摘要:
A secure forensic watermarking system is disclosed that distributes the same encrypted content to all users. The decryption key is different for each user, so that the decrypted content differs slightly from the original, i.e. is watermarked. Forensic tracking is possible by distributing unique decryption keys to individual users. The invention allows a forensic mark to be securely embedded in the compressed domain signal. In an embodiment of this invention, the content (x) and an encryption sequence (r) are entropy encoded using a homomorphic Huffman table. A homomorphic Huffmann table is a table H having the property that there exists an operation f( ) such that H-1 (f(H(a),H(b)))=a+b.
摘要翻译:公开了一种安全的法医水印系统,其将相同的加密内容分发给所有用户。 解密密钥对于每个用户是不同的,使得解密的内容与原始内容略有不同,即被加密。 通过向个别用户分发唯一的解密密钥可以进行取证跟踪。 本发明允许将法医标记安全地嵌入到压缩域信号中。 在本发明的一个实施例中,内容(x)和加密序列(r)使用同态霍夫曼表进行熵编码。 同形霍夫曼表是具有存在使得H-1(f(H(a),H(b)))= a + b的操作f()的性质的表H。
摘要:
The present invention relates to methods and apparatus for digital content distribution. A method of transferring digital content from a first entity (60) to a second entity (70) includes the steps of: a transfer control entity (50) transmitting a transmission key (KA) to the first entity, the first entity storing content data comprising digital content embedded with a first watermark (WA). The first entity applies the transmission key to the content data to remove the first watermark from the digital content and encrypt the digital content. The first entity transmits the encrypted digital content (CX) to the second entity. The transfer control entity transmits a receive key (KB) to the second entity and the second entity applies the receive key to the encrypted digital content to generate decrypted data comprising the decrypted digital content embedded with a second watermark (WB).
摘要:
The invention relates to a method of searching for a watermark in a data signal, and to a watermark detector, such as a copy-control watermark detector. The search is conducted in order to find a watermark in content which possibly has been attacked and/or altered. The search is conducted by the steps of determining or setting a search space for the data signal, selecting a subspace of the search space, and searching for the presence of the watermark in the subspace. The subspace may be selected from a multitude of regions, the selection e.g. being based on a deterministic or probabilistic function.
摘要:
The invention relates to embedding auxiliary data in the form of a multibit payload in a host signal, and encrypting the associated detection key. Moreover, the invention relates to extracting the auxiliary data in the form of the multibit payload from a data signal. Auxiliary data is embedded in a host signal by the following steps. First a reference watermark is provided, subsequently an encrypted detection key associated only with the reference watermark is generated. The encrypted detection key may be a scrambled version of the watermark. In a further step, the multibit watermark is generated and a multibit payload is encoded into the reference watermark. Finally, the multibit watermark is embedded into the host signal.
摘要:
A system and a method of effectively detecting watermarks in a significant amount of data signals. The method, in overview, consists in pre-filtering the significant amount of data signals in order to eliminate from the final watermark detection the segments of the data signals which have no significant relevance to the owner of the copyrights of the watermark under investigation, and then performing the actual watermark detection over the remaining segments of data signals relevant to the investigation. The pre-filtering feature being implemented by a definition of one or more goal descriptors, extraction of one or more descriptors from the data signals and its content and a comparison between goal descriptors and extracted descriptors.
摘要:
The invention relates to embedding a spread spectrum watermark in a data signal as well as to detection of the embedded watermark. A data signal (4) is encrypted (15) or received in the form of an encrypted data signal (9), the signal being encrypted by modifying (3) it in accordance with one or more entries of a look-up-table (2) in which an encryption table (6) is stored. The encryption is carried out by a first computing device (15) such as a server device. The watermark is actually embedded while decrypting (13) the signal. This takes place in a second computing device (16), possibly in a client device, in a similar manner The client device employs a decryption table (8), which is a modified (i.e. watermarked) version of the encryption table (6). The decryption table may generated by the server and securely communicated to the client. The data signal is decrypted in accordance with entries of a look-up-table (12). The look-up-tables (2,12) in server and client are addressed by the same sequence of pointers generated by respective index generators (1). The mismatch between encryption table (6) and decryption table (8) causes the de-signal (14) to have an embedded watermark.
摘要:
A system and a method for secure remote informed watermark detection making use of a side-information. The system in overview comprises a remote detector and a server computing system wherein a database with side-information assigned to specific descriptors of data signals is stored at the server computing system and wherein a remote detector intending to identify the watermark of a data signal will derive the descriptor of the data signal and subsequently contact the trusted server computing system in order to obtain the necessary side-information for the informed watermark detection.
摘要:
Disclosed are a method and a system for secure watermark embedding in a server-client configuration (60,70). The method comprises encrypting (210) the data signal (x) and generating (240) a decryption key wherein a watermark (Wi) is included. The client decrypts (420) the encrypted data signal in order to obtain a watermarked data signal (xw). In accordance with the invention, the encryption mechanism and decryption key are made dependent on a perceptual mask (m1,m2) so as eventually make the embedded watermark more robust.
摘要:
In watermarking systems, hackers may try to remove the watermark using a so-called collusion attack. If the attacker has access to multiple identical signals with different watermarks (this typically occurs in electronic content delivery systems), simply averaging the signals will remove the watermark energy. A known solution to this problem is phase modulation. By modulating the phase of the signals, the averaging attack will cause phase cancellation to occur and annoying artifacts to be introduced. In the prior art, said phase modulation is carried out in the base-band domain, prior to watermark embedding. The present invention enables phase modification efficiently to be applied to transform coded signals, in particular DCT or MDCT coded signals such as MP3 or AAC audio signals, or MPEG2 video signals. The bitstream is partially decoded (4) and re-encoded (7). In accordance with the invention, the phase modification is now performed by an appropriately modified version of the forward or inverse (M)DCT transform algorithm (9). The phase modulation is thus an integral part of the decoding process (before watermark embedding) or the encoding process (after watermark embedding), which is very efficient. The phase modulation is controlled by parameters provided by a control function (5).
摘要:
There is described a system (10; 300) for processing an input signal (340) to generate a corresponding encoded output signal (380). The system (10; 300) includes a plurality of quantizing devices (30, 70; 350, 370) coupled in series, the system (10; 300 being configured in operation to reduce tandem quantization noise arising therein by: (a) analyzing the system (10; 300) to determine signal regions (290) in which tandem noise errors occur; and (b) modifying one or more earlier quantizing devices (30; 350) in the system (10; 300) with backward correction to reduce tandem noise arising therein from said determined signal regions (290), said one or more earlier quantizing devices (30; 350) not including a last quantizing device (70; 370) in series the system (10; 300).