1. SECURITY IN WIRELESS BODY
AREA NETWORK
PRESENTED BY : ANKITA DUTTA
SUBHRADEEP MITRA
(MCA student of Rajabazar sc college, kolkata)

2. Overview
 Wireless Body Area Network
 Challenges
 Security Requirements
 Possible Solutions
 Identity Based Encryption
 Weil Pairing
 Tate Pairing
 Weil Pairing Vs. Tate Pairing
 Conclusions

3. Wireless Body Area Network
• It is the integration of intelligent, miniaturized, low power sensor node in, on or
around
a human body to monitoring body function
• Different nodes such as ECG, EMG and EEG are deployed on the human body to
collect the physiological parameters and forward them to a remote medical server
for further service
• WBAN consist of two types:-
1) In-body area network
2) On-body area network
( Security in Wireless Body Area Networks:
A survey by M. Somasundaram+ and R.
Sivakumar )

4. Challenges
 Sensor nodes are Low energy devices
 Security threats
 Data consistency
 Interference
 Cost
 Consistent performance

5. Possible Security Threats and Attacks
Layers DoS Attacks Defenese
Physical Jamming
Tampering
Spread-spectrum, priority
messages, lower duty
cycle, region mapping,
Tamper-proof, hiding
Link Collision
Unfairness
Exhaustion
Error correcting code
Small frames
Rate limitation
Network Spoofing
Selective Forwarding
Sybil
Encryption
Egress filtering,
authorization monitoring
Authorization, monitoring,
redundancy
Transport Flooding
De-synchronization
Client Puzzles
Authentication

6. Security Requirements
 Data integrity
 Data Authentication
 Data freshness
 Secure localization
 Availability
 Secure management
 Data confidentiality
• In WBAN, data confidentiality is
considered to be the most important
issues.
• Protect the data from disclosure.
• Should not leak patient’s vital
information to external or
neighboring networks.
• To solve this security risk public-
key cryptography is too costly.

7. Possible Solutions
 Identity based encryption scheme is used to achieve Data confidentiality in
Wireless Sensor Networks.
Importance of using IBE:
• Ideal for low energy sensor devices
• Reduces cost
 Elliptic Curve Cryptography
 Bilinear Pairing Function

8. Identity Based Encryption
ALICE BOB
PKG
C
M
skIDbob
Upon receiving IDbob
M
ID bob
pkPKG
Sender Receiver
IBE has 4 steps :-
1) Setup
2) Private key Extraction
3) Encryption
4) Decryption ( A Survey of Identity-Based Cryptography by
Joonsang Baek, Jan Newmarch, Reihaneh
Safavi-Naini, and Willy Susilo)

9. Elliptic Curve
• Two families of elliptic curve E for use in pairing based cryptosystems:
1. The pairing takes values in the prime field Fp over which the curve is defined.
2. This family consists of super singular curves with embedding degree k=2
Let E be the elliptic curve Y2=x3+ax+b Defined over a finite field Fq, and let p be a
base point having prime order n dividing #E(Fq), where we assume that n does not
divide q.
• Usefulness of Elliptic curve in IBE:
Elliptic curve divide the keys (public key) one half or one forth then the power
consume and energy loss decreases in case of key exchange

10. Bilinear Pairing
• Bilinearity : ȇ(aP , bQ)=ȇ(P , Q)ab, where P , Q Є G and a,b Є Zq
*
• Non-degenerate: ȇ does not send all pair of points in G * G to the identity in F(Hence
if R is a generator of G then ȇ(R,R) is a generator of F)
• Computable: For all P , Q Є G the map ȇ(P , Q) is efficiently computable
• Type of Bilinear pairing:
Diffie-Hellman problem: Given( G, q, ȇ, P, aP, cP) where a,b and c are chosen at
random from Zq
* compute ȇ(P,P)abc
Other billnear pairing: 1) Boneh and Frankin’s IBE
2 ) Hierarchical IBE scheme
3) Cha and Cheon's IBE Scheme

11. Selected IBE Schemes
• Weil Pairing :
In mathematics, the Weil pairing is a pairing on the points of order
dividing n of an elliptic curve E, taking values in nth roots of unity. More
generally there is a similar Weil pairing between points of order n of an
abelian variety and its dual.
• Tate Pairing :
The Tate pairing was introduced by G. Fray and H.G. Ruck. Tate pairing
was firstly used to construct FR attack. Tate pairing is now an alternative
to Weil pairing due to its somewhat better computation efficiency.

12. Weil Pairing
Weil pairing have 4 stages:-
1. Setup
2. Extract
3. Encryption
4. Decryption
(Identity-Based Encryption from the Weil
Pairing by Dan Boneh Matthew Frankliny )

13. Weil Pairing (Contd…)
Setup : The PKG specifies
• A group G generated by P Є G* and the bilinear pairing
ȇ: G * G  F
• Two hash functions H1 : {0,1}*  G* and H2 : F {0,1}l where l denotes the length
of a plaintext
• PKG then picks a master key s Є Zq
* at random and computes a public key
PPKG = sP
Private key extraction:
• Bob,the receiver ,then contacts the PKG to get his private key DID = sQID
where QID= H1(ID)

14. Encryption:
Alice the sender, can now encrypt her message M {0,1}l using Bob’s identity ID by
computing U=rP and V=H2 (ȇ(QID, PPKG)r) M, where r is chosen at random from Zq
*
and QID = H1(ID).
Decryption:
• The resulting cipher text C=(U,V) is send to Bob
• Bob decrypts C by computing M=V H2 (ȇ(DID, U))
Weil Pairing (Contd…)

