JP2002152180A - Radio communication system, transmission device, and contents data transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission device which can transmit AV data having been ciphered for copyright protection with high quality from a transmission side to a reception side through a radio network on which a bit error and a burst error are possibly caused. SOLUTION: A process contents selection part 206 selects whether or not the AV data are ciphered according to whether the AV data requires copyright protection processing and selects the intensity level of an error-correcting code used for the AV data according to at least whether or not the AV data requires the copyright protection processing. When the AV data are ciphered, a copyright protection processing part 204 after exchanging a cipher key with a reception device ciphers the AV data. An error correction processing part 203 finds an error-correcting code of the selected intensity level and adds it to the AV data. The AV data with the added error-correcting code are transmitted by a communication processing part 202 and an interface 201.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system for transmitting AV data requiring copyright protection via radio, a transmission apparatus, and a content data transfer method.

[0002]

2. Description of the Related Art Recent advances in digital AV technology have been remarkable. There are many digital AV technologies, such as MPEG2 used for digital broadcasting and DVD, and MP3 used for music distribution and the like, which have entered a full-fledged period.

[0003] Among them, recently, "AV in a mobile environment" has attracted attention. This is due to the explosive spread of mobile phones and the emergence of small AV players due to the development of memory card technology.

[0004] On the other hand, "support of networks for mobile devices" has also attracted considerable attention. For example, the spread of mobile phones will be a typical example of “networking of mobile devices”, and Bluetooth is characterized by low cost.
The development of wireless LAN technologies such as these is also supporting them.

[0005] In such an environment, A attracts attention.
The V encoding method is MPEG4. MPEG4 is a coding method standardized on the premise that data is transferred on a transmission path where an error such as wireless transmission is considered to occur. The coding method is excellent in "error tolerance" against bit errors and burst errors. Has become. From such a background, MPEG4
Has also been adopted as a video encoding method used in the video phone of IMT-2000 which is a next-generation mobile phone.

[0006] Now, when digital AV data is transmitted on a network, in particular, when a copyright owner wants to eliminate or prevent copyright infringement of the AV data, copyright protection should be considered. There is a need. The technology for protecting copyright is a technology for mainly preventing unauthorized copying beforehand, and has been already implemented on a typical network such as IEEE 1394 or USB by DTCP (Di
digital Tramsmission Conten
(ts Protection) method is a de facto standard, and realizes copyright protection for transmission lines.

More specifically, as a technique for realizing copyright protection, "encryption of transmitted AV data"
Is the center. For example, in DTCP, an encryption method of M6 is adopted. That is, Bluetooth
A on which the copyright should be protected
When V data is transferred, it is considered that the data should be transmitted after being encrypted.

On the other hand, in the case of a mobile AV device having a wireless interface, AV data is transmitted wirelessly. However, due to the wireless network, bit errors and burst errors may occur during data transmission. Is inevitable.

On the other hand, the transmitted AV data is
For example, in the case of a coding method having a characteristic of error resilience, such as MPEG4, even if a bit error or a burst error occurs during transmission over the radio where the data is transmitted, the reception is performed by the error resilience of the coding method itself. On the side, it is possible to take measures to overcome this and perform the reproduction processing as much as possible.

However, when such error-resistant data is transmitted over a wireless network after being encrypted for copyright protection as described above, the original data, ie, AV data, Although there is an error resistance, error resistance is generally not always guaranteed for data obtained by encrypting the encrypted data. Therefore, AV data encrypted for copyright protection (whether with or without error resilience) is transmitted on a wireless transmission path when a bit error or burst error occurs. In this case, there is a possibility that all received data may be discarded without correcting any errors.

[0011]

As described above,
Conventionally, when the AV data is encrypted for copyright protection and transferred on a wireless network, the receiving side cannot correct bit errors or burst errors occurring on the wireless network, and However, there is a problem that there is a possibility of being discarded.

[0012] The present invention has been made in view of the above circumstances, and allows AV data encrypted for copyright protection to be transmitted via a wireless network in which bit errors and burst errors may occur. It is another object of the present invention to provide a wireless communication system, a transmitting apparatus, and a content data transfer method that enable transmission from a transmitting side to a receiving side while maintaining a certain level of quality or high quality.

Also, the present invention provides an encrypted or unencrypted A
A wireless communication system, a transmitting apparatus, and a wireless communication system capable of transmitting V data from a transmitting side to a receiving side while maintaining a certain level of quality or high quality over a wireless network in which a bit error or a burst error may occur. It is an object to provide a content data transfer method.

[0014]

SUMMARY OF THE INVENTION According to the present invention, there is provided a transmitting apparatus for transmitting, via a wireless network, content data requiring processing for copyright protection or other content data, and a transmitting apparatus for transmitting the content data. In a wireless communication system including a receiving device that receives the content data via the wireless network, when the content data to be transmitted / received requests processing for copyright protection, the wireless network Key exchange means for exchanging an encryption key between the transmitting device and the receiving device via the communication device, and when the content data to be transmitted / received is content data requesting a process for copyright protection Encrypts the content data based on the encryption key, and the content data is protected by copyright. Transfer means for transferring from the transmitting device to the receiving device via the wireless network without encrypting the content data if the content data does not require processing, and the encrypted content data to be transferred. Or error correction means for correcting an error generated on the wireless network by causing a predetermined error correction code to accompany the unencrypted content data, wherein the error correction means determines whether or not the content data is copyrighted. An error correction code of an intensity level selected based on whether or not the content data requires processing for rights protection is used for the content data.

