Tutorial on Wirless Security in Medical Devices


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Tutorial on Wirless Security of medical devices By Dr G V Rangaraj

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Tutorial on Wirless Security in Medical Devices

  1. 1. ICRTIT-2011 Half-day Tutorial on Wireless Security in Medical Devices Dr G V Rangaraj, IEEE Senior Member Senior Technical Manager HCL Technologies, Chennai, INDIA
  2. 2. Motivation & Objective Scope Generally in telecommunications, the security design is complex and requires a deep study of the cryptography theory. However due the time constraint in the production cycle it is necessary to come with an elegant design that also meets the standard constraints in a relatively short duration. This tutorial would help to overcome this issue by providing brief and precise security algorithm concepts necessary for the design of such pragmatic WPAN/WBAN sensor based medical device receiver.
  3. 3. Abstract Wireless communication is playing a key role in connecting medical devices to the outside world and has various advantages over the wired-connections. However it still has only a slow acceptance in the medical equipment market due to its vulnerable nature of security attacks in such environments compared to its wired counterpart. In this tutorial we would be providing a comprehensive overview of the security attacks possible in the various layers of the wireless embedded medical devices network and the corresponding counter-measures. We would then provide an overview of the wireless security issues in a Zigbee healthcare network, which, is being projected as the most common wireless technology for next generation embedded medical devices. The main challenge in the embedded medical device community is the wireless body area network (WBAN) which typically deals with implantable medical devices like implantable cardioverter-defibrillator (ICD). In this tutorial, we would also discuss some of the wireless security solutions proposed in the currently evolving IEEE 802.15 TG 6 WBAN initiatives in an implant environment.
  4. 4. Tutorial Outline: (Duration: 3 hours) <ul><li>Introduction – 15 minutes </li></ul><ul><li>  Typical Wireless Medical Devices Network - 15 minutes </li></ul><ul><li>  Security Threats in a Wireless Medical Devices Network </li></ul><ul><ul><li>PHY Layer- 10 minutes </li></ul></ul><ul><ul><li>Data Link/MAC Layer - 10 minutes </li></ul></ul><ul><ul><li>Higher Layer - 10 minutes </li></ul></ul><ul><li>Security Solutions </li></ul><ul><ul><li>Data Confidentiality and Privacy - 15 minutes </li></ul></ul><ul><ul><li>Data Integrity and Authenticity - 15 minutes </li></ul></ul><ul><ul><li>Freshness and Availability - 15 minutes </li></ul></ul><ul><ul><li>Secure Management - 15 minutes </li></ul></ul><ul><li>  Case Studies </li></ul><ul><ul><li>WPAN (Zigbee) – 20 minutes </li></ul></ul><ul><ul><li>WBAN (IEEE 802.15. TG 6) – 20 minutes </li></ul></ul><ul><li>Conclusions - 5 minutes </li></ul><ul><li>Question and Answers – 15 minutes </li></ul>
  6. 6. <ul><li>FDA’s draft guidance for industry on RF wireless technology in medical devices specifies: </li></ul><ul><ul><li>Wireless coexistence </li></ul></ul><ul><ul><li>Performance </li></ul></ul><ul><ul><li>Data Integrity </li></ul></ul><ul><ul><li>Security </li></ul></ul><ul><ul><li>Electromagnetic Compatibility (EMC) </li></ul></ul><ul><li>FDA has left the Software Engineering Community’s to develop medical devices. </li></ul><ul><ul><li>Quote from FDA Guidelines : “Appropriate security of medical devices which should ensure reliable, secure communication and continued functionality while preserving patient’s safety, confidentiality and data integrity” </li></ul></ul>FDA Guidelines
