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SHE
Secure Hardware Extension
Data Security for Automotive Embedded Systems
Workshop on Cryptography and Embedded Security
Embedded World @ Nuremberg, February 2012
INTERNAL USE ONLY
Copyright 2012 FUJITSU SEMICONDUCTOR EUROPE GMBH
Content
 Data Security - What does it mean for Automotive?
 SHE - Secure Hardware Extension - A new Standard?
 SHE - Implementation
 Outlook
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Data Security
What does it mean for Automotive?
 Areas of Use
 Applications
 EVITA Security Categories
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Areas with Demand for Security
 It’s not only onboard electronics that have an impact
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In-Vehicle Data Security
 Data Security on the road today
 On-chip Flash/ROM read-out protection against unauthorized access
 Solution by Fujitsu: Flash/ROM security
• Available on 16LX,16FX, FR, FCR4
 Future, Enhanced Data Security
 Protect entire car system
• not limited to Flash/ROM read-out prevention
 Authentication, Secure Communication and Data Storage
• within vehicle
• between vehicles (C2C)
• between vehicle and infrastructure (C2X)
 En-/Decryption is key for future state-of-the-art MCUs
• Embedded and ASSP solutions will find their market segment
 Complexity of security implementations scales with use case
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Target Applications
 Theft protection / Immobilizer
 Prevent unauthorized operation of vehicle
 Disable ignition and alike
 Component Protection
 Membership validation of all ECUs built in a particular vehicle
 Exchanging 1 ECU without authentication
• degrades functionality as unauthenticated functions will not work
• stops operation of all networked ECUs at next system start
• E.g. when engine control ECU is affected
 Feature Activation
 Enables certain functions in the delivered SW-package
 Gives OEM opportunity in after sales revenues
INTERNAL USE ONLY
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ECUs to be protected by Cryptography
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Gateway
Body Computer Module 1
Body Computer Module 2
Climate Control
Thermo Management Unit
Active Engine Mount
Instrument Cluster
Night Vision
Battery Management System
Charger
Safety Computer
21 ECU in total
INTERNAL USE ONLY
Adaptive Cruise Control
Engine Control
Gear Box
Electronic Steering Column Lock
Power Electronics Hybrid
Central Computer
Rear Seat Entertainment
Sound
DVDC
TV-Tuner
SOP 2014
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EVITA
 European research project June 2008 –Dec 2011
 E-safety vehicle intrusion protected applications
 Objective:
Design, verify, and prototype an architecture for automotive on-board
networks where security-relevant components are protected against
tampering and sensitive data are protected against compromise when
transferred inside a vehicle.
 More found at http://evita-project.org/index.html
INTERNAL USE ONLY
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Security Models - Categorization
Full EVITA HSM
Medium EVITA HSM
Light EVITA HSM
V2X communication
On-board communication
On-board communication
Maximum level of
functionality,
security and performance
Maximum level of
functionality and
security
Optimized for low cost
HW-solution
Asymmetric
cryptographic engine
&
Hash engine
Symmetric
cryptographic engine
Symmetric
cryptographic engine
e.g. AES-128
User-programmable
functionality
User-programmable
functionality
Pre-defined functionality
Secure CPU @ 100 MHz
Secure CPU @ 25 MHz
Secure Zone
no CPU needed
64k
64k
Optional NV Memory
512k
512k
Optional NV RAM
PRNG with TRNG seed
PRNG with TRNG seed
Optional T/PRNG
Security LT > 20 years
INTERNAL USE ONLY
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SHE
Secure Hardware Extension – A New Standard?
 SHE - Security Objectives
 SHE - Building Blocks
 SHE - Performance Requirements
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HIS - SHE
 HIS = Hersteller Initiative Software
 SHE = Secure Hardware Extension - meets ‘Light EVITA HSM’
 Specification by HIS
 Concept:
 Add a Secure Zone
 Prevent user access to
security functions other
than those given by logic
 Link to HIS & SHE: HIS portal on Security
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SHE - Security Objectives
 Protect cryptographic keys from software attacks
 Provide an authentic software environment
 Let the security only depend on the strength of the underlying
algorithm and the confidentiality of the keys
 Allow for distributed key ownerships
 Keep the flexibility high and the costs low
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SHE – Building Blocks (1)
 MCU with
Secure Zone
 SHE data storage
- volatile
- non-volatile
- for KEY & MAC
 Access only via
defined command
interface
INTERNAL USE ONLY
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SHE – Perspective from Specification (2)
 SHE specifies Secure Zone components and algorithms
 Cryptography
• En-/decryption unit
• AES 128 algorithm
 ROM
• Secret key storage
SECRET_KEY
• Unique key storage
UID
Cryptography
RAM
NV-Memory
ROM
 RAM
• RAM key storage
• PRNG key storage
 NV-Memory
• Boot key & MAC storage
• Master key, general purpose key storage
INTERNAL USE ONLY
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SHE – Perspective from Specification (3)
 Cryptography carries
 Encryption unit
• AES 128-based
Applicable Standard
 Decryption unit
Cryptography
RAM
• AES 128-based
 CMAC
NV-Memory
ROM
• Cipher-based
Message
Authentication
Code generator
 Miyaguchi-Preneel
• One-way compression function; compressed data cannot be recovered
• Input requests 128-bit wide chunks of data stream
• Outputs Hash-values to en-/decoding unit
INTERNAL USE ONLY
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SHE – Perspective from Specification (3)
 Cryptography carries
 Encryption unit
• AES 128-based
Applicable Standard
 Decryption unit
RAM
NV-Memory
• AES 128-based
 CMAC
ROM
• Cipher-based
Message
Authentication
Code generator
 Miyaguchi-Preneel
• One-way compression function; compressed data cannot be recovered