The present invention also relates to a transmitting apparatus for transmitting content data requesting processing for copyright protection or other content data to a receiving apparatus via a wireless network, and First selecting means for selecting whether or not to encrypt the content data based on whether or not the content data requires processing for copyright protection; and
Based on at least whether or not the content data to be transmitted / received requires processing for copyright protection, an error correction code used for the content data among error correction codes of a plurality of intensity levels is determined. A second selecting unit for selecting, and a case where encryption of the content data is selected by the first selecting unit,
Key exchange means for exchanging an encryption key with the receiving device via the wireless network, and when it is selected to encrypt the content data by the first selection means, Encrypting means for encrypting the content data; and encrypting the content data or the encrypted content data when encrypting the content data is selected by the first selecting means. When the first selection unit selects not to perform encryption on the content data, the second encryption unit performs the second encryption on the unencrypted content data.
Error correction processing means for obtaining and adding an error correction code of the intensity level selected by the selection means, and a wireless interface for transmitting the content data added with the error correction code via the wireless network Means.

Preferably, the second selecting means is used for content data requesting a process for copyright protection and for content data other than content data requesting a process for copyright protection. An error correction code having a stronger strength than the error correction code to be executed may be selected.

[0017] Preferably, the second selecting means is a content data requesting a process for copyright protection, and is a content data other than a content data requesting a process for copyright protection. Select an error correction code having a stronger strength than the error correction code to be used for the one having the tolerance, and have no error tolerance because the content data is a content data other than the content data requiring the processing for copyright protection. An error-correcting code having a stronger strength than an error-correcting code used for error-resistant content data other than content data for which copyright protection processing is required. It may be.

Preferably, the second selecting means is provided for protecting the copyright when the encryption method applied to the content data requiring the process for protecting the copyright does not have an error resilience capability. An error correction code having a stronger strength than an error correction code used when the encryption method applied to the content data requiring the above processing has an error resilience capability may be selected.

Further, the present invention provides a transmitting apparatus for transmitting content data requesting processing for copyright protection or other content data via a wireless network, and transmitting the content data transmitted from the transmitting apparatus. A content data transfer method in a wireless communication system including a receiving device that receives data via the wireless network, wherein the transmitting device requests processing for copyright protection of the content data to be transmitted / received. And whether to encrypt the content data based on whether or not the content data requires processing for copyright protection. Based on at least the error correction code of a plurality of intensity levels to select the one to be used for the content data When encryption of the content data is selected, an encryption key is exchanged between the transmitting device and the receiving device via the wireless network, and the transmitting device transmits the content data. When encryption is selected for the content data, the content data is encrypted using the encryption key exchanged with the reception device, and the transmission device encrypts the content data. For the encrypted content data when encryption is selected for the content data or for the unencrypted content data when encryption is not selected for the content data. The transmission device determines and adds an error correction code of the selected intensity level, and specifies the error correction code and the intensity level of the error correction code. Transmitting the content data to which the information for the content has been added to the receiving device via the wireless network, wherein the receiving device receives the content data and the error correction code received from the transmitting device via the wireless network. An error correction process is performed on the content data based on the strength level of the error correction code, and the reception device encrypts the received content data by requesting a process for copyright protection. And decrypting the content data using the encryption key exchanged with the transmitting device.

It should be noted that the present invention relating to the category of apparatus is also established as an invention relating to the category of the corresponding method, and the present invention relating to the category of method is also established as an invention relating to the category of the corresponding apparatus. Further, the present invention according to an apparatus or a method has a function of causing a computer to execute a procedure corresponding to the present invention (or causing a computer to function as means corresponding to the present invention, or a computer having a function corresponding to the present invention). The present invention is also realized as a program (for realizing), and is also realized as a computer-readable recording medium on which the program is recorded.

According to the present invention, based on at least whether or not the content data to be transmitted / received requires processing for copyright protection, the content data is selected from among error correction codes of a plurality of strength levels. Since the data used for the content data is selected, AV data encrypted for copyright protection can be transmitted to a certain level of quality over a wireless network where bit errors and burst errors may occur. It enables the transmission from the transmitting side to the receiving side while maintaining or high quality.

[0022]

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

FIG. 1 shows a configuration example of a wireless communication system according to the present embodiment.

As shown in FIG. 1, a portable AV player 101 serving as a source device and a wireless AV reproducing device 102 serving as a sink device for the source device each have a wireless interface of a predetermined local area wireless network. The wireless interface allows for interconnecting via the local area wireless network (when located within the coverage area).

Here, a description will be given of Bluetooth as an example of the local area wireless network. Bluetooth is a type of wireless LAN characterized by low cost, low power consumption, and the like, and is expected to be mounted on many mobile terminals and home electric appliances (for example, h.
http: // www. Bluetooth. The explanation is detailed in the document disclosed so as to be able to be obtained by com.).

The portable AV player 101 has a function of subjecting designated AV data to processing of contents selected according to the AV data, as described later in detail, and transmitting the processed data to the wireless AV reproducing apparatus 102. Here, it is assumed that there are a plurality of types of AV data to be transferred in the encoding method. For example, when dealing with two types of AV data of a specific encoding system and unencoded AV data, two types of AV data of two encoding systems are used.
Various cases are conceivable, such as handling data, handling AV data of two or more encoding systems and unencoded AV data, treating AV data of three encoding systems, and the like.

As a coding method of AV data, for video contents, for example, there is MPEG4. MP
EG4 is a coding method standardized on the premise that data is transferred on a transmission path where an error such as wireless transmission is considered to occur, and is a coding method excellent in resistance to bit errors and burst errors. . On the other hand, as an audio content encoding method, for example, there is MP3.

In the present embodiment, MPEG4 will be described as an example of a coding method having excellent error resilience (of course, the present invention is also applicable when AV data other than MPEG4 data is handled).