  7. 7. <ul><li>EMC is “the ability of a device to function properly in its intended Electromagnetic environment, without introducing excessive Electromagnetic energy that may interfere with other devices” </li></ul><ul><li>FDA recommends EMC be an integral part of the design, testing and performance for RF medical devices </li></ul><ul><li>FDA recommends that elaborate testing be performed to demonstrate the wireless function will operate as intended in the expected environment of use </li></ul>EMC (Electromagnetic Compatibility)
  9. 9. Medical Devices Network
  10. 10. <ul><li>Wireless Bands are allocated by FCC </li></ul><ul><li>Medical Implant Communication Service (MICS); </li></ul><ul><ul><li>Spectrum: 402-405 MHz; </li></ul></ul><ul><ul><li>Technologies: WBAN like IEEE 802.15 TG 6 </li></ul></ul><ul><li>Unlicensed Industrial, Scientific & Medical (ISM); </li></ul><ul><ul><li>Spectrum: 902-928; 2400-2483.5; 5725-5850 MHz; </li></ul></ul><ul><ul><li>Technologies: WBAN, WPAN like Zigbee, Bluetooth & WLAN like Wi-Fi (802.11 a,b,g. & n) </li></ul></ul>MD Network Components
  12. 12. Physical Layer <ul><ul><li>Jamming the radio signal using another radio source </li></ul></ul><ul><ul><li>Similar to military applications pose a serious threat </li></ul></ul><ul><ul><li>The jammer could make the medical device node not to function as expected </li></ul></ul><ul><ul><li>Can block part or the complete network </li></ul></ul><ul><ul><li>Physical layer threats could be broadly classified as Denial of Service (DoS) attacks </li></ul></ul>
  13. 13. Data Link/MAC Layer <ul><ul><li>The threats in this layer requires more intelligent hacking device to identify at least the frame boundaries </li></ul></ul><ul><ul><li>With the frame boundaries identified the hacker could potentially corrupt the checksum portion of the frame </li></ul></ul><ul><ul><ul><li>The received frames are always in errors which is referred to as link-layer jammer </li></ul></ul></ul><ul><ul><ul><li>Increase in collisions and congestion in the network or entirely block the network </li></ul></ul></ul>
  14. 14. Data Link/MAC Layer <ul><ul><li>A more intelligent hacker could potentially create an unfairness in the scheduling mechanism </li></ul></ul><ul><ul><li>Disturb the smooth functioning of the scheduler which is the main functional unit in the MAC layer </li></ul></ul><ul><ul><li>An extreme case of the unfairness attack </li></ul></ul><ul><ul><ul><li>Hacker acts itself acts like a self-sacrificing node and cause exhaustion of the battery </li></ul></ul></ul><ul><ul><ul><li>Noting but draining of the power source by keeping the channel busy always </li></ul></ul></ul><ul><ul><li>Thus data link layer threats could be broadly classified as DoS attacks only </li></ul></ul>
  15. 15. Higher Layer <ul><ul><li>DoS attack in these layers is also possible </li></ul></ul><ul><ul><ul><li>Typically where either same data is sent repeatedly as in “hello” flooding attack in the network layer </li></ul></ul></ul><ul><ul><ul><li>The control information is sent repeatedly in the transport layer in the normal flooding attacks. </li></ul></ul></ul><ul><ul><li>A large number of possible attacks other than denial of service are also possible </li></ul></ul><ul><ul><li>Such attacks should be able to identify the packet boundaries </li></ul></ul>
  16. 16. Higher Layer <ul><ul><li>Such attacks other than DoS needs to be very intelligent and complex than the physical/link layer hackers </li></ul></ul><ul><ul><li>This includes the unauthorized and unauthenticated access of data </li></ul></ul><ul><ul><ul><li>Can lead to the threat of message disclosure </li></ul></ul></ul><ul><ul><ul><li>Can further lead to the threat of message modification. </li></ul></ul></ul><ul><ul><li>Typical routing attacks possible in any network connected to the Internet is also a threat in medical devices network </li></ul></ul>
