Outline

1. ONEChat: an Efficient Group Chatting Platform for Opportunistic NetworksStudent: Heming CuiMaster candidate at CS@CU

2. Outline • 1 Motivation • 2 Two transmission modes in implementation • 3 Security • 4 File Transfer • 5 Demo • 6 Conclusion

3. Outline • 1 Motivation • 2 Two transmission modes in implementation • 3 Security • 4 File Transfer • 5 Demo • 6 Conclusion

4. 1.1 Motivation • Last semester, we proposes a group chatting application named ONEChat for opportunistic networks. • mDNS is not a data transfer protocol. • Three Improvements at this semester: • Real Time Text: Replace current data distribution approach with real data transfer protocol. • Improving its security. • File transfer over RTP.

5. 1.2 ONEChat Framework

6. Outline • 1 Motivation • 2 Two transmission modes in implementation • 3 Security • 4 File Transfer • 5 Demo • 6 Conclusion

7. 2.1 Message-by-message mode

8. 2.2 Char-by-char mode

9. Outline • 1 Motivation • 2 Two transmission modes in implementation • 3 Security • 4 File Transfer • 5 Demo • 6 Conclusion

10. 3.1 Security for RTT messages • 1 We use the GNU ZRTP4J library. • 2 Use the SRTP-compatible libraries in ZRTP4J, actually AES and counter mode. • 3 The key for each group is distributed by out-of-bound methods, e.g., secure email. • All group messages/files within a group are encrypted/decrypted by a group key. • Key verification mechanism to kick out malicious users.

11. 3.2 Key verification mechanism to kick out malicious users(encryption/decryption are SRTP compatible)

12. Outline • 1 Motivation • 2 Two transmission modes in implementation • 3 Security • 4 File Transfer • 5 Demo • 6 Conclusion

13. 4 File Transfer • File transfer is embedded in text transfer mechanism. • Can transfer up to 64K bytes for each file. • Two file transfer modes: • Updating buddy icon • Normal file transfer

14. 4.1 Updating buddy icon

15. 4.2 Normal file transfer

16. Outline • 1 Motivation • 2 Two transmission modes in implementation • 3 Security • 4 File Transfer • 5 Demo • 6 Conclusion

17. Outline • 1 Motivation • 2 Two transmission modes in implementation • 3 Security • 4 File Transfer • 5 Demo • 6 Conclusion

18. 6 Conclusion • Last semester, we proposes a group chatting application named ONEChat for opportunistic networks. • Three Improvements at this semester: • Real Time Text: Replace current data distribution approach with real data transfer protocol. • Improving its security. • File transfer over RTP. • Next Step: Write a technical paper (there is a previous version for the work at last semester).

19. Thanks very much for your advice!