Further, the portable AV player 101 has a function of acquiring AV data via a predetermined medium. For example, it has a function of reading AV data from a removable recording medium such as a DVD, a memory card, or a tape. Further, for example, a wired connection or a wireless connection (for example, a wide area wireless network, the Internet, a wired LA
N or wireless LAN, direct connection with AV cable, etc.)
And a function of receiving AV data from another device (for example, a server device, a home video, or the like) via the Internet.
The portable AV player 101 may have only one type of AV data acquisition function or a plurality of types of AV data acquisition functions. In some cases, it has a function of storing the acquired AV data.

The wireless AV playback device 102 is a portable A
This is for reproducing and outputting AV data received from the V player 101. Typically, it is a device for displaying an image on a screen, a device for outputting a sound to a speaker, and a device having both of them.

Mobile AV player 101 and wireless AV
The playback device 102 is a stationary device,
A portable type is considered. Portable AV player 101
When both the wireless AV playback device 102 and the wireless AV playback device 102 are portable, for example, the portable AV player 101 is put in a chest pocket or a bag or attached near the waist, and (in the case of an image) the wireless AV playback device 102 102 is worn like a wristwatch or like glasses or goggles, and (for voice / music)
May be worn like headphones.

When the user gives an instruction to the portable AV player 101, the operation for the user's instruction is as follows:
For example, it is performed directly on the panel of the portable AV player 101 or the panel of the wireless AV player 102 (this is performed on the portable AV player 10).
1 is notified to a portable AV player 1 or a panel of another device different from the above.
01 is notified).

The AV data (for example, MPEG4 data) transferred from the portable AV player 101 to the wireless playback device 102 is subjected to processing for copyright protection (for example, encryption for encrypted communication) in those devices at the time of the transfer. AV data that should support
It is divided into other AV data. For example, the former is a person who has the authority to receive support for processing for copyright protection by the device (for example, a movie company or a broadcasting station).
Suppose that restrictions are imposed on the copying performed by the user and the latter is, for example, the AV content supplied by a person authorized to receive support for copyright protection processing by the device. AV content of a user who does not have restrictions on copying performed by the user or who does not have the authority to receive support for copyright protection processing by the device (for example, a video taken by an individual at a travel destination or the like) ).

When transferring AV data that should support a copyright protection process over a network via a Bluetooth interface, for example, DTC
P (Digital Transmission Co
contents (for example, ht
tp: // www. dtla. It is preferable to perform a process for copyright protection for a transmission path such as a document disclosed in a form that can be acquired by a com. In DTCP, the processing for copyright protection includes procedures for authentication and key exchange, encryption of AV data, and the like.

In this embodiment, copyright protection processing such as DTCP is performed on AV data that should support copyright protection processing, but copyright protection processing such as DTCP is performed on other AV data. (Note that a part of the AV data other than the AV data that should support the copyright protection processing is also subjected to the same copyright protection processing or another processing. A configuration that performs processing for copyright protection is also possible).

In the present embodiment, the AV data to be processed is an AV data that must support a process for copyright protection.
When it is determined whether the data is data or other AV data, the determination is made based on predetermined control information attached to the AV data (to prevent general users from falsifying). Shall be.

For example, there is a method of explicitly attaching, to the AV data, a flag indicating whether or not the AV data should support processing for copyright protection. There is also a method of sharing other information. For example, when copy control information is attached to the AV data (to prevent a general user from falsifying), based on the content of the copy control information, the AV data to be supported for processing for copyright protection. There is a method of determining whether or not there is. More specifically, for example, when the copy control information has the following four states, 00: Any number of times can be copied freely 01: Only 1 time can be copied 10: Because the specified number of copies has been reached No more copy is possible. ・ 11: Copy prohibited Copy control information is “01” or “10” or “1”.
If "1", it is determined that the data is AV data that should support the processing for copyright protection, and the copy control information is "00".
Then, AV that should support processing for copyright protection
A method of determining that the data is AV data other than the data is also possible.

Also, for example, in the present embodiment, the AV data which should support the processing for copyright protection includes DT
A process for copyright protection such as CP is performed, but other AV data is not processed for copyright protection. For example, the copy control information is set to “01” or If “10” or “11”, the AV
The data is subjected to copyright protection processing. If the copy control information is "00", the copyright protection processing is not performed.

The predetermined control information includes, for example,
Only for AV contents supplied by a person (for example, a movie company or a broadcasting station) who has the authority to receive support for processing for copyright protection by the device, an AV for which the device should support processing for copyright protection. It can be set to the contents determined to be data.

For example, in the case of AV content such as a video taken by an individual at a travel destination or the like, the AV content includes (AV data other than the AV data that should support the processing for copyright protection is indicated. A) a method in which predetermined control information is attached, a method in which the device makes a determination based on the predetermined control information, and a method in which the predetermined control information used in the determination is not attached, and the predetermined control information is attached in the device. If there is no such data, there is a method of determining that the AV data is AV data other than the AV data that should support the processing for copyright protection.

A portable A having an AV data storage function
For the V player 101, when the AV data determined to be the AV data that should support the processing for copyright protection is stored therein, for example, CPRM (Co
nents Protection for Rec
addable Media) (for example, http: //
/ Www. forsee. It is desirable to perform the accumulation after performing copyright protection such as a document disclosed in a form that can be acquired by a com.

Now, the portable AV player 10 of the present embodiment
1 and the portable AV player 101 are, for example, Bluetooth
th and other wireless interfaces.
From the player 101 to the wireless playback device 102,
It is possible to transfer data via Bluetooth.

Here, in a wireless network such as Bluetooth, occurrence of a bit error or a burst error during data transmission is inevitable.

On the other hand, in the case of AV data having an error tolerance such as MPEG4, even if a bit error or a burst error occurs, the error can be overcome on the receiving side by the error tolerance of the AV data itself. The device is designed so that the regeneration process can be performed as much as possible. Therefore,
If the transmitted AV data has error tolerance, even if a bit error or a burst error occurs during transmission on a wireless network such as Bluetooth, the receiving side is expected to be able to reproduce the AV data. it can.

