VLSI Design Project Project Proposal Team BUNI 2

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VLSI Design ProjectProject ProposalTeam BUNI
2!!

• Team Members
• Ben Doherty Chris Campetti
• Jeremy Gummeson Phil Murray

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Proposal

• Create an encrypted audio steganography
  (information hiding) device
• Store a DES-encrypted message into an audio
  stream
• Resultant audio stream should have no detectable
  changes from original
• Allow encrypting/encoding as well as
  decoding/decrypting
• Public-key encrypted message subtly stored within
  a seemingly benign audio signal

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System Overview
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Possible Applications

• On-the-Fly MIDI watermarking
• Compact implementations
• Wrist watches
• PDAs
• Integration into SoC
• Inline internet phone message encoding

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Encoding Operation

• User generates DES key pair (via keygen program)
• Options are set in device via serial interface
  (most likely SPI)
• Encode Command
• DES public key
• Encoding key (to seed PRNG)
• Message
• Audio stream is presented to device along with
  control signals
• Modified audio stream output captured by external
  device

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Encoding Pseudocode

• encode(short audio_stream)
• / obtain and encrypt message
• for stego from register file /
• char crypt_msg des3_encrypt(REGFILEmsg,
  REGFILEpubKey)
• // seed PRNG using key from register file
• seed_prng(REGFILEkey)
• // for every sample i in the audio_stream
• for(i 0, j 0 i lt len(audio_stream) i,
  j)
• // get random number k in 0..3
• k get_prn() 4
• // set bit k in sample i to equiv bit from
  crypt msg
• audio_streami.bitk crypt_message.bitj
• end
• end

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Decoding Operation

• Recipient knows DES private key from key
  generation
• Options are set in device for decoding
• Decode Command
• DES Private Key
• Decoding Key (must be identical to encoding key)
• Modified audio stream given to device along with
  control signals
• Output scrubbed audio stream
• Decoded/Decrypted message stored on device for
  later serial access

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Decoding Pseudocode

• encode(u16_t audio_stream)
• // Seed PRNG from key in register file
• seed_prng(REGFILEkey)
• // For every sample i in the audio_stream
• for(i 0, j 0 i lt len(audio_stream) i,
  j)
• // Obtain next random
• k get_prn() 4
• // Add bit k from stream sample i to cryptmsg
• cryptmsg.bitj audio_streami.bitk
• end
• // decrypt message using private key in register
  file
• char msg des3_decrypt(cryptmsg,
  REGFILEprivKey)
• // save message to register file
• REGFILEmsg msg
• end

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Design Components

• Pseudo-Random Number Generator (PRNG)
• OpenCores Triple-DES (3DES) Core
• Stego CODEC (Possibly separate)
• Register File
• SPI Configuration Interface

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Datapath Overview
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Security

• Two levels of security encryption (3DES) and
  obfuscation (Steganography)
• Emphasis on stealth
• Should not be detectable
• Operate only on data with sufficient magnitude in
  audio stream
• Research steganalysis algorithms

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Emulation

• Put system in physical form
• FPGA (Altera Cyclone II)
• Should fit on a single chip
• All components in Verilog
• Get a feel for why system would be useful as a
  chip
• Audio Device?A/D Converter?System?Storage

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Testing

• Can use same verification method developed for
  software simulation
• Dont have to wait for system completion
• Hide the US constitution in an album
• Exhibit proper extraction of data from CD
• Fool a steganography detection program

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Limitations

• Only works on decompressed audio streams
• Requires lossless compression for transmission
• Lossy compression would obliterate message due to
  encryption
• Surface data vs. message data
• Size ratio must be sufficient (ss/sm gt R) in
  order to embed message into surface

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Rough Labor Estimate

• Emulation / Verification Chris
• Datapath Design Ben
• Cryptography Jeremy
• Synthesis and Layout - Phil

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References

• Artz, Donavan Digital Steganography Hiding Data
  within Data IEEE Internet Computing
  Magazine June 2001
• Mora, F Torrubia, A Perceptual Cryptography on
  MPEG Layer III Bit-Streams IEEE Transactions on
  Consumer Electronics, Vol. 48 No. 4 Novermber
  2002
• Vasiltsov Karpinskyy Sagan Development of
  VHDL-based Core with Embedded Steganography
  Function Lviv-Slasko, Ukraine Feb 2003
• Adli Nakao Three Steganography Algorithms for
  MIDI Files University of Ryukyus, Okinawa
  Japan Aug 2005