  17. 17. Security threats - Summary Layers DoS Attacks Defenses Physical Jamming Spread-Spectrum, priority messages, lower duty cycle, region mapping, mode changes Link Tampering Tamper proof, hiding Collision Error Correction Code Unfairness Small frames Network Exhaustion Rate limitation Neglect and greed Redundancy, probing Homing Encryption Misdirection Egress filtering, authorization monitoring Black holes Authorization monitoring, redundancy Transport Flooding Client Puzzles Desynchronisation Authentication
  19. 19. Security Requirements & Solutions Security Requirements Possible Security Solutions Data Confidentiality and Privacy Symmetric Key Encryption/Decryption Data Integrity and Authenticity Secure Symmetric Key Hashing Digital signature Freshness and Availability Encrypted counter Redundancy Secure Management Random Key Distribution, Public Key Cryptography, Secure Group Communication, Intrusion detection
  20. 20. <ul><ul><li>It is possible for an eavesdropper to just tap the bits sent over the wireless medical device personal area network </li></ul></ul><ul><ul><ul><li>Decipher the information to get out secret personal and medical information of the patient </li></ul></ul></ul><ul><ul><ul><li>Violates his/her privacy </li></ul></ul></ul><ul><ul><li>Encrypting the patient’s data with a secret symmetric private key </li></ul></ul><ul><ul><li>The key is shared on a secure communications channel between sender and the receiver </li></ul></ul><ul><ul><li>The key is used for both encryption and decryption </li></ul></ul>Data Confidentiality and Privacy
  21. 21. <ul><ul><li>An intruder can possibly send fake messages in medical devices wireless network which might look like the original </li></ul></ul><ul><ul><li>In order to protect this threat, messages have to be authenticated </li></ul></ul><ul><ul><li>A possible solution to this issue is to use a secure hashing method based on a symmetric key cryptography </li></ul></ul><ul><ul><ul><li>The transmitter computes a message authentication code (MAC) based on a known hashing function </li></ul></ul></ul><ul><ul><ul><li>Hashing function derived from the this symmetric private key </li></ul></ul></ul><ul><ul><ul><li>MAC is transmitted along with the message </li></ul></ul></ul><ul><ul><ul><li>The receiver authenticates it by computing the MAC and checking if it is same as the one that was sent. </li></ul></ul></ul><ul><ul><ul><li>This can also help to protect against flooding attacks. </li></ul></ul></ul>Data Integrity and Authenticity
  22. 22. <ul><ul><li>An intruder can capture the data and replay it even if data confidentiality and authenticity is taken care already </li></ul></ul><ul><ul><li>Data freshness needs to be provided which is basically ensuing the data frames are in order </li></ul></ul><ul><ul><li>A simple mechanism is to use an encrypted counter </li></ul></ul><ul><ul><li>Ensure the ordering by checking the counter value at the receiver </li></ul></ul><ul><ul><li>The intruder can cause unavailability of the embedded medical device </li></ul></ul><ul><ul><li>Results in absence of life critical information for diagnosis </li></ul></ul><ul><ul><li>Ensuring redundancy i.e. having a provision for substitute nodes in the network to gather life-critical information. </li></ul></ul>Freshness and Availability