However, this is a case where the AV data having the error tolerance is transferred without being encrypted, and the AV data having the error tolerance is encrypted (as a process for protecting the copyright). In the case of transferring over Bluetooth, even if the original data (for example, MPEG4 data) has an error tolerance, the error resistance is generally not guaranteed for the data obtained by encrypting the data.

Therefore, MPEG4 data encrypted as a process for protecting copyright (AV data having error tolerance such as) is transmitted as a bit when transmitted on a wireless transmission path such as Bluetooth. When an error or a burst error occurs, the receiving side may not be able to correct the error and may all be discarded.

On the other hand, in the case where reliable communication is performed over the radio, for data for which transmission delay is allowed,
There is a method of performing error control by retransmission control such as retransmission of a portion where an error has occurred. (Especially for those for which transmission delay is not permitted), an AV data is transmitted with an error correction code added thereto and transmitted during transmission. Even if an error occurs, there is a method that allows the receiving side to perform error correction (in general, such an error correction code is FEC (Forward Error).
r Correction). However, if a method of adding an error correction code to AV data unnecessarily is used (especially when an error correction code having a large error correction capability is used), the data length becomes longer, the processing load on the device is increased, and the use of band resources is increased. Disadvantages such as a reduction in efficiency can appear.

In this embodiment, a method of adding an error correction code to AV data and transferring the data is used (for example,
In Bluetooth, FEC with a plurality of levels of strength is defined.) As will be described in detail later, a plurality of types of error correction codes having different strengths are provided, and the target AV data supports processing for copyright protection. The type of the error correction code to be added to the target AV data is selected based at least on whether or not the AV data is to be processed.

In the case where the target AV data is selected based only on whether or not the AV data should support the processing for copyright protection, for example, if the target AV data is the processing for copyright protection, If the AV data is to be supported (when the AV data is transferred after being subjected to a copyright protection process), the AV data is other than the AV data that should support the copyright protection process The configuration is such that an error correction code having a stronger error correction capability is selected as compared with (when the AV data is transferred without performing a process for copyright protection).

The criterion used for this selection is, in addition to whether the target AV data is one that supports processing for copyright protection, for example, whether the target AV data has error tolerance. Or not.

As the error correction code, there is a method of adding at least a weak error correction code and a method of not adding an error correction code to AV data allocated to the lowest level. In the present embodiment, the former case will be described as an example.

By using the method of adding the error correction code (for example, FEC of the Bluetooth layer) to the AV data and transferring the data, even if the AV data is encrypted for copyright protection, The error correction code enables the receiving device to perform processing on the assumption that no error has substantially occurred on the wireless transmission path, thereby enabling correct reception and reproduction of AV data in the receiving device. Become like

Further, the following advantages can be obtained by appropriately selecting the error correction capability of the error correction code. (1) When the error correction capability of the error correction code is large, the data length tends to be long. However, if the error correction code having the optimum error correction capability can be selected according to the AV data, the error correction capability may be dependent on the AV data. Since it is only necessary to add an error correction code having a small (short data length), the bandwidth resource can be used effectively and a larger amount of data can be transferred. This is very effective especially in a wireless environment where band resources are limited. (2) If the error correction capability of the error correction code is large, the processing load is applied to the device. However, if the error correction code having the optimum error correction capability can be selected according to the AV data, the processing load applied to the device will be increased. Can also be optimized. In a wireless environment, a battery-driven mobile terminal or the like is predominant. In this case, optimization of the processing load also contributes to optimization of battery life.

Hereinafter, this embodiment will be described in more detail.

In the following, the portable AV player 101 and the wireless AV playback device 102 are Bluetooth
Has a function of wireless communication. Further, the portable AV player 101 and the wireless AV playback device 1
02 has at least a function of handling MPEG4 data.

FIG. 2 shows an example of the internal structure of the portable AV player 101.

As shown in FIG. 2, the portable AV player 101 includes a Bluetooth interface (I / F) processing unit 201 for executing a Bluetooth physical layer process, a Bluetooth data link layer process (for example, an AV packet and a Bluetooth). Bluetooth that executes packet conversion processing between packets)
The Bluetooth communication processing unit 202, a Bluetooth error correction processing unit 203 that performs processing related to error correction in Bluetooth, a processing for copyright protection (for example,
A copyright protection processing unit 204 that performs an authentication / key exchange procedure with a communication partner and data encryption by DTCP)
A signaling processing unit 205 for performing a signaling process, A
A processing content selection unit 206 that selects processing content for V data (AV packets), executes processing relating to AV data such as MPEG4 data (for example, packet conversion processing between AV data such as MPEG4 data and AV packets). An AV data processing unit 207 is provided. MPEG
In some cases, a storage for storing AV data such as 4 is provided.

When the copyright protection processing unit 204 performs a key exchange procedure or an authentication / key exchange procedure and performs encryption, the copyright protection processing unit 204 may be divided into a key exchange procedure unit and an encryption unit.

Further, the processing content selection unit 206 may be divided into a first selection unit for selecting the presence or absence of encryption and a second selection unit for selecting an error correction code.

FIG. 3 shows an example of the internal structure of the wireless AV playback device 102.

