SECURITY SYSTEM ENCRYPTION FOR A WIRELESSHART
Rajesh Yeredla
B.Tech. Jawaharlal Nehru Technological University, India, 2007
Pavan Telukuntla
B.Tech. Jawaharlal Nehru Technological University, India, 2003
M.Tech. DR. MGR University, India, 2006
PROJECT
Submitted in partial satisfaction of
The requirements for the degree of
MASTER OF SCIENCE
in
ELECTRICAL AND ELECTRONIC ENGINEERING
at
CALIFORNIA STATE UNIVERSITY, SACRAMENTO
SUMMER
2010
SECURITY SYSTEM ENCRYPTION FOR A WIRELESSHART
A Project
by
Rajesh Yeredla
Pavan Telukuntla
Approved by:
________________________________, Committee Chair
John.C.Balachandra, Ph.D.
________________________________, Second Reader
Russ Tatro, M.S.
_________________________
Date
ii
Students:
Rajesh Yeredla
Pavan Telukuntla
I certify that these students have met the requirements for format contained in the
University format manual, and that this project is suitable for shelving in the Library and
credit is to be awarded for the project.
________________________, Graduate Coordinator
Suresh Vadhva, Ph.D.
Department of Electrical and Electronic Engineering
Abstract
iii
_____________________
Date
of
SECURITY SYSTEM ENCRYPTION FOR A WIRELESSHART
by
Rajesh Yeredla
Pavan Telukuntla
WirelessHART is a secure Time Division Multiple Access (TDMA) based wireless mesh
networking technology operating in the 2.4 GHz Industrial, Scientific and Medical (ISM)
radio band. The specifications in the WirelessHART have been organized well, but
security standards are loosely defined. This project will focus on the security aspects, that
is the keying and design of a security system for the Data-link layer of the
WirelessHART network using the AES algorithm. The data in the WirelessHART
network is encrypted using the AES algorithm and transmitted in the mesh network. The
report on our design of this security system will include the understanding of the types of
security provided in WirelessHART network, threats in the network, cryptography,
programming in Verilog and use of matrices.
________________________________, Committee Chair
John.C.Balachandra, Ph.D.
______________________
Date
iv
ACKNOWLEDGMENT
Firstly, we would like to thank Professor Dr. John C Balachandra for giving us an
opportunity to do this project. His continuous support was the main thing that helped us
develop immense interest on the project that led to designing a new security system for
one of the emerging technologies. Dr. Balachandra helped us by providing many sources
of information that we needed from beginning of the project till the end. He was always
there to meet, talk and answer the questions that we came across during the project.
Special thanks to our advisor Dr Suresh Vadhva for helping us complete the writing of
this dissertation, without his encouragement and constant guidance we could not have
finished this report.
We would also like to acknowledge and thank Professor Russ Tatro, Faculty Member,
EEE department for being part of the review committee and extending his guidance for
better formulation of our project. We also thank him for his review and comments on the
project report.
We also thank all our friends and Electrical engineering department who helped us to
complete our project work successfully. Without any of the above-mentioned people the
project would not have come out the way it did. Thank you all.
v
TABLE OF CONTENTS
Page
Acknowledgment .......................................................................................................... v
List of Tables .............................................................................................................. ix
List of Figures ................................................................................................................x
Chapter
1. INTRODUCTION ...................................................................................................1
2. BACKGROUND RESEARCH ON HART AND WIRELESSHART ................... 3
2.1 Point to Point............................................................................................... 5
2.2 Multi Drop .................................................................................................. 5
2.3 WirelessHART Architecture .................................................................... 6
2.3.1 Physical Layer .................................................................................. 10
2.3.2 Data-link Layer ................................................................................ 10
2.3.3 Network Layer ................................................................................. 11
2.3.4 Transport Layer ................................................................................ 12
2.3.5 Application Layer ............................................................................ 13
3. SECURITY IN WIRELESSHART ...................................................................... 14
3.1 End to End Security ....................................................................................... 14
3.2 Per-Hop Security ........................................................................................... 16
3.3 Peer to Peer Security ..................................................................................... 17
3.4 Threats in Security......................................................................................... 17
3.4.1 Interference ............................................................................................ 17
3.4.2 Jamming ................................................................................................. 18
3.4.3 Sybil Attack ........................................................................................... 18
3.4.4 Tampering .............................................................................................. 18
vi
3.4.5 Collusion ................................................................................................ 19
3.4.6 Exhaustion.............................................................................................. 19
3.4.7 Spoofing ................................................................................................. 20
3.4.8 Denial of Service.................................................................................... 20
3.4.9 De-Synchronization ............................................................................... 20
3.4.10 Traffic Analysis ................................................................................... 21
3.4.11 Wormhole ............................................................................................ 21
3.4.12 Selective Forwarding Attack................................................................ 22
4. ADVANCED ENCRYPTION STANDARD ....................................................... 23
4.1 Why AES? ..................................................................................................... 25
4.2 AES Algorithm Implementation ................................................................... 26
4.2.1 Sub-Byte Transformation....................................................................... 28
4.2.2 Matrix-row Shift Transformation .......................................................... 29
4.2.3 Mix-Column Transformation ................................................................. 30
4.2.4 Adding Round Key Transformation ...................................................... 32
5. DESIGN AND IMPLEMENTATION ....................................................................34
5.1 Assumptions And Specifications................................................................... 34
5.2 Tools and Languages ..................................................................................... 35
5.3 Features of Virtex FPGA ............................................................................... 36
5.4 Project Design Flow ....................................................................................... 37
5.4.1 Design Entry .......................................................................................... 37
5.4.2 Simulation ..............................................................................................40
5.4.3 Synthesis ................................................................................................41
6. CONCLUSION ..................................................................................................... 43
vii
Appendix A ................................................................................................................ 45
References .................................................................................................................. 52
LIST OF TABLES
Page
viii
Table 3.1 WirelessHART Network layer PDU........................................................... 15
Table 4.1 Different types of key sizes ........................................................................ 24
Table 4.2 Adding round key transform ....................................................................... 33
LIST OF FIGURES
Page
ix
Figure 2.1 Frequency shift keying enabling simultaneous signals ............................... 4
Figure 2.2 Point to point mode ..................................................................................... 5
Figure 2.3 Multidrop mode ........................................................................................... 6
Figure 2.4 wireless mesh network ................................................................................ 8
Figure 2.5 Layers in WirelessHART ........................................................................... 9
Figure 4.1 Encryption of AES .................................................................................... 27
Figure 4.2 AES specified substitution matrix ............................................................. 29
Figure 4.3 Matrix-row shift transformation matrix, circular left shift ........................ 30
Figure 4.4 AES provided standard matrix .................................................................. 31
Figure 5.1 Virtex Board .............................................................................................. 35
Figure 5.2 Block diagram for AES Encryption .......................................................... 38
Figure 5.3 Finite State Machine for Encryption ......................................................... 39
Figure 5.4 Output of Sub-byte Matrix ........................................................................ 40
Figure 5.5 Key Scheduling ......................................................................................... 41
Figure 5.6 Script for generating timing reports ...........................................................42
Figure 5.7 Gate level diagram of Encryption after synthesis .......................................42
Chapter 1
x
1
INTRODUCTION
In this project our aim is to concentrate on several aspects of security in wireless
Highway Addressable Remote Transducer (HART) and design an algorithm in Verilog
HDL to encrypt data. The input data is encrypted using a key and the transmitted this
data to the receiver. We designed an algorithm that can secure the WirelessHART
network and it will be useful as a future reference to anyone who intends to design a
security system for a specific layer in WirelessHART or for the total network as a whole.
