1

" "

: . -

2013

2

, . , . . / . .

3

, . , , . , , . , . , , , . . , , , . , , , . , , .

4

...2

..3

..3

..3

1 : ..6

1.1 ....6

1.1.1 .6

1.1.2 7

1.1.3 .7

1.1.4 8

1.1.5 .9

1.1.6 9

1.1.7 10

1.2 ....10

1.2.1 10

1.2.2 ..10

1.2.3 ...11

1.2.4 .12

1.2.5 ...15

1.2.6 15

1.2.7 .17

2: , , ...18

2.1 ..18

2.1.1 ..18

2.1.2 ..20

2.1.3 ....22

2.1.4 23

2.2 ....26

2.2.1 Amplitude Modification...26

2.2.2 Dither Watermarking....27

2.2.3 Echo Watermarking..28

2.2.4 Phase Coding.29

5

2.2.5 Spread Spectrum....30

3: , ...32

3.1 32

3.1.1 Data Payload.35

3.1.2 35

3.2 ...35

3.2.1 ...........................................37

3.2.2 Audio restoration attack ......37

3.2.3 Invertibility Attack..38

3.2.4 Specific attack on echo watermarking....................39

3.2.5 Collusion Attack.39

3.2.6 Signal Diminishment Attacks and Common Processing Operations ....40

3.2.7 False positives.42

3.3 ....43

3.3.1 .43

3.3.2 45

3.3.3 46

3.3.4 47

3.4 49

3.4.1 .51

3.4.2 53

3.4.3 .54

4: 56

4.1 PCM ..56

4.1.1 PCM ..56

4.1.2 Low Bit Coding..56

4.1.3 Phase Coding....57

4.1.4 Spread Spectrum Coding...58

4.1.5 Echo hiding.59

4.1.6 Perceptual masking..60

4.1.7 Content-adaptive watermarking61

4.2 Wav-table synthesis64

4.2.1 Wav-table synthesis audio.64

4.2.2 WAV-Tables .64

6

4.2.3 ..66

4.2.4 ...66

4.2.5 Parameters hiding69

4.2.6 ...71

4.3 72

4.3.1 72

4.3.2 Partially uncompressed domain watermarking74

4.4 .77

..........80

7

1. .[ 12] 2. . ..[ 12] 3. ..[ 14] 4. ..[ 16] 5. .[ 17] 6. ..[ 18] 7. QIM. .[ 29] 8. . [ 46] 9. . . [ 49] 10. PCM audio . [ 64] 11. . [ 65] 12 PCM audio . [ 66] 13. DLS. . [ 67] 14. WAV-table synthesis audio. . [ 68] 15. bit . [ 69] 16. . [ 71] 17. . . [ 72] 18. WAV-table synthesis audio. . [ 73] 19. . . [ 75] 20. . . [ 76] 21. . . [ 77]

8

22. . [ 78] 23. . . [ 78] 24. . . [ 79]

1. . . [ 34] 2. [. 35] 3. ITU-R Rec. 500 . [ 36] 4. SDMI,STEP IFPI . [ 43] 5. , . . [ 54]

9

1 : 1.1 1.1.1 . . , (.. , e-business ). , , . .. , , , . :

, . , .

10

(, ) . . , , , ..

. . . .

, .

1.1.2 (e-commerce) , . . . . : e-tailing, e-operations e-fulfillment, e-strategy.To e-tailing / , (e-catalogues). , ... e-operations , . e-fulfillment . e-tailing e-operations . e-fulfillment , , ( ) . (, , ). , .

11

, .

1.1.3 , , . , , . . , , , . . . , . . . , , .

1.1.4

. , , . , , . (, , ), , .

12

. . , , . . , . Data Hiding ( ). . , , , . . . . . . , . , . . , .

1.1.5

. , . . . , . , , . . . . , . format. bitmap (BMP) JPEG. . JPEG 70%

13

. .

1.1.6

, . 1993, Tirkel . least significant bit (LSB) pixels.

1.1.7 . , , , , . discrete wavelet transform . , (, , ), .

1.2

1.2.1 : . . . . , . , , . , , ...

14

, . . . , . , .

1.2.2 . . (host signal), , , , .. . , ( 1). 2 .

1. .

2. .

15

1.2.3

, :

1. 2. 3. 4.

2 . tracing () , . , , . , , . . , .