As shown in FIG. 3, the wireless AV playback device 102 has a Bluetooth interface (I / I / O) that executes a Bluetooth physical layer process.
F) The processing unit 301, a data link layer process of Bluetooth (for example, an AV packet and a Bluetooth
B that performs packet conversion processing between the
Bluetooth communication processing unit 302, Bluetooth
h that performs processing related to error correction in h
th error correction processing unit 303, a copyright protection processing unit 304 that performs a process for copyright protection (for example, an authentication / key exchange procedure with a communication partner and data decryption by DTCP), and performs a signaling process. Signaling processing unit 3
05, a processing content selection unit 306 for selecting the processing content for the AV data (AV packet), and processing for AV data such as MPEG4 data (for example, packet conversion processing between AV data such as MPEG4 data and AV packets). An AV data processing unit 307 to be executed is provided.
One or more types of decoders for decoding encoded AV data (for example, an MPEG4 decoder for decoding MPEG4 data) and a display for displaying AV data including video contents such as still images or moving images on a screen. And a speaker device for outputting audio / music content.

When the copyright protection processing section 304 performs a key exchange procedure or an authentication / key exchange procedure and decryption, the copyright protection processing section 304 may be divided into a key exchange procedure section and a decryption section.

FIG. 4 shows an example of the overall schematic procedure in the system of FIG.

First, a signaling process is performed by the signaling processing unit 205 of the portable AV player 101 and the signaling processing unit 305 of the wireless AV playback device 102 (step S1). In the signaling processing, AV control and the like such as network setting, designation of the content of the content (for example, designation of a movie name and a music piece), and an instruction for operation of the content (for example, a reproduction instruction) are performed.

Subsequently, as described above, for example, as described above, the copyright protection processing unit 304 refers to the copy control information of the AV data to be transferred to determine whether or not encryption has been performed. Copyright protection processing unit 2 of AV player 101
04 and the copyright protection processing unit 304 of the wireless AV playback device 102, for example, authentication / key exchange is performed by DTCP (step S2). Thereby, the portable AV player 101 and the wireless AV player 102
Can share an encryption key Kc (for example, according to DTCP), thereby enabling encrypted communication of AV data.

The AV data is encrypted with the encryption key Kc in the copyright protection processing unit 204 of the portable AV player 101, error-corrected by the Bluetooth error correction processing unit 203, transferred via a wireless network, and Bluetooth of the AV playback device 102
The error correction processing unit 303 performs error correction processing, and the copyright protection processing unit 304 decrypts the data using the encryption key Kc (step S3). As a result, AV data can be decoded and output for display and / or audio as required.

Even if another device exists in the same Bluetooth piconet, the other device will not
Since the AV data is not shared, even if the AV data is received, its encryption cannot be decrypted and cannot be reproduced.

If the AV data to be transferred is not encrypted, step S2 is not performed. In step S3, unencrypted AV data (including AV packets) is transferred.

FIG. 5 shows another example of the overall schematic procedure in the system of FIG.

In this case, step S11 is the same as step S1 in FIG. 4, but when encrypting the AV data to be transferred, the authentication / key exchange procedure is not performed as in step S2 in FIG. Next, the copyright protection processing unit 204 of the portable AV player 101 encrypts the AV data with an appropriate encryption key and transmits the encrypted AV data to the wireless AV playback device 102 (step S12). Wireless AV that received this
When the playback device 102 knows that the received AV data is encrypted (in this case, the playback device 102 knows that the AV data is encrypted from the header information of the packet, for example). Here, for the first time, the copyright protection processing unit 204 of the portable AV player 101
And the copyright protection processing unit 304 of the wireless AV playback device 102, for example, performs authentication and key exchange by DTCP, and shares the encryption key Kc (step S13).

The AV data is encrypted by the copyright protection processing unit 204 of the portable AV player 101 with the encryption key Kc, transferred via the wireless network, and transmitted to the copyright protection processing unit 304 of the wireless AV playback device 102. Decryption is performed using the encryption key Kc (step S14).

When the AV data to be transferred is not encrypted, the operation is the same as that in step S1 in FIG.

A method of using the same encryption key from the time the network is set in the signaling process to the time the network is released, a method of changing the encryption key for each group of contents, and a method of changing the encryption key for each content Method,
There are various methods, such as a method of changing for each component in one content, a method of changing after a certain time elapses, and a method of changing according to the content of copy control information of the content. When changing the encryption key, step S2 is performed again.
The authentication / key exchange procedure or a part thereof may be performed.

Note that procedures other than those shown in FIGS. 4 and 5 are also possible.

FIG. 6 shows a format example of a Bluetooth packet for transferring an AV packet including AV data.

As shown in FIG. 6, the packet in this example is a Bluetooth packet of Bluetooth.
It includes a header, an AV transfer header of the AV packet, AV data, and an error correction code. In the Bluetooth header, error correction code type information indicating the type of the error correction code used for the AV data (indicating which level of the error correction code the strength is) is described. Further, the AV transfer header describes predetermined control information from which it is determined whether or not the AV data is AV data that should support a process for copyright protection. Here, the above-described example of the copy control information is used as the predetermined control information. When the AV data is encrypted, it is assumed that only the AV data portion in the packet format of FIG. 6 is encrypted.

FIG. 7 shows an example of a procedure after the signaling process of the portable AV player 101.

First, the AV data processing unit 207 reads the designated AV data (step S21) and converts it into an AV packet (step S22). At that time, the AV
With reference to the copy control information attached to the data source, the field of the copy control information in the AV transfer header of the AV packet is set to the value obtained by the reference. For example, as described above, the copy control information can be freely copied: 00: Any number of copies can be freely made. 01: Only one copy can be made. 10: No more copies can be made because the specified number of copies has been reached. Indicates prohibition. Of course, other variations are also possible.

When it is possible to handle AV data having no copy control information, the copy control information field in the AV transfer header of the AV packet includes
A value (for example, 00) for determining that the AV data is not AV data that should support processing for copyright protection may be set.

