Audio steganography - LSB
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This document discusses audio steganography techniques. It describes how digital audio works through sampling and quantization. It then explains how least significant bit coding can be used to hide messages in audio files by replacing the least significant bit of samples with bits of the hidden message. The document provides details of the encoding algorithm, including using the RC4 encryption algorithm to determine which bits to replace. It notes that wav files are commonly used as they do not involve lossy compression. The document provides an overview of audio steganography and how covert messages can be embedded and extracted from digital audio files.
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Audio steganography - LSB
- 2. STEGANOGRAPHY No one apart from the Art and A form of sender and science of security intended writing hidden through recipient, messages obscurity suspects the existence of the message www.company.com
- 3. STEGANOGRAPHY TECHNIQUE www.company.com
- 4. Embedded Data Hidden MESSAGE Audio File MESSAGE
- 5. Audio
- 6. AUDIO TERMS • Sampling is the process in which the analogue values are only captured at regular time intervals. • Quantization converts each input value into one of a discrete value. • Popular sampling rates for audio include 8 kHz, 9.6 kHz, 10kHz, 12 kHz, 16 kHz, 22.05 kHz and 44.1 kHz www.company.com
- 7. Audio File Types File Format Uncompressed Compressed Lossy Loseless WAV AIEF ALAC, FlAC, Mp3, AAC, WMA WavPack www.company.com
- 8. WHY .WAV ? Most popular Audio format Don’t lose any quality in recording Easier format for Development No Compression!! www.company.com
- 9. WAVE FILE FORMAT www.company.com
- 10. WAVE FILE FORMAT HEX Values of Wave File Size Chunk Length of Format Data Chunk Audio Attributes www.company.com
- 12. TYPES OF STEGANOGRAPHY LSB CODING PHASE CODING ECHO HIDING SPREAD www.company.com SPECTRUM
- 13. WHY LSB? Low computational complexity Easier Implementation Variation in choosing LSB www.company.com
- 14. LSB ALGORITHM Step 2 Step 4 • Receives the • Check which LSB • Replaces the LSB audio file • Each character to Replace By bit from audio convert it into bit in the message is RC4 Algorithm with LSB bit from pattern. converted into character in the bit pattern. message. Step1 Step 3 www.company.com
- 15. CONT. ALGORITHM : CHANGING BITS www.company.com
- 16. CONT. ALGORITHM : CHANGING BITS RC4 Algorithm www.company.com
- 17. RC4 ALGORITHM RC4 The pseudo- The key- random scheduling generation algorithm (KSA) algorithm (PRGA) www.company.com
- 18. RC4 ALGORITHM • The key-scheduling algorithm (KSA) • initialize the permutation in the array "S • Array "S" is initialized to the identity permutation • Swap values of S[i] and S[j]. www.company.com
- 19. RC4 ALGORITHM • The pseudo-random generation algorithm (PRGA) • Used as many iterations as are needed www.company.com
- 20. Live Demo
- 22. RESOURCES • Source Code : http://www.codeproject.com/Articles/6960/Steganography- VIII-Hiding-Data-in-Wave-Audio-Files • Other Online • http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.88.9413& rep=rep1&type=pdf • deepaldhariwal.weebly.com/uploads/4/9/0/9/4909109/report.docx • http://en.wikipedia.org/wiki/RC4 www.company.com
Editor's Notes
- The key-scheduling algorithm is used to initialize the permutation in the array "S." "keylength" is defined as the number of bytes in the key and can be in the range 1 ≤ keylength ≤ 256, typically between 5 and 16, corresponding to a key length of 40 – 128 bits. First, the array "S" is initialized to the identity permutation. S is then processed for 256 iterations in a similar way to the main PRGA, but also mixes in bytes of the key at the same time.
- or as many iterations as are needed, the PRGA modifies the state and outputs a byte of the keystream. In each iteration, the PRGA increments i, looks up the ith element of S, S[i], and adds that to j, exchanges the values of S[i] and S[j], and then uses the sum S[i] + S[j] (modulo 256) as an index to fetch a third element of S, (the keystream value K below) which is XORed with the next byte of the message to produce the next byte of either ciphertext or plaintext. Each element of S is swapped with another element at least once every 256 iterations.