JP2002247542A - Video secrecy device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video secrecy device by which the secrecy of images is secured with simple constitution. SOLUTION: At the time of imparting an index to a cipher key and transmitting the cipher key selected by a cipher key and index selection part 1, a multiplex part 2 multiplexes the index to input video signals and a cipher part 3 ciphers and outputs a part to which the cipher key is not multiplexed. An index extraction part 4 extracts the index from the signals outputted by the cipher part 3 and a decipher part 6 deciphers the signals outputted by the cipher part 3 by the cipher key selected from the extracted index by a cipher key reproduction part 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to concealment control of video information that controls a video signal so that it is not displayed in an unintended state and displays normally in an intended state.

[0002]

2. Description of the Related Art Conventionally, regarding concealment control of video information,
For example, one described in JP-A-04-223787 is known.

FIG. 7 shows the structure of a conventional video information concealment control device.

[0004] First, a first field including both a random digital code and program identification data encrypted by a code encryption key and a non-viewable video previously converted from a video signal viewable by the random digital code are transmitted to a terminal 72. A video program is provided that includes a series of television fields including a second field that includes a signal. The terminal 72 transmits the terminal identification data recorded in the recording means 77 and the program identification data of the program to be viewed to the central mechanism 71 by the transmission means 78 via the full-duplex communication link 73. The central mechanism 71 searches at least one code encryption key corresponding to the program identification data sent from the terminal 72 from the database 79 and transmits the key to the terminal 72. The terminal 72 receives the code encryption key transmitted from the central mechanism 71 by the receiving means 82, and the decoding means 83 decodes the encrypted random digital code of the first frame by the code encryption key, and converts the video signal. Means 84 converts the unviewable video signal of the second frame into a viewable video signal using the decoded random digital code.

If the transmission of the code encryption key by the central mechanism 71 is delayed, the decryption by the decryption means 83 becomes impossible, so that it is necessary to transmit the key sufficiently quickly.

[0006]

In a video concealment apparatus, it is required to secure sufficient confidentiality with a simple configuration. However, when transmitting the encryption key itself as in the conventional example, it is necessary to prepare a separate signal line in addition to the encrypted video signal, and this key must be transmitted sufficiently quickly. Further, when a key having a long word length (having a large number of bits) is used to enhance confidentiality, it is still difficult to transmit the key sufficiently quickly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a video concealment device capable of securing confidentiality of an image with a simple configuration.

[0008]

In order to solve this problem, a video concealment apparatus of the present invention holds a plurality of encryption keys to which a transmitting side and a receiving side have unique indexes, and the transmitting side has The index of the used encryption key is multiplexed with the video signal and encrypted, and the receiving side extracts the index from the received signal and decrypts the video signal with the encryption key corresponding to the index.

With this configuration, the video concealment device of the present invention does not need to prepare a separate signal line for the encryption key, and can secure image confidentiality with a simple configuration.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to a first aspect of the present invention, a unique index is assigned to each of a plurality of encryption keys and held, and one encryption key is selected from the plurality of encryption keys. An encryption key and an index selection means for outputting an encryption key and the index corresponding thereto, and multiplexing for multiplexing the index selected by the encryption key and the index selection means to an unencrypted portion in the input video signal. Means for encrypting an unmultiplexed portion of the index of the signal output from the multiplexing means with the encryption key selected by the encryption key and the index selecting means and outputting an encrypted signal. Encryption means, index extraction means for extracting the index from the encrypted signal, and encryption key and index selection means. Said plurality of decryption keys and indexes same plurality of encryption keys and the index are held,
An encryption key reproducing unit that selects an encryption key corresponding to the index extracted by the index extracting unit, and decrypting the encrypted signal using an encryption key output from the encryption key reproducing unit. A video concealment device characterized by comprising decoding means for outputting an output video signal, by adding a unique index to the encryption key, multiplexing the index into the video signal, and transmitting the multiplexed index.
There is no need to prepare a separate signal line for the encryption key.

According to a second aspect of the present invention, when a characteristic portion such as a synchronizing signal is detected in an input video signal from an input video signal, an input signal characteristic detecting section for outputting a detection signal, And an encryption key selection unit that selects the encryption keys in the selection order according to the detection signal output from the input signal feature detection unit. Encrypting the input video signal with the encrypted encryption key and outputting an encrypted signal, and holding the same plurality of encryption keys with the same selection order as the encryption key selection means, Decryption key selection means for selecting the encryption key in the selection order, and decryption for decrypting the encrypted signal with the encryption key selected by the decryption key selection means and outputting an output video signal Conversion means and the output video Output signal characteristic detection means for outputting a detection signal when detecting the same characteristic part as the input signal characteristic detection part detects from the signal, and the decryption encryption key selection means comprises the output signal characteristic A video concealment device characterized by performing the selection of the encryption key in the selection order according to the detection signal output from the detection means, does not directly transmit the encryption key, and with time in a predetermined order By making a change, higher confidentiality can be realized.