  23. 23. <ul><ul><li>An intruder can get access to secure keys in some situations </li></ul></ul><ul><ul><li>Secure management is required to ensure secure key exchanges happen and ensure </li></ul></ul><ul><ul><ul><li>This could be done using random key distribution using public key cryptography </li></ul></ul></ul><ul><ul><ul><li>Secure group communication </li></ul></ul></ul><ul><ul><li>Ensures intruder does not get access to the secure keys in any situation </li></ul></ul>Secure Management
  24. 24. <ul><li>Data Confidentiality </li></ul><ul><ul><li>Encrypting the patient’s data with a secret key </li></ul></ul><ul><ul><li>The key is shared on a secure communications channel </li></ul></ul><ul><li>Data Authentication and Integrity </li></ul><ul><ul><li>Authentication using symmetric techniques , node and controller share a secret key </li></ul></ul><ul><ul><li>This secret key is used to find the Message Authentication Code (MAC) </li></ul></ul><ul><li>Data Freshness </li></ul><ul><ul><li>Weak Freshness : Guarantees partial data frame ordering but no guaranteed delay, low duty cycle like BP </li></ul></ul><ul><ul><li>Strong Freshness : Guarantees data frame ordering and delay, synchronization when a beacon is transmitted by controller </li></ul></ul><ul><li>Secure Management </li></ul><ul><ul><li>It is required at the controller since it provides key distribution to the nodes in order to allow encryption and decryption </li></ul></ul><ul><ul><li>In case of association and disassociation controller adds and removes the nodes in a secure manner </li></ul></ul><ul><li>Availability </li></ul><ul><ul><li>The adversary may target the availability of a WBAN by disabling an ECG node , which may result in loss of life </li></ul></ul>Security Solutions - Summary
  25. 25. Security Solutions - Summary Security Threats Security Requirements Possible security solutions Unauthenticated or unauthorized access Key establishment and trust setup Random key distribution Public key cryptography Message disclosure Confidentiality and privacy Link/network layer encryption Access control Message modification Integrity and authenticity Keyed secure hash function Digital signature Denial of Service (DoS) Availability Intrusion detection Redundancy Node capture & compromised node Resilience to node compromise Inconsistency detection of node and revocation Tamper-proofing Routing attacks Secure routing Secure routing protocols Intrusion and high level security attacks Secure group management, intrusion detection, secure data aggregation Secure group communication Intrusion detection
  26. 26. CASE STUDY – I WPAN - Zigbee
  27. 27. WPAN <ul><li>Application Layer: Explicitly enables the security by adjusting certain control parameters </li></ul><ul><li>Example: IEEE 802.15.4 </li></ul><ul><ul><li>Security modes to control the different security levels </li></ul></ul><ul><ul><li>Best is AES-CCM-128 : Could be used for most critical applications </li></ul></ul><ul><ul><ul><ul><li>Updating programs in pacemakers and implantable cardiac-defibrillators </li></ul></ul></ul></ul>Security Modes Description Null No security AES-CTR Encryption only, CTR Mode AES-CBC-MAC-128 128 bit MAC AES-CBC-MAC-64 64 bit MAC AES-CBC-MAC-32 32 bit MAC AES-CCM-128 Encryption & 128 bit MAC AES-CCM-64 Encryption & 64 bit MAC AES-CCM-32 Encryption & 32 bit MAC
  28. 28. AES - CTR <ul><ul><li>Plain text is xored with the AES encrypted counter using a symmetric secret key to obtain the cipher text </li></ul></ul><ul><ul><li>At the receiver the plain text is obtained by xoring the cipher text with the AES encrypted counter </li></ul></ul><ul><ul><li>Receiver uses the same symmetric secret key used by the transmitter </li></ul></ul><ul><ul><li>There is secure encryption </li></ul></ul><ul><ul><li>There is no authentication provided </li></ul></ul>
