JPH08265313A - Data scrambling device - Google Patents

Abstract

PURPOSE: To perform scrambling processing with simple constitution by multiplexing the output of a means which inverts the polarity of a prescribed bit in a bit stream and enciphers position data representing a bit position with the one of an inversion means. CONSTITUTION: The bit stream of digital image data compressed by combining orthogonal transform processing and motion compensation prediction processing is supplied to a Huffman encoder circuit 12 and a pointer generation circuit 13. The pointer generation circuit 13 generates pointer data by synchronizing a prescribed bit with an inputted timing. The bit at a pointer position out of the bit stream outputted from the Huffan encoder circuit 12 is polarity-inverted and outputted from an EXOR circuit 14. A position enci-phering circuit 15 enciphers pointer position data. The output of the EXOR circuit 14 is multiplexed in time division with that of the position enciphering circuit 15 by a multiplexer 16, and outputted as the bit stream to which the scrambling processing is applied, and supplied for transmission and recording on a recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data compression system using an entropy coding method, and more particularly to an improvement of a data scrambler for scrambling the compression-coded digital data.

[0002]

2. Description of the Related Art As is well known, MPEG (Moving Picture Image Coding Experts) is an international standard method for performing compression encoding processing on digitized image data.
Group). This MPEG is a data compression method that combines motion compensation prediction processing with DCT (Discreat Cosine Transform) processing, which is one of orthogonal transformation technologies for converting digital image data from a spatial coordinate system to a frequency coordinate system, The DCT process is used to reduce the spatial information amount, and the motion compensation prediction process is used to reduce the temporal information amount.

The digital image data compressed by combining the DCT process and the motion compensation prediction process is
By performing the variable-length coding process by Huffman coding, which is one of the entropy coding, the code amount can be further reduced.

By the way, when the digital image data compressed and encoded as described above is transmitted or recorded on a recording medium, the data is recorded in order to protect the copyright and prevent illegal copying. It is considered to perform scramble processing. That is, paying a predetermined price in advance,
Only the person who has acquired the means for canceling the scramble process can correctly reproduce the digital image data transmitted or recorded on the recording medium.

In this case, as a method of scrambling the digital image data, a means for performing an exclusive OR operation of the digital image data and the pseudo random data string has been widely adopted. However, such a conventional scramble means has a problem that the structure is likely to be complicated due to the complicated processing, resulting in an increase in size and weight and an economical disadvantage.

[0006]

As described above, the conventional scramble means for scrambling digital data has a problem that the structure is complicated and the economical disadvantage is brought about because the process is complicated.

Therefore, the present invention has been made in consideration of the above circumstances, and provides a very good data scramble apparatus which can easily realize scramble processing with a simple structure and can be economically advantageous. The purpose is to

[0008]

A data scramble apparatus according to the present invention comprises an inverting means for inverting the polarity of a predetermined bit in a bit stream data-compressed by entropy coding, and a bit whose polarity is inverted by this inverting means. The encryption means for encrypting the position data indicating the position of (1) and the multiplexing means for multiplexing the output of the encryption means and the output of the inverting means are provided.

Further, the data scramble apparatus according to the present invention includes an inserting means for inserting scrambling bit data at a predetermined position in a bit stream data-compressed by entropy coding, and a bit inserted by this inserting means. An encryption means for encrypting the position data indicating the position of the data and a multiplexing means for multiplexing the output of the encryption means and the output of the inserting means are provided.

[0010]

According to the above configuration, the polarity of a predetermined bit in a bitstream that has been data-compressed by entropy coding is inverted, or bit data for scrambling is inserted at a predetermined position in the bitstream. In this way, the scramble processing can be easily performed with a simple configuration in which the position data indicating this position is encrypted and multiplexed in the bit stream.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In FIG. 1, reference numeral 11 is an input terminal, to which a bit stream of digital image data compressed by combining the above-described DCT processing and motion compensation prediction processing is supplied. The bit stream supplied to the input terminal 11 is supplied to the Huffman coding circuit 12 and the pointer generation circuit 13, respectively.

Of these, the Huffman coding circuit 12 performs the Huffman coding process on the input bit stream and outputs it to one input end of the EX or (exclusive OR) circuit 14. In addition, the pointer generation circuit 13
Pointer data is generated in synchronization with the timing at which a bit at a predetermined position in the input bit stream is input.

The pointer data output from the pointer generation circuit 13 is supplied to the other input terminal of the EX OR circuit 14 and the position encryption circuit 15, respectively. Therefore, first, the EX OR circuit 14 outputs the bit stream output from the Huffman encoding circuit 12 in which the polarity of the bit at the position where the pointer data is generated is inverted.

Further, the position encryption circuit 15 generates position data indicating the position where the pointer data is generated,
The position data is encrypted and output to the multiplexer 16. Then, the output of the EX OR circuit 14 and the output of the position encryption circuit 15 are supplied to a multiplexer 16 and time-division multiplexed to be taken out from the output terminal 17 as a scrambled bit stream, It is used for transmission and recording on recording media.

FIG. 2 shows a bit stream extracted from the output terminal 17. This bit stream is composed of a header part in which header data is arranged and a data part in which substantial data is arranged. And the predetermined position of this data part (the shaded area in the figure)
The polarity of the bit of is reversed by the pointer data, and the position data indicating this predetermined position is encrypted,
It is located in the header section.

