after the quantization step in jpeg compression standard. It is based on decomposed application, if encryption and watermark are commutative, some computational .. fingerprint embedding and decryption for video distribution,” IEEE. 1 1 Commutative Encryption and Watermarking in Video Compression Ieee Transactions On Circuits And Systems For Video Technology, Vol. 17, No. 6, June. 1 1 Commutative Encryption and Watermarking in Video Compression 交換式 加密及浮水印法應用在視頻壓縮 IEEE Transactions on Circuits and Systems for.

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For example, cloud computing clients need to secure their data, not only to protect their data from public attacks, but also to protect their data from their cloud service provider [ 7 ]. In order to evaluate the robustness against general signal manipulations, the well-known benchmarking tool StirMark for Audio, V1. Proposed watermarking and encryption scheme Watermark Extraction W: Although the watermarking watermafking is based on the histogram, it cannot be used in conjunction with a permutation cipher watefmarking form CWE scheme, because only a certain number of sample values in a histogram bin are modified.

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For these parameter choices, the proposed watermarking algorithm is extremely robust against TSM attacks in resample mode, while the robustness against pitch-invariant mode is slightly worse, but still very good.

If the commutatjve is not satisfied by the three bins, a certain number of samples is shifted from the first and third bin of the triple into the second bin by adding and subtracting, respectively, a bin width to the samples. This makes sure that the padded values cannot be distinguished from the original values by an attacker.

## Advances in Multimedia

Thus, clients need to encrypt their data in the cloud. More generally, it should be possible to protect multimedia data throughout the distribution chain in a flexible way by allowing the encryption and watermarking operations to commute [ 6 ]. Because in principle the required permutations can be generated in a different way, it is more interesting in this context to look at the security of permutation ciphers for watermarkihg files in general.

It is therefore an easy task for an attacker to modify those bins accordingly in order to remove the watermark. View at Google Scholar Z.

Performance analysis Perception Security. To receive news and publication updates for Advances in Multimedia, enter your email address in the box below. In order to generate the permutations, the discrete encryptiln of Arnolds Cat Map [ 14 ] was used, because it is a well-known chaotic map used by many authors for generating permutations in image ciphering see e.

In [ 2 ], Katzenbeisser and Craver propose a probabilistic protocol which is in principle able to integrate any symmetric watermarking algorithm. As a first step, the embedder generates the amplitude histogram of the audio signal and forms its relevant part as described in Section 3. In the present paper, an existing CWE concept for still images [ 1 ] is extended to audio files. Wateemarking attacker would not, however, be able to prove knowledge of or itself.

In all scenarios the mark could be extracted without any errors from all test files. If the permutation is generated by some alternative mechanism like, for encrypton, the one proposed in [ 21 ], which does not require wattermarking, the scheme is fully commutative by construction. CWE schemes can provide such a solution, if metadata are used as watermarks and embedded into the encrypted data. If the distributor takes the role of the seller in this protocol and the rightsholder performs the en- and decryption operations in steps 1 and 4respectively, the problem mentioned above can be solved, if a CWE scheme for the media object is available.

If the verification is successful, encrption her own encryption and sends the result back to the buyer. The mean value associated with the minimum distance is used to extract the remaining watermark bits. An obvious solution is that vompression a watermark identifying as the rightful owner into and provides the marked object to.

The watermarking bit is now embedded in the following encryphion By usingthe attacker could also embed a permuted mark.

On the other hand, sample manipulations like inserting Zero-Samples, periodic deletion of samples cropping, or CutSamples in StirMarkor manipulating the least significant bits LSBs of the samples do not affect the watermark. Alice now generates some secret permutation and publishes along with a random graph having nodes and.

### Commutative Watermarking-Encryption of Audio Data with Minimum Knowledge Verification

The watermarkwhich ckmmutative also lengthis embedded by the prover using some sncryption watermarking algorithm.

For a bit watermark, the amount of data to be transferred between prover and verifier is about 4 Kilobytes per step. The invariant encryption approach to CWE as introduced in [ 1 ] is to encrypt the media data completely as opposed to the partial encryption approach, which leaves part of the data unencrypted to host the watermarkbut to use a weaker cipher that leaves a feature space of the media data invariant. In our modified version of the protocol, we take advantage of the special structure of our watermarking algorithm and strive to eliminate the two drawbacks mentioned above.

If this is not the case, swap the bins by assigning new values to all samples in the bins. The detector needs to know the compressjon mean value of the samples of the unmarked cover workalong with qatermarking synchronization sequence sync of length and the sequence of bin pairs used for embedding the markwhich serves as a watermarking key.

In our opinion, anv protocol, while being very ingenious, has two drawbacks: Let the audio signal consist of a set of sample values. The audio files include artificially generated signals as well as speech, single instruments, and pop music https: The resulting PSNR between original and enciphered signal is Ifthe relation should hold, where is a predefined threshold value.

The histogram part leading to the minimum dissimilarity is used to extract the remaining bits from.

Therefore, after application of the permutation cipher, different sample values than before are modified, which destroys the commutativity property. Snd present a scheme for commutative watermarking-encryption CWE of audio data and demonstrate its robustness against an cokpression class of attacks, Time-Scale Modifications TSM.

The result is the marked work. Revised Selcted Papersvol. To make this website work, we log user data and fommutative it with processors. Section 5 provides experimental results on the robustness and fidelity of the watermarking part. For each mean value inthe corresponding histogram is formed and the distance between the first extracted bits and a known synchronization sequence sync is computed. However, this procedure can imply a substantial change of the histogram mean.

Moreover, it is clear how to do this without knowledge of the watermarking key, as the permuted key will yield the permuted mark. Digital Signal Processing, Vol. Statistical Mechanics and Its Applicationsvol. The prime motivation to look at CWE schemes originates from the need to implement so-called Dispute Resolve Protocols, where a rights owner provides a digital media wwatermarking to a distributorwho in turn sells to some customer.

The flattening of the histogram makes it impossible to use the histogram for embedding a watermark.