Next, in the case of this example, the processing content selection unit 206 refers to the copy control information field in the AV transfer header of the AV packet and, for example, sets the copy control information to “01” or “10”. Or, if it is “11”, it is determined that the data is AV data that should support the processing for copyright protection, and the AV packet is passed to the copyright protection processing unit 204. It is determined that the data is AV data other than the AV data that should support the process for protecting the right, and is passed to the Bluetooth error correction processing unit 203 (step S23). Further, the processing content selection unit 206 selects the type of the error correction code to be added to the AV data (selects which level of the error correction code to use), as described later in detail. The type of the selected error correction code is notified to the Bluetooth error correction processing unit 203.

When the AV packet is passed to the copyright protection processing unit 204, the copyright protection processing unit 204
The AV data portion of the packet is encrypted using the encryption key Kc, and this is encrypted by the Bluetooth error correction processing unit 203.
(Step S24).

[0082] Bluetooth error correction processing section 203
Then, the error correction code of the type selected by the processing content selection unit 206 is calculated and added to the AV packet (step S25).

Then, the Bluetooth communication processing unit 2
02, the AV packet is converted to a Bluetooth packet (step S26), and this is converted to a Bluetooth packet.
It is transmitted from the interface processing unit 201 (step S27). Note that the processing content selection unit 206 or Blue
Bluetooth error correction processing unit 203 to Bluetooth
h communication processing unit 202 is notified of the error correction code type information, and the Bluetooth communication processing unit 202
The field of the error correction code type information in the Bluetooth header is set to the notified value.

FIG. 8 shows an example of a procedure after the signaling processing of the wireless AV reproducing apparatus 102.

First, when the Bluetooth packet is
It is received from the Bluetooth interface processing unit 301 (step S31), and is converted into an AV packet by the Bluetooth communication processing unit 302 (step S3).
2), the AV packet to which the error correction code is added is Bl
The error is passed to the Bluetooth error correction processing unit 303. At this time, the Bluetooth communication processing unit 302
Bluetooth error correction processing unit 303, Bluetooth
The error correction code type information described in the h header is notified.

Next, the Bluetooth error correction processing section 303 performs an error correction process based on the error correction code added to the AV data according to the type indicated by the notified error correction code type information (step S33). The AV packet subjected to the error correction processing is passed to the processing content selection unit 306.

In the case of this example, the processing content selection unit 306 refers to the copy control information field in the AV transfer header of the AV packet and, for example, sets the copy control information to “0”.
If it is "1", "10" or "11", it is determined that the data is AV data that should support the processing for copyright protection, and the AV packet is passed to the copyright protection processing unit 304.
If the copy control information is "00", it is determined that the data is AV data other than the AV data that should support the processing for copyright protection, and is passed to the AV data processing unit 307 (step S34).

When the AV packet is passed to the copyright protection processing unit 304, the copyright protection processing unit 304
The AV data portion of the packet is decrypted using the encryption key Kc, and the AV packet is passed to the AV data processing unit 307 (step S35).

The AV data processing unit 307 reassembles the AV packet into AV data (step S3).
6) If necessary, perform MPEG4 decoding, for example.

Then, the designated AV data is output for display and / or audio to a predetermined output device (step S37).

Now, a method for selecting an error code to be used for the target AV data will be described below.

FIG. 9 shows an example of an error correction method selection procedure in the processing content selection section 206.

In this example, it is checked whether or not the target AV data is AV data that should support the processing for copyright protection (whether or not the AV data is encrypted and transferred). If the AV data is AV data that should support processing for copyright protection, for example, the copy control information is “01”, “10”, or “11”.
Is satisfied (step S41), an error correction code at a stage having a high intensity level is selected (step S42). If the target AV data is not AV data that should support processing for copyright protection, For example, when the copy control information is "00" (step S41), an error correction code of a stage having a weak intensity level is selected (step S43).

In the error correction code type information in the Bluetooth header, for example, “1” is set in step S42, and “0” is set in step S43.

If the error correction code has three levels, the strongest error correction code (step S4) is used.
2) and the method using the weakest error correction code (step S43) are also possible. The method using the strongest error correction code (step S42) and the medium error correction code (step S43) is also possible. Error correction code (step S42) and the weakest error correction code (step S4)
The method using 3) is also possible. Even when the error correction code has four or more intensity levels, two error correction codes to be selected can be appropriately set. Further, in the case of a system that can not use an error correction code, it may be selected that no error correction code is used in step S43.

This method is particularly effective when handling only error-resistant AV data such as MPEG4 data, for example, but is also applicable when handling error-resistant AV data.

In the case of the example of FIG. 9, an example of a packet of the AV data determined to be the AV data that should support the processing for copyright protection is shown in FIG.
AV that should support copyright protection processing
FIG. 10B shows an example of a packet for AV data determined to be non-data.

FIG. 11 shows another example of the procedure for selecting an error correction method in the processing content selection unit 206.

FIG. 9 shows an example in which only one encryption method is used, or a case in which a plurality of encryption methods are used but the error resistance of each encryption method does not matter, or a case in which a plurality of encryption methods are used but all encryption methods are used. 11 corresponds to the case where the encryption method does not have error resilience. In the example of FIG.
This is an example of a case where an encryption method having no error resilience is used together and an encryption method having error resilience is distinguished from an encryption method having no error resilience.

That is, when encryption for copyright protection is performed, the type of the encryption becomes a problem. if,
If the encryption method is not error resilient,
Even if a small bit error occurs, recovery on the receiving side cannot be performed. Therefore, it is desirable to use a strong error correction code. On the other hand, if the encryption method is an error-tolerant method, an error correction code that is weaker than the strongest error correction code described above can be used. Here, assuming that the error resilience applied to the encryption scheme is weaker than the error resilience of the AV encoding scheme, it is assumed that the strength of the error correction code in the latter case is moderate. I have.