We are using the Advanced Encryption Standard (AES) to encrypt the data in a
WirelessHART network. AES is a part of the Data-link layer of the WirelessHART
network. The algorithm is implemented as a Verilog program that does the actual job of
encryption.
This algorithm generates the coding keys that are necessary for the
encryption of data; the keys are generated continuously as long as the WirelessHART
network is in use. This is because the keys in the network are continuously changed to
avoid them from being easily breached.
Our main focus is on the security of the Data-link layer; this is because Data-link layer is
the most important layer in the WirelessHART network. The Data-link layer is
responsible for secure, reliable and error free communication of the data between the
devices in WirelessHART network, it is used to provide security within the network
which is called Per-hop security.
2
Verilog hardware descriptive language is used to implement the algorithm because it is
very convenient to change or modify the program later, may it be the logic or addition of
extra modules to strengthen security. Another reason for preferring Verilog is that we
can design the logic for other devices in the system or network and tie them all together.
A control system or a host application controls all the devices in a network; programming
the hardware can control the entire automatic operations that can be done by using
Verilog.
Understanding the architecture and behavior of the WirelessHART network and
providing security using AES is all that we do in this project. The chapter 1 is an
introduction to WirelessHART and its security.
Chapter 2 gives the background
knowledge of HART and WirelessHART, modes of operation and their architecture.
Chapter 3 explains the types of security and threats faced by WirelessHART networks in
general. Chapter 4 details the how we use the AES to provide security, how AES is
implemented and the different states that occur which form the base for implementing the
algorithm in Verilog, finally chapter 5 which explains design flow which means it
explains how simulation and synthesis are carried out and what are the tools used to
design encryption, followed by the conclusions and references.
3
Chapter 2
BACKGROUND RESEARCH ON HART AND WIRELESSHART
HART protocol is used for communication and control purposes, which is widely
accepted in the industry as the standard for digitally enhanced communication with smart
field instruments. Rosemount Inc. developed the HART protocol in 1980’s and the
protocol was later made open to all. HART user group was formed in 1990, after three
years all the rights in the protocol and registered trademark were transferred to the HART
communication Foundation (HCF). The main goal of any organization is improving the
production, deliver the products rapidly, and improve quality, cut down operational and
maintenance costs and HART protocol achieves the above. [1]
HART Protocol plays a major part in cost saving, the cost saving could be done in
following:
1. Commissioning and installation
2. Plant operations and improved quality
3. Maintenance
The HART protocol uses the Bell 202 Frequency Shift Keying (FSK) standard; it is used
to superimpose digital signals with 4-20 mA analog signals.
This enables HART
protocol to carry out multiple operations; a field device returns two or more digital
4
updates per second without interrupting any analog signal transmission that is taking
place. This produces a simultaneous communication with a very good response time.
Figure 2.1 – Frequency Shift Keying enabling simultaneous signals [17]
There are two types of devices in HART communications; master or host and slave or
field device. The master device is generally a PC based workstation or a control room
full of workstations; the slave devices can be handheld devices, sensors, transmitters etc.
The variety ranges from two-wires and four-wired devices to intrinsically safe versions
for use in hazardous environments. The host devices have a FSK modem connected
externally in series to them and the field (slave) devices have an integrated FSK modem.
If we intend to connect many (> 1000) devices a multiplexer is used. HART enables
networking of these devices to suit various applications. These networks include pointto-point and multidrop.
5
2.1 Point to Point:
In the point-to-point mode the master device is connected to only one field device. The
digital signal takes care of other operations, commissioning, network diagnosis and
maintenance. The signals do not interfere with each other.
Figure 2.2 – Point-to-point mode [18]
2.2 Multi Drop:
In this mode of operation there are multiple field devices that are connected in parallel
through a single pair of wires; a maximum of 15 devices can be connected. The field
devices are mostly powered externally since the power required for all the devices cannot
be channeled from the control center; the current in each field devices is fixed to a
minimum value of 4mA.
6
Figure 2.3 – Multidrop Mode [18]
2.3 WirelessHART Architecture:
WirelessHART is a secure and TDMA-based wireless mesh networking technology
operating in the 2.4 GHz ISM radio band [13].
WirelessHART
was
specifically
designed
for
Unlike other wireless protocols,
process
control
applications.
WirelessHART is first open standard for automation industry specified by HART
Communication Foundation (HCF) and approved by IEC was officially released in
September 2007.
Before the advent of WirelessHART there have been several
technologies such as Bluetooth, WI-FI and Zigbee. However, these technologies failed to
meet the requirements of automation industry standards because wireless devices should
be able to get updates from sensors every second. Neither Zigbee nor Bluetooth can
update from sensors this quick [5]. Zigbee specification has low transmission rate, low
power wireless and has no built-in channel hopping technique, thus would surely fail in
automation environment. Bluetooth assumes quasi-static star network, which is not
scalable enough to be used in large process control systems. WirelessHART is
7
specifically designed to solve these problems and provide a complete solution for process
control applications [5].
With the release of version 7.0 of the HART protocol referred as WirelessHART,
vendors showed greater interest in developing different products based on this protocol.
WirelessHART is a secure and robust mesh networking technology and also backward
compatible with existing HART devices. The WirelessHART is user friendly, reliable
and interoperable wireless mesh sensor protocol [14]. In Wireless Mesh Network
(WMNs) all devices acts like router that in turn provides multiple network paths for
communication. In each wireless device there should be at least two connected neighbors
that can route traffic. The WMNs are combination of ad hoc and sensor networks where
sensor nodes act as router and hence support multi-hopping. Wireless mesh nodes are
easy to install, making the network extremely adaptable and expandable as more or less
coverage is needed. More nodes means bigger and faster network.
8
Figure 2.4 - Wireless Mesh Network [14]
Figure 2.4 shows how WirelessHART devices are connected with each other; it consists
of five core devices. The wireless sensor devices that are connected to actual processes
are called Field devices. An access point that connects wireless network with plant
automation network is called Gateway. These gateways are responsible for enabling the
communication between host applications and field devices.
Network manager is
responsible for configuration of the network, scheduling communication between
WirelessHART devices; there must be only one active network manager per
WirelessHART network. Adaptors are used to connect existing wired HART to
9
WirelessHART devices. Handheld devices can be connected with any field device and is
normally used for network monitoring.
WirelessHART architecture is similar to the seven layered OSI model with some
extensions for more security and reliability. WirelessHART is command oriented; this
means all the messages are combinations of commands that flows through the network.
WirelessHART protocol is self-healing and self organized, devices are able to find
neighbors and establish network by getting channel hopping and measuring signal
strength.
Figure 2.5 – Layers in WirelessHART [5]
10
All the data transmitting through WirelessHART is well defined and is highly secured.
AES-128 (Advanced Encryption Standard) is used for encrypting the data. Figure 2.5
shows different layers in WirelessHART which looks similar to seven layered OSI except
for the presentation and session layers.
2.3.1 Physical Layer: The WirelessHART physical layer is based mostly on the IEEE
STD 802.15-2006 2.4GHz DSSS physical layer. This layer defines radio characteristics,
such as the signaling method, signaling strength, and device sensitivity. WirelessHART
operates in 2400-2483.5MHZ license free ISM band with a data rate of up to 250Kbits/s.
Its channels are numbered from 11 to 26, with a 5MHz gap between two adjacent
channels. Modulation used in this layer is Quadrature Phase Shift Keying (QPSK) with
direct sequence spread spectrum [5]. WirelessHART requires that the expected indoor
communications distance should be 35 meters with 0dBm transmitter and 75 meters with
the transmit power of 10dBm and also it is adjustable in discrete steps.
