经过前两章节,CryptoAuthlib库已经成功适配在代码中了,下面简单测试一下API函数,并分析下I2C通讯流程:
利用lib/atca_basic.c中的函数,简单封装成业务所需API
函数功能比较简单,只是读取508A串号,并打印出来:
其中SerialNum是全局变量,用来存储串号(9byte);atcab_init
,在经常调用508情况下,只需要init一次,并不用release
,
ATCAIfaceCfg *gCfg = &cfg_ateccx08a_i2c_default;
uint8_t SerialNum[ATCA_SERIAL_NUM_SIZE];
ATCA_STATUS At508_GetSernum( uint8_t *sernum )
{
ATCA_STATUS status;
atcab_init( gCfg );
status = atcab_read_serial_number( sernum );
atcab_release();
char displayStr[ATCA_SERIAL_NUM_SIZE*3];
int displen = sizeof(displayStr);
atcab_bin2hex(sernum,ATCA_SERIAL_NUM_SIZE,displayStr,&displen);
atcab_printbin_label((const uint8_t*)"\r\n Serial Number from atcab is: ",sernum, ATCA_SERIAL_NUM_SIZE);
return status;
}
而结构体指针gCfg 是ATCAIfaceCfg 类型,其实就是前几节所说的Iface对象,定义如下:
typedef struct {
ATCAIfaceType iface_type; // active iface - how to interpret the union below
ATCADeviceType devtype; // explicit device type
union { // each instance of an iface cfg defines a single type of interface
struct ATCAI2C {
uint8_t slave_address; // 8-bit slave address
uint8_t bus; // logical i2c bus number, 0-based - HAL will map this to a pin pair for SDA SCL
uint32_t baud; // typically 400000
} atcai2c;
struct ATCASWI {
uint8_t bus; // logical SWI bus - HAL will map this to a pin or uart port
} atcaswi;
struct ATCAUART {
int port; // logic port number
uint32_t baud; // typically 115200
uint8_t wordsize; // usually 8
uint8_t parity; // 0 == even, 1 == odd, 2 == none
uint8_t stopbits; // 0,1,2
} atcauart;
struct ATCAHID {
int idx; // HID enumeration index
uint32_t vid; // Vendor ID of kit (0x03EB for CK101)
uint32_t pid; // Product ID of kit (0x2312 for CK101)
uint32_t packetsize; // Size of the USB packet
uint8_t guid[16]; // The GUID for this HID device
} atcahid;
};
uint16_t wake_delay; // microseconds of tWHI + tWLO which varies based on chip type
int rx_retries; // the number of retries to attempt for receiving bytes
void *cfg_data; // opaque data used by HAL in device discovery
} ATCAIfaceCfg;
gCfg 被初始化为:cfg_ateccx08a_i2c_default,既默认的508 I2C配置。可以看出,508芯片默认I2C地址都是0xC0(默认地址存在ConfigZone,可更改),波特率为400k。
ATCAIfaceCfg cfg_ateccx08a_i2c_default = {
.iface_type = ATCA_I2C_IFACE,
.devtype = ATECC508A,
.atcai2c.slave_address = 0xC0,
.atcai2c.bus = 2,
.atcai2c.baud = 400000,
//.atcai2c.baud = 100000,
.wake_delay = 800,
.rx_retries = 20
};
可以看出,At508_GetSernum是调用了508API:
atcab_read_serial_number()
函数实现了读取串号,其实现如下:
ATCA_STATUS atcab_read_serial_number(uint8_t* serial_number)
{
// read config zone bytes 0-3 and 4-7, concatenate the two bits into serial_number
uint8_t status = ATCA_GEN_FAIL;
uint8_t bytes_read[ATCA_BLOCK_SIZE];
uint8_t block = 0;
uint8_t cpyIndex = 0;
uint8_t offset = 0;
do {
memset(serial_number, 0x00, ATCA_SERIAL_NUM_SIZE);
// Read first 32 byte block. Copy the bytes into the config_data buffer
block = 0;
offset = 0;
