ChatCrypt

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A JavaScript based online chat encryption addon for Google Chrome

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ChatCrypt

  1. 1. Maninda Edirisooriya
  2. 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. 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. 4. Design and Implementation Design – JavaScript and HTML Run as an extension in web browser – In Application Layer.
  5. 5. Design and Implementation At each end Encryption/Decryption occurs. Cipher text in Base-64 encoded is sent via network.
  6. 6. Design and Implementation Encryption – change text to Base-64 Decryption – show text in tooltip and copy to clipboard.
  7. 7. Design and ImplementationSetting 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. 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. 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. 10. Demonstration Start a session – enter password Enter again.
  11. 11. Demonstration If passwords are not matching or Empty password – Error
  12. 12. Demonstration When want to chat type and press Alt + z or Select “Encrypt Text” from menu. Alt + z or
  13. 13. Demonstration At receiver’s end – select text and press Alt +d or Select “Decrypt Text” from menu.
  14. 14. Demonstration Can be used without a chat box – Real Time Mode Select “Real Time” from menu.
  15. 15. Demonstration Other features – Google bubble translator and Password generator.
  16. 16. Demonstration When want to end conversation – End Session Select “End Session” from menu and confirm.
  17. 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. 18. Questions and AnswersAny Questions ?

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