1.2.4 , : , , . : (watermark carrier), (watermark generator) (carrier modifier).O data elements, , , . (Pseudorandom PN ), (secret keys), .

16

. , , . . , . : orig ( , clip ), . W Iwater . block , 3. 3.

W orig E: E(orig , W ) = Iwater orig. , W = (w1,w2, ), pixel sample orig.

17

, D, W, orig, W R, : D(R, orig ) = W' R Iwater, Iwater, . W W R . , . W W, :

W,W . :

.To 1 , 0 . , W W ( ), R , . W . , . 4 600 . , . , :

c . .

18

(Human Visual System - HVS). 4.

1.2.5

, . , , Cox(2002), , , . , , . , . , , , . .

19

, . , , , . bitstream , (bitstream) (Czerwinski, Fromm, & Hodes, 1999)

1.2.6 . - : . 5 , . , . , , W , A x K x W A'. , A ( ) W . 5.

, , . = < C, W, K, Dk ,Ek >, C , W |C| |W |, , Ek : C K W C, Dk : C K W, Dk (Ek (c, k,

20

w) k) = w w W, c C , . . . W . . , , :

) (Private Watermarking

Schemes). W. W.

) - (Semi-private Watermarking

Schemes). . W {Yes , No}

) (Public Watermarking),

(blind) . A W. n bits . , .

1.2.7

. , . , . . 6. . m Wa, . , . . Wa .

21

6. .

, . An. . , . , . blind public decoder,

mn. 6. informed. An Wn , .

2: , ,

, . . , . : , payload .

2.1

22

2.1.1 Imperceptibility (-). . , (audibility) . , (perceptibility). - , . (fidelity), , perceptually-based. , . , . , / . , . - . , , , . .

Robustness (). . , , ... , . . . , . : . . .

23

, .

Effectiveness (). . . 100%. . , . , false negative type-II error. , . , , .

Data payload. . bits . bits N-bit 2

. m bitstream . (P Sequence). , . . bit (one bit watermarks) . data payload, . , . , .

2.1.2

24

, .

False positive rate : false positive type-I error , . false positive rate , . . false positive . , DVD player (.. ), . , DVD players .

Statistical invisibility : / . , , . .

Redundancy (): , . .

Compression Ratio ( ): , MPEG-Layer 3. , . .

Multiple Watermarks ( ): . , .

Secret Keys ( ): .

25

, , , , . , (keyspace) , . (cipher key), . . . , , . unrestricted-key .

Computational Cost ( ): O . . , , . , . . DVD copy control embedders detector DVD player. .

2.1.3 , , .

Robust watermarks ( ). . , .

Fragile watermarks ( ). .

26

, . . . , , , . - .

Perceptible watermarks ( ). . (logos), , .

Bitstream watermarks. . bitstreams .

Fingerprinting labelling. . , , . fingerprinting , , . labelling .

2.1.4 .

Broadcasting monitoring ( ). . , , . . , , , . , . ,

27

. . (, ), , . , , , , , header files.

Copyright owner identification ( ). ..., . , , . , , . , . , . , , . , . . : , . .

Proof of ownership ( ). . , . , , , , . . ( ) .

28

Content authentication ( ). , . , . . . , . . . , , . .

Transactional watermarks ( ). , . . fingerprinting .

Copy control/device control ( / ). , . . . , . : , ( ) . , recorder . , ( DVD recorders) .

29

play control ( ), , . . , : , . . device control ( ). firmware , .

Covert Communication ( ). , . . , , , .

2.2 , . ( ) , . : (temporal sampling rate).H (Human Auditory System HAS ) . . . HAS , . . masking () .

30

. .

2.2.1 Amplitude Modification , Least Significant Bit Substitution (LSB), , . , . : , bits , PN , m, , bitstream, , n- bit n- . , 1 kbps 1kHz . 44 kHz, 44 kilobits . , . . . . , ... . , , . , PN , . bits . , . . , . bits , W. , A. coefficient quantization ( ).

31

Fourier (discrete Fourier transform - DFT), o (DCT), Mellin Fourier (Wavelet ransform). .

2.2.2 Dither Watermarking (dither) , . , , . , , . , . (dither quantizer). Quantization Index Modulation QIM ( E K). , bit (m=1 m=2) , m. , , dither quantizers ( ) dither modulation ( ). QIM , , . 7. , , . . dmin , ( ), . m 1, . m=2 . . . , , . . 7. QIM.

32

, , , . PN dither vectors ( ). , , . .

