ateccx08: inttial implementation for ATECCx08

This working implementation for the ATECCx08 family of cryptgraphic processors
has random number generation and other needed supporting functions.

It also includes a sample of how to connect it to the Go crypto/rand package.

More cryptographic functions await a future interation.

Signed-off-by: deadprogram <ron@hybridgroup.com>

README.md

@@ -52,7 +52,7 @@ func main() {
 
 ## Currently supported devices
 
-The following 90 devices are supported.
+The following 91 devices are supported.
 
 | Device Name                                                                                                                                                                                         | Interface Type |
 |-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|
@@ -63,6 +63,7 @@ The following 90 devices are supported.
 | [APA102 RGB LED](https://cdn-shop.adafruit.com/product-files/2343/APA102C.pdf)                                                                                                                      | SPI |
 | [APDS9960 Digital proximity, ambient light, RGB and gesture sensor](https://cdn.sparkfun.com/assets/learn_tutorials/3/2/1/Avago-APDS-9960-datasheet.pdf)                                            | I2C |
 | [AT24CX 2-wire serial EEPROM](https://www.openimpulse.com/blog/wp-content/uploads/wpsc/downloadables/24C32-Datasheet.pdf)                                                                           | I2C |
+| [ATECCx08 cryptographic processor](https://datasheet.octopart.com/ATSAMA5D27-WLSOM1-Microchip-datasheet-149595509.pdf)                                                                           | I2C |
 | [AXP192 single Cell Li-Battery and Power System Management](https://github.com/m5stack/M5-Schematic/blob/master/Core/AXP192%20Datasheet_v1.1_en_draft_2211.pdf)                                     | I2C |
 | [BBC micro:bit LED matrix](https://github.com/bbcmicrobit/hardware/blob/master/SCH_BBC-Microbit_V1.3B.pdf)                                                                                          | GPIO |
 | [BH1750 ambient light sensor](https://www.mouser.com/ds/2/348/bh1750fvi-e-186247.pdf)                                                                                                               | I2C |