An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows an embodiment of a video concealing apparatus according to the present embodiment. In FIG. 1, reference numeral 1 denotes an encryption key and an index generated in advance (the generation method is arbitrary). An appropriate set is selected from the set, and the selected encryption key is output to the encryption unit 3 and the index is output to the multiplexing unit 2. The encryption key and index selection unit 2 outputs the encryption key and the index selection unit 1. A multiplexing unit for multiplexing the output index from the input video signal with the input video signal; 3, an encryption unit for encrypting the output of the multiplexing unit 2 with the encryption key and the encryption key given from the index selection unit 1; An index extraction unit 5 for extracting an index of an encryption key from a signal output from the encryption unit 3, and an encryption key 5 to be reproduced by selecting an encryption key from the index extracted by the index extraction unit 4. Key reproducing unit, 6 encryption key reproducing unit 5
A decryption unit that decrypts the signal output from the encryption unit 3 using the encryption key given by the encryption unit.

The operation of the video concealment device configured as described above will be described with reference to the flowcharts of FIGS. FIG. 2 is a flowchart illustrating the operation of the transmission unit of the video concealment device of the present embodiment, and FIG. 3 is a flowchart illustrating the operation of the reception unit of the video concealment device of the present embodiment.

When the input video signal is input, the encryption key and index selection unit 1 selects an appropriate pair from a pair of an encryption key and an index generated in advance (the generation method is arbitrary). The selected index is provided to the multiplexing unit 2 and the selected encryption key is provided to the encrypting unit 3 (steps 301 and 302 in FIG. 2).

Table 1 shows a correspondence table between the encryption key and the index held by the encryption key and index selection unit 1.

[0017]

[Table 1]

As shown in Table 1, each encryption key is assigned a unique index. In this case, the encryption key and index selection unit 1 selects the encryption key 3 whose index is 3, and sends the index 3 and the index 3 to the multiplexing unit 2.
The encryption key 3 is given to the encryption unit 3.

The multiplexing section 2 multiplexes the given index 3 with the input video signal and outputs the multiplexed index. The index is multiplexed with a portion of the video signal that is not encrypted by the encryption unit 3 (step 303). The encryption unit 3 includes an encryption key 3 provided from the encryption key and index selection unit 1.
To encrypt the output of the multiplexing unit 2. At this time, the portion where the index of the encryption key is multiplexed is not encrypted as described above. This is because if a part where the index is multiplexed is also encrypted, it becomes difficult to extract the index for decryption at a later stage (step 30).
4).

The portion for multiplexing the index is, for example, a video signal in a vertical blanking period. This is because, in general, a signal whose characteristics are known or can be easily estimated, such as a video signal in a vertical blanking period, is not desirable as an object to be encrypted.

The signal output from the encryption unit 3 cannot be displayed as it is because the signal is encrypted by the encryption 3. Therefore, even if this signal is output to the outside of the device, the signal is not stolen. On the other hand, the index extraction unit 4 receives the output of the encryption unit 3 and extracts the index 3 of the encryption key 3 multiplexed therein (see FIG. 3).
Steps 401 and 402). The encryption key reproducing unit 5 holds the correspondence table between the encryption key and the index shown in (Table 1), like the encryption key and index selection unit 1,
The encryption key 3 is selected from the extracted index 3 and given to the decryption unit 6 (step 403). The decoding unit 6
The output of the encryption unit 3 is decrypted using the encryption key 3 given from the encryption key reproduction unit 5. In the decryption, if the encryption key is known, an inverse operation of the encryption may be performed to decrypt this output (step 404).

Here, when an encryption method that cannot be decrypted by the inverse operation is employed, the decryption key may be reproduced by the encryption key reproducing unit 5. For example, as shown in (Table 2), the encryption key reproducing unit 5 holds a correspondence table between the index and the decryption key, and selects a decryption key from the extracted index. In this case, since the index is 3,
The decryption key 3 is selected.

[0023]

[Table 2]

As described above, according to the present invention, the encryption key is not transmitted between the output of the encryption unit 3 and the index extraction unit 4, and only the encrypted video signal is transmitted. By storing the unit up to the unit 4 in the main body of the video transmitting apparatus and the index extracting unit 4 and subsequent units in the video display unit
You can build a system that will not be stolen by third parties.

In the present embodiment, a unique number is given as an index. However, the present invention is not limited to this, and any index can be used as long as it can identify each encryption key.