2.3.2 Data-link Layer: Data-link layer is responsible for secure, reliable, error free
communication of data between HART compatible devices. For collision free
communication, WirelessHART uses Time Division Multiple Access (TDMA) and
channel hopping. A series of time slots form a TDMA superframe, superframe is
periodical with total length of the member slots as the period. Communication in a
WirelessHART network is defined through the superframe, timeslots and wireless links.
WirelessHART defines a strict 10ms time slot and utilizes TDMA technology to provide
11
collision free and deterministic communications. All superframes in a WirelessHART
network start from the ASN (Absolute Slot Number) 0; it is the time when the first
network is created. Each superframe repeats itself along the time base on its period, one
superframe is always enabled while additional superframes can be enabled or disabled.
Superframe length is fixed when it is active and length can be modified when inactive.
All devices support multiple superframes with differing numbers of timeslots to allow
mixing of fast, slow, cyclic and acyclic network traffic.
Communication occurs in
designated timeslot and frequency channel for that message [16].
Each device supports a class of data units and these units again have different priorities.
Commands that include control, configuration information and network related
diagnostics are classified to have high priority. The low priority packets belong to ‘alarm’
class that contains only alarm and event payload. All other packets are then grouped into
the ‘normal’ class. Priority classification is useful for flow control, which decides how
many of which type of packets can be buffered at a relay device.
2.3.3 Network Layer: WirelessHART uses mesh communication technology, so each
WirelessHART device must be able to forward packets on behalf of other devices. Two
types of routing are supported first one is graph routing and second is source routing. All
devices must support both graph and source routing. A graph is a collection of paths that
connect network nodes; a path in each graph is explicitly created by the network manager
and downloaded to each individual network device. To send a packet, the source device
12
writes a specific graph ID in the network header. All the network devices on the way to
the destination must be pre-configured with graph information that specifies the
neighbors to whom the packets may be forwarded. Source routing is a supplement of the
graph routing aiming at network diagnostics. To send a packet to its destination, the
source device includes in the header an ordered list of devices through which the packet
must travel. As the packet is routed, each routing device utilizes the next network device
address in the list to determine the next hop until the destination device is reached [5].
2.3.4 Transport Layer:
Transport layer provides end-to-end acknowledgement
communication, which does automatic retries to confirm successful data transfer. This is
a thin layer in WirelessHART that ensures reliable data transmission. A unique feature of
this layer is block data transfer mechanism. It sets up a connection oriented
communication link between the host application and the field devices. The host
application can configure the slave device by opening a port onboard the device using a
HART command. The port specifications are also part of the WirelessHART standard.
Once the port is opened, transmission rate between the device and host application is
negotiated with the network manager to maximize throughput. The block data transfer is
required for reliability and end-to-end acknowledgement is necessary to keep track of the
data stream. This may call for the network manager to update its routing and scheduling
plan to provide the necessary priority. Transport layer is responsible for continuously
monitoring the neighbor devices. Devices listen for new neighbors and report if they
13
discover a new neighbor. Each device maintains statistics on communication with other
devices like received signal level and packet count.
2.3.5 Application Layer:
Application layer is the top-most layer in architecture, WirelessHART uses the standard
HART application layer, which is command based. Universal, device family and wireless
commands are specified in application layer. Communication between devices and
gateway is based on commands and responses. The application layer is responsible for
parsing the message content, extracting the command number, executing the specified
command, and generating responses. Several new features were added to new version of
WirelessHART for better wireless communication and to enhance wired HART
capabilities like:
1) Smart data publishing to generate process data messages only when needed.
2) Process values published based on time, variation of signal, or crossing a userdefined threshold.
3) Measurements can be triggered at specific time allowing synchronized operation
across multiple devices.
4) Command aggregations enable multiple read commands in one transaction for
faster configuration uploads.
14
Chapter 3
SECURITY IN WIRELESSHART
In this chapter we will discuss in detail the security in WirelessHART, the security
schemes it needs, the security keys needed and the role they play in keeping the system
secure. We also analyze and discuss the capabilities and tasks of the security manager,
thereby setting up standards for a security manager’s design, specifications, and
performance. The WirelessHART standard secures communication between two devices
involved in a data transfer, for example a source and the destination at the Network layer
and between two neighboring devices at the Data-link layer. The main security services
are Confidentiality, data integrity, authenticity and availability. Let us discuss them in
detail now:
3.1 End-to-end security: Generally the network layer is used to provide end-to-end
security; it can also provide routing and transport services. The network layer gets the
Protocol Data Unit (PDU) from Data-link layer and sends it to specific device and if the
PDU taken from Data-link layers reaches the wrong device it is sent back to the Data-link
layer. The network layer can get the PDU from transport layer directly too. The data that
is sent from network layer is enciphered and it can be deciphered only by one particular
destination device that is destined to receive that data. The data that travels from the
source field device to the end field device always passes through the gateway. The
gateway decrypts the data sent by the source field device that has been encrypted by the
15
source field device with a unique session key, the gateway again encrypts with another
unique session key which refers to the destination field device and only that destination
device can decrypt that. All this is done because two field devices cannot create a
session, only gateways and network managers can create sessions with devices [3].
Now let us see how the Network layer implements the end-to-end security using the keys.
In any WirelessHART network four session keys, one join key and one network key are
used by a device. The transport layer PDU used in the Network layer PDU is encrypted
using Advanced Encryption Standard (AES) with a 128-bit key, we will discuss about
AES in coming chapters.
HEADER
SCB
COUNTER
MIC
NPDU Payload
Table 3.1 – Wireless HART Network layer PDU
SCB – Security control bit
MIC – Message Integrity Code
SCB: The SCB consists of eight bits, four of which are used to define the type of
security and the first four bits are intentionally left blank for security purposes to provide
further security in future.
16
MIC: MIC is used for authentication purposes. The data received at the destination
device is authenticated by the MIC given by the source device. The MIC is calculated
using a process, which will be discussed in detail in the chapter covering AES.
3.2 Per-hop security: The Data-link layer is used to provide Per-hop security, which is
basically, the security provided within the system or a network. This security is essential
because any network may be tough and secured from the outside but is vulnerable from
the inside, thereby can be easily breached. Security is provided between two devices in a
network using a network key, which is known to all the devices in that WirelessHART
network.
The MIC here is calculated for the entire layer. The MIC at the destination device is
compared with the one in the Data-link layer PDU by the device, and if both the MICs do
not match the data transferred is sent back. The last bit in the Data-link layer is Cyclic
Redundancy Check (CRC), it is used to check the errors in data and communication.
Devices in a WirelessHART should have a network key to communicate with each other,
but the devices only have the join key at beginning and need some key in order to
calculate the MIC [2]. The specifier in the Data-link layer PDU is responsible for
classifying the type of key being used for authentication, and if that specifier bit is set
then the network key is used to authenticate the Data-link layer PDU. If the specifier bit
is not set then a key called well-known key is used which is a specified standard in
WirelessHART for Per-hop security.
17
3.3 Peer to peer Security: Handheld devices can communicate with one another directly
without the involvement of any other manager in the network using a handheld key. First
the handheld device has to join the network in order to communicate with the field
device, so it needs to get the handheld key from the network manager. As each device
has a unique handheld key, the handheld device must acquire that particular key which
enables communication with the required field device.
The peer-to-peer process is
generally used for maintenance purposes.
3.4 THREATS IN SECURITY
Threat is defined as an occurrence of an undesirable event in the network. As the
WirelessHART network uses both wired and wireless communication, the wireless
communication medium is easily prone to threats compared to the wired counterpart [7].
Different kinds of threats are:
3.4.1 Interference: In a mesh network, a number of signals with identical modulation
technique and frequency are transmitted at a single event. This sometimes results in the
interference of one signal with another within the same band spectrum resulting in the
overriding of the actual signal. Some of the devices that share the same spectrum (24002483.5 MHZ) as WirelessHART are Zigbee, and WI-FI.
