| Summary: | 碩士 === 國防大學 === 資訊管理學系 === 102 === Internet telephony (VoIP) has been widely used in enterprises, smartphones App, the bureaus even carrier voice transmission technology. Which, SIP is a standard protocol for Internet telephony (RFC-3261) has been widely used in the protocol design because the SIP protocol emphasizes simplified and voice compression efficiency, there for ignoring the telephone communication network security problems.
This paper presents the architecture of SIP based encrypted Internet telephony integration system, including the mobile user's smart phone, the application of traditional voice switches on office communications systems as well as Microsoft's Lync / OCS's. We also provided hardware cryptographic modules which were designed in integrated MicroSD, will be strengthen organization outside employees communications security. In addition, this study proposes the use of a pseudo-random number generating mechanism to dynamically permutation table (Sbox) and reverse permutation table (ISbox), the system call is established before each randomly generated permutation table, with talks on key encryption and decryption process makes the system itself has a dual conversion factor characteristics, can improve the security of the ciphertext disrupt the system.
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