2.2.3 Echo Watermarking (echo watermarking) (t), , t, , . A(t) = A(t)+ (t - t). , , . t t , , . , . () , . . . , , . t millisecond.

33

bit , block . , block bit, . block samples, . block . , 16 bits , . . cepstrum autocorrelation ( cepstrum). cepstrum DFT DFT. . , . . , .

2.2.4 Phase Coding HAS , . (phase coding) , . : , bit . , W . i l . (DFT) . . , , A. HAS . , , . , , , . , , , 0. , , . , ,

34

, ( ). , . , , . . , DFT. , , DFT . , 0 W. , 8 32 bits . , . .

2.2.5 Spread Spectrum (spread spectrum) . ( ), ( ). W , . , , , PN . , , . , . . . , . . : direct sequence ( ) frequency hopping ( ). , , . direct sequence, m PN , . , m . m ,

35

W. To , , . , m 0.5% . , , PN , . W. , . W, . frequency hopping, . PN . W , , . . , PN , . , , . , , PN . PN .

3: ,

3.1

O . . , , . , .

36

, . , , . , : . , . . (fidelity), , . : difference metrics ( ) correlation metrics ( ). difference metrics . . , , (signal to noise ratio - SNR). decibels (dB), SNR (dB) = 10log10 (SNR). SNR dB :

n, - n - . . peak signal to noise ratio (PSNR), , . PSNR, , 1. 1. .

37

, SNR, 35 dB. correlation metrics , . . 2 . 2. .

, SNR . , . SNR HAS. decibels, . . ITU-R Rec. 500,

38

, 1 5. 3 ,

:

SNR . F, . 3. ITU-R Rec. 500.

3.1.1 Data Payload , . , . payload , , . , , , . , . , .

39

. 100 bits . payload, W, m .

3.1.2 , , . ( , ), . , , , . , , .

3.2

, , . , . , , . , , . , , .

3.2.1 , . , , , . , .

40

, , error-correcting codes ( ) . error-correcting code , W, m. , . , , , . , , , . , , . , . . , , , ( , ). , , :

1. , W A, , .

2. .

3. , .

, . ( , ). , BER - bit-error rate ( bit), , . BER bits , bits , :

l , Wn - bit Wn - bit . ,

41

. , , . , W .

3.2.2 Audio restoration attack (sound restoration techniques) , , . , . , samples . , samples . stationary autoregressive process - AR of finite order ( ). , AR samples. . , . : blocks, m samples. m = 1000 samples . block l, block AR. block, m. , . . , . , , . , . l, . , l = 80 samples .

3.2.3 Invertibility Attack , ,

42

, . . , . , , , W, . . . , W , A' = A+W, + . , W . , W = A. W W, . f( W, W) W W. , 1 W W . : ( ) w , . = w = A + W w, w . , . , , A = W w ( ) f( W-w, W) 1. = w W, f(w W, w) 1 . , . , . . , , , , , . , non-invertible cryptographic signature ( ), W.

3.2.4 Specific attack on echo watermarking

43

, , . , . Blind echo cancellation ( ) . , , . Cepstrum autocorrelation ( cepstrum). : A(t) = A(t) + A(t - t), , (ln()). , t. , , t 0,5 3 ms. 0,5 2 ms, .

3.2.5 Collusion Attack (collusion attack), averaging, fingerprinting. . , . , . (10 ) . , , .

3.2.6 Signal Diminishment Attacks and Common Processing Operations , , . (processing operation) ,

44

. , . , (signal diminishment

attacks) . , . , . , :

Dynamics (). . . , . .

Filters (). , . equalizers () , . low-pass, high-pass, all-pass, FIR ,.

Ambience (). . .

Conversion (). format. . .

Lossy Compression Algorithms ( ). , . . , .

45

, , . , , .

Noise (). . . . , .

Modulation (). (vibrato) (chorus).

Time stretch and Pitch shift ( ). , pitch . .

Sample Permutations ( ). , . samples, .

. . , . . , , Secure Digital Music Initiative (SDMI), International Federation of the Phonographic Industry (IFPR) Japanese Society for Rights of Authors, Composers and Publishers (JASRAC). . , . 4. SDMI,STEP IFPI

46

3.2.7 False positives false positives ( ), . , . W W. false positives . . , W K W, . false positive , . , false positive. , false positive . , , DVD, false positive 1 1012. , . , false positive.