To overcome the interference, WirelessHART standard employs a Frequency Hopping
Spread Spectrum (FHSS) [4] that utilizes a pseudorandom code to uniquely identify the
receiver and transmitter. Specifying the time and path of the communication also reduces
18
interference. In the wireless medium a reliability of anything less than 100% results in
adverse effects.
3.4.2 Jamming: An interruption of the transmitted signal in the target network with the
introduction of noise with same frequency and modulation technique is termed jamming.
As the WirelessHART communication shares the same band spectrum with most
commonly used Bluetooth devices, jamming occurs more frequently compared to
interference.
Blacklisting technique is used to increase the reliability of communication in
WirelessHART. The channel with the most number of jammed communications is
identified and it is blacklisted. The blacklisting of a channel results in the reduction of the
performance as the number of active channels for communication is reduced.
3.4.3 Sybil Attack: The attacks caused on the communication due to multiple identities of
a single device are called Sybil attacks [11]. The previously used sensory and wireless
communication systems adapted security systems that allowed a single device to have
multiple identities resulting in these attacks.
Assigning a unique name to each and every device with in the network reduces the Sybil
attacks in a WirelessHART system. All the devices are also tagged with a unique ID to
identify them globally. These tags are maintained by the gateway in WirelessHART.
3.4.4 Tampering: The process of modification of communicated data during transmission
is called Tampering or modification attack. Generally the data to be transmitted is
associated with a protection scheme such as Cyclic Redundancy Check (CRC) or a hash
19
is tagged to the data. The tampering can be easily done in Data-link layer when compared
to network layer, but if it is done in network layer the damage will be very serious. Using
keyed MIC at both the Data-link layer and Network layer can reduce the data tampering.
Frequently changing the network key and protecting the network devices physically can
also reduce this.
3.4.5 Collusion: The WirelessHART network consists of many devices that require
identical frequency channels for communication. When more than one of these devices
try to communicate with the same channel at exactly the same time leads to collusion.
The collusion can be caused either by an attacker or even by a device with less timing
restrictions. Collusion can be detected by Cyclic Redundancy Check (CRC) [2]. Using
specified timing slots for devices and setting the device priorities can reduce collusion.
Collusion can also be reduced by proper integration of the Data-link layer and Physical
layer.
3.4.6 Exhaustion: All the devices that are part of the WirelessHART network are
familiar with all the network parameters that are required to communicate with other
device using the well-known key. An attacker device can use this well-known key to
calculate the MIC for Data-link layer PDU and uses a fake join key for Network layer
PDU. When the Network manager receives the data that is transmitted from the attacker
device it checks for the join key and denies the data because a fake join key was used.
The exhaustion problem does not cause any damage to the devices but it reduces the
20
performance as the time and resources in the transmission of fake data are wasted.
Protecting the network parameters can reduce this problem.
3.4.7 Spoofing: All the devices in the WirelessHART network are associated with a
network key, used to connect to a network and communicate with in the network.
Sometimes this network key is also used to advertise and attract other devices to join the
network. An attacker tracks down the network key, changes it and advertises the
modified one. This false network key attracts more number of devices to send join
requests causing more network traffic blockages. Frequently changing and monitoring the
network key by the network manager can reduce the Spoofing problem in the network.
3.4.8 Denial of Service: The denial of service is the most common and effective attack
for the normal operation interruption in the WirelessHART. The denial of service is more
frequent in WirelessHART compared to HART protocol. The denial can be caused due to
many reasons such as increase in the number of join requests in the network,
advertisements by the attacker, jamming or by exhaustion [5].
3.4.9 De-synchronization: The WirelessHART system is designed with strict timing
requirements. The introduction of false timing specifications by an attacker in the
network causes the device to miss the timing requirements and this leads the transmission
to abort and restart again which means wastage of both resources and time.
The timing problem is reduced by introducing a timer module and fixing all the time slots
for the devices to a defined amount (10ms). Whenever a node receives an
21
acknowledgement signal, the timer is reset to default value.
This helps in keeping the
devices in synchronization.
3.4.10 Traffic Analysis: In the wired network there should exist a physical connection
between the communicating devices. In a wireless network the transmission medium is
air, this makes the wireless communication more prone to traffic analysis by the attacker
because the Network layer PDU header and Data-link layer PDU are not encrypted. By
using the information from the header the attacker can analyze the network. For example,
the join requests from the devices outside the network can be analyzed and fake
permission can be issued to the device
To minimize the traffic analysis affects the Data-link layer PDU can be encrypted with
network key. This results in the increase of the time taken for the communication,
because the intermediate devices between the source and destination have to decrypt the
Network layer PDU at the Data-link layer to know the information of the destination
device.
3.4.11 Wormhole: The attacker can accomplish the wormhole attack by using wired
HART devices connected to WirelessHART network. Connecting them either by a wired
or wireless link to create a wormhole creates a tunnel.
Transferring the data in a pre-specified route from source to destination can minimize the
wormhole attacks. These attacks can also be minimized by packet leashing techniques
[6]. Providing physical protection to the network can minimize the wormhole attacks in
wired connections.
22
3.4.12 Selective Forwarding Attack: Some of the received data packets at a node that are
not legitimate are discarded. For example if a fake join key is used for Network layer
PDU and transmitted to the destination device, on receiving data the destination device
checks for the join key and discards the data because it used a fake join key. A node
generally forwards and drops packets of data selectively to be considered as a good
device [5].
Monitoring the network by using good network manager can minimize these selective
forwarding attacks. The network manager can also be used along with handheld device to
monitor the entire network.
23
Chapter 4
ADVANCED ENCRYPTION STANDARD
Security plays an important role in communication as it contains sensitive data, especially
in wireless communication where the data is shared between different wireless devices.
We have to make sure that information must be transmitted over secured networks, so
that it cannot be misused by unauthorized person. Cryptography is the process of hiding
the data by using secured keys; it provides a method for securing and authenticating the
transmission of information over channels. We used Advanced Encryption Standard
(AES-128) in WirelessHART protocol to ensure a secured communication [12].
AES specifies the Rijndael algorithm, a symmetric block cipher that can process data
blocks of 128 bits using cipher keys with lengths of 128,192 and 256 bits. National
Institute of Standards and Technology (NITS) announced AES in 2001. The AES
algorithm is performed in Nr (Number of Rounds). The architecture of one round
contains two different data-paths, the encryption data-path and key scheduling data-path.
The size of data block in AES is 128 bit long and the key size can be 128, 192 and 256
bits. The AES algorithm contains mainly three parts; cipher, inverse cipher and key
expansion. Cipher converts data into unintelligible form called ciphertext while inverse
cipher converts data back into its original form called plaintext. Key expansion generates
a key schedule that is used in cipher and inverse cipher procedure. We have designed
24
AES algorithm using Verilog and RTL code of AES was simulated on Modelsim and
synthesized using VCS synopsis.
Block size (Nb) Key length (Nk) Number
words
words
Rounds (Nr)
AES-128 bits key
4
4
10
AES-192 bits key
4
6
12
AES 256 bits key
4
8
14
of
Table 4.1 Different types of key sizes
The above table 4.1 shows that number of rounds depend on AES key size. For a 128 bit
key, the key is divided into 4X4 matrix in which each element is 8 bits. Similarly, for 192
bit size, the key is divided into 6X6 matrix with each element is 8bit. It is the same case
for 256-bit size that is divided into 8X8 matrix. The AES algorithm starts with initial
transformation of data matrix followed by ten iteration rounds. A round consists of four
transformations they are
1) Byte substitution (SubByte)
2) Row shifting (Shiftrows)
3) Mixing of columns (Mixcoloumns)
25
4) Addition of round key (Addroundkey).
