Abstract: On a recording medium, first information obtained by enciphering data with the first key and second information obtained by enciphering the first key with each of the predetermined second keys are recorded. A deciphering method is characterized by comprising the steps of inputting the first and second information, deciphering the first key using at least one of the second keys, determining by a specific method that the obtained first key is correct, and then deciphering the data using the first key to obtain the data.

Abstract: On a recording medium, first information obtained by enciphering data with the first key and second information obtained by enciphering the first key with each of the predetermined second keys are recorded. A deciphering method is characterized by comprising the steps of inputting the first and second information, deciphering the first key using at least one of the second keys, determining by a specific method that the obtained first key is correct, and then deciphering the data using the first key to obtain the data.

Abstract: A record medium comprises an original data obtained by superimposing a presentation target data, to which an error correction encoding is performed and an identification information.

Abstract: A cryptographic communication terminal serving as one of information transmitting and receiving terminals in cryptographic communication includes a cryptographic algorithm storage section for storing one or more types of cryptographic algorithm used for cryptographic communication, and outputting a designated cryptographic algorithm, a key information storage section for storing a key used for cryptographic communication corresponding to the cryptographic algorithm, and outputting a designated key, a control section for designating, with respect to the cryptographic algorithm storage section and the key information storage section, which cryptographic algorithm and key are to be used in the cryptographic communication, and an encryption/decryption section for decrypting received encryption information by using the cryptographic algorithm designated with respect to the cryptographic algorithm storage section and the key designated with respect to the key information storage section, and encrypting information

Abstract: A system (300, 500) for scrambling digital samples (115, 200, 250, 260, 270) of multimedia data, including audio and video data samples, such that the content of the samples is degraded but still recognizable, or otherwise provided at a desired quality level. The samples may be in any conceivable compressed or uncompressed digital format, including Pulse Code Modulation (PCM) samples, samples in floating point representation, samples in companding schemes (e.g., ?-law and A-law), and other compressed bit streams. The quality level may be associated with a particular signal to noise ratio, or quality level that is determined by objective and/or subjective tests, for example. A number of LSBs can be scrambled in successive samples in successive frames (FRAME A, FRAME B, FRAME C). Moreover, the parameters for scrambling may change from frame to frame. Furthermore, all or part of the scrambling key (310) can be embedded (340) in the scrambled data and recovered at a decoder (400, 600) to be used in descrambling.

Abstract: A source of MPEG2 video data is connected with a dedicated AV device or personal computer by means of an IEEE 1394 interface. A transmission unit in the source has an IEEE 1394 encryption unit and a sending I/F unit. A reception unit varies between the dedicated AV unit and the personal computer. In the reception unit of the dedicated AV device, a receiving I/F unit and a decryptor are integrally incorporated into one semiconductor chip and an MPEG2 decoder is incorporated into one semiconductor chip. In the reception unit of the personal computer, the receiving I/F unit is formed of one semiconductor chip, and the decryptor connected to the I/F unit through a bus, and the MPEG2 decoder are formed of one semiconductor chip. Thus, data before decryption will not appear on the bus, which prevents MPEG2 video data from being taken out of the computer for illegal copying purposes.

Abstract: A conditional access broadcast system for realizing conditional access while maintaining the safety level is disclosed. A contract management device at a broadcast station side delivers a reception contract information containing at least a contract information for controlling decryption of encrypted contents information delivered from a broadcast station by broadcast and a reception device ID in correspondence, which is encrypted using a master key which is commonly provided with respect to all the broadcast reception devices. At each broadcast reception device, whether or not to give a channel key for decrypting the encrypted contents information to the decryption unit is controlled according to the contract information for own broadcast reception device which is acquired from the encrypted reception contract information.

Abstract: A conditional access broadcast system for realizing conditional access while maintaining the safety level is disclosed. A contract management device at a broadcast station side delivers a reception contract information containing at least a contract information for controlling decryption of encrypted contents information delivered from a broadcast station by broadcast and a reception device ID in correspondence, which is encrypted using a master key which is commonly provided with respect to all the broadcast reception devices. At each broadcast reception device, whether or not to give a channel key for decrypting the encrypted contents information to the decryption unit is controlled according to the contract information for own broadcast reception device which is acquired from the encrypted reception contract information.

Abstract: In an embodiment, a copy-guard system is provided that includes a decoding section for decoding digital data, which is encoded and error-correction-coded, from an information recording medium in which key information encoded for the digital data is recorded, an encoded digital data acquisition section for acquiring digital data encoded by error-correcting the digital data decoded by the decoding section, a detection section for detecting an error position and an error symbol value of the encoded digital data, identification information detection section for detecting an identification information representing whether the information recording medium is original or copied and which is replaced with a part of the digital data encoded and error-correction-coded, based on the error position and the error symbol value detected by the detection section, a determination section for determining whether a copy of the information recording medium is protected, and a copy protection section.