(Embodiment 2) FIG. 4 shows an example of a video concealment apparatus according to the present embodiment. In FIG. An encryption key selection unit for selecting a plurality of encryption keys in a predetermined order, encrypts an input video signal using the encryption key selected by the encryption key selection unit 22, and outputs an encrypted signal An input signal feature detector 24 detects a characteristic portion of the input video signal and outputs a timing clock which is a detection signal, and an input signal feature detector 25 outputs a timing clock which is a detection signal of the output signal feature detector 27 in accordance with the timing clock. ,
A decryption key selection unit for selecting a plurality of stored encryption keys in a predetermined order, a decryption unit 26 decrypts an encrypted signal using the encryption key selected by the decryption key selection unit 25. A decoding unit 27 that outputs an output video signal, 27 is an output signal feature detection unit that detects a characteristic portion of the output video signal and outputs a timing clock that is a detection signal.

The operation of the video concealment apparatus of the present embodiment configured as described above will be described with reference to the flowcharts of FIGS. FIG. 5 is a flowchart illustrating the operation of the transmission unit of the video concealment device of the present embodiment, and FIG. 6 is a flowchart illustrating the operation of the reception unit of the video concealment device of the present embodiment.

The input signal characteristic detecting section 24 sends a timing clock to the encryption key selecting section 22 every time a characteristic portion (for example, a vertical synchronizing signal) is detected from the input signal (step 501 in FIG. 5). The encryption key selection unit 22 holds the plurality of encryption keys in a table in an ordered manner. This table holds the same table on the encryption side and the decryption side in advance by separate means. (Table 3) shows a table held by the encryption key selection unit 22.

[0029]

[Table 3]

As shown in Table 3, numbers are given to the respective encryption keys in the order of selection. Encryption key selector 2
In 2, when receiving the clock from the input signal characteristic detecting unit 24, the encryption key selecting unit 22 selects the next key from the table shown in (Table 3) as the encryption key. When the last encryption key in the order is selected, the encryption key is selected again from the first encryption key. In this way, the encryption key is sequentially changed. In this case, encryption key 3, encryption key 5,
An encryption key 1, an encryption key 2, and an encryption key 4 are selected in this order,
Next to the encryption key 4, the encryption key 3 is selected again (steps 502 to 504). The encryption key selection unit 22
One encryption key is selected from the key table shown in (Table 3) and given to the encryption unit 23. In this case, it is assumed that the encryption key 3 is selected. The encryption unit 23 encrypts the separately input video signal using the encryption key 3 selected by the encryption key selection unit 22, and decrypts the input video signal via a transmission path (not shown).
(Step 505).

The decryption encryption key selection section 25 holds the same table as the table shown in (Table 3) held by the encryption key selection section 22.
The encryption keys are sequentially selected. In this case, it is assumed that the encryption key 1 is selected. The decryption unit 26 decrypts the signal transmitted based on the encryption key 1 selected by the decryption encryption key selection unit 25 (steps 601 and 60 in FIG. 6).
2). Each time the output signal characteristic detecting section 27 detects a characteristic portion (for example, a vertical synchronization signal) from the output signal, it sends a timing clock to the decryption encryption key selecting section 25 (Steps 603 and 604). Upon receiving the timing clock from the output signal characteristic detecting unit 27, the decryption encryption key selection unit 25 selects the encryption key ordered next to the current encryption key and outputs it to the decryption unit 26.
Similarly to the encryption key selection unit 22, the decryption encryption key selection unit 25, when selecting the last encryption key in the order, selects again from the first encryption key. (Step 605 to Step 60
7).

At the beginning of the operation, generally, the encryption key selection unit 2
The key (encryption key 3) selected in step 2 does not match the key (encryption key 1) selected by the decryption encryption key selection unit 25.
Since the decoding unit 26 cannot correctly decode the received signal, the output signal feature detection unit 27 cannot detect a characteristic portion (for example, a vertical synchronization signal) from the output video signal, and the output of the output signal feature detection unit 27 is Remain inactive.
Therefore, in this state, the key is not updated on the decryption side. However, if this state is continued for a while, the keys will eventually match and a normal output video signal will be decoded. In this case, upon receiving the next timing clock from the input signal feature detection unit 25, the encryption key selection unit 22 receives the next encryption clock from the encryption key 3 as shown in (Table 3).
Select Also in this case, the key (encryption key 5) selected by the encryption key selection unit 22 and the key (encryption key 1) selected by the decryption encryption key selection unit 24 do not match, so the output signal characteristic The output of the detection unit 27 is inactive. Next, upon receiving the next timing clock from the input signal feature detection unit 24, the encryption key selection unit 22 receives the next encryption clock from the encryption key 5, as shown in (Table 3).
Select In this case, since the key (encryption key 1) selected by the encryption key selection unit 22 and the key (encryption key 1) selected by the decryption encryption key selection unit 25 match, the decryption unit The normal output signal is decoded from the output signal 26, and the output signal characteristic detection unit 27 can detect a characteristic portion (for example, a vertical blanking period) of the input signal from the output signal of the decoding unit 26. Therefore, the decryption key selection unit 25 is also provided with the encryption key selection unit 22.
Then, the same clock is input, and thereafter, the same key is selected on the encryption side and the decryption side, and the normal output video signal continues to be output.