From each round, a round key is generated from the original key through key
scheduling process. The last round consists of subbytes, shiftrows and addroundkey
transformation.
4.1 Why AES?
There are many algorithms like Data Encryption Standard (DES) and triple DES, then
why is AES used for security in the WirelessHART? [15]
The reasons for using AES
1) It has strong resistance against all known attacks because it uses a minimum of 10
rounds for generating ciphertext. The number of rounds is not fixed; they are
varied according to the security level and size of the key.
2)
As it is symmetric algorithm the operation is faster compared to other
cryptography algorithms. The round transformation is parallel by design; this
makes all the round calculations faster, which generates output block.
3) Compared to other cryptographic algorithms the AES algorithm has a simple
design.
4) It is hard to crack AES because it uses different steps like shifting, mixing and
adding schedule keys.
26
5) Guarantees high diffusion over multiple rounds.
6) Corresponds to the parallel application of S-boxes that have optimum worst-case
non-linearity properties.
7) Finally the AES is well suited to be implemented efficiently on a wide range of
processors and in dedicated hardware typical for a PC.
4.2 AES Algorithm Implementation:
In the implementation of the algorithm, the data to be transmitted is divided into equal
blocks of 128 bits each. The data is further divided into a 4x4 matrix in which each
element is of 8-bits. The elements in the matrix are represented in hexadecimal form. The
matrix is formed such that the four elements in the first column are the first 32 bits of the
data. The length of the data block (Nb) is defined as the number of 32-bit words in each
block and is equal to 4. The length of the key that is used for encryption of the data can
be 128, 192 or 256 bits in length. The length of the key (Nk) is defined as the number of
32-bit words in the key. The length of the key for 128, 192 and 256 bits are 4, 6 and 8
respectively. Depending on the length of the encryption key the number of iterations
performed to encrypt the data increases. The number of rounds (Nr) required encrypting
the data for a key length of 128, 192 and 256 bits are 10, 12 and 14 respectively [12].
27
PLAIN TEXT
ROUND KEY (0)
ADD ROUND KEY
Ro
SUB BYTES
SHIFT ROWS
MIX COLUMNS
ROUND KEY (i)
ADD ROUND KEY
SUB BYTE
SHIFT ROWS
ADD ROUND KEY
ROUND KEY (Nr)
CIPHER TEXT
Figure 4.1- Encryption of AES [12]
28
The encryption starts by copying the input data in matrix form into a two-dimensional
array called data array and performing the addition operation on the array with the initial
cipher key. The data array is then transformed 10, 12 or 14 times depending on the length
of the cipher key. The length of cipher key used in our project is 128 bits and the number
of transformation rounds required to encrypt the data with the key is 10. Each
transformation round consists of four basic steps and they are
1) Sub-byte transformation
2) Matrix-row shift transformation
3) Mix-column Transformation
4) Adding round key transformation
All the rounds of transformation perform these four steps in the same order except the
final round, which skips the third step.
4.2.1 Sub-Byte Transformation: In the sub-byte transformation each element of the
matrix is replaced by a corresponding element from the substitution table provided by the
AES in figure 4.2. The elements of both the sub-byte matrix and the substitution matrix
are represented in hexadecimal format. As the elements in the matrix are in hexadecimal
form each element can only be represented by two digits and can be easily substituted
from the substitution table. For example if the element in the sub-byte matrix is [A5] it
will be replaced by [06] after the transformation. The first digits ‘A’ matches with the
29
digit represented by row ‘a’ and the second digit ‘5’ corresponds to the column ‘5’. The
element in the substitution table representing this combination replaces the sub-byte
element.
Figure 4.2 AES specified substitution matrix [12]
4.2.2 Matrix-row shift transformation: In the matrix-row shift transformation the
elements of the matrix obtained after the sub-byte transformation are shifted left in
circular shift method. In the circular row shift method the first element is replaced by
second element, second by third, third by fourth and fourth element by the first. In this
step the first row is not shifted, second row is shifted one time, third row is shifted two
times and the fourth row by three times. This step is illustrated in figure 4.3.
30
Figure 4.3 Matrix-row shift transformation matrixes, circular left shift [12]
4.2.3 Mix-column Transformation: In the mix-column transformation step, the matrix
obtained after the matrix-row transformation is multiplied with a standard matrix (in fig
4.4) provided by AES. The matrix multiplication performed in this step is not the general
matrix multiplication, because in general if we multiply two 2-digit numbers we get a
result with more than two digits. As we just have only 2-hexadecimal digits to represent
each element before and after transformation, the multiplication and addition required in
the general matrix multiplication are not performed here. Instead, the multiplication is
performed by representing both the elements to be multiplied in the polynomial form and
then multiplying them and reducing the obtained polynomial with modulo by an
irreducible polynomial of 8th degree. The standard irreducible polynomial provided by
AES is ‘x8+x4+x3+x+1’.
31
Figure 4.4 AES provided standard matrix [12]
For example if the two elements to be multiplied are ‘63’ and ‘34’, 63 is
represented in binary form as 01100011 and 34 as 00110100 and in polynomial form as
63= x6+x5+x+1, 34= x5+x4+x2. The multiplication of these two polynomials results in
(63). (34) = (x6+x5+x+1) (x5+x4+x2) = x11+x9+x8+x7+x6+x4+x3+x2.
The modulo is performed on the above result using the AES standard irreducible
polynomial to obtain a polynomial with a degree less than eight.
(x11+x9+x8+x7+x6+x4+x3+x2) modulo (x8+x4+x3+x+1) = x5+x3+1.
As the elements in the standard matrix consist of only 01, 02 and 03 a easy method can
be used to obtain the multiplication result. If an element is multiplied by 01, the result is
the element itself and the multiplication with 02 can be obtained by left shifting the
element bit-wise. The multiplication by 03 can be obtained by splitting the 03 into (01 ⨁
02) ⨁ represents XOR. For example:
(63). (03) = (63). (01 ⨁ 02) = [(63). (01)] ⨁ [(63). (02)] = (63) ⨁ (C6) = [A5]
32
The addition part of the matrix multiplication is done by performing bit-wise XOR
operation on the numbers that are to be added after multiplication of each element.
4.2.4 Adding round key Transformation: In this transformation step, a bit-wise XOR
operation is performed for the matrix obtained from step 3 and the round key obtained in
the respective stage. To obtain the round key for the first round, the encryption key that is
used to XOR with the original data before the start of first round is used. The original
encryption key is divided into four 32-bit words and the first 32-bit word of the round key
for first round is obtained by performing a bit-wise XOR operation for first 32-bit word
and last 32-bit word of the original encryption key. The second word of round key is
obtained by XOR operation between the second word of original encryption key and the
first word of round key. For third word of round key the XOR operation is performed
between third word of original encryption key and second word of round key. The fourth
word is obtained by performing the XOR operation between fourth 32-bit word of
original encryption key and the third word of round key obtained above. The round key
obtained in the first round is used as the original encryption key for the second round and
so on. For example consider
Encryption key = 6c 9d 7e b3 4d 5e 63 34 80 52 1e 22 de 34 2c cd
The 32-bit words will be
w1 = 6c9d7eb3 w2 = 4d5e6334 w3 = 80521e22 w4 = de342ccd
33
Original encryption Word to be XOR Round Key
key
with
6c9d7eb3
de342ccd
b2a9527e
4d5e6334
b2a9527e
fff7314a
80521e22
fff7314a
7fa52f68
de342ccd
7fa52f68
a19103a5
Table4.2 Adding round key transform
In the last round of the data encryption the mix-column transformation step is skipped
and XOR operation is performed between the matrix obtained from the row-shift
transformation step and the round key to obtain the final encrypted data matrix.
