/******************************************************************************
*
* Copyright (C) 2008-2012 Broadcom Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
******************************************************************************/
/******************************************************************************
*
* This file contains the implementation of the AES128 CMAC algorithm.
*
******************************************************************************/
#include "bt_target.h"
#if SMP_INCLUDED == TRUE
#include <stdio.h>
#include <string.h>
#include "btm_ble_api.h"
#include "smp_int.h"
#include "hcimsgs.h"
typedef struct
{
UINT8 *text;
UINT16 len;
UINT16 round;
}tCMAC_CB;
tCMAC_CB cmac_cb;
/* Rb for AES-128 as block cipher, LSB as [0] */
BT_OCTET16 const_Rb = {
0x87, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
void print128(BT_OCTET16 x, const UINT8 *key_name)
{
#if SMP_DEBUG == TRUE
UINT8 *p = (UINT8 *)x;
UINT8 i;
SMP_TRACE_WARNING1("%s(MSB ~ LSB) = ", key_name);
for (i = 0; i < 4; i ++)
{
SMP_TRACE_WARNING4("%02x %02x %02x %02x",
p[BT_OCTET16_LEN - i*4 -1], p[BT_OCTET16_LEN - i*4 -2],
p[BT_OCTET16_LEN - i*4 -3], p[BT_OCTET16_LEN - i*4 -4]);
}
#endif
}
/*******************************************************************************
**
** Function padding
**
** Description utility function to padding the given text to be a 128 bits
** data. The parameter dest is input and output parameter, it
** must point to a BT_OCTET16_LEN memory space; where include
** length bytes valid data.
**
** Returns void
**
*******************************************************************************/
static void padding ( BT_OCTET16 dest, UINT8 length )
{
UINT8 i, *p = dest;
/* original last block */
for ( i = length ; i < BT_OCTET16_LEN; i++ )
p[BT_OCTET16_LEN - i - 1] = ( i == length ) ? 0x80 : 0;
}
/*******************************************************************************
**
** Function leftshift_onebit
**
** Description utility function to left shift one bit for a 128 bits value.
**
** Returns void
**
*******************************************************************************/
static void leftshift_onebit(UINT8 *input, UINT8 *output)
{
UINT8 i, overflow = 0 , next_overflow = 0;
SMP_TRACE_EVENT0 ("leftshift_onebit ");
/* input[0] is LSB */
for ( i = 0; i < BT_OCTET16_LEN ; i ++ )
{
next_overflow = (input[i] & 0x80) ? 1:0;
output[i] = (input[i] << 1) | overflow;
overflow = next_overflow;
}
return;
}
/*******************************************************************************
**
** Function cmac_aes_cleanup
**
** Description clean up function for AES_CMAC algorithm.
**
** Returns void
**
*******************************************************************************/
static void cmac_aes_cleanup(void)
{
if (cmac_cb.text != NULL)
{
GKI_freebuf(cmac_cb.text);
}
memset(&cmac_cb, 0, sizeof(tCMAC_CB));
}
/*******************************************************************************
**
** Function cmac_aes_k_calculate
**
** Description This function is the calculation of block cipher using AES-128.
**
** Returns void
**
*******************************************************************************/
static BOOLEAN cmac_aes_k_calculate(BT_OCTET16 key, UINT8 *p_signature, UINT16 tlen)
{
tSMP_ENC output;
UINT8 i = 1, err = 0;
UINT8 x[16] = {0};
UINT8 *p_mac;
SMP_TRACE_EVENT0 ("cmac_aes_k_calculate ");
while (i <= cmac_cb.round)
{
smp_xor_128(&cmac_cb.text[(cmac_cb.round - i)*BT_OCTET16_LEN], x); /* Mi' := Mi (+) X */
if (!SMP_Encrypt(key, BT_OCTET16_LEN, &cmac_cb.text[(cmac_cb.round - i)*BT_OCTET16_LEN], BT_OCTET16_LEN, &output))
{
err = 1;
break;
}
memcpy(x, output.param_buf, BT_OCTET16_LEN);
i ++;
}
if (!err)
{
p_mac = output.param_buf + (BT_OCTET16_LEN - tlen);
memcpy(p_signature, p_mac, tlen);
SMP_TRACE_DEBUG2("tlen = %d p_mac = %d", tlen, p_mac);
SMP_TRACE_DEBUG4("p_mac[0] = 0x%02x p_mac[1] = 0x%02x p_mac[2] = 0x%02x p_mac[3] = 0x%02x",
*p_mac, *(p_mac + 1), *(p_mac + 2), *(p_mac + 3));
SMP_TRACE_DEBUG4("p_mac[4] = 0x%02x p_mac[5] = 0x%02x p_mac[6] = 0x%02x p_mac[7] = 0x%02x",
*(p_mac + 4), *(p_mac + 5), *(p_mac + 6), *(p_mac + 7));
return TRUE;
}
else
return FALSE;