Abstract: A conditional access broadcast system for realizing conditional access while maintaining the safety level is disclosed. A contract management device at a broadcast station side delivers a reception contract information containing at least a contract information for controlling decryption of encrypted contents information delivered from a broadcast station by broadcast and a reception device ID in correspondence, which is encrypted using a master key which is commonly provided with respect to all the broadcast reception devices. At each broadcast reception device, whether or not to give a channel key for decrypting the encrypted contents information to the decryption unit is controlled according to the contract information for own broadcast reception device which is acquired from the encrypted reception contract information.

Abstract: A conditional access broadcast system for realizing conditional access while maintaining the safety level is disclosed. A contract management device at a broadcast station side delivers a reception contract information containing at least a contract information for controlling decryption of encrypted contents information delivered from a broadcast station by broadcast and a reception device ID in correspondence, which is encrypted using a master key which is commonly provided with respect to all the broadcast reception devices. At each broadcast reception device, whether or not to give a channel key for decrypting the encrypted contents information to the decryption unit is controlled according to the contract information for own broadcast reception device which is acquired from the encrypted reception contract information.

Abstract: A conditional access broadcast system for realizing conditional access while maintaining the safety level is disclosed. A contract management device at a broadcast station side delivers a reception contract information containing at least a contract information for controlling decryption of encrypted contents information delivered from a broadcast station by broadcast and a reception device ID in correspondence, which is encrypted using a master key which is commonly provided with respect to all the broadcast reception devices. At each broadcast reception device, whether or not to give a channel key for decrypting the encrypted contents information to the decryption unit is controlled according to the contract information for own broadcast reception device which is acquired from the encrypted reception contract information.

Abstract: This invention protects the unauthorized copy of multimedia data, recorded on an information recording medium, by using electronic watermark information and key information. The electronic watermark information embedded in the multimedia data is extracted by an electronic watermark extraction unit on the decryption system side. A disk key is obtained using the electronic watermark information and a part master key. The multimedia data is decrypted using the resultant disk key.

Abstract: On a recording medium, first information obtained by enciphering data with the first key and second information obtained by enciphering the first key with each of the predetermined second keys are recorded. A deciphering method is characterized by comprising the steps of inputting the first and second information, deciphering the first key using at least one of the second keys, determining by a specific method that the obtained first key is correct, and then deciphering the data using the first key to obtain the data.

Abstract: Each embodiment of the present invention uses an information recording medium comprising an area A recording key management information and a read-only area B recording compressed data comprising compressed key management information. This information recording medium can verify validity of the key management information by confirming a match between the compressed data for the key management information read from the area A and the compressed data read from the read-only area B. Accordingly, it is possible to record the key management information by preventing unauthorized rewriting even on an information recording medium with a limited read-only area size.

Abstract: On a recording medium, first information obtained by enciphering data with the first key and second information obtained by enciphering the first key with each of the predetermined second keys are recorded. A deciphering method is characterized by comprising the steps of inputting the first and second information, deciphering the first key using at least one of the second keys, determining by a specific method that the obtained first key is correct, and then deciphering the data using the first key to obtain the data.

Abstract: This invention protects the unauthorized copy of multimedia data, recorded on an information recording medium, by using electronic watermark information and key information. The electronic watermark information embedded in the multimedia data is extracted by an electronic watermark extraction unit on the decryption system side. A disk key is obtained using the electronic watermark information and a part master key. The multimedia data is decrypted using the resultant disk key.

Abstract: This invention protects the unauthorized copy of multimedia data, recorded on an information recording medium, by using electronic watermark information and key information. The electronic watermark information embedded in the multimedia data is extracted by an electronic watermark extraction unit on the decryption system side. A disk key is obtained using the electronic watermark information and a part master key. The multimedia data is decrypted using the resultant disk key.

Abstract: On a recording medium, first information obtained by enciphering data with the first key and second information obtained by enciphering the first key with each of the predetermined second keys are recorded. A deciphering method is characterized by comprising the steps of inputting the first and second information, deciphering the first key using at least one of the second keys, determining by a specific method that the obtained first key is correct, and then deciphering the data using the first key to obtain the data.

Abstract: A transmission apparatus 100 includes a secret key storage unit 103 that stores three secret keys K1, K2 and K3, a secret key selection unit 104 that selects one secret key Ks from the secret keys, a message generation unit 106 for generating a message M used as a carrier for indicating a secret key, an encryption module 105 for generating a cryptogram Ca by encrypting the generated message M using the secret key Ks, an encryption module 107 for generating a cryptogram Cm by encrypting the message M using the message M itself as the secret key, and two transmission units 111 and 112 for transmitting the cryptograms Ca and Cm to the reception apparatus 200 to indicate the selected secret key Ks.