PC-based voice cryptography via telephone lines

Date of Publication

1995

Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Electronics and Communications Engineering

College

Gokongwei College of Engineering

Department/Unit

Electronics and Communications Engineering

Abstract/Summary

The main objective of this study was to design a PC-based voice encryption/decryption system using telephone lines.To accomplish this objective, a CODEC COMBO CHIP IC with an 8-bit resolution and a sampling rate of 8 kHz was used at the transmitting end to sample the analog voice data coming from the telephone handset. It sends its output into the IBM PC through port no. 300H. The encryption software designed employs bit transposition and substitution sequences, and is used in conjunction with Telix communications software. The software outputs the encrypted data to COM1, which is connected to a modem with a minimum speed of 2400 bps and has built-in MNP error detection and correction. At the transmitting end, the process is reversed to return the encrypted message to its original form.Although the two PCs can communicate at half-duplex mode, the encryption/decryption system's operation is one-way, i.e. Point A (Transmit) contains only an encryption module and Point B (Receive contains only a decryption module.

Abstract Format

html

Language

English

Format

Print

Accession Number

TU06839

Shelf Location

Archives, The Learning Commons, 12F, Henry Sy Sr. Hall

Physical Description

27 numb. leaves

Keywords

Analog-to-digital converters; Data transmission systems; Voice; Telephone lines; Cryptography; Computer software; Electronic digital computers--Programming

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