• Input requests 128-bit wide chunks of data stream
• Outputs Hash-values to en-/decoding unit
INTERNAL USE ONLY
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SHE – Perspective from Specification (4)
 RAM carries
 RAM_KEY
• Temporary key
used for arbitrary
operations
 PRNG_KEY
Cryptography
RAM
NV-Memory
ROM
• Key used by the
Pseudo Random
Number Generator
 PRNG_STATE
• Keeps status of
Pseudo Random
Number Generator
INTERNAL USE ONLY
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SHE – Perspective from Specification (4)
 RAM carries
 RAM_KEY
• Temporary key
used for arbitrary
operations
 PRNG_KEY
Cryptography
NV-Memory
ROM
• Key used by the
Pseudo Random
Number Generator
 PRNG_STATE
• Keeps status of
Pseudo Random
Number Generator
INTERNAL USE ONLY
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SHE – Perspective from Specification (5)
 ROM carries
 SECRET_KEY
• Unique key
• Used for im-/export
of all other keys
• Has to be created
with true random
number generator
(off-chip TRNG )
at production
Cryptography
RAM
NV-Memory
ROM
 UID
• Unique identifier
• Authenticates MCU
 Both SECRET_KEY and UID have to be fixed at production time
• 16 byte for SECRET_KEY and ≤15 byte for UID
INTERNAL USE ONLY
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SHE – Perspective from Specification (5)
 ROM carries
 SECRET_KEY
• Unique key
• Used for im-/export
of all other keys
• Has to be created
with true random
number generator
(off-chip TRNG )
at production
Cryptography
RAM
NV-Memory
 UID
• Unique identifier
• Authenticates MCU
 Both SECRET_KEY and UID have to be fixed at production time
• 16 byte for SECRET_KEY and ≤15 byte for UID
INTERNAL USE ONLY
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SHE – Perspective from Specification (6)
 NV-Memory carries
 MASTER_ECU_KEY
• Set up by OEM
(owner)
• Enables change of
other keys
 BOOT_MAC_KEY
• Enables particular
boot request and
thus establishing
secure boot
 BOOT_MAC
Cryptography
RAM
NV-Memory
ROM
• Authentication of
boot code
 KEY_<n>
• Dedicated key storage
for arbitrary functions
• 3 – 10 keys
 PRNG_SEED
• Starting value for pseudo
random number generator
 Irreversible Write Protection of keys in NV-memory
• Any key in NV-memory area shall not be changeable throughout life time of the device once
write-protection was applied by user
INTERNAL USE ONLY
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Copyright 2012 FUJITSU SEMICONDUCTOR EUROPE GMBH
SHE – Perspective from Specification (6)
 NV-Memory carries
 MASTER_ECU_KEY
• Set up by OEM
(owner)
• Enables change of
other keys
 BOOT_MAC_KEY
• Enables particular
boot request and
thus establishing
secure boot
 BOOT_MAC
Cryptography
RAM
ROM
• Authentication of
boot code
 KEY_<n>
• Dedicated key storage
for arbitrary functions
• 3 – 10 keys
 PRNG_SEED
• Starting value for pseudo
random number generator
 Irreversible Write Protection of keys in NV-memory
• Any key in NV-memory area shall not be changeable throughout life time of the device once
write-protection was applied by user
INTERNAL USE ONLY
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Copyright 2012 FUJITSU SEMICONDUCTOR EUROPE GMBH
SHE - Performance Requirements
 Start-up / Secure Boot is Critical Path
 All SHE-equipped nodes have to perform secure boot process
 Availability to be established before 1 sec elapses
 MAC latency according SHE
 < 2 µsec for a 128-bit block
• MAC = Message Authentication Code
 Authentication of Flash contents at power up
 << 100 msec for 1 MByte required
 Exact requirement depends on
• Oscillator start-up times
• Network start-up,
• NM communication,
• MCU initializations
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SHE
Implementation
 SHE System
 SHE Integration
 SHE Implementation
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SHE System Diagram
Host System
SHE
EEFLASH
SHECO
SHE Firmware
Public
Secured
NV_MEM IF
Host Interface
Data IF
Command IF
SHE Host Driver
INTERNAL USE ONLY
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Timing
Protection
EEFlash
SHE
MPU
MPU
MPU
Ethernet
MediaLB
CRC
32-bit AHB slave bus
MPU
SRAM
32-bit AHB master bus
TCFlash
Cache
Sec.
Cortex R4
CPU
Boot ROM
Interrupt
Controller
Sec.
Debug /
Trace
64-bit AHB slave bus
SHE - System Integration (ATLAS-L/TITAN)
I2S
DMA
USB
MPU
System
Controller
Watchdog
RTC
External
Interrupt
32-bit AHB slave bus
64-bit Multilayer AXI bus
Retention
RAM
Quad-SPI
Peripheral bus 3
Timers
Timers
Timers
Timers
Content is
protected
INTERNAL USE ONLY
System RAM
GPIO
Peripheral
Protection
Peripheral
Peripheral
BusPeripheral
Bridge
Bus Bridge
Bus Bridge
Peripheral bus 1
Peripheral bus 0
Peripherals
Peripherals
Peripherals
Peripherals
Contains security
config
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MPU
PPU
Subsystem
Peripherals
Peripherals
Peripherals
Peripherals
Bus master
Bus slave
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SHE Implementation
SHE
SHECO
TRNG
I bus
En-/decode
Flash security
64-bit AHB bus
EEFLASH
CMAC
FR60
CPU
AHB
Secured
Sectors
(2 x 8 K)
RAM
Cycle
counter
D
Miyaguchi-Preneel
Public
Sectors
(6 x 8 K)
ROM
32-bit D bus
AES-128
32-bit AHB bus
NV_MEM_MASTER
HW barrier
PRNG
Tx/Rx FIFOs
Register I/F
AXI Master
PPU protection
Data I/F
Command/Data I/F
Host Interface
Bus master
MPU
Bus slave
Host AXI bus
INTERNAL USE ONLY
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Host AHB bus
Copyright 2012 FUJITSU SEMICONDUCTOR EUROPE GMBH
SHE - Secured Key Storage (1)
 Common features
EEFLASH
 32 byte large key slots
SECRET_KEY
EMPTY FLAGS
UID
EMPTY FLAGS
MASTER_ECU_KEY
EMPTY FLAGS
COUNTER
 Empty flag to distinguish between
erased keys and keys written to 0xFF
BOOT_MAC_KEY
EMPTY FLAGS
COUNTER
 Flags and 28bit counters are stored in
the same slot as the key
BOOT_MAC
EMPTY FLAGS
COUNTER
KEY_<n>
EMPTY FLAGS
COUNTER
 Access only by SHECO CPU
 NV memory
 SECRET_KEY and UID slots are write
protected before device delivery
 No PRNG_SEED storage needed
since on-chip TRNG is implemented
 RAM
RAM
PRNG_KEY
FLAGS
PRNG_STATE
FLAGS
RAM_KEY
FLAGS
INTERNAL USE ONLY
 PRNG_KEY is calculated from
SECRET_KEY during
CMD_INIT_RNG command and
stored in RAM slot
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SHE - Secured Key Storage (2)

