Cryptography – Video cryptography – Video electric signal modification
Patent
1998-03-05
2000-09-19
Swann, Tod R.
Cryptography
Video cryptography
Video electric signal modification
380 37, 380269, 708203, H04N 144
Patent
active
061223786
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to compression and encryption of data and more particularly to a data compression/encryption method and a system therefor which are designed to enhance the processing efficiency while reducing power consumption in performing compression processing as well as encryption processing on data.
BACKGROUND ART
In accompanying with rapid increase in utilization of communication facilities, there arises an increasing trend of compressing and encrypting (hereinafter referred to as compression/encryption or compressing/encrypting for short) the data with a view to enhancing the efficiency of communications and preventing unauthorized acquisition and falsification of the data for communication. In particular, in the case of wireless communications, since interception is easy because of narrow band, the compression/encryption is indispensable. On the other hand, in the portable type computers commanding high popularity in recent years, duration of a battery provides an important problem, giving rise to a demand for the data processing methods suited for economization of electric energy. For these reasons, the compression/encryption techniques which can ensure high efficiency and low power consumption are demanded as being indispensable.
In the conventional compression/encryption techniques known heretofore, data is first compressed and then written into a secondary storage such as a hard disk drive or the like, whereon the compressed data is read out from the secondary storage to be encrypted. In the encryption processing, the same encryption processing as that for the non-compressed data is adopted without taking into consideration the fact that the data are compressed. Further, in the processing for restoring the original data from the compressed/encrypted data (this process will hereinafter be referred to as the decryption/decompression processing), the data is decrypted at first and then written in the secondary storage, whereon the decrypted data is read out from the secondary storage to be restored or decompressed.
In the conventional compression/encryption technique described above, the compression processing and the encryption processing are executed independent of each other without exploiting the possibility that the processing efficiency can be enhanced by integrating or combining together the compression processing and the encryption processing. Besides, because the compression processing and the encryption processing on one hand and the decryption processing and the decompression processing on the other hand are interlocked by way of the secondary storage, not only a time is taken for reading/writing data in/from the secondary storage but also a large amount of electric energy is consumed for the read/write operation.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a data compression/encryption method and a system therefor which are capable of enhancing the efficiency of processings involved in the compression/encryption as well as the decryption/decompression while reducing the power consumption by combining together the compression processing and the encryption processing for thereby rendering it unnecessary to interlock the compression processing and the decompression processing on one hand and the decryption processing and the decompression processing on the other hand by way of the secondary storage.
In order to make the interlock unnecessary between the compression processing and the encryption processing on one hand and between the decryption processing and the decompression processing on the other hand by way of the secondary storage, an amount of data processed at a time is limited so that a memory capacity required for performing the compression/encryption processings and the decryption/decompression processings does not exceed the capacity of a main storage of a relevant information processing system. In other words, the amount of the data processed at a time is partitioned such that a memory capacity required
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Hino Yusuke
Otsu Yutaka
Takaragi Kazuo
Yoshiura Hiroshi
Darrow Justin T.
Hitachi , Ltd.
Swann Tod R.
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