  29. 29. AES - CTR <ul><li>Counter (CTR) : This mode is used by the sender to encrypt data </li></ul><ul><li>Encryption </li></ul><ul><ul><li>Clear text is broken into 16-byte data blocks </li></ul></ul><ul><ul><li>The cipher text is computed using </li></ul></ul><ul><ul><li>Where, is the encryption of the counter </li></ul></ul><ul><li>Decryption </li></ul><ul><ul><li>The receiver recovers the plain text by computing </li></ul></ul>
  30. 30. AES – CBS - MAC <ul><ul><li>Variable length 32, 64 or 128 bits message authentication code (MAC) - Cyclic block chaining (CBC) mechanism </li></ul></ul><ul><ul><li>Secure hashing function method </li></ul></ul><ul><ul><ul><li>Plain text is divided into number of blocks </li></ul></ul></ul><ul><ul><ul><li>In each block the plain text is xored with the AES encrypted cipher text of the previous block </li></ul></ul></ul><ul><ul><ul><li>Repeated in a cyclic mechanism in which the first block’s plain text is xored with an initialization vector </li></ul></ul></ul><ul><ul><ul><li>End result of these operations is the MAC </li></ul></ul></ul><ul><ul><li>This MAC is transmitted along with the message </li></ul></ul><ul><ul><li>The receiver re-computes the MAC using an identical scheme and checks with the received MAC to authenticate the message. </li></ul></ul><ul><ul><li>Thus there is a secure authentication, however, there is no encryption provided in this mode. </li></ul></ul>
  31. 31. AES – CBS - MAC <ul><li>Cipher Block Chaining (CBC-MAC) : In this mode, the plaintext is XORed with the previous cipher text until the final encryption </li></ul><ul><li>Message Authentication Code (MAC) could be either 32, 64 or 128 bits </li></ul><ul><li>Receiver computes its own MAC and compare it with senders MAC and accepts the packet if both the MACs are identical </li></ul><ul><li>CBC-MAC Operation : </li></ul>
  32. 32. AES - CCM <ul><ul><li>Variable length 32, 64, or 128 bit MAC same as in AES – CBC – MAC scheme and appended to the plain text </li></ul></ul><ul><ul><li>Then both the plain text and MAC together is encrypted using the AES –CTR scheme. </li></ul></ul><ul><ul><li>At the receiver decryption is first done as illustrated in AES – CTR scheme </li></ul></ul><ul><ul><li>Followed by authentication as illustrated in AES – CBC – MAC </li></ul></ul><ul><ul><li>Thus there is both secure authentication and encryption provided in this mode </li></ul></ul><ul><ul><li>AES – CCM – 128 is highest level of security that could be provided </li></ul></ul><ul><ul><li>Hence it the best mode which is to be mandated for most critical applications </li></ul></ul>
  33. 33. AES - CCM <ul><li>CTR and CBC-MAC modes are combined to ensure high-level security that includes both data integrity and encryption </li></ul><ul><li>The sender first apply the integrity protection to the data frames and then encrypt the frames using CTR mode </li></ul><ul><li>This mode can be used to send or receive sensitive information such as updating programs in pacemakers and implantable cardiac-defibrillators </li></ul><ul><li>Possible suggestion for improvement: </li></ul><ul><li>The addition of security protocols to a WBAN consumes extra energy due to the overhead transmission required by the protocol </li></ul><ul><li>Best way is to use a stream cipher for encryption , where the size of cipher-text is same as that of the plain-text. </li></ul>
  34. 34. CASE STUDY – II WBAN – IEEE 802.15 WG 6
  35. 35. <ul><li>Medical environments are getting more and more wireless connectivity </li></ul><ul><li>Due to the emerging electronic healthcare’s gaining popularity </li></ul><ul><li>The medical devices themselves are increasingly getting connected using the personal area network (PAN) technologies </li></ul><ul><li>One type of such connectivity is the wireless body area network (WBAN) technologies </li></ul>Need for WBAN?
