Maninda Edirisooriya

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.

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 )

Design and Implementation Design – JavaScript and HTML

Run as an extension in web browser – In Application Layer.

Design and Implementation At each end Encryption/Decryption occurs.

Cipher text in Base-64 encoded is sent via network.

Design and Implementation Encryption – change text to Base-64

Decryption – show text in tooltip and copy to clipboard.

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.

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.

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.

Demonstration Start a session – enter password

Enter again.

Demonstration If passwords are not matching or

Empty password – Error

Demonstration When want to chat type and press Alt + z or

Select “Encrypt Text” from menu.

Alt + z

or

Demonstration At receiver’s end – select text and press Alt +d or

Select “Decrypt Text” from menu.

Demonstration Can be used without a chat box – Real Time Mode

Select “Real Time” from menu.

Demonstration Other features – Google bubble translator and

Password generator.

Demonstration When want to end conversation – End Session

Select “End Session” from menu and confirm.

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.

Questions and Answers

Any Questions ?