3.3

47

, . , . ( ), . . , , , . , , SNR THD (total-harmonic-distortion), , . . , , . . , . . , , , . . . .

3.3.1 8 . . (pinna) HRTF (Head Related Transfer Function). HRTF , ,. , . , 5 kHz . , (timpanic membrane ear drum), (malleus) (incus) (). . (cochlea), . (basilar membrane - ). , .

48

. , , . (outer hair cells), , , . , . , (inner hair cells) , . , , . , . , . , , , . (Automatic gain control) 8.

, , . . , . . . . , , , .

49

3.3.2 , (HAS), , .To S . , , , , . (sensitivity) , . , . , , . . HAS . . 3 kHz 20 Hz 20kHz. , . , , . (masking) : , , ( - masker), . (maskee). , , . , , . : (simultaneous) (temporal) . . , . , . 5 dB , . , . , . ,

50

. 5 ms 150 ms . pooling. , . , . pooling. :

d[i] , , sample. , p = 1 .

3.3.3 (listening test). , . , 3 clips: , , , ( ), . . , . , (transparent) . ITU Recommendation ITU-R BS.1116 , . , . . (Basic audio quality) . (five level impairment scale)

51

. BAQ 0 -4 . , , . , . , . , noise-free . . , HAS. , . , . , , . , . .

3.3.4 , , . . , . . , (ITU,2001). 9. 9. .

52

, , HAS. HAS . FIR , . . -, . , , , . Bark, . . (Fast Transform Fourier FFT) ). , . , . . (feedback loop) , . , . decibels. , , . . ITU Recommendation ITU-R BS.1387, , ,

53

(excitation, modulation and loudness patterns), . . ITU, , BAQ (objective difference grade - ODG). , (implementation dependant units). , , ITU-R. 500 . , . , . .

3.4 , . , . , (final benchmark score). : . , . , . . . . . . . (evaluation template) , . : (evaluation profiles) (application specific benchmarking).

54

(evaluation profiles) . . , 4, , , . , . , , , . . (application specific benchmarking) , . . , : (, ) . , (overall watermarking scheme score) , : Score = wf *sf + wr *sr + wp *sp

w , s, , f, r, p, , . , . . , . , , . , :

55

3.4.1

, . , . , . .

56

, , , . , , . , . , . , . , . , . 5. 5. , .

receiver operating characteristic (ROC), false positives false negatives, . . ROC, , : W. , ( ) ( ). , : false positives false negative. ROC true positive fraction TPF ( true positive), - false positive faction FPF ( false positive), -. TPF :

57

TP, true positive FP, false negative. , FPF :

, false-positive FP, true negative. . , , , samples, false positive .

3.4.2 , (automated evaluation) . , , , . , . : , :

,

. , . . , . projects Certimark StirMark benchmarks . . . , . , : . ,

58

, testers. To tester, . basic zero knowledge , , tester. H A, tester . tester, . , , . , , . .

3.4.3

. , . , : , . , . . , . . , . . . . . ,

59

. , . . , , . . , . , . . , . Stirmark Certimark . , .

60

4: , . , , PCM, wav-table synthesis .

4.1 PCM

4.1.1 PCM PCM (Pulse-code modulation) (sampled) . , CD, . PCM stream, . PCM streams : (sampling rate), , bit depth, , .

4.1.2 Low Bit Coding

61

H low-bit coding amplitude modification, . . . , . string , bits, , bits . bits , . . , , bits . . . . . .

4.1.3 Phase Coding . PCM . H , , . , . , . , . , , : ( ). , . , .

62

, . . :

1. s[i], (0 i I-1) N sn[i], (0 n N-1).

2. - DFT (Discrete Fourier Transform) n- , sn[i] K = I/N , n(k), , An(k) (0 k K-1).

3. (0 n N-1) :n+1() = n+1() n()

4. data = /2 /2 0 1 : = data

5. n > 0 :

6. n ()

n (k) DFT.

, . , DFT . 0 1, string. () , . , . HAS .

4.1.4 Spread Spectrum Coding . stream , .

63

. , , , bits , . , , . , (Direct Sequence - DC), . , ( chips) 1 -1. chip (data rate).To 100 . , string error-correction coding ( ) . , . , . . , , . , DS . , 0,5% . . string averaging , . .