  36. 36. <ul><li>There are a lot of practical issues that need to be addressed in a WBAN </li></ul><ul><ul><li>Energy efficiency & Network efficiency </li></ul></ul><ul><ul><li>Scalability & Interoperability </li></ul></ul><ul><ul><li>Reliability & Traffic heterogeneity </li></ul></ul><ul><ul><li>Coexistence & Wireless security </li></ul></ul><ul><ul><li>PHY and MAC layer of the upcoming IEEE 802.15 WG 6 BAN is in the process of getting finalized </li></ul></ul><ul><ul><li>Various practical issues are addressed well in IEEE 802.15 WG 6 BAN </li></ul></ul>IEEE 802.15 WG 6 - WBAN
  37. 37. WBAN PHY & MAC <ul><li>  IEEE 802.15 WG 6 PHY </li></ul><ul><ul><li>NB PHY : Narrow Band PHY </li></ul></ul><ul><ul><ul><li>Differential Phase Shift Keying (D-PSK) with SRRC </li></ul></ul></ul><ul><ul><ul><li>Gaussian Minimum Shift Keying (GMSK). </li></ul></ul></ul><ul><ul><li>UWB PHY : Ultra-wide Band PHY </li></ul></ul><ul><ul><ul><li>Non-coherent modulation </li></ul></ul></ul><ul><ul><ul><li>Differentially coherent modulation </li></ul></ul></ul><ul><ul><ul><li>FM-UWB modulation </li></ul></ul></ul><ul><ul><li>HBC PHY : Human Body Communication PHY </li></ul></ul><ul><li>IEEE 802.15 WG 6 MAC </li></ul><ul><ul><li>Beacon enabled mode </li></ul></ul><ul><ul><li>Non-beacon mode </li></ul></ul>
  38. 38. <ul><li>Three types of nodes are possible in a IEEE 802.15 BAN </li></ul><ul><ul><li>Implant node : A node that is placed inside the human body. This could be immediately below the skin to further deeper inside the body tissue </li></ul></ul><ul><ul><li>Body Surface node : A node that is placed on the surface of the human skin or at most 2 centimeters away </li></ul></ul><ul><ul><li>External node : A node that is not in contact with human skin (between a few centimeters and up to 5 meters away from the body) </li></ul></ul><ul><li>The maximum power limitation for WBAN is approximately 25 µW </li></ul>WBAN Nodes
  39. 39. <ul><li>Four types of channels between different nodes are possible </li></ul>WBAN Channels
  40. 40. WBAN Frequency Bands Scenario Description Frequency Band Channel Model S1 Implant to Implant 402-405 MHz CM1 S2 Implant to Body Surface 402-405 MHz CM2 S3 Implant to External 402-405 MHz CM2 S4 Body Surface to Body Surface (LOS) 13.5,50,400,600, 900 MHz 2.4,3.1-10.6 GHz CM3 S5 Body Surface to Body Surface (NLOS) 13.5,50,400,600, 900 MHz 2.4,3.1-10.6 GHz CM3 S6 Body Surface to External (LOS) 900 MHz 2.4,3.1-10.6 GHz CM4 S7 Body Surface to External (NLOS) 900 MHz 2.4,3.1-10.6 GHz CM4
  41. 41. WBAN <ul><li>Implants and Wearable Sensors: Helps to monitor health status </li></ul><ul><li>Applications: Health care systems, Sporting activities & Military </li></ul><ul><li>WBAN Communication classifications </li></ul><ul><ul><li>In-body: Implantable devices and monitoring equipment </li></ul></ul><ul><ul><li>On-body: Within on-body networks </li></ul></ul><ul><ul><ul><li>Off-body: BS to Transceiver on a human being </li></ul></ul></ul>
  42. 42. WBAN Architecture <ul><li>Level 1 : In-Body and on-body nodes which are Implant node : </li></ul><ul><ul><li>A node that is placed inside the human body. </li></ul></ul><ul><ul><li>Role: This could be immediately below the skin to further deeper inside the body tissue and act as sensors </li></ul></ul><ul><ul><li>Examples : ECG; Oxygen saturation sensor </li></ul></ul><ul><li>Level 2 : Body Surface node </li></ul><ul><ul><li>A node that is placed on the surface of the human skin or at most 2 centimeters away </li></ul></ul><ul><ul><li>Role: To collect patient’s vital information from the Level 1 nodes and communicate it to the Level 3 nodes </li></ul></ul><ul><ul><li>Example : BAN Network Coordinator (BNC) contains wakeup circuit, a main radio & security circuit ; </li></ul></ul><ul><li>Level 3 : External node </li></ul><ul><ul><li>A node that is not in contact with human skin (between a few centimeters and up to 5 meters away from the body </li></ul></ul><ul><ul><ul><li>Role: Keep patient’s medical records; provides relevant diagnostic recommendations </li></ul></ul></ul><ul><ul><li>Example: Number of remote BS ; </li></ul></ul>
