Secuered Chat

1
Secuered Chat

• Over Bluetooth

2
What Is Bluetooth ?

• Bluetooth is a technology specification.
• Describes how various electronic products such as
  mobile phones, computers, and personal digital
  assistants (PDAs) can interconnect with each
  other using a short-range wireless connection.
• The wireless connection is established using a
  low-power radio link among the devices.
• The primary benefit of this technology is the
  elimination of proprietary cables which are
  currently required to connect devices for
  information synchronization.
• Examples LAN connection, email downloading,
  Automatic house.

3
Project target

• Creating a Bluetooth based secured communication.
  
• Two devices will be able to chat via a secured
  channel.

4
Project basic specifications

• Add an encryption/authentication package to an
  existing API over Ericcson Bluetooth stack.
• The application is modular - it is prepared for
  adding replacing functionalities, e.g. adding
  or changing methods for encryption.

5
Further aims

• Add network capabilities allow several Blutooth
  devices secured piconet.
• Use the built-in hardware encryption.

6
Implementation

• Language C.
• Bluetooth interface Ericson COM driver for
  windows 2000.
• Existing socket-like API for Ericsson Bluetooth
• Encryption algorithm is AES, implemented in
  software

7
Connection establishment

• A Bluetooth device tries to establish a secured
  chat with a peer. Another device responds.
• Both devices, verifies its peers identity by
  using a public key security scheme.
• The chat session can now begin.

8
Public Key System
9
AES Round

• SubBytes (S-Box substitution)
• ShiftRows (rotations)
• MixColumn (linear comb. in GF(28) )
  (skipped for last round)
• AddRoundKey (State xor RoundKey)

• Block cypher
• Symmetric key
• Arithmetic based in the Galois ?eld GF(28)
• Fast and scalable
• Resistant to all known cryptanalysis attacks

Diagram by John Savard Edmunton, CA