Abstract  Security in Voice over Internet Protocol (VoIP) ne twork has turned to be the most challenging issue in recent years.  VoIP  packets  are  easy  to  eavesdrop  on  by  hackers  du e  to  the  use  of  Diffie-Hellman  (DH)  algorithm  for  single  common  key  exchange between  two  end-users.  As  a  result  the  con fidentiality  of  voice  data  turns  to  be  a  challenging  issue.  There  is  a  need  for strong key management algorithm to secure voice  data from all kinds of attacks. In this paper, an efficient Modified Elliptic  Curve  Diffie-Hellman  (MECDH)  using  Split  Scalar  Mul tiplication  (SSM)  algorithm  is  proposed,  which  secures  voice  data  from  Man-in-the  Middle  (MITM)  attack  by  dynamically   generating  the  shared  key.  Further,  in  order  to  speed  up  the  Scalar  Multiplication (SM) used in traditional Elliptic Cu rve Diffie Hellman (ECDH) algorithm,  the SSM techni que is adopted in the  proposed  MECDH  algorithm.  The  performance  of  the  pr oposed  MECDH  algorithm  is  compared  with  the  traditional  ECDH  and  validated  in  Java  platform.  From  the  results  ob tained,  it  is  observed  that  the  computation  time  taken  by  the  proposed  MECDH  algorithm  is  89%  lesser  than  the  traditional  ECDH  algorithm  and  11%  lesser  than  the  key  changing   ECDH.  Also,  high security level is achieved with the proposed i dea of using dynamic keys instead of single common  shared secret key.

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[37] Yooni E. and Yoo K., A New Elliptic Curve Diffie%Hellman Two%Party Key Agreement Protocol, in Proceedings of the 7 th International Conference on Service System and Service Management , Tokyo, pp. 1%4, 2010. Subashri Thangavelu received her BE degree in Electronics and Communication Engineering from College of Engineering, Guindy, ME degree in Applied Electronics and PhD from Madras Institute of Technology, Chennai. She was a recipient of academic exchange fellowship of Association of Common wealth Universities. She has carried out funded projects on Tracking Algorithm f or ship borne RADARS%funded by LRDE; GPS signal simulator%funded by Ministry of Information Technology; University Micro satellite%funded by ISRO; Semantic Intrusion Detection System%funded by Xambala Inc. Multi Sensor Data and Image Fusion, Power optimization in Wireless Sensor Network% funded by TCS. Currently, she is a Professor and He ad of Department of Information Technology, Madras Institute of Technology, Chennai. Her areas of inte rests are networking, parallel processing and embedded systems. Vaidehi Vijaykumar received her BE degree in Electronics and Communication Engineering from Thiayagarajar College of Engineering, Madurai, ME degree in Communication Systems from Thiayagarajar College of Engineering, Kamaraj University, Madurai. Her areas of interests are networking, cryptography and netwo rk security, communication systems. Currently, she is pursuing her PhD from Anna University.