
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CONFIG_BLUETOOTH_SIGNING=y
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CONFIG_BLUETOOTH_TINYCRYPT=y
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CONFIG_BLUETOOTH_PERIPHERAL=y
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CONFIG_BLUETOOTH_L2CAP_DYNAMIC_CHANNEL=y
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CONFIG_NETWORKING=y
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@ -3,6 +3,5 @@ CONFIG_BLUETOOTH_LE=y
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CONFIG_BLUETOOTH_DEBUG=y
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CONFIG_BLUETOOTH_SMP=y
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CONFIG_BLUETOOTH_SIGNING=y
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CONFIG_BLUETOOTH_TINYCRYPT=y
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CONFIG_BLUETOOTH_PERIPHERAL=y
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CONFIG_BLUETOOTH_GATT_DYNAMIC_DB=y
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@ -2,6 +2,5 @@ CONFIG_BLUETOOTH=y
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CONFIG_BLUETOOTH_LE=y
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CONFIG_BLUETOOTH_DEBUG=y
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CONFIG_BLUETOOTH_SMP=y
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CONFIG_BLUETOOTH_TINYCRYPT=y
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CONFIG_BLUETOOTH_PERIPHERAL=y
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CONFIG_BLUETOOTH_GATT_DYNAMIC_DB=y
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@ -10,6 +10,5 @@ CONFIG_BLUETOOTH_SMP=y
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CONFIG_BLUETOOTH_SIGNING=y
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CONFIG_BLUETOOTH_GATT_CLIENT=y
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CONFIG_BLUETOOTH_L2CAP_DYNAMIC_CHANNEL=y
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CONFIG_BLUETOOTH_TINYCRYPT=y
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CONFIG_BLUETOOTH_TINYCRYPT_ECC=y
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CONFIG_CONSOLE_HANDLER_SHELL=y
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