}
/*******************************************************************************
**
** Function cmac_prepare_last_block
**
** Description This function proceeed to prepare the last block of message
** Mn depending on the size of the message.
**
** Returns void
**
*******************************************************************************/
static void cmac_prepare_last_block (BT_OCTET16 k1, BT_OCTET16 k2)
{
// UINT8 x[16] = {0};
BOOLEAN flag;
SMP_TRACE_EVENT0 ("cmac_prepare_last_block ");
/* last block is a complete block set flag to 1 */
flag = ((cmac_cb.len % BT_OCTET16_LEN) == 0 && cmac_cb.len != 0) ? TRUE : FALSE;
SMP_TRACE_WARNING2("flag = %d round = %d", flag, cmac_cb.round);
if ( flag )
{ /* last block is complete block */
smp_xor_128(&cmac_cb.text[0], k1);
}
else /* padding then xor with k2 */
{
padding(&cmac_cb.text[0], (UINT8)(cmac_cb.len % 16));
smp_xor_128(&cmac_cb.text[0], k2);
}
}
/*******************************************************************************
**
** Function cmac_subkey_cont
**
** Description This is the callback function when CIPHk(0[128]) is completed.
**
** Returns void
**
*******************************************************************************/
static void cmac_subkey_cont(tSMP_ENC *p)
{
UINT8 k1[BT_OCTET16_LEN], k2[BT_OCTET16_LEN];
UINT8 *pp = p->param_buf;
SMP_TRACE_EVENT0 ("cmac_subkey_cont ");
print128(pp, (const UINT8 *)"K1 before shift");
/* If MSB(L) = 0, then K1 = L << 1 */
if ( (pp[BT_OCTET16_LEN - 1] & 0x80) != 0 )
{
/* Else K1 = ( L << 1 ) (+) Rb */
leftshift_onebit(pp, k1);
smp_xor_128(k1, const_Rb);
}
else
{
leftshift_onebit(pp, k1);
}
if ( (k1[BT_OCTET16_LEN - 1] & 0x80) != 0 )
{
/* K2 = (K1 << 1) (+) Rb */
leftshift_onebit(k1, k2);
smp_xor_128(k2, const_Rb);
}
else
{
/* If MSB(K1) = 0, then K2 = K1 << 1 */
leftshift_onebit(k1, k2);
}
print128(k1, (const UINT8 *)"K1");
print128(k2, (const UINT8 *)"K2");
cmac_prepare_last_block (k1, k2);
}
/*******************************************************************************
**
** Function cmac_generate_subkey
**
** Description This is the function to generate the two subkeys.
**
** Parameters key - CMAC key, expect SRK when used by SMP.
**
** Returns void
**
*******************************************************************************/
static BOOLEAN cmac_generate_subkey(BT_OCTET16 key)
{
BT_OCTET16 z = {0};
BOOLEAN ret = TRUE;
tSMP_ENC output;
SMP_TRACE_EVENT0 (" cmac_generate_subkey");
if (SMP_Encrypt(key, BT_OCTET16_LEN, z, BT_OCTET16_LEN, &output))
{
cmac_subkey_cont(&output);;
}
else
ret = FALSE;
return ret;
}
/*******************************************************************************
**
** Function AES_CMAC
**
** Description This is the AES-CMAC Generation Function with tlen implemented.
**
** Parameters key - CMAC key in little endian order, expect SRK when used by SMP.
** input - text to be signed in little endian byte order.
** length - length of the input in byte.
** tlen - lenth of mac desired
** p_signature - data pointer to where signed data to be stored, tlen long.
**
** Returns void
**
*******************************************************************************/
BOOLEAN AES_CMAC ( BT_OCTET16 key, UINT8 *input, UINT16 length,
UINT16 tlen, UINT8 *p_signature)
{
UINT16 len, diff;
UINT16 n = (length + BT_OCTET16_LEN - 1) / BT_OCTET16_LEN; /* n is number of rounds */
BOOLEAN ret = FALSE;
SMP_TRACE_EVENT0 ("AES_CMAC ");
if (n == 0) n = 1;
len = n * BT_OCTET16_LEN;
SMP_TRACE_WARNING1("AES128_CMAC started, allocate buffer size = %d", len);
/* allocate a memory space of multiple of 16 bytes to hold text */
if ((cmac_cb.text = (UINT8 *)GKI_getbuf(len)) != NULL)
{
cmac_cb.round = n;
memset(cmac_cb.text, 0, len);
diff = len - length;
if (input != NULL && length > 0)
{
memcpy(&cmac_cb.text[diff] , input, (int)length);
cmac_cb.len = length;
}
else
cmac_cb.len = 0;
/* prepare calculation for subkey s and last block of data */
if (cmac_generate_subkey(key))
{
/* start calculation */
ret = cmac_aes_k_calculate(key, p_signature, tlen);
}
/* clean up */
cmac_aes_cleanup();
}
else
{
ret = FALSE;
SMP_TRACE_ERROR0("No resources");
}
return ret;
}
#if 0 /* testing code, sample data from spec */
void test_cmac_cback(UINT8 *p_mac, UINT16 tlen)
{
SMP_TRACE_EVENT0 ("test_cmac_cback ");
SMP_TRACE_ERROR0("test_cmac_cback");
}
void test_cmac(void)
{
SMP_TRACE_EVENT0 ("test_cmac ");
UINT8 M[64] = {
0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c,
0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11,
0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,
0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17,
0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10
};
UINT8 key[16] = {
0x3c, 0x4f, 0xcf, 0x09, 0x88, 0x15, 0xf7, 0xab,
0xa6, 0xd2, 0xae, 0x28, 0x16, 0x15, 0x7e, 0x2b
};
UINT8 i =0, tmp;
UINT16 len;
len = 64;
for (i = 0; i < len/2; i ++)
{
tmp = M[i];
M[i] = M[len -1 - i];
M[len -1 - i] = tmp;
}
memset(&cmac_cb, 0, sizeof(tCMAC_CB));
SMP_TRACE_WARNING1("\n Example 1: len = %d\n", len);
AES_CMAC(key, M, len, 128, test_cmac_cback, 0);
}
#endif
#endif