Secure 3 click

Secure 3 click carries the ATSHA204A, a cryptographic coprocessor with secure hardware-based key storage from Microchip. The click is designed to run on either 3.3V or 5V power supply. Secure 3 click communicates with the target microcontroller over an I2C interface. 

It is ideal to use for:

• Secure download and boot - authentication and protect code in-transit
• Ecosystem control - ensure only OEM/licensed nodes and accessories work
• Anti-cloning - prevent building with identical BOM or stolen code
• Message security - authentication, message integrity, and confidentiality of network nodes (IoT)

NOTE: The click comes with stacking headers which allow you to combine it with other clicks more easily by using just one mikroBUS™ socket.

ATSHA204A features

The ATSHA204A is a member of the Microchip CryptoAuthentication™ family of high-security hardware authentication devices, which uses Secure Hash Algorithm (SHA-256) with 256-bit key length, message authentication code (MAC) and hash-based message authentication code (HMAC) options. It has a flexible command set that allows use in many applications.

The ATSHA204A device includes an Electrically Erasable Programmable Read-Only Memory (EEPROM) array that can be used for key storage, miscellaneous read/write data, read-only, secret data, consumption logging, and security configuration. Access to the various sections of memory can be restricted in a variety of ways, and the configuration can then be locked to prevent changes.

Specifications

Pinout diagram

This table shows how the pinout on Secure 3 click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	NC
	NC	2	RST	INT	15	NC
	NC	3	CS	TX	14	NC
	NC	4	SCK	RX	13	NC
	NC	5	MISO	SCL	12	SCL	I2C clock
	NC	6	MOSI	SDA	11	SDA	I2C data
Power supply	+3.3V	7	3.3V	5V	10	+5V	Power supply
Ground	GND	8	GND	GND	9	GND	Ground

Jumpers and settings

Programming

Code examples for Secure 3 click, written for MikroElektronika hardware and compilers are available on Libstock.

Code snippet

The following code snippet creates a MAC for a given input and then checks if it is valid using verify function.

01 static void MACTest ()
02 {
03     //Generates nonce for use in MAC generation
04     memset (bufferIn, 0x45, 128);
05     if (atcab_nonce(bufferIn) == ATCA_SUCCESS)
06     {
07         LOG( "rnrn Nonce generated." );
08     }
09     else  LOG( "rnrn Nonce generation failed..." );
10     delay_ms (1500);
11
12    //Generates MAC for given input
13     memset (bufferOut, 0x00, 128);
14     memset (bufferIn, 0x14, 128);
15     if (atcab_mac( 0, 0, bufferIn, bufferOut ) == ATCA_SUCCESS)
16     {
17         LOG( "rnrn MAC generated: " );
18         outputHex (bufferOut, 32);
19     }
20     else  LOG( "rnrn Mac generation failed..." );
21      delay_ms (1500);
22
23    //Checks if the generated MAC is valid
24     memset (bufferIn, 0x14, 128);
25     if (atcab_checkmac( 0, 0, bufferIn, bufferOut, otherData) == ATCA_SUCCESS)
26     {
27         LOG( "rnrn Check MAC successful. " );
28     }
29     else  LOG( "rnrn Check MAC failed..." );
30 }