First, it is checked whether or not the target AV data is AV data that should support the processing for copyright protection, and A should be supported for the processing for copyright protection.
If the data is not V data (step S51), the error correction code of the weakest level (out of three predetermined levels) is selected (step S55).

On the other hand, if the AV data is to support processing for copyright protection (step S51), it is next checked whether or not the encryption scheme used for the AV data has error tolerance. .

If the encryption method is not an error-resistant encryption method (step S52), an error correction code having the highest strength level (out of three predetermined levels) is selected (step S53). If the encryption method is a robust encryption method (step S52), an error correction code having a middle strength level (out of three predetermined levels) is selected (step S54).

The error correction code type information contains step S5
In the case of 3, for example, “11” is set, and step S
In the case of 54, for example, "10" is set, and in the case of step S55, for example, "01" is set.

When the error correction code has four or more strength levels, it is possible to appropriately set which of the four or more strength levels to use. Further, in the case of a system that can not use the error correction code, the step S
At 55, it may be selected not to use the error correction code.

This method is particularly effective when only error-resistant AV data such as MPEG4 data is handled, but is also applicable when error-resistant AV data is handled.

FIG. 12 shows still another example of the procedure for selecting an error correction method in the processing content selection unit 206.

The example of FIG. 9 is an example in which the target AV data is selected based only on whether or not the AV data should support the processing for copyright protection. FIG. This is an example of a case where selection is made based on whether or not the target AV data has error tolerance.

In other words, in a system that can handle error-resistant AV data, if the target AV data is not AV data that should support processing for copyright protection, the AV data is error-resistant. If it is not AV data, the AV data is transferred to Bluetooth
If the transfer is performed on the above, an error may occur on the transmission path and the receiving side may not be able to recover. Therefore, in this example, a strong error correction code is used in this case.
On the other hand, in a system that can handle error-resistant AV data, if the target AV data is not AV data that should support processing for copyright protection, the AV data is error-resistant AV data. If there is, even if an error occurs on the transmission path, it becomes possible to recover on the receiving side by the error tolerance of the AV data itself.
In this case, the error correction code may be weak.

First, it is checked whether or not the target AV data is AV data that should support the processing for copyright protection, and A should be supported for the processing for copyright protection.
If the data is V data (step S61), an error correction code of the weakest level (out of two predetermined levels) is selected (step S63).

On the other hand, if the AV data is not AV data that should support the processing for copyright protection (step S61), it is next checked whether or not the AV data itself has error tolerance.

Then, if it does not have error resilience (step S62), it selects an error correction code of the stage having the highest strength level (out of two predetermined stages) (step S63) and has error resilience. If (Step S6
2), selecting the error correction code of the stage having the weakest intensity level (out of three predetermined stages) (step S6)
4).

FIG. 13 shows still another example of the procedure for selecting an error correction method in the processing content selection unit 206.

The example of FIG. 13 is a combination of the example of FIG. 11 and the example of FIG.

First, it is checked whether or not the target AV data is the AV data that should support the processing for copyright protection, and A should be supported for the processing for copyright protection.
If the data is V data (step S71),
A check is made to see if the encryption method used for the data has error tolerance.

If the encryption method is not an error-resistant encryption method (step S72), an error correction code having the highest strength level (out of three predetermined levels) is selected (step S74). If the encryption method is resistant (step S72), an error correction code having a medium strength level (out of three predetermined levels) is selected (step S75).

On the other hand, if the AV data is not AV data that should support the processing for copyright protection (step S71), it is next checked whether or not the AV data itself has error tolerance.

If the error correction code has no error resilience (step S73), an error correction code of the highest strength level (out of three predetermined levels) is selected (step S64), and the error correction code having the error resilience is selected. If (Step S7
3), selecting the error correction code of the stage having the weakest intensity level (out of three predetermined stages) (step S7)
6).

In the example of FIG. 13, an example of a packet in the case of “Whether encryption is performed: Yes, encryption having error resilience: No” is shown in FIG. : Yes, error-resistant encryption: Yes "
FIG. 14 (b) shows an example of the packet in the case of “No., is encryption performed: No, error-resistant AV data: Ye
An example of a packet in the case of “s” is shown in FIG. 14C, “Whether encryption is performed: No, error-resistant AV data:
An example of the packet in the case of “No” is shown in FIG.

Note that, as shown in FIG. 15 and FIG.
A variation that determines whether or not the data itself has error tolerance is also possible.

In the present embodiment, Bluetooth has been described as an example of a wireless LAN.
2.11 Many wireless LANs have security functions such as authentication / key exchange and encryption at the link layer level, such as wireless LANs, WECA and HomeRF wireless LANs. The present invention can be applied to these various wireless LANs.

Further, in the present embodiment, the case where AV data is transferred has been described, but the present invention is also applicable to a system for transferring other data.

The above functions can be realized as software. Also, the present embodiment can be implemented as a program for causing a computer to execute predetermined means (or for causing a computer to function as predetermined means, or for causing a computer to realize predetermined functions), The present invention can also be implemented as a computer-readable recording medium on which the program is recorded.

The configuration illustrated in the present embodiment is an example, and is not intended to exclude other configurations. Some of the illustrated configuration may be replaced with another, or one of the illustrated configurations may be replaced. Another configuration obtained by omitting a part, adding another function to the illustrated configuration, or combining them is also possible. In addition, another configuration that is logically equivalent to the illustrated configuration, another configuration including a portion that is logically equivalent to the illustrated configuration, another configuration that is logically equivalent to the main part of the illustrated configuration, and the like are also possible. is there. Also, another configuration that achieves the same or similar purpose as the illustrated configuration,
Another configuration that has the same or similar effect as the illustrated configuration is also possible. In addition, various variations of various components can be implemented in appropriate combinations. In addition, the present embodiment is an invention as an individual device, an invention about two or more related devices, an invention as a whole system, an invention about components inside the individual device, an invention of a method corresponding thereto, and the like. It encompasses and implies inventions relating to various aspects, stages, concepts or categories. Therefore, the present invention can be extracted from the contents disclosed in the embodiments of the present invention without being limited to the illustrated configuration.

