Extraction of electronic evidence from VoIP: identification and analysis of digital speech
Additional Document Info
The Voice over Internet Protocol (VoIP) is increasing in popularity as a cost effective and efficient means of making telephone calls via the Internet. However, VoIP may also be an attractive method of communication to criminals as their true identity may be hidden and voice and video communications are encrypted as they are deployed across the Internet. This produces a new set of challenges for forensic analysts compared with traditional wire-tapping of the Public Switched Telephone Network (PSTN) infrastructure, which is not applicable to VoIP. Therefore, other methods of recovering electronic evidence from VoIP are required. This research investigates the analysis and recovery of digitised human voice, which persists in computer memory after a VoIP call. This paper outlines the ongoing development of a software tool, the purpose of which, determines how remnants of digitised human speech from a VoIP call may be identified within a forensic memory capture based on how the human voice is detected via a microphone and encoded to a digital format using the sound card of a personal computer. This digital format is unencrypted whist stored in Random Access Memory (RAM) before it is passed to the VoIP application for encryption and transmission over the Internet. Similarly, an incoming encrypted VoIP call is decrypted by the VoIP application and passes through RAM unencrypted in order to be played via the speaker output.