34
Chapter 5
DESIGN AND IMPLEMENTATION
WirelessHART is now an emerging network technology which was standardized in 2007
and it is growing and flourishing rapidly. There are more than 30 companies engaged in
bringing WirelessHART products to market. Many challenges are being set: like
increasing the speed, bringing down the cost of producing firmware and radios, gateways,
and adapters. After doing research on WirelessHART we found that it is a layered
protocol and out of which Data Link Layer is important. Here in this project we made an
attempt to design security system in Data Link Layer so that we can integrate the design
logic in chips (ASIC/FPGA).
5.1 Assumptions and Specifications:
1) 128-bit key is used for encryption to generate cipher text from plain text.
2) The data input which comes to the Data-link layer is considered as four words in
size so that encryption is done properly.
3) The Sub-byte matrix which is used in encryptions is generated from Verilog test
bench and is not used for synthesis.
4) Xilinx Virtex FPGA (Model: XC5VLX30-1FF324C) is used for implementation.
5) The plain text is assumed as serial data input for our design.
35
5.2 Tools and Languages:
1) Environments used: Windows is used for RTL design and simulation. UNIX is
used for synthesis and generating timing and area reports.
2) The RTL design was performed using Verilog HDL. The coding is done using
Modelsim simulation tool.
3) The synthesis of the design was performed using Synopsys VCS.
4) Virtex board: Virtex board has a FPGA connected to switches and LEDs. The
FPGA is at the bottom of the silk screening. The program developed to run our
logic is dumped into the FPGA.
5) TCL scripting is used for generating timing and area reports.
Figure 5.1 Virtex Board
36
5.3 Features of Virtex FPGA:
We used a Virtex-5 FPGA for our project because of its salient features, these are:
1. It has five platforms LX, LXT, SXT, TXT, and FXT.
2. It is cross-platform compatible.
3. Power clock management tile (CMT) clocking.
4. 36-kbit blocks RAM/FIFOs.
5. High-performance parallel select IO technology.
6. Advanced DSP48E slices.
7. Flexible configuration options.
8. System monitoring capability on all devices.
9. Integrated endpoint blocks for PCI express designs.
10. Tri-mode 10/100/1000 Mb/s Ethernet MACs.
11. Rocket IO GTP transceivers 100 Mb/s to 3.75 GB/s and 150 Mb/s to 6.5 Gb/s.
12. PowerPC 440 Microprocessors.
13. 65-nm copper CMOS process technology.
37
14. High signal-integrity flip-chip packaging available in standard or Pb-free package
options.
5.4 Project design flow:
There are three phases in our project, they are:
5.4.1 Design Entry: The block diagram (Figure 6.2) shows how the data is encrypted in
the message handling module. The data which comes into the module is first converted
into four 32-bit chunks (represented in a 4x4 matrix form) using serial to parallel
converter. Then these 32-bit chunks are XORed with a key (user-defined). The resulting
32-bit chunks are converted into sub-byte blocks of data using s-chart as shown in figure
4.2. We have designed a shifter block to manipulate the 4x4 matrix using three different
functions; first function will shift one byte of substitution matrix, second function shifts
two and the third shifts three respectively. After generating shifter block we have
designed a matrix multiplier method in which we multiply the elements of the 4x4 matrix
with AES specified mixed column matrix as described in section 4.2. This process
repeats for ten rounds to generate a ciphertext.
38
Serial data
input
Serial to parallel
converter
Serial data
output
Parallel to serial
converter
Xor block
Shifter
Mix columns
Key
scheduler
Matrix
column
Test bench
Figure 5.2 Block diagram for AES Encryption
Finite State Machine (FSM) for data Encryption: Figure 5.3 shows the state diagram of
data encryption. Each state represents a transform; there are a total of 6 states in this
finite state machine. S0 is the idle state, initialization of all the signal is done in this state
and whenever the FSM is reset it returns to this state. In S1, S2, S3 and S4 sub-byte
transform, matrix-row shift transform, mix-column transform and adding round key
transform are performed respectively. Each state has a counter (cnt) which counts from
39
zero to three (four 32-bit words). S5 is final state where the ciphertext is generated when
round key equals to ten (tenth round).
Figure 5.3 Finite State Machine for Encryption
40
5.4.2 Simulation:
In this phase we used Modelsim tool to write the Verilog program for our logic design.
We simulated the Verilog program and checked the functionality of the design. The
following waveforms show the simulated output which were generated using Modelsim.
Figure 5.4 shows the sub-byte matrix output for two rounds. Figure 5.5 shows the
simulated waveform of Key scheduling module. The simulation results are included in
appendix A.
Figure 5.4 Output of sub-byte matrix
41
Figure 5.5 Key scheduling
5.4.3 Synthesis:
Logic synthesis is a process by which an abstract form of desired circuit behavior
(typically register transfer level (RTL)) is turned into a design implementation in terms of
logic gates. In this phase we used Synopsys VCS for synthesis of Verilog code which
was developed in simulation phase using Modelsim. During synthesis TCL script
importing symbol library, target library and link library to synthesize the RTL code to get
a gate level design. Synthesizer uses the gate delays, gate size from symbol library for
generating the gate circuit.
42
Figure 5.6 Script for generating timing reports
Figure 5.6 shows the TCL script which generates timing, area and attribute reports. In
this script we set constraints like clock, clock delay, area and operating conditions. The
timing, area and attribute reports are included in the appendix A.
Figure 5.7 Gate level diagram of Encryption after synthesis
43
Chapter 6
CONCLUSION
The security requirements for a WirelessHART network have been studied and security
system is designed using AES algorithm. The algorithm is implemented using Verilog.
The data in the WirelessHART network is encrypted using AES algorithm and
authenticated using keys. The Verilog code written to implement the AES algorithm is
simulated using Modelsim and the results are generated. Therefore the security provided
for the WirelessHART is strong and can protect the network.
The encrypted data is compared with the decrypted data and the results differed slightly
at the first two trails, this was because the algorithm implementation went wrong.
Verilog executes the program in a parallel fashion unlike the programs in C language or
any other programming language, so we had to carefully go through each and every step
of the procedure of encryption of data many times. We represented the bits of the data in
matrix form which helped us a lot as there are a lot of ways in which a matrix can be
manipulated and also because matrix operations can be easily done.
The major success in our attempt to secure a WirelessHART network came from a
decision which we made at early stages of our project; we used Verilog HDL for
implementation of the AES algorithm which made our task easy as the simulation process
makes it easy to figure out the errors if any in our program. Some previous attempts were
made using different algorithms and programming languages to encrypt data, but our
44
attempt is unique and it also is very beneficial since the algorithms can be easily
implemented without much effort, error detection in implementation can be easily
rectified and can be maintained easily by the control system of the WirelessHART
network.
This was a sincere attempt to make WirelessHART a secure communication network. As
we work towards the goal of making WirelessHART a reliable and productive option for
networking, this effort will help understand the use of implementing AES algorithm
using Verilog to secure the WirelessHART better.
45
APPENDIX A
Simulation Results
Round key results
Chronologic VCS simulator copyright 1991-2005
Contains Synopsys proprietary information.
Compiler version Y-2006.06-SP1; Runtime version Y-2006.06-SP1;
12:05 2010
May
3
VCD+ Writer Y-2006.06-SP1 Copyright 2005 Synopsys Inc.