ateccx08/ateccx08.go

@@ -0,0 +1,258 @@
+// Package ateccx08 provides a driver for the ATECCx08 I2C cryptographic co-processor.
+//
+// Datasheet: https://datasheet.octopart.com/ATSAMA5D27-WLSOM1-Microchip-datasheet-149595509.pdf
+package ateccx08 // import "tinygo.org/x/drivers/ateccx08"
+
+import (
+	"errors"
+	"time"
+
+	"tinygo.org/x/drivers"
+)
+
+var (
+	maxCommandTime = (200 + 50) * time.Millisecond
+)
+
+var (
+	ErrWakeup          = errors.New("error on wakeup")
+	ErrInvalidCRCCheck = errors.New("invalid CRC check")
+	ErrLockFailed      = errors.New("locked failed")
+)
+
+type Device struct {
+	bus     drivers.I2C
+	Address uint8
+}
+
+// New returns ATECCx08 device for the provided I2C bus using default address.
+func New(i2c drivers.I2C) *Device {
+	return &Device{
+		bus:     i2c,
+		Address: Address,
+	}
+}
+
+// Configure the ATECCx08 device.
+func (d *Device) Configure() error {
+	return nil
+}
+
+// Connected returns whether ATECCx08 has been found.
+func (d *Device) Connected() bool {
+	if err := d.Wakeup(); err != nil {
+		return false
+	}
+
+	v, err := d.Version()
+	if err != nil {
+		return false
+	}
+
+	return (v == ATECC508 || v == ATECC608)
+}
+
+// Wakeup the ATECC by trying to write something to address 0x00
+func (d *Device) Wakeup() error {
+	d.bus.Tx(uint16(0x0), []byte{0x00}, nil)
+	time.Sleep(1500 * time.Microsecond)
+	d.bus.Tx(uint16(d.Address), []byte{0x00}, nil)
+	time.Sleep(maxCommandTime)
+
+	var status [4]byte
+	if err := d.readResponse(status[:]); err != nil {
+		return err
+	}
+
+	if status[0] != StatusAfterWake {
+		return ErrWakeup
+	}
+
+	return nil
+}
+
+// Sleep puts the ATECC to sleep.
+func (d *Device) Sleep() {
+	d.bus.Tx(uint16(d.Address), []byte{0x01}, nil)
+	time.Sleep(time.Millisecond)
+}
+
+// Idle puts the ATECC in idle mode.
+func (d *Device) Idle() {
+	d.bus.Tx(uint16(d.Address), []byte{0x02}, nil)
+	time.Sleep(time.Millisecond)
+}
+
+type ATECCVersion uint16
+
+func (at ATECCVersion) String() string {
+	switch at {
+	case ATECC508:
+		return "ATECC508"
+	case ATECC608:
+		return "ATECC608"
+	case ATECCNone:
+		return "No ATECCx08"
+	default:
+		return "Unknown"
+	}
+}
+
+// Version returns what version of ATECC is being used.
+// Either ATECC508, ATECC608, or ATECCNone.
+func (d *Device) Version() (ATECCVersion, error) {
+	var version [4]byte
+	d.Wakeup()
+	defer d.Idle()
+
+	d.sendCommand(cmdInfo, 0x00, 0, nil)
+
+	time.Sleep(maxCommandTime)
+	if err := d.readResponse(version[:]); err != nil {
+		return ATECCNone, err
+	}
+
+	return ATECCVersion(uint16(version[2])<<8 | uint16(version[3])&0xf000), nil
+}
+
+// Random returns an array of 32 byte-sized random numbers.
+func (d *Device) Random() ([32]byte, error) {
+	var random [32]byte
+	d.Wakeup()
+	defer d.Idle()
+
+	d.sendCommand(cmdRandom, 0x00, 0, nil)
+	time.Sleep(23 * time.Millisecond)
+
+	err := d.readResponse(random[:])
+	return random, err
+}
+
+// Read reads from the device memory.
+func (d *Device) Read(zone, address int, data []byte) error {
+	d.Wakeup()
+	defer d.Idle()
+
+	d.sendCommand(cmdRead, byte(zone), uint16(address), nil)
+	time.Sleep(5 * time.Millisecond)
+
+	return d.readResponse(data)
+}
+
+// IsLocked checks to see if the ATECC is locked.
+// Config zone (0) must be locked to generate random numbers.
+func (d *Device) IsLocked() bool {
+	return d.IsZoneLocked(0)
+}
+
+// IsZoneLocked checks to see if a specific zone in the ATECC is locked.
+func (d *Device) IsZoneLocked(zone int) bool {
+	var config [4]byte
+
+	if zone < 0 || zone > 8 {
+		return false
+	}
+
+	switch zone {
+	case 0, 1:
+		if err := d.Read(0, 0x15, config[:]); err != nil {
+			return false
+		}
+
+		// LockConfig
+		loc := 3
+
+		// LockData
+		if zone == 1 {
+			loc = 2
+		}
+
+		if config[loc] == 0 {
+			return true
+		}
+
+	default:
+		if err := d.Read(0, 0x16, config[:]); err != nil {
+			return false
+		}
+
+		slot := byte(zone<<2) | 2
+
+		if (config[0] & slot) == 0 {
+			return true
+		}
+
+		return false
+	}
+
+	return false
+}
+
+// Lock locks a zone in the device.
+// Note that you cannot unlock a device zone once locked,
+// so make sure you know what you are doing!
+func (d *Device) Lock(zone int) error {
+	var status [1]byte
+	d.Wakeup()
+	defer d.Idle()
+
+	d.sendCommand(cmdLock, byte(zone)|0x80, 0, nil)
+	time.Sleep(32 * time.Millisecond)
+
+	d.readResponse(status[:])
+
+	if status[0] != 0 {
+		return ErrLockFailed
+	}
+
+	return nil
+}
+
+var cmdBuf [64]byte
+
+func (d *Device) sendCommand(opcode, param1 byte, param2 uint16, data []byte) error {
+	cmdBuf[0] = 0x03
+	cmdBuf[1] = byte(8 + len(data) - 1)
+	cmdBuf[2] = opcode
+	cmdBuf[3] = param1
+	cmdBuf[4] = byte(param2 & 0xff)
+	cmdBuf[5] = byte(param2 >> 8)
+	copy(cmdBuf[6:], data)
+
+	crc := crc16(cmdBuf[1 : 6+len(data)])
+	cmdBuf[6+len(data)] = crc[0]
+	cmdBuf[6+len(data)+1] = crc[1]
+
+	if err := d.bus.Tx(uint16(d.Address), cmdBuf[:6+len(data)+2], nil); err != nil {
+		return err
+	}
+
+	time.Sleep(time.Millisecond)
+	return nil
+}
+
+func (d *Device) readResponse(data []byte) error {
+	var sz [1]byte
+	if err := d.bus.Tx(uint16(d.Address), []byte{cmdAddress}, sz[:]); err != nil {
+		return err
+	}
+
+	rx := make([]byte, sz[0])
+	if err := d.bus.Tx(uint16(d.Address), []byte{cmdAddress}, rx); err != nil {
+		return err
+	}
+
+	size := len(rx) - 2
+	payload := rx[:size]
+	payloaddata := rx[1:size]
+	payloadcrc := rx[size:]
+
+	crcCheck := crc16(payload)
+	if !(crcCheck[0] == payloadcrc[0] &&
+		crcCheck[1] == payloadcrc[1]) {
+		return ErrInvalidCRCCheck
+	}
+
+	copy(data, payloaddata)
+	return nil
+}

ateccx08/crc16.go

@@ -0,0 +1,32 @@
+// from https://github.com/usbarmory/armoryctl/blob/master/atecc608/atecc608.go#L104
+// thank you!
+package ateccx08
+
+const (
+	CRC16Poly uint16 = 0x8005
+)
+
+func crc16(data []byte) []byte {
+	var crc uint16
+
+	for i := 0; i < len(data); i++ {
+		for shift := uint8(0x01); shift > 0x00; shift <<= 1 {
+			// data and crc bits
+			var d uint8
+			var c uint8
+
+			if uint8(data[i])&uint8(shift) != 0 {
+				d = 1
+			}
+
+			c = uint8(crc >> 15)
+			crc <<= 1
+
+			if d != c {
+				crc ^= CRC16Poly
+			}
+		}
+	}
+
+	return []byte{byte(crc & 0xff), byte(crc >> 8)}
+}

