PC-based voice cryptography via telephone lines

• المؤلف الرئيسي: Alarcon, Cirilo
• التنسيق: text
• اللغة: English
• منشور في: Animo Repository 1995
• الموضوعات: Analog-to-digital converters; Data transmission systems; Voice; Telephone lines; Cryptography; Computer software; Electronic digital computers > Programming
• الوصول للمادة أونلاين: https://animorepository.dlsu.edu.ph/etd_bachelors/1251
• المؤسسة: De La Salle University

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.