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Author

博文 村谷

Bio: 博文 村谷 is an academic researcher. The author has contributed to research in topics: Watermark & Code (cryptography). The author has an hindex of 3, co-authored 13 publications receiving 33 citations.

Papers
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Patent
28 Nov 2000
TL;DR: In this paper, an electronic watermark burying device is used to estimate the number of copies of digital contents used for a coalition attack against the copy of the digital contents where a coalition resistance code is buried.
Abstract: PROBLEM TO BE SOLVED: To provide an electronic watermark system for estimating the number of the copies of digital contents used for a coalition attack against the copy of the digital contents where a coalition resistance code is buried. SOLUTION: An electronic watermark burying device 1 buries the coalition resistance code uniquely corresponding to the user ID of a use in the copy of the digital contents before giving the copy to the user. An electronic watermark analyzer 2 detects the coalition resistance code from the copy of the digital contents to be analyzed after the contents pass through a circulation route 3, detects position information related to the position of an alternation part concerning each component code among more than one component codes which constitute the detected code, obtains a prescribed statistic amount with respect to the alternation part of the component codes based on position information and estimates the number of the copies used for the coalition attack against the digital contents based on the prescribed statistic amount.

6 citations

Patent
12 Jul 2000
TL;DR: In this paper, the extended key is used in reverse order at the time of ciphering and deciphering, respectively, two round functions f1 and fn+1 are set to be inverse functions to each other having the same number of stages from the first stage as that from the last stage.
Abstract: PROBLEM TO BE SOLVED: To provide a ciphering device capable of avoiding the occurrence of a delay time for generating an extended key, and also generating On-the-fly key. SOLUTION: In an extended key generating part 3 of a ciphering device using a common key block ciphering system in which the extended key is used in reverse order at the time of ciphering and deciphering, respectively, two round functions f1 and fn+1 are set to be inverse functions to each other having the same number of stages from the first stage as that from the last stage, respectively. Thus, it is possible to sequentially generate the extended key immediately and also in order of use by using the extended key as an input at the time of both ciphering and deciphering. Moreover, the extended key generation at the time of ciphering is fundamentally the same as that at the time of deciphering.

4 citations

Patent
30 Nov 2001
TL;DR: In this paper, the authors proposed a digital watermark embedding scheme that is capable of embedding watermark information to contents in a way that the watermarks can correctly be detected and the presence/absence of the digital watermarks embedded to the contents can hardly be discovered.
Abstract: PROBLEM TO BE SOLVED: To provide a digital watermark embedding apparatus capable of embedding watermark information to contents in a way that the watermark information embedded in the contents can correctly be detected and the presence/absence of the digital watermark embedded to the contents can hardly be discovered. SOLUTION: The digital watermark embedding apparatus includes: a superimposition component composite section 11 that applies conversion to an embedding object contents 10 by using a filter whose coefficients are a periodic pseudo random number sequence 13 from a pseudo random number generating section 12 to compose a superimposing component 14 to be superimposed on the embedding object contents 10 with the embedding object contents 10; and a superimposing section 15 that superimposes the superimposing component 14 on the embedding object contents 10 to produce embedded contents resulting from embedding the watermark information to the embedding object contents 10. COPYRIGHT: (C)2003,JPO

4 citations

Patent
11 Jul 2000
TL;DR: In this article, a small SPN structure is recursively buried in an S-box part of an ordinary SPN, and a large spreading over a block width is operated by a spread module, followed by small and local spreading by the nonlinear converter modules.
Abstract: PROBLEM TO BE SOLVED: To provide an ciphering device permitting highly uniform dispersion with a calculation cost suppressed. SOLUTION: Small local spreading is operated by each of non-linear converter modules 2 which are plurally arranged in parallel in each stage; following this, a large spreading over a block width is operated by a spread module 3; small and local spreading is operated by the non-linear converter modules 2 again; and this operation is repeated by the prescribed number of stages. Further, the non-linear converter modules 2 are configured of an alternate arrangement of the non-linear converter modules 4 and the spreading modules 5. Namely, a small SPN structure is recursively buried in an S-box part of an ordinary SPN structure into this nesting SPN structure.

