Uncovering spoken phrases in encrypted VoIP conversations BY, RITESH CHANDRA REDDY GUNNA. PRASAD VUNNAM.

Authors  Charles V. Wright  Lucas Ballard  Scott E. Coull  Fabian Monrose  Gerald M. Masson

Introduction  Encrypted data is sent through VoIP.  We need to check the efficiency.  Hack the voice data over IP.

Capturing Voice  Voice is captured using HMM.  HMM- Hidden Markov Model.  Uses the phonetic pronunciation of the words from the database.  TIMIT- It is the database that contains the phonetic words.

Codecs and software used  Speex codec: This codec is used to encode the recordings from TIMIT which is used to find the relationship between the bit rates. This all happens in wideband. When coming to the narrow band, it is used to test the precision between narrow band and wide band.  HMER: It is a software package that is used to build Hidden Morkov Model (HMM) to recognize the English phrases and pronunciation.

CELP Encoder (Code exited linear prediction)

Distribution of bit rates used to encode four phonemes with Speex

Training and Detection Process

Extendibility  We can also use languages other than English which was not done in this paper.  For this we need to develop phonetic pronunciation libraries called TIMIT for different languages.

Conclusion  The intention of the authors of this paper is to find out all the possibilities of hacking the voice over IP and then find out for the remedies. That is the methods to protect the data over IP and to improve them to give more efficient results.

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