0subin=xxxxxxxx, subout=xxxxxxxx,
shiftrows=xxxxxxxx,key=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx,datain=xxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxx
10subin=xxxxxxxx, subout=xxxxxxxx,
shiftrows=xxxxxxxx,key=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx,datain=00110010
010000111111011010101000
20subin=xxxxxxxx, subout=xxxxxxxx,
shiftrows=xxxxxxxx,key=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx,datain=10001000
010110100011000010001101
30subin=xxxxxxxx, subout=xxxxxxxx,
shiftrows=xxxxxxxx,key=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx,datain=00110001
001100011001100010100010
40subin=xxxxxxxx, subout=xxxxxxxx,
shiftrows=xxxxxxxx,key=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx,datain=11100000
001101110000011100110100
50subin=xxxxxxxx, subout=xxxxxxxx,
shiftrows=xxxxxxxx,key=00101011011111100001010100010110,datain=11100000
001101110000011100110100
60subin=xxxxxxxx, subout=xxxxxxxx,
shiftrows=xxxxxxxx,key=00101000101011101101001010100110,datain=11100000
001101110000011100110100
70subin=xxxxxxxx, subout=xxxxxxxx,
shiftrows=xxxxxxxx,key=10101011111101110001010110001000,datain=11100000
001101110000011100110100
Subbyte Values after First Round
80subin=xxxxxxxx, subout=xxxxxxxx,
shiftrows=xxxxxxxx,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
90subin=19a09ae9, subout=d4e0b81e,
shiftrows=d4e0b81e,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
100subin=3df4c6f8, subout=27bfb441,
shiftrows=bfb44127,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
46
110subin=e3e28d48, subout=11985d52,
shiftrows=5d521198,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
Subbyte Values after Second Round
120subin=be2b2a08, subout=aef1e530,
shiftrows=30aef1e5,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
130subin=a4686b02, subout=49457f77,
shiftrows=30aef1e5,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
140subin=9c9f5b6a, subout=dedb3902,
shiftrows=dedb3902,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
150subin=7f35ea50, subout=d2968753,
shiftrows=968753d2,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
Subbyte Values after Third Round
160subin=f22b4349, subout=89f11a3b,
shiftrows=1a3b89f1,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
170subin=aa618268, subout=acef1345,
shiftrows=45acef13,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
180subin=8fddd232, subout=73c1b523,
shiftrows=45acef13,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
190subin=5fe34a46, subout=cf11d65a,
shiftrows=cf11d65a,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
Subbyte Values after Fourth Round
200subin=03efd29a, subout=7bdfb5b8,
shiftrows=dfb5b87b,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
210subin=48674dd6, subout=5285e3f6,
shiftrows=e3f65285,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
220subin=6c1de35f, subout=50a411cf,
shiftrows=cf50a411,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
230subin=4e9db158, subout=2f5ec86a,
shiftrows=cf50a411,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
Subbyte Values after Fifth Round
240subin=ee0d38e7, subout=28d70794,
shiftrows=28d70794,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
250subin=e0c8d985, subout=e1e83597,
shiftrows=e83597e1,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
47
260subin=9263b1b8, subout=4ffbc86c,
shiftrows=c86c4ffb,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
270subin=7f6335be, subout=d2fb96ae,
shiftrows=aed2fb96,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
Subbyte Values after Sixth Round
280subin=e8c05001, subout=9bba537c,
shiftrows=aed2fb96,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
290subin=f1c17c5d, subout=a178104c,
shiftrows=a178104c,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
300subin=0092c8b5, subout=634fe8d5,
shiftrows=4fe8d563,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
310subin=6f4c8bd5, subout=a8293d03,
shiftrows=3d03a829,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
Subbyte Values after Seventh Round
320subin=55ef320c, subout=fcdf23fe,
shiftrows=fefcdf23,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
330subin=263de8fd, subout=f7279b54,
shiftrows=fefcdf23,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
340subin=0e4164d2, subout=ab8343b5,
shiftrows=ab8343b5,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
350subin=2eb7728b, subout=31a9403d,
shiftrows=a9403d31,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
Subbyte Values after Eighth Round
360subin=177da925, subout=f0ffd33f,
shiftrows=d33ff0ff,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
370subin=5a19a37a, subout=bed40ada,
shiftrows=dabed40a,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
380subin=4149e08c, subout=833be164,
shiftrows=dabed40a,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
390subin=42dc1904, subout=2c86d4f2,
shiftrows=2c86d4f2,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
Subbyte Values after Ninth Round
400subin=b11f650c, subout=c8c04dfe,
shiftrows=c04dfec8,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
48
410subin=ea046585, subout=87f24d97,
shiftrows=4d9787f2,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
420subin=83455d96, subout=ec6e4c90,
shiftrows=90ec6e4c,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
430subin=5c3398b0, subout=4ac346e7,
shiftrows=90ec6e4c,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
Subbyte Values after Final Round
440subin=f02dadc5, subout=8cd895a6,
shiftrows=8cd895a6,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
450subin=eb598b1b, subout=e9cb3daf,
shiftrows=cb3dafe9,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
460subin=402ea1c3, subout=0931322e,
shiftrows=322e0931,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
470subin=f2381342, subout=89077d2c,
shiftrows=2c89077d,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
480subin=1e84e7d2, subout=725f94b5,
shiftrows=2c89077d,key=00001001110011110100111100111100,datain=11100000
001101110000011100110100
$finish at simulation time
2000
V C S
S i m u l a t i o n
R e p o r t
Time: 2000
CPU Time:
0.010 seconds;
Data structure size:
0.0Mb
Mon May 3 12:05:12 2010
Shiftrow results
Chronologic VCS simulator copyright 1991-2005
Contains Synopsys proprietary information.
Compiler version Y-2006.06-SP1; Runtime version Y-2006.06-SP1;
02:13 2010
Subbyte Values after First Round
VCD+ Writer Y-2006.06-SP1 Copyright
0subin=19a09ae9,
10subin=3df4c6f8,
20subin=e3e28d48,
Subbyte Values after Second Round
30subin=be2b2a08,
40subin=a4686b02,
May
3
2005 Synopsys Inc.
subout=d4e0b81e, shiftrows=d4e0b81e
subout=27bfb441, shiftrows=bfb44127
subout=11985d52, shiftrows=5d521198
subout=aef1e530, shiftrows=30aef1e5
subout=49457f77, shiftrows=30aef1e5
49
50subin=9c9f5b6a, subout=dedb3902, shiftrows=dedb3902
60subin=7f35ea50, subout=d2968753, shiftrows=968753d2
Subbyte Values after Third Round
70subin=f22b4349, subout=89f11a3b, shiftrows=1a3b89f1
80subin=aa618268, subout=acef1345, shiftrows=45acef13
90subin=8fddd232, subout=73c1b523, shiftrows=45acef13
100subin=5fe34a46, subout=cf11d65a, shiftrows=cf11d65a
Subbyte Values after Fourth Round
110subin=03efd29a, subout=7bdfb5b8, shiftrows=dfb5b87b
120subin=48674dd6, subout=5285e3f6, shiftrows=e3f65285
130subin=6c1de35f, subout=50a411cf, shiftrows=cf50a411
140subin=4e9db158, subout=2f5ec86a, shiftrows=cf50a411
Subbyte Values after Fifth Round
150subin=ee0d38e7, subout=28d70794, shiftrows=28d70794
160subin=e0c8d985, subout=e1e83597, shiftrows=e83597e1
170subin=9263b1b8, subout=4ffbc86c, shiftrows=c86c4ffb
180subin=7f6335be, subout=d2fb96ae, shiftrows=aed2fb96
Subbyte Values after Sixth Round
190subin=e8c05001, subout=9bba537c, shiftrows=aed2fb96
200subin=f1c17c5d, subout=a178104c, shiftrows=a178104c
210subin=0092c8b5, subout=634fe8d5, shiftrows=4fe8d563
220subin=6f4c8bd5, subout=a8293d03, shiftrows=3d03a829
Subbyte Values after Seventh Round
230subin=55ef320c, subout=fcdf23fe, shiftrows=fefcdf23
240subin=263de8fd, subout=f7279b54, shiftrows=fefcdf23
250subin=0e4164d2, subout=ab8343b5, shiftrows=ab8343b5
260subin=2eb7728b, subout=31a9403d, shiftrows=a9403d31
Subbyte Values after Eighth Round
270subin=177da925, subout=f0ffd33f, shiftrows=d33ff0ff
280subin=5a19a37a, subout=bed40ada, shiftrows=dabed40a
290subin=4149e08c, subout=833be164, shiftrows=dabed40a
300subin=42dc1904, subout=2c86d4f2, shiftrows=2c86d4f2
Subbyte Values after Ninth Round
310subin=b11f650c, subout=c8c04dfe, shiftrows=c04dfec8
320subin=ea046585, subout=87f24d97, shiftrows=4d9787f2
330subin=83455d96, subout=ec6e4c90, shiftrows=90ec6e4c
340subin=5c3398b0, subout=4ac346e7, shiftrows=90ec6e4c
Subbyte Values after Final Round
350subin=f02dadc5, subout=8cd895a6, shiftrows=8cd895a6
360subin=eb598b1b, subout=e9cb3daf, shiftrows=cb3dafe9
370subin=402ea1c3, subout=0931322e, shiftrows=322e0931
380subin=f2381342, subout=89077d2c, shiftrows=2c89077d
390subin=1e84e7d2, subout=725f94b5, shiftrows=2c89077d
$finish at simulation time
500
V C S
S i m u l a t i o n
R e p o r t
Time: 500
CPU Time:
0.020 seconds;
Data structure size:
0.0Mb
Mon May 3 02:13:07 2010
50
Sub-byte results
Chronologic VCS simulator copyright 1991-2005
Contains Synopsys proprietary information.