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



4



KEY_<n>
4



PRNG_KEY
5
PRNG_STATE
5
RAM_KEY
5
UID
F1
T2
MASTER_ECU_KEY
4

BOOT_MAC_KEY
4
BOOT_MAC

Plain key
3
F1
Key usage
Debugger activation
3
SECRET_KEY
Wildcard UID
Secure boot failure
T2
Empty
Write-protection
Flags to be used for keys


 – used
F – used, always false
T – used, always true
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Empty flags for SECRET_KEY and UID are set after the keys have been written (by Fujitsu)
Write-protection flags for SECRET_KEY and UID are set after the keys have been written (by Fujitsu)
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SECRET_KEY inherits its protection flags from MASTER_ECU_KEY
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The initial value after production will be TRUE
5
The initial value after power-up/HW-Reset will be TRUE
2
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SHE – Software (Firmware)
 SHE firmware
 Implements SHE control logic + EEPROM emulation for key storage
 Is ROM based (no modification possible!)
 No debugging possible
 Entirely developed by Fujitsu
 Secure Boot
 Extension of FCR4 Boot-ROM for Secure Boot
 Validation of boot loader with support of SHE and DMA
 Block length configured by of SHE_BL_SIZE (SHE parameter)
 SHE evaluates the status via valid BOOT_MAC_KEY
INTERNAL USE ONLY
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SHE – Software (AUTOSAR Driver)
 AUTOSAR driver V4.xx
 Implements SHE user accessible
functions
 Handles hardware Interaction
 E.g I/F error handling
 Host driver for SHE will become
a Fujitsu product
INTERNAL USE ONLY
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Outlook
 Cryptography becomes general trend for embedded systems
 Majority of ECU/MCU will have to support en-/decryption
 Data security will become mandatory feature for automotive
applications
 Scaled between low-cost solutions like SHE for many ECUs and
 High protection requirements for a subset of ECUs
 SHE will be on the road in 2014
INTERNAL USE ONLY
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Thank you for your attention
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INTERNAL USE ONLY
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