4.1.5 Echo hiding . , . , . , , . .

64

: , . , . , HAS . . , 1 0. , HAS . , , . , (v(t)) . , (c(t)), : c(t) = v(t) + v(t-d) . d d stego key. Cepstrum (. logF(c(t)) ) . F-1(log(F(c(t))). d d max . stream. . , .

4.1.6 Perceptual masking :

Perceptual-based watermarking procedure ( ). . , . , , . . , .

. . author-dependent, signal-

65

dependent.H .

. . , , .. , . , .

, , . , HAS. . si(k) 512 , i = 0, 1,..,floor(N/512 ) 1 k = 0, 1, , 511.T 512 . si(k), :

1. Si(k) si(k) 2. Mi(k) 3. ,

Pi(k) = Yi(k)Mi(k) 4. FFT pi(k) = IFFT(Pi(k)) 5. ti(k) si(k). 6. ti(k)

, wi(k) = ti(k)pi(k)

7. block si'(k) = si(k) + wi(k). wi 512. yi i x1 x2.

4.1.7 Content-adaptive watermarking HAS. , . , , , . ,

66

. . , . , . , . . . . 10 . (audio segmentation). , . , , . , multiple-bit hopping. (classifier) . 10. PCM audio.

11 . , . ,

67

. . , . clusters partition . cluster , cluster HAS . . , .

11. .

, . . 9, , . . , content-adaptive embedding scheme ( ). , . 12 . . , . bit

68

bit . bit bits , . bit. bits . bits. To bit bits. , cepstrum . . bits. cepstrum , bits bits. 12. PCM audio.

4.2 Wav-table synthesis

4.2.1 Wav-table synthesis audio

Wav-table synthesis audio synthesizers additive synthesis . additive synthesis ,

69

. Wav-table synthesis , . : . .

4.2.2 WAV-Table , , , . , , . , MIDI (Musical Instrument Digital Interface) . DI (samples) .. . samples . , MIDI. , Downloadable (Downloadable Sounds - DLS) hardware software .To DLS WAV-table synthesis 128 MIDI . DLS samples (articulation parameters) . DLS . MIDI (articulation information) (loop points). . 13 DLS. 13. DLS.

70

DLS . , MIDI , . , PCM , . DLS . .

4.2.3 H 14 WT . WT : sample DLS, MIDI. PCM , sample WT . , . , , sample ( ) . , WT sample . . , WT . 14. WAV-table synthesis audio.

71

4.2.4 15 . , , . , bits sample HAS sample . string . bit bit sample . sample HAS . 15. bit

72

bit . , resampling . sampled , WT . sample WT samples, . , bits WT . sample , bits . : = - ( ), - ( ), S - ( M), d : S x X S ( ) : S x XY ( ). X, Y, S, , : X = { 0,1 } Y = { y1, y2, y3, y4 } S = { S0, S1, S2, S3, S4 } Si+1 = (Si, x) yi = (Si, x) yi (i = 1, 2, 3, 4) sample bits Si (i = 0 4) 0, 00, 01, 10 11 S0 . 16. low-bit, HAS :

1. 2.

sample : y1 : 00 y2 : 01 y3 : 10 y4 : 11

3. 0 1 bit r0 : o 0 bit r1 : o 1 bit

73

4. HAS 5. bit

sample sample WT, sample

HAS. if A < T , else

yi(i= 1,2,3,4) lower bit rj (j=0,1) , bit .

bits .

16. .

4.2.5 Parameters hiding

74

WT , . 17. bits stream . , stream WT . , . , sample WT bits . 17. .

(parameters hiding) , WT,

75

. DLS Level 1 ,

1. low-bits

2. stream n

3. DLS .

: LIST ins LIST INFO Inam Instrument name (watermark Info part 1) (watermark Info part 2) LIST lrgn LIST rgn (watermark Info part 3) (watermark Info part 4) (watermark Info part 5) LIST rgn . . . LIST lart (watermark Info part n )

4.2.6 18 . , WT . WT , sample . bits sample . sample , . sample , bits bit sample . ,

76

. 18. WAV-table synthesis audio.

4.3 bits, . , MP3 . HAS. format online CD 11 1 (128kb/s).

4.3.1 , , . . , 30 WAV, 5 6 128kb/s. online . , . . .

77

MP3 MP3Stego. , MP3 . , bit stream MP3. Layer III inner_loop. inner_loop bits. , . part2_3_length bits main_data Huffman bit stream MP3. bits inner_loop. part2_3_length bit SHA-1, . . bit stream . MP3Stego . PCM . , : DES audio . . / audio stream . 19 block , audio stream . audio stream . audio samples block ECC (error correction code). samples bit-rate , . samples bit stream. 19. .

