Sony Corporation

Kazunobu Tsujikawa

Yujiro Ito

Tsutomu Shimosato

Mitsushige Tatami

Video data exploitation by alteration of data is prevented. An extractorextracts valid video data in dataand predetermined data in the data. An inserterinserts an arithmetic operation result of the predetermined data by an arithmetic operation unitinto the valid video data encrypted by an encryptor. An output of the inserteris supplied to an extractorthrough a transmission path. The encrypted valid video data and arithmetic operation resultant data of the arithmetic operation unitare extracted. An arithmetic operation unitexecutes the same arithmetic operation as that of the arithmetic operation unitto data corresponding to the data used in the arithmetic operation unitfrom the valid video data decrypted by a decryptorand extracted by an extractor. A comparatorcompares an output of the arithmetic operation unitwith an arithmetic operation result extracted from data. When both of them do not coincide, it is determined that there is a possibility that the transmission data has been altered. An output of an another-output generatoris outputted as output data

Transmitting apparatus, receiving apparatus, and data transmitting system

Transmitting apparatus, receiving apparatus, and data transmission system

An encryption apparatus for encrypting input picture data with high secrecy and restoration against an error of encrypted data. An EXOR circuit calculates input picture data and a pseudo random sequence and obtains encrypted data. The obtained encrypted data are held in a first FF circuit. The first FF circuit is reset for each line. Counters count for each line or each frame and are reset for each frame or at the beginning of a program. An encryption device encrypts outputs of a second FF circuit that holds a fixed value, the counters and the first FF circuit with a key and generates a pseudo random sequence. A shift register divides the bit sequence. The EXOR circuit calculates the output of the shift register and the input picture data and obtains encrypted data. Since the encrypted output is fed back, data cannot be stolen using a successive input of the same data. In addition, since an encrypted output that is fed back is reset for each line, the encrypted output can be recovered from an error.

Encryption/decryption device and method

Improved time base error correcting apparatus of the type wherein time base errors in a video signal, such as a video signal reproduced by a video signal playback device, are corrected. The apparatus includes a main memory into which picture elements contained in each line interval of the video signal are written at a write-in rate that is synchronized with the time base information contained in that video signal, and from which the picture elements are read out at a reference rate. A drop-out detector detects drop-out conditions which may occur in the video information and synchronizing information portions of the video signal. Drop-out indications are stored in a drop-out condition memory so as to represent the positions within a line interval that drop-out has occurred. These drop-out indications are written into and read out of the drop-out condition memory in synchronism with the writing in and reading out of picture elements from the main memory. Each picture element read out from the main memory is supplied to a drop-out compensator which is responsive to a read out drop-out indication to replace a dropped out picture element that is read out from the main memory with the picture element which had been in the same relative position in the immediately preceding line interval. A velocity error correcting device also is provided in order to correct velocity errors which may be present in each line interval. In the event that a velocity error cannot be detected, for example, because drop-out has occurred in the synchronizing portion of a line interval, the velocity error which had been detected for the previous line interval is used again in this and then the next-following interval, i.e., for a total of three consecutive line intervals. An offset voltage is added to the velocity error correcting operation for this third line interval, except that this offset voltage is subtracted during a drop-out compensating operation in that third line interval.

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Kanagawa, Japan

Kazunobu Tsujikawa