if ( (status = atcab_read_zone(ATCA_ZONE_CONFIG, 0, block, offset, bytes_read, ATCA_WORD_SIZE)) != ATCA_SUCCESS )
break;
memcpy(&serial_number[cpyIndex], bytes_read, ATCA_WORD_SIZE);
cpyIndex += ATCA_WORD_SIZE;
block = 0;
offset = 2;
if ( (status = atcab_read_zone(ATCA_ZONE_CONFIG, 0, block, offset, bytes_read, ATCA_WORD_SIZE)) != ATCA_SUCCESS )
break;
memcpy(&serial_number[cpyIndex], bytes_read, ATCA_WORD_SIZE);
_atcab_exit();
return status;
}
在
atcab_read_serial_number()
中,其实是通过atcab_read_zone()
读取了508A芯片中配置区所存储的串号,然后返回而已。atcab_read_zone()
里面,其实就是实现了508A Read命令消息封装,以及发送。如下代码:
ATCA_STATUS atcab_read_zone(uint8_t zone, uint8_t slot, uint8_t block, uint8_t offset, uint8_t *data, uint8_t len)
{
ATCA_STATUS status = ATCA_SUCCESS;
ATCAPacket packet;
uint16_t addr;
uint16_t execution_time = 0;
do {
// Check the input parameters
if (data == NULL)
return ATCA_BAD_PARAM;
if ( len != 4 && len != 32 )
return ATCA_BAD_PARAM;
// The get address function checks the remaining variables
if ( (status = atcab_get_addr(zone, slot, block, offset, &addr)) != ATCA_SUCCESS )
break;
// If there are 32 bytes to write, then xor the bit into the mode
if (len == ATCA_BLOCK_SIZE)
zone = zone | ATCA_ZONE_READWRITE_32;
// build a read command
packet.param1 = zone;
packet.param2 = addr;
if ( (status = atRead( _gCommandObj, &packet )) != ATCA_SUCCESS )
break;
execution_time = atGetExecTime( _gCommandObj, CMD_READMEM);
if ( (status = atcab_wakeup()) != ATCA_SUCCESS ) break;
// send the command
if ( (status = atsend( _gIface, (uint8_t*)&packet, packet.txsize )) != ATCA_SUCCESS )
break;
// delay the appropriate amount of time for command to execute
atca_delay_ms(execution_time);
// receive the response
if ( (status = atreceive( _gIface, packet.data, &(packet.rxsize) )) != ATCA_SUCCESS )
break;
// Check response size
if (packet.rxsize < 4) {
if (packet.rxsize > 0)
status = ATCA_RX_FAIL;
else
status = ATCA_RX_NO_RESPONSE;
break;
}
if ( (status = isATCAError(packet.data)) != ATCA_SUCCESS )
break;
memcpy( data, &packet.data[1], len );
} while (0);
_atcab_exit();
return status;
}
atcab_read_zone()
首先会根据传入参数(所读取的zone、slot),通过atRead
组建read
命令,存储在packet中;之后通过atcab_wakeup()
命令唤醒508A,也起到了查找设备的作用,atcab_wakeup()
会调用atwake(),最终还是通过Hal层的hal_i2c_wake()
函数,执行wake操作。
ATCA_STATUS hal_i2c_wake(ATCAIface iface)
{
ATCAIfaceCfg *cfg = atgetifacecfg(iface);
ATCA_STATUS status = ATCA_WAKE_FAILED;
int bus = cfg->atcai2c.bus;
uint8_t response[4] = { 0x00, 0x00, 0x00, 0x00 };
uint8_t expected_response[4] = { 0x04, 0x11, 0x33, 0x43 };
i2c_set_pin(i2c_hal_data[bus]->pin_sda, i2c_hal_data[bus]->pin_scl);
i2c_send_wake_token();
atca_delay_us(cfg->wake_delay);
uint16_t len = 4;
//! Receive Wake Response
//status = hal_i2c_receive(iface, response, sizeof(response));
status = hal_i2c_receive(iface, response, &len);
if (status == ATCA_SUCCESS) {
