Audio Steganography Core

1
Audio Steganography Core

• Feasibility Presentation
• Team BUNI 2
• Ben Doherty, Jeremy Gummeson
• Chris Campetti, Phil Murray

2
Datapath Block Diagram
3
Pseudo Random Number Generator

• Linear feedback shift register design
• 32 bit shift register with XOR gates tapped at
  optimized locations.
• Tap points have been researched for optimal
  randomness 1
• 232 1 4,294,967,295

4
PRNG
32 flip-flops 2 inv_1 31 mux2_2 9 nand2_1 1 or2_1
5
PRNG Test Results

• seed_in 32hC0_29_A2_BD
• 11, 01, 00, 00, 10, 01, 00, 11, 10, 11, 10,
• After 10,000 Iterations
• Occurrences of 00 2548
• Occurrences of 01 2434
• Occurrences of 10 2486
• Occurrences of 11 2532

6
Register file

• Standard Cell References of Register file.
• Reference Library Unit Area
  Count Total Area -----------------------
  -------------------------------------------------
• and2_1 vtvtlib25 69.984001
  2080 145566.718750
• and3_1 vtvtlib25 83.980797
  64 5374.770996
• dp_2 vtvtlib25 265.939209
  4096 1089287.000000
• inv_1 vtvtlib25 41.990398
  2060 86500.218750
• mux2_2 vtvtlib25 97.977600
  4096 401316.250000
• nand2_1 vtvtlib25 55.987202
  384 21499.085938
• nand3_1 vtvtlib25 69.984001
  512 35831.808594
• nor2_1 vtvtlib25 41.990398
  5144 215998.609375
• nor3_1 vtvtlib25 55.987202
  640 35831.808594
• or2_1 vtvtlib25 69.984001
  576 40310.785156
• --------------------------------------------------
  ----------------------
• Total 10 references 2077517
• 2.077mm2 area just for register file. Most
  significant size consumer on chip.

7
3DES Encryption

• 3 64-bit keys (56 8 bits parity)
• 64-bit inputs and outputs
• 48 cycle generation time

8
DES3 Algorithm
Overall Comb. LUs 3018 Overall Seq. LUs 128
9
CODEC

• Drop-in replacements for adding message to a
  Digital Audio Stream, or a MIDI Stream.
• Other stream formats possible and will be looked
  into.

10
Timing Considerations

• fs is arbitrary,
• Low quality at about 8kHz, but less data can be
  hidden in the stream (16,000 bits/sec 2,000
  bytes/sec of encoded data) MAXIMUM
• Typical applications _at_ 44.1kHz
• 11,012 bytes/second MAXIMUM
• Will be significantly less based on proportion of
  samples with sufficient magnitude in audio stream
• Bit Clock must run at least 256fs
• This will allow DES to complete
  encryption/decryption

11
Why Hardware?

• Low cost, low power, inline watermarking without
  CPU
• Can generate hardware to do MIDI or Digital Audio
  Stream
• Can store message in register file for
  watermarking purposes
• Possibly write another CODEC module which can
  take message in serially for arbitrary message
  sizes
• High data storage rate in CD-quality audio
  streams
• Very small devices for covert ops
• Possibly run on watch battery relatively low
  frequency system
• 32kHz for MIDI stream

12
References

• 1 Sung, R Sung A Chan P Mah, J Linear
  Feedback Shift Registers
• http//www.ece.ualberta.ca/elliott/ee552/studentA
  ppNotes/1999f/Drivers_Ed/lfsr.html
• 2 Keller S Smid M Modes of Operation
  Validation System
• http//csrc.nist.gov/publications/nistpubs/800-17/
  800-17.pdf