Therefore, when the bit stream taken out from the output terminal 17 is reproduced by a device having no means for decrypting the cipher of the position data, the bit stream after the polarity-inverted bits cannot be reproduced correctly. It will be. However, even if it is played back by a device that does not have a means for decrypting the position data code, it is possible to correctly play back the bit stream before the polarity-inverted bit, so perform so-called effect control that partially shows the image. Is possible.

Therefore, according to the configuration of the above embodiment, the polarity of the bit at the predetermined position in the bit stream compressed by the Huffman coding is inverted, and the position data indicating the position is encrypted to generate the bit stream. The scramble processing can be easily performed with a simple configuration in which it is added to the header portion.

Next, FIG. 3 shows another embodiment of the present invention. In FIG. 3, reference numeral 18 is an input terminal to which a bit stream of digital image data compressed by combining the DCT processing and the motion compensation prediction processing described above is supplied. The bit stream supplied to the input terminal 18 is supplied to the Huffman coding circuit 19, the scrambling bit generating circuit 20, and the pointer generating circuit 21, respectively.

Of these, the Huffman coding circuit 19 performs Huffman coding processing on the input bit stream, and the bit stream output from the Huffman coding circuit 19 is temporarily stored in the buffer circuit 22. After being held, it is supplied to the multiplexer 23. Also,
The scramble bit generation circuit 20 generates scrambled bit data to be inserted into a predetermined position of the input bit stream, and outputs the scrambled bit data to the multiplexer 23.

Further, the pointer generation circuit 21 generates position data indicating the position where the bit data is inserted. The position data output from the pointer generating circuit 21 is supplied to the multiplexer 23 after being encrypted by the encryption circuit 24 and encrypted. And
The output of the buffer circuit 22, the output of the scramble bit generation circuit 20, and the output of the encryption circuit 24 are supplied to a multiplexer 23 and time-division multiplexed, whereby an output terminal 25 is provided as a scrambled bit stream. It is used for transmission and recording on a recording medium.

The multiplexer 23 inserts the bit data output from the scrambling bit generation circuit 20 into the bit stream output from the buffer circuit 22 based on the position data output from the pointer generation circuit 21. Is controlled.

FIG. 4 shows a bit stream extracted from the output terminal 25. This bit stream is composed of a header part in which header data is arranged and a data part in which substantial data is arranged. And the predetermined position of this data part (the shaded area in the figure)
The bit data is inserted into, and the position data indicating this insertion position is encrypted and placed in the header part.

Therefore, when the bit stream taken out from the output terminal 25 is reproduced by a device having no means for decrypting the position data code, the bit stream after the inserted bit data cannot be reproduced correctly. It will be. However, since the bit stream before the inserted bit data can be correctly reproduced even when it is reproduced by a device that does not have a means for decrypting the position data code, so-called effect control for partially displaying an image should be performed. Is possible.

Therefore, even with the configuration of the above embodiment, the scrambled bit data is inserted at a predetermined position in the bit stream compressed by the Huffman coding, and the position data indicating the insertion position is encrypted. The scramble processing can be easily performed with a simple configuration in which the header is added to the bit stream. The present invention is not limited to the above-described embodiments, but can be variously modified and implemented without departing from the scope of the invention.

[0025]

As described above in detail, according to the present invention,
It is possible to easily realize the scramble processing with a simple structure, and to provide an extremely good data scramble apparatus which can be economically advantageous.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a data scramble device according to the present invention.

FIG. 2 is a diagram shown for explaining a bitstream output in the embodiment.

FIG. 3 is a block diagram showing another embodiment of the present invention.

FIG. 4 is a diagram shown for explaining a bitstream output in another embodiment.

[Explanation of symbols]

11 ... Input terminal, 12 ... Huffman coding circuit, 13 ... Pointer generation circuit, 14 ... EX OR circuit, 15 ... Position encryption circuit, 16 ... Multiplexer, 17 ... Output terminal, 18
... input terminal, 19 ... Huffman coding circuit, 20 ... scrambling bit generation circuit, 21 ... pointer generation circuit, 2
2 ... Buffer circuit, 23 ... Multiplexer, 24 ... Encryption circuit, 25 ... Output terminal.

Claims (4)

[Claims] 1. An inverting means for inverting the polarity of a predetermined bit in a bitstream data-compressed by entropy coding, and an encrypting means for encrypting position data indicating the position of the bit whose polarity is inverted by this inverting means. And a multiplexing means for multiplexing the output of the encryption means and the output of the inverting means. 2. The data scrambler according to claim 1, wherein the multiplexing means arranges the output of the encryption means in the header part of the bit stream output from the inverting means. 3. An inserting means for inserting bit data for scrambling into a predetermined position in a bit stream data-compressed by entropy coding, and position data indicating the position of the bit data inserted by this inserting means is encrypted. A data scrambler, comprising: an encryption unit for encrypting, and a multiplexing unit for multiplexing the output of the encrypting unit and the output of the inserting unit. 4. The data scramble apparatus according to claim 3, wherein the multiplexing means arranges the output of the encryption means in the header part of the bit stream output from the inserting means.