3 citations

Patent
13 Jul 2000
TL;DR: In this article, a method for determining an MDS matrix given the optimal complexity in the combination with the S-box, and a ciphering device adopting the MDS matrices obtained by the method are provided.
Abstract: PROBLEM TO BE SOLVED: To solve the problem that an S-box and an MDS matrices comprised in a ciphering device as the system components offset their effects against each other in spite of the X-box and the MDS intended to realize optimal complexity according to the design policies independent of each other, therefore, the ciphering device has had a probability of being rather unsafe. SOLUTION: By evaluating complexity of a result of multiplication of each candidate of MDS matrix elements by the matrix elements of a given S-box; evaluating, based on a evaluation result of this complexity, the complexity of the combinations of the matrix element candidates composing the MDS matrix; further, evaluating similar complexity also of an inverse matrix to this MDS matrix; and based on the evaluation results of the complexity of these matrices, a method for determining an MDS matrix giving the optimal complexity in the combination with the S-box, and a ciphering device adopting the MDS matrix obtained by the method are provided.

3 citations


Cited by
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Patent
17 Nov 2003
TL;DR: In this article, a delivery server encipher the data by using a current use cipher key to generate enciphered data and transmits a multicast packet containing the encoded data.
Abstract: In a multicast delivery system, A delivery server enciphers delivery data by using a current use cipher key to generate enciphered data and transmits a multicast packet containing the enciphered data and a current use key identifier indicative of a pair of the current use cipher key and a current use decipher key as current use keys A key management server holds as a current use key data, a set of the current use decipher key and the current use key identifier, and transmits a set of the current use decipher key and the current use key identifier as a current use decipherment key data in response to a current use key data request

60 citations

Patent
Hirofumi Muratani1
27 Aug 2003
TL;DR: A digital watermark embedding apparatus comprises below units as mentioned in this paper : a first generation unit generates a plurality of symbol sequences, each of which includes ranks, each rank being uniquely numbered among each of the symbol sequences.
Abstract: A digital watermark embedding apparatus comprises below units. A first generation unit generates a plurality of symbol sequences each of which includes a plurality of symbols including ranks, each of the ranks being uniquely numbered among each of the symbol sequences, each of the symbol sequences uniquely corresponding to each of a plurality of identification information items to be embedded as digital watermark information into each of copies of digital contents. A second generation generates a plurality of to-be-embedded codes corresponding to each of the symbols in each of the symbol sequences. An embedding unit embeds the to-be-embedded codes in each of the copies.

55 citations

Patent
Nakaba Kogure1, Tomoo Yamakage1
28 Aug 2003
TL;DR: In this article, a digital watermark embedding apparatus includes a scaling unit configured to scale at least a specific frequency component of an input image signal to generate a scaled image signal.
Abstract: A digital watermark embedding apparatus includes a scaling unit configured to scale at least a specific frequency component of an input image signal to generate a scaled image signal, a control unit configured to control at least one of a phase and amplitude of the scaled image signal in accordance with watermark information to generate a controlled image signal, and a combiner to combine the input image signal and the controlled image signal to generate an output image signal embedded with the watermark information.

51 citations

Patent
23 May 2007
TL;DR: In this paper, a specific frequency component extraction unit extracts a specific component signal from an input image signal and a correlator computes the cross-correlation value of the phase-controlled specific frequency components signal and the image signal.
Abstract: A specific frequency component extraction unit extracts a specific frequency component signal from an input image signal. A phase controller controls the phase of the specific frequency component signal. A correlator computes the cross-correlation value of the phase-controlled specific frequency component signal and the input image signal. A watermark information estimation unit filters the cross-correlation value to detect watermark information embedded in the input image signal.

50 citations

Patent
29 Aug 2007
TL;DR: In this article, a common-key blockcipher processing configuration with enhanced immunity against attacks such as saturation attacks and algebraic attacks (XSL attacks) is realized, where S-boxes serving as non-linear transformation processing parts set in round-function executing parts are configured using at least two different types of s-boxes.
Abstract: A common-key blockcipher processing configuration with enhanced immunity against attacks such as saturation attacks and algebraic attacks (XSL attacks) is realized. In an encryption processing apparatus that performs common-key blockcipher processing, S-boxes serving as non-linear transformation processing parts set in round-function executing parts are configured using at least two different types of S-boxes. With this configuration, the immunity against saturation attacks can be enhanced. Also, types of S-boxes present a mixture of different types. With this configuration, the immunity against algebraic attacks (XSL attacks) can be enhanced, thereby realizing a highly secure encryption processing apparatus.

50 citations