//! Compare response with expected_response
if (memcmp(response, expected_response, 4) != 0)
status = ATCA_WAKE_FAILED;
}
return status;
}
hal_i2c_wake()
中,通过I2C驱动向设备发送了一串为0的数,而根据508A Datasheet,508A接受到00会返回一条固定的数据:0x04, 0x11, 0x33, 0x43 ,因此hal_i2c_wake()
就是发送00然后接受数据,判断是否为上述数据,如果是,则唤醒成功。。同理,atcab_read_zone()
在wakeup后,通过atsend()
发送组装好的packet数据,也是同样的流程,只不过底层调用的是hal_i2c_send()
罢了。
–这些步骤也对应了上一节的API访问底层I2C驱动的逻辑结构关系。
通过逻辑分析仪连接到MCU与508A通讯的I2C总线上,执行At508_GetSernum()就可以看到如下抓包记录:(遵循Datasheet命令格式)
I2C发送唤醒:MCU向0xC0地址设备发送wakeup数据帧,(图片看不清可右键在新页面打开观看。)
I2C接收唤醒:508A返回的唤醒相应消息
I2C接收串号:508A返回串号数据(该芯片串号为 0123…)
总体效果图:
与GetSN类似,GetRandom调用了
atcab_random()
实现随机数获取,其中RandomNum是一个508A返回的32Byte随机数的全局变量,atcab_bin2hex
只是打印输出需要。
uint8_t RandomNum[RANDOM_RSP_SIZE];
ATCA_STATUS At508_GetRandom( uint8_t *randomnum)
{
ATCA_STATUS status = ATCA_GEN_FAIL;
char displayStr[RANDOM_RSP_SIZE*3];
int displen = sizeof(displayStr);
atcab_init( gCfg );
status = atcab_random( randomnum );
atcab_release();
atcab_bin2hex(randomnum,32,displayStr,&displen);
atcab_printbin_label((const uint8_t*)"\r\n Random Number is: ",randomnum, RANDOM_RSP_SIZE);
return status;
}
官方API函数
atcab_random()
与上面atcab_read_zone()
如出一辙,也是先wakeup
,之后atsend
发送组装的命令,然后atreceive
等待接收508返回的数据。
ATCA_STATUS atcab_random(uint8_t *rand_out)
{
ATCA_STATUS status = ATCA_GEN_FAIL;
ATCAPacket packet;
uint16_t execution_time = 0;
if ( !_gDevice )
return ATCA_GEN_FAIL;
// build an random command
packet.param1 = RANDOM_SEED_UPDATE;
//packet.param1 = RANDOM_NO_SEED_UPDATE;
packet.param2 = 0x0000;
status = atRandom( _gCommandObj, &packet );
execution_time = atGetExecTime( _gCommandObj, CMD_RANDOM);
do {
if ( (status = atcab_wakeup()) != ATCA_SUCCESS )
break;
// send the command
if ( (status = atsend( _gIface, (uint8_t*)&packet, packet.txsize )) != ATCA_SUCCESS)
break;
// delay the appropriate amount of time for command to execute
atca_delay_ms(execution_time);
// receive the response
if ( (status = atreceive( _gIface, packet.data, &packet.rxsize)) != ATCA_SUCCESS)
break;
// Check response size
if (packet.rxsize < 4) {
if (packet.rxsize > 0)
status = ATCA_RX_FAIL;
else
status = ATCA_RX_NO_RESPONSE;
break;
}
if ( (status = isATCAError(packet.data)) != ATCA_SUCCESS )
break;
memcpy( rand_out, &packet.data[1], 32 ); // data[0] is the length byte of the response
} while (0);
_atcab_exit();
return status;
}
####GetRandom抓包记录:
–>wakeup省略。以下是508A返回:
注意:508A拿到手是需要先手动config,并且Lock的(官方叫做Provision)。如果不进行该步骤,既没有Lock配置区,很多功能是不能使用,例如GetRandom,如果ConfigZone和DataZone没有被Lock,就会返回FFFF0000FFFF00…只有Lock后才能正确产生随机数。
–>然而ConfigZone Lock后就是一次性的,无法再解锁,所以下节会介绍如何根据需求正确配置508的ConfigZone以及DataZOne,既如何实现Provison流程。
我之前记录的读写508 某个Slot的数据,GetSN、GetRandom的截图(数据只是测试所用):
(slot是508A存储的一个单元区,可以放密钥、证书等其他数据,下节会介绍)
##欢迎转载,Howie原创作品,本文地址:
http://write.blog.csdn.net/mdeditor#!postId=75208753
##谢谢