  43. 43. Security in WBAN <ul><ul><li>Various operation involve are life critical applications </li></ul></ul><ul><ul><ul><li>Like updating programs in implantable cardiac-defibrillators </li></ul></ul></ul><ul><ul><li>Hence network security is more critical in WBAN environment than a simple WPAN scenario </li></ul></ul><ul><ul><li>802.15 TG 6 draft has provision of the following modes and are very similar to that of ZigBee </li></ul></ul><ul><ul><ul><li>Unsecured communication </li></ul></ul></ul><ul><ul><ul><li>Authentication but not encryption </li></ul></ul></ul><ul><ul><ul><li>Authentication and encryption of data </li></ul></ul></ul>
  44. 44. Key Security Differences from WPAN <ul><ul><li>Apart from the standard AES-128 forward cipher function which was the only option in ZigBee there is 2 nd option </li></ul></ul><ul><ul><li>IEEE 802.15 TG 6 draft provides a provision to opt for a different Cammillia-128 forward cipher function </li></ul></ul><ul><ul><li>The complexity is kept low in IEEE 802.15 WG 6 draft unlike the ZigBee </li></ul></ul><ul><ul><ul><li>No provision for variable message authentication code size of different security modes </li></ul></ul></ul><ul><ul><ul><li>Message authentication code, referred to as Message Integrity Code (MIC), size is fixed to 32 bits. </li></ul></ul></ul>
  45. 45. Secure Management in WBAN <ul><ul><li>Security starts with a negotiation of desired security suite between the two communicating parties, node and hub </li></ul></ul><ul><ul><li>The security selection in turn sets off a security association between the two parties </li></ul></ul><ul><ul><ul><li>For activating a pre-shared or generating a new shared master key (MK). </li></ul></ul></ul><ul><ul><li>Security association protocols are done based on </li></ul></ul><ul><ul><ul><li>The Diffie-Hellman key exchange employing elliptic curve public key cryptography </li></ul></ul></ul><ul><ul><li>Some of the possible security association protocols are </li></ul></ul><ul><ul><ul><li>Master key pre-shared association </li></ul></ul></ul><ul><ul><ul><li>Unauthenticated association </li></ul></ul></ul><ul><ul><ul><li>Public key hidden association </li></ul></ul></ul><ul><ul><ul><li>Password authenticated association </li></ul></ul></ul><ul><ul><ul><li>Display authenticated association </li></ul></ul></ul>
  47. 47. Thank you! QUESTIONS & ANSWERS
  48. 48. Biography Rangaraj received his B.Tech in Electrical Engineering from Indian Institute of Technology (IIT) Madras, India in 1998, M.S in Electrical and Computer Engineering from Georgia Tech, U.S.A. in 2000 and PhD in Electrical Engineering from IIT Madras, India in 2005 with specialization in communication systems. His current areas of interest include design and development of wireless solutions/ PHY/MAC layer chipsets for future wireless systems involving wireless personal/body area networks and signal processing algorithms for 4G wireless communication systems. During his doctoral studies, he also worked as Project Officer for the DECT Wireless in Local Loop project with the Tenet Group. After graduation, he worked as Technical Lead Engineer at HCL Technologies, Chennai, where he was developing physical layer of MBOA UWB wireless system on FPGA platforms and at NXP Semiconductors, Bangalore developing physical layer for Wireless LAN on embedded vector processors. He then worked as Wireless Specialist at Tata Elxsi, Chennai in design of Physical layer for LTE wireless systems and other 4G wireless systems on DSP platforms. Currently he is working as Senior Technical Manager at HCL Technologies, Chennai in design of wireless solutions in medical, automotive and industrial verticals. He has published more than ten papers in various national and international conferences and journals and also an active reviewer. He is the recipient of the Philips award and Seimens award for being the student with best academic record in Electrical Engineering Department at IIT Madras during 1994–1998. He is also the recipient of the Colonel Oscar Cleaver award for being the outstanding graduate student in the School of Electrical and Computer Engineering, Georgia Institute of Technology during 1998–1999.  
  49. 49. Thank You