A JavaScript based online chat encryption addon for Google Chrome

1. Maninda Edirisooriya

2. Introduction
 Extension for Google Chrome.
 Privacy protection system for online chat.
 Encrypts chat text using 128 bit AES.
 Decrypts at the receiver.
 Common password for both users.

3. Motivation
 No existing cheap solution.
 Lot of Information analyzers in use for advertisements.
 No freedom against governments – filter key words
 For people who do not trust on servers. (Like me )

4. Design and Implementation
 Design – JavaScript and HTML
 Run as an extension in web browser – In Application
Layer.

5. Design and Implementation
 At each end Encryption/Decryption occurs.
 Cipher text in Base-64 encoded is sent via network.

6. Design and Implementation
 Encryption – change text to Base-64
 Decryption – show text in tooltip and copy to
clipboard.

7. Design and Implementation
Setting Password
 Step 1 – Convert password to ASCII numeric
 Step 2 – Get MD5 digest of ASCII as key.
Encryption
 Step 1 – Identify the text box in focus and convert the
text string to ASCII numeric
 Step 2 – Break it into 128 bit blocks. Assign nulls for
padding.
 Step 3 – Apply AES 128 block cipher using key.

8. Design and Implementation
 Step 4 – Convert encrypted numeric values to base 64
character encoding.
 Step 5 – Replace original string with this. This will be
sent via server.
Decryption
 Step 1 – Select received text and convert to numeric
values.
 Step 2 – Break into blocks.

9. Design and Implementation
 Step 3 – Apply AES 128 decryption to each set of
blocks.
 Step 4 – Remove padding nulls from the result.
 Step 5 – Convert to ASCII characters and show in a
tooltip while copying it to clipboard.
Ending Session
 Replace the variables with key value with another
value.

10. Demonstration
 Start a session – enter password
 Enter again.

11. Demonstration
 If passwords are not matching or
 Empty password – Error

12. Demonstration
 When want to chat type and press Alt + z or
 Select “Encrypt Text” from menu.
Alt + z
or

13. Demonstration
 At receiver’s end – select text and press Alt +d or
 Select “Decrypt Text” from menu.

14. Demonstration
 Can be used without a chat box – Real Time Mode
 Select “Real Time” from menu.

15. Demonstration
 Other features – Google bubble translator and
Password generator.

16. Demonstration
 When want to end conversation – End Session
 Select “End Session” from menu and confirm.

17. Conclusion
 Simple and cheap way to communicate confidentially.
 But impossible to send emoticons.
 No key sharing mechanism.
 AES 128 simple cipher is vulnerable to language
statistics based attacks.
 Therefore
 Could and should be developed more for commercial
use.

18. Questions and Answers
Any Questions
?