Compiler version Y-2006.06-SP1; Runtime version Y-2006.06-SP1;
01:39 2010
Subbyte Values after First Round
VCD+ Writer Y-2006.06-SP1 Copyright
0subin=xxxxxxxx,
10subin=19a09ae9,
20subin=3df4c6f8,
30subin=e3e28d48,
Subbyte Values after Second Round
40subin=be2b2a08,
50subin=a4686b02,
60subin=9c9f5b6a,
70subin=7f35ea50,
Subbyte Values after Third Round
80subin=f22b4349,
90subin=aa618268,
100subin=8fddd232,
110subin=5fe34a46,
Subbyte Values after Fourth Round
120subin=03efd29a,
130subin=48674dd6,
140subin=6c1de35f,
150subin=4e9db158,
Subbyte Values after Fifth Round
160subin=ee0d38e7,
170subin=e0c8d985,
180subin=9263b1b8,
190subin=7f6335be,
Subbyte Values after Sixth Round
200subin=e8c05001,
210subin=f1c17c5d,
220subin=0092c8b5,
230subin=6f4c8bd5,
Subbyte Values after Seventh Round
240subin=55ef320c,
250subin=263de8fd,
260subin=0e4164d2,
270subin=2eb7728b,
Subbyte Values after Eighth Round
280subin=177da925,
290subin=5a19a37a,
300subin=4149e08c,
310subin=42dc1904,
Subbyte Values after Ninth Round
320subin=b11f650c,
2005 Synopsys Inc.
subout=xxxxxxxx
subout=d4e0b81e
subout=27bfb441
subout=11985d52
subout=aef1e530
subout=49457f77
subout=dedb3902
subout=d2968753
subout=89f11a3b
subout=acef1345
subout=73c1b523
subout=cf11d65a
subout=7bdfb5b8
subout=5285e3f6
subout=50a411cf
subout=2f5ec86a
subout=28d70794
subout=e1e83597
subout=4ffbc86c
subout=d2fb96ae
subout=9bba537c
subout=a178104c
subout=634fe8d5
subout=a8293d03
subout=fcdf23fe
subout=f7279b54
subout=ab8343b5
subout=31a9403d
subout=f0ffd33f
subout=bed40ada
subout=833be164
subout=2c86d4f2
subout=c8c04dfe
May
3
51
330subin=ea046585, subout=87f24d97
340subin=83455d96, subout=ec6e4c90
350subin=5c3398b0, subout=4ac346e7
Subbyte Values after Final Round
360subin=f02dadc5, subout=8cd895a6
370subin=eb598b1b, subout=e9cb3daf
380subin=402ea1c3, subout=0931322e
390subin=f2381342, subout=89077d2c
400subin=1e84e7d2, subout=725f94b5
$finish at simulation time
500
V C S
S i m u l a t i o n
R e p o r t
Time: 500
CPU Time:
0.020 seconds;
Data structure size:
Mon May 3 01:39:48 2010
0.0Mb
52
REFERENCES
[1]
HART Communication Foundation http://www.hartcomm.org/ (2010-03-17)
[2]
W. Simpson, “PPP in HDLC Framing”. Network Working Group, Request for
Comments (RFC): 1549; December 1993
[3]
Morris Dworkin, “Recommendation for Block Cipher Modes of Operation: The
CCM Mode for Authentication and Confidentiality”. NIST Special Publication 80038C; NIST Technology Administration, US Department of Defense.
[4]
Frequency
Hopping
Spread
Spectrum
(FHSS)
http://en.wikipedia.org/wiki/Frequency- hopping_spread_spectrum (2010-03-04)
[5]
Jianping Song, et al., “WirelessHART: Applying Wireless Technology in Real-Time
Industrial Process Control”. IEEE Real-Time and Embedded Technology and
Applications Symposium, DOI 10.1109/RTAS.2008.15
[6]
Yih-Chun Hu, et al., “Wormhole Attacks in Wireless Networks”. IEEE JOURNAL
ON SELECTED AREAS IN COMMUNICATIONS, VOL. 24, NO. 2,
FEBRUARY 2006.
[7]
Christopher Alberts, at al., “Managing Information Security Risks: The OCTAVE
Approach”., Addison Wesley July 09, 2002 (ISBN: 0-321-11886-3)
[8]
Hiran Kumar, et al., “Security Threats in Wireless Sensor Networks”. IEEE A&E
Systems Magazine, June 2008.
[9] William Stallings, Data and Computer Communications, 8th Edition. Page 713
53
[10] Leung C, “Evaluation of the Undetected Error Probability of Single Parity-Check
Product Codes”. IEEE Transactions on Communications- vol. 31 No. 2 page 250253 (1983)
[11] J. R. Douceur, “The Sybil Attack”. Proceedings of the 1st International workshop on
Peer- To-Peer Systems (IPTPS), March 2002
[12] Announcing the ‘ADVANCED ENCRYPTION STANDARD (AES)’, Federal
Information, Processing Standards Publication 197, November 26, 2001
[13] A Complete WirelessHART Network, Jianping Song, Song Han, Xiuming Zhu, Al
Mok, Deji Chen, Mark Nixon
[14] “The Official source for HART communication technology”, HCF_LIT-89 May
2007
[15] C. Sanchez – Avila and R. Sanchez Reillo, “The Rijndael Block Cipher (AES
Proposal): A comparison with DES, IEEE 2001
[16] Anna N. Kin, Fredrik Hekland, Stig Petersen and Paula Doyle, “When HART Goes
Wireless: Understanding and Implementing the WirelessHART Standard”, IEEE
2008
[17] “HART: An introduction for users and manufacturers”, revised on oct-1995.
[18] “Hart application guide”, HCF_LIT-34 1999.
[19] Shahid Raza, Adriaan Slabbert, Thiemo Voigt, “Security Consideration for the
WirelessHART Protocol” IEEE April, 2009.