The present invention is not limited to the above-described embodiments, but can be implemented with various modifications within the technical scope.

[0126]

According to the present invention, based on at least whether or not content data to be transmitted / received requires processing for copyright protection, error correction codes of a plurality of strength levels are determined. Since the content to be used for the content data is selected, AV data encrypted for copyright protection is transmitted to a certain extent through a wireless network where bit errors and burst errors may occur. It is possible to transmit from the transmission side to the reception side with high quality or with high quality.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a wireless communication system according to an embodiment of the present invention.

FIG. 2 is an exemplary view showing an example of the internal structure of the portable AV player according to the embodiment;

FIG. 3 is an exemplary view showing an example of an internal structure of the wireless AV reproducing apparatus according to the embodiment;

FIG. 4 is an exemplary diagram showing an overall schematic procedure in the wireless communication system according to the embodiment;

FIG. 5 is an exemplary view showing another example of the overall schematic procedure in the wireless communication system according to the embodiment;

FIG. 6 is an exemplary view showing a format example of AV data transferred in the embodiment;

FIG. 7 is an exemplary flowchart showing an example of the processing order of the portable AV player according to the embodiment;

FIG. 8 is an exemplary flowchart illustrating an example of a processing order of the wireless AV playback device according to the embodiment.

FIG. 9 is an exemplary flowchart illustrating an example of an error correction method selection procedure in the embodiment.

FIG. 10 is an exemplary view showing a format example of AV data transferred in the embodiment;

FIG. 11 is a flowchart showing another example of an error correction method selection procedure in the embodiment.

FIG. 12 is an exemplary flowchart showing still another example of the error correction method selection procedure in the embodiment;

FIG. 13 is a flowchart showing still another example of the error correction method selection procedure in the embodiment.

FIG. 14 is an exemplary view showing a format example of AV data transferred in the embodiment;

FIG. 15 is a flowchart showing still another example of the error correction method selection procedure in the embodiment;

FIG. 16 is a flowchart showing still another example of the error correction method selection procedure in the embodiment.

[Explanation of symbols]

101: portable AV player 102: wireless AV playback device 201, 301 ... Bluetooth interface processing unit 202, 302 ... Bluetooth communication processing unit 203, 303 ... Bluetooth error correction processing unit 204, 304 ... copyright protection processing unit 205, 305 ... signaling Processing units 206, 306: Processing content selection units 207, 307: MPEG4 data processing unit

Claims (15)

[Claims] 1. A transmitting apparatus for transmitting content data requesting processing for copyright protection or other content data via a wireless network, and transmitting the content data transmitted from the transmitting apparatus to the wireless network. In a wireless communication system including a receiving device that receives data via the wireless communication device, if the content data to be transmitted / received requests processing for copyright protection, the transmitting device and the Key exchange means for exchanging an encryption key with a receiving device; and, when the content data to be transmitted / received is content data requesting a process for copyright protection, the content data is encrypted. The content data is encrypted based on a key, and the content data does not require processing for copyright protection. Transfer means for transferring from the transmitting device to the receiving device via the wireless network without encrypting the content data if the content data is not encrypted; and the transferred encrypted content data or the unencrypted content data. Error correction means for correcting an error generated on the wireless network by causing a predetermined error correction code to accompany the content data, wherein the error correction means performs processing for protecting the copyright of the content data. Error correction code of the strength level selected based on whether the content data
A wireless communication system used for the content data. 2. The error correction means according to claim 1, wherein said error correction means uses an error correction to be applied to content data other than the content data requiring the copyright protection processing. The wireless communication system according to claim 1, wherein an error correction code having a stronger strength than the code is used. 3. The error correction means is content data other than content data for which copyright protection processing is requested, and has error tolerance with respect to content data for which copyright protection processing is requested. Use error-correcting codes that have stronger strength than the error-correcting codes used for content, and use non-error-resistant content data other than content data that requires processing for copyright protection. The use of an error correction code having a stronger strength than the error correction code used for content data other than the content data requiring the processing for copyright protection and having error tolerance. The wireless communication system according to claim 1, wherein: 4. The method according to claim 1, wherein the error correction means performs the processing for copyright protection when the encryption method applied to the content data requiring the processing for copyright protection does not have an error resilience capability. 4. The error correction code according to claim 2, wherein an error correction code having a stronger strength than an error correction code used when an encryption method applied to requested content data has an error resilience capability is used. Wireless communication system. 5. A transmitting apparatus for transmitting content data requesting processing for copyright protection or other content data to a receiving apparatus via a wireless network, wherein the content data to be transmitted and received is: First selecting means for selecting whether or not to encrypt the content data based on whether or not a request for copyright protection processing is made; and A second step of selecting a content data to be used for the content data from among a plurality of error correction codes of a plurality of strength levels based at least on whether the content data requires processing for copyright protection. Selecting means for encrypting the content data by the first selecting means; Key exchange means for exchanging an encryption key with a receiving device; and, when encrypting the content data is selected by the first selecting means, encrypting the content data. Encrypting means for performing encryption, and encrypting the content data or encrypting the content data when the first selecting means selects to encrypt the content data. When the content data is selected not to be encrypted, an error correcting code of the strength level selected by the second selecting means is obtained and added to the unencrypted content data. Error correction processing means for transmitting, via the wireless network, the content data to which the error correction code has been added. Transmission apparatus being characterized in that a Esu means. 6. The method according to