15. Tate Pairing
Definition: Tate pairing is essentially a bilinear map from G1 * G2  G3 where
G1 = S[q], G2 =T[q] and G3 is the multiplicative group of GF(p2)
Stages of ID based Tate pairing:-
1. Setup
2. Extract(Registration)
3. Encrypt
4. Decrypt
(An Identity based Encryption using Elliptic Curve Cryptography for Secure M2M
Communication by B S Adiga, Balamuralidhar P,Rajan M A, Ravishankara Shastry, Shivraj V L)

16. 1. Setup :-
• PKG generates a prime p, the elliptic curve E/GF(p) with order n= #E/GF(p)
• Generate a torsion group of prime order q
• PKG selects a random master secret key “s” in range 0<s<q
2. Extract(Registration):-
• Alice submits her identity to PKG
• PKG convert its to a string and maps it to an element of GF(p)
• Find a point (Q_ida) on the torsion group
• Computes a point S_ida belongs to that group
• PKG sends the alice her public and private key along with the public
parameters
Tate Pairing (Contd…)

17. 3. Encrypt:-
• Alice computes Q_idb of Bob knowing public parameters p,q,P,Q and Bob’s
identity.
• Alice selects a random no “r” in range 0<r<q
• Computes
C1=[r]P and C2 = m.e(Q_idb, φ(q))r
4. Decrypt:-
• Bob receives the ciphertext (C1, C2 )
• Computes m`= C2 * e(S_ida, φ(C1 )-1
• Check if m=m` or not
Tate Pairing (Contd…)

18. Why these two Schemes are selected?
• Weil pairing and Tate pairing both provide good functionality for use in
cryptosystems
• Fast implementations of these pairings
• Uses Elliptic Curve Cryptography and a very small number of bits
• Irrelevant factors and denominators are eliminated
• Super singular curves are used
• Uses random number generation to provide better security

19. Weil Pairing Vs. Tate Pairing
• Tate pairing is faster than Weil pairing..
Weil pairing is er (p , p) =
thus two application of Tate pairing.
According to computation facts, Weil pairing takes twice the computational time than
that of the Tate pairing.
However Weil pairing usually takes more than twice the time to compute than that of the
Tate pairing

20. • Tate pairing is used to reduce the discrete logarithm problem on certain elliptic curves
to the discrete logarithm problem over finite field.
Weil pairing of a point with itself is trivial as er (p , p) = 1
however, Tate pairing of a point with itself is not trivial as t (p , p) ≠ 1
• Tate pairing consumes less power and useful for Low-energy devices.
For example : the TinyTate implemented for sensor networks require the system
configuration :– 8-bit/7.3828-MHz ATmega128L microcontroller.
However for Weil pairing the computation requires two Hash function evaluation, two
Tate pairing computation which will gradually require higher system configuration.
( Weil Pairing vs. Tate Pairing in IBE systems
by Ezra Brown, Eric Errthum, David Fu )
Weil Pairing Vs. Tate Pairing (Contd…)

21. Implementation Tools
 Java
 JPBC Library (Java Pairing Based Cryptography
 PBC Library
 GMP Library
 MinGW (MSYS base system)
 Netbeans Profiler

22. Performance Analysis
Performance Analysis can be done in the following ways :
 Memory Analysis
 Runtime Analysis
 Power Consumption, requirement of resources and cost of
implementation
 Security Parameters
Among the above mentioned we will measure the performance on the basis of
Memory and Runtime analysis.

23. Memory Analysis
Weil Pairing Tate Pairing

24. Runtime Analysis
Weil Pairing Tate Pairing

25. Future Scope
Wireless Body Area Network comprised of low energy devices such as sensor nodes.
Smart Phones are used to store the medical data gathered by the sensor nodes. In
future these features can be implemented in android platform and then can be
deployed in a small network of low energy sensor nodes.

26. Conclusions
Through this presentation we have given an overview of the various Security issues in
Wireless Body Area Networking and the possible solutions to overcome these issues.
The solutions should be efficient in such a way that the low-energy sensor devices can
be able for functioning the entire implementation. As well as Data security and Data
confidentiality must be maintained and unauthorized accesses should be prohibited. For
these the optimistic cryptographic and IBE schemes are invented such that Weil pairing
and Tate pairing. And then to find the best scheme among the chosen options that is the
Tate pairing depending upon various measurements.

27. References
[1] A. Shamir, “Identity-based cryptosystems and signature schemes, “in Proc.
Crypto ’84, Santa Barbara, CA, Aug, 1984, pages 47-53.
[2] Dan Boneh, Matthew Franklin, “Identity-Based Encryption from the Weil
pairing”, in SIAM J. of Computing, Vol. 32, No. 3, pages 586-615, 2003.
[3] B S Adiga, Balamuralidhar P, Rajan M A, Ravishankara Shastry, Shivraj V L, "An
Identity based Encryption using Elliptic Curve Cryptography for Secure M2M
Communication", in TCS Innovation Labs, Bangalore, Karnataka, India, pp 68-75.
[4] IEEE 5931464, Moncef Amara, Amar Siad, "ELLIPTIC CURVE
CRYPTOGRAPHY AND ITS APPLICATIONS", in 7th International Workshop on
Systems, Signal Processing and their Applications (WOSSPA), pages 247-250, 2011.