ateccx08/registers.go

@@ -0,0 +1,39 @@
+package ateccx08
+
+const (
+	// Address is default I2C address.
+	Address = 0x60
+)
+
+const (
+	ATECCNone = 0
+	ATECC508  = 0x5000
+	ATECC608  = 0x6000
+)
+
+const (
+	cmdAddress = 0x03
+	cmdCounter = 0x24
+	cmdGenKey  = 0x40
+	cmdInfo    = 0x30
+	cmdLock    = 0x17
+	cmdNonce   = 0x16
+	cmdRandom  = 0x1B
+	cmdSHA     = 0x47
+	cmdSign    = 0x41
+	cmdWrite   = 0x12
+	cmdRead    = 0x02
+)
+
+const (
+	StatusSuccess         = 0x00
+	StatusMiscompare      = 0x01
+	StatusParseError      = 0x03
+	StatusECCFault        = 0x05
+	StatusSelfTestError   = 0x07
+	StatusHealthTestError = 0x08
+	StatusExecutionError  = 0x0f
+	StatusAfterWake       = 0x11
+	StatusWatchdogExpire  = 0xee
+	StatusCRCError        = 0xff
+)

examples/ateccx08/lock/main.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"machine"
+
+	"encoding/hex"
+	"time"
+
+	"tinygo.org/x/drivers/ateccx08"
+)
+
+func main() {
+	time.Sleep(5 * time.Second)
+	println("Looking for ATECCx08...")
+
+	machine.I2C0.Configure(machine.I2CConfig{})
+
+	atecc := ateccx08.New(machine.I2C0)
+	atecc.Configure()
+
+	if !atecc.Connected() {
+		for {
+			println("could not connect to ATECCx08")
+			time.Sleep(time.Second)
+		}
+	}
+
+	version, _ := atecc.Version()
+
+	println(version.String(), "started")
+
+	if !atecc.IsLocked() {
+		for i := 10; i > 0; i-- {
+			println(version.String(), "is not locked. Locking in", i, "seconds...")
+			time.Sleep(time.Second)
+		}
+
+		// locks the Configuration zone... PERMANENTLY!
+		atecc.Lock(0)
+	}
+
+	println(version.String(), "locked.")
+
+	for {
+		data, err := atecc.Random()
+		if err != nil {
+			println(err)
+		}
+
+		println(hex.EncodeToString(data[:]))
+		time.Sleep(500 * time.Millisecond)
+	}
+}

examples/ateccx08/random/main.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"machine"
+
+	"crypto/rand"
+	"encoding/hex"
+	"time"
+
+	"tinygo.org/x/drivers/ateccx08"
+)
+
+var atecc *ateccx08.Device
+
+func main() {
+	time.Sleep(5 * time.Second)
+	println("Looking for ATECCx08...")
+
+	machine.I2C0.Configure(machine.I2CConfig{})
+
+	atecc = ateccx08.New(machine.I2C0)
+	atecc.Configure()
+
+	if !atecc.Connected() {
+		for {
+			println("could not connect to ATECCx08")
+			time.Sleep(time.Second)
+		}
+	}
+
+	version, _ := atecc.Version()
+
+	println(version.String(), "started")
+
+	if !atecc.IsLocked() {
+		for {
+			println(version.String(), "is not locked. Random numbers will not actually be random.")
+			time.Sleep(time.Second)
+		}
+	}
+
+	var result [13]byte
+	for {
+		rand.Read(result[:])
+		encodedString := hex.EncodeToString(result[:])
+		println(encodedString)
+		time.Sleep(500 * time.Millisecond)
+	}
+}

examples/ateccx08/random/rand.go

@@ -0,0 +1,52 @@
+// connects the Go crypto/rand package to the random number generation
+// on the ATECCx08 cryptographic processor.
+package main
+
+import (
+	"crypto/rand"
+	"errors"
+)
+
+var (
+	errNoATECC = errors.New("no ATECCx08")
+)
+
+func init() {
+	rand.Reader = &reader{}
+}
+
+type reader struct{}
+
+func (r *reader) Read(b []byte) (n int, err error) {
+	if len(b) == 0 {
+		return
+	}
+
+	if atecc == nil {
+		return 0, errNoATECC
+	}
+
+	if !atecc.IsLocked() {
+		panic("ATECCx08 is not locked and cannot produce random numbers!")
+	}
+
+	rnds, err := atecc.Random()
+	if err != nil {
+		return 0, err
+	}
+
+	for i := 0; i < len(b); i += 32 {
+		if i+32 > len(b) {
+			copy(b[i:], rnds[:(len(b)-i)])
+			break
+		}
+
+		copy(b[i:], rnds[:])
+		rnds, err = atecc.Random()
+		if err != nil {
+			return 0, err
+		}
+	}
+
+	return len(b), nil
+}