In this embodiment, when an encryption method that cannot be decrypted by the inverse operation is adopted,
The decryption key selection unit 25 may reproduce the decryption key. For example, as shown in (Table 4), the decryption encryption key selecting unit 25 holds a decryption key correspondence table, and upon receiving a timing clock from the output signal characteristic detecting unit 27, decrypts in a predetermined order. Choose a key.

[0034]

[Table 4]

Also, in the present embodiment, the transmitting side,
The receiving side changes the encryption key every time the timing clock is detected, but the present invention is not limited to this. For example, the encryption key may be changed every time a predetermined number of timing clocks are detected.

In the present invention, the characteristic portion of the input signal has been described as the vertical blanking period, but the present invention is not limited to this.

In the present invention, the case where five encryption keys and five decryption keys are held has been described as an example. However, the present invention is not limited to this, and any number of encryption keys and decryption keys may be stored. The same operation can be performed also when is held.

Further, in the present invention, the encryption keys are managed in the form of a table. However, the present invention is not limited to this.

[0039]

As described above, according to the present invention, a remarkable effect that the confidentiality of an image can be continuously maintained without providing a separate transmission means for transmitting an encryption key is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a video concealment device according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart showing an operation of a transmission unit of the video concealment device.

FIG. 3 is a flowchart showing the operation of a receiving unit of the video concealment device.

FIG. 4 is a block diagram illustrating a configuration of a video concealment device according to Embodiment 2 of the present invention.

FIG. 5 is a flowchart showing the operation of the transmission unit of the video concealment device.

FIG. 6 is a flowchart showing the operation of a receiving unit of the video concealment device.

FIG. 7 is a block diagram showing a configuration of a conventional video concealment device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Encryption key and index selection part 2 Multiplexing part 3, 23 Encryption part 4 Index extraction part 5 Decryption key reproduction part 6, 26 Decryption part 22 Encryption key selection part 24 Input signal characteristic detection part 25 Decryption encryption Key selection unit 27 Output signal feature detection unit

Claims (3)

[Claims] A unique index is assigned to each of a plurality of encryption keys and held, and one encryption key is selected from the plurality of encryption keys, and the encryption key and the corresponding index are output. Encryption key and index selection means, multiplexing means for multiplexing the index selected by the encryption key and index selection means with an unencrypted portion in the input video signal, and the encryption key and index selection means Encrypting means for encrypting a non-multiplexed portion of the index of the signal output from the multiplexing means with the selected encryption key and outputting an encrypted signal; Index extraction means for extracting an index; and the plurality of decryption keys managed by the encryption key and the index selection means. An encryption key reproducing unit that holds a plurality of encryption keys and an index identical to the index, and selects an encryption key corresponding to the index extracted by the index extraction unit; A video concealing device, comprising: a decryption unit that decrypts using an encryption key output from a reproduction unit and outputs an output video signal. 2. When detecting a characteristic portion such as a synchronizing signal in the input signal from an input video signal, an input signal characteristic detecting section for outputting a detection signal; According to the detection signal output from the input signal feature detection unit,
Encryption key selection means for selecting the encryption key in the selection order, encryption means for encrypting the input video signal with the encryption key selected by the encryption key selection means and outputting an encrypted signal, A plurality of encryption keys that are the same as the encryption key selection unit, are given and held in the same selection order, and a decryption encryption key selection unit that selects the encryption keys in the selection order; Decryption means for decrypting the output video signal with the encryption key selected by the decryption encryption key selection means and outputting an output video signal; and the same features as those of the feature detected by the input signal feature detection unit from the output video signal. Output signal feature detection means for outputting a detection signal when the portion is detected, wherein the decryption encryption key selection means selects an encryption key in accordance with the detection signal output from the output signal feature detection means. Rows in the selection order Image concealment and wherein the. 3. The video concealment device according to claim 2, wherein the input video signal feature detection unit and the output signal feature detection unit detect a vertical synchronization signal as a feature portion of the video signal.