78

H . MPEG-1. 20 block audio stream MPEG-1. 20. .

79

IP streaming, live broadcasting, video/audio on demand, .. bitrate . key-based .

4.3.2 Partially uncompressed domain watermarking . , . 21 block . . . . feature extraction model

80

. , . 22. . . , . online . . 21. .

22 block . , . . , HAS . , . , , . , . .

22. .

81

23. .

, . 23 . . . . , . 24. 24. .

82

24 block . , . , bits (spike) bit.

4.4 . HAS, . , PCM, WAV-audio synthesis . PCM , , , , . , . WAV-table synthesis , . . . , . HAS , , . , . . , . .

83

Xu, C., Zhu, Y., & Feng, D. (2001a). Digital audio watermarking based-on multiple-bit hopping and human auditory system. ACM International Conference on Multimedia, pp. 568-571, Ottawa, Canada. Xu, C., Zhu, Y., & Feng, D. (2001b). A robust and fast watermarking scheme for compressed audio. IEEE International Conference on Multimedia and Expo, pp. 253-256, Tokyo, Japan. Xu, C., Feng, D., & Zhu, Y. (2001). Copyright protection for WAV-table synthesis audio using digital watermarking. Lecture Note in Computer Science 2195. In H.-Y. Shum, M. Liao & S.-F. Chang (Eds.), Advances in multimedia information processing (pp. 772-779). The Second IEEE Pacific-Rim Conference on Multimedia, PCM 2001, Beijing, P.R. China Xu, C., & Feng, D. (2002). Robust and efficient content-based digital audio watermarking. ACM Journal of Multimedia Systems, 8(5), 353-368. Gordy, J.D., & Bruton, L.T. (2000). Performance evaluation of digital audio watermarking algorithms. Proceedings of IEEE MWSCAS 2000. Voloshynovskiy, S., Pereira, S., Iquise, V., & Pun, T. (2001, June). Attack modelling: Towards a second generation benchmark. Paper presented at the Signal Processing. Petitcolas, F.A.P. (2000). Watermarking schemes evaluation. IEEE Signal Processing, 17(5), 58-64. Meerwald, P., & Pereira, S. (2002, January). Attacks, applications, and evaluation of known watermarking algorithms with Checkmark. Paper presented at the Proceedings of the SPIE, Security and Watermarking of Multimedia Contents IV, San Jose, CA. Craver, S., Wu, M., Liu, B., Stubblefield, A., Swartzlander, B., Wallach, D.S., Dean, D., & Felten, E.W. (2001, August). Reading between the lines: Lessons from the SDMI challenge. Paper presented at the USENIX Security Symposium, Washington, DC. Cox, I.J., Miller, M.L., & Bloom, J.A. (2002). Digital watermarking (1st ed.). San Francisco: Morgan Kaufmann. Arnold, M., & Schilz, K. (2002, January). Quality evaluation of watermarked audio tracks. Paper presented at the Proceedings of the SPIE, Security and Watermarking of Multimedia Contents IV, San Jose, CA. Certimark. (2001). Certimark benchmark, metrics & parameters (D22). Geneva, Switzerland.

84

Zhihui, W., & Liang, X. (2000, July). An evaluation method for watermarking techniques. IEEE International Conference on Multimedia and Expo, ICME 2000, 1, 373-376. Wolfgang, R., Podlchuk, C., & Delp, E. (1999, July). Perceptual watermarks for digital images and video. Proceedings of IEEE Special Issue on Identification and Protection of Multimedia Information, 7, 1108-1126. Tilki, J.F., & Beex, A.A. (1996). Encoding a hidden digital signature onto an audio signal using psychoacoustic masking. Proceeding of 7th International Conference on Signal Processing Applications and Techniques, (pp. 476-480). Cox, I., Kilian, J., Leighton, F.T., & Shamoon, T. (1996, September). Secure spread spectrum watermarking for images, audio and video. International Conference on Image Processing Proceedings, ICIP 96, (vol. 3, pp. 243- 246). Tilki, J.F., & Beex, A.A. (1996). Encoding a hidden digital signature onto an audio signal using psychoacoustic masking. Proceeding of 7th International Conference on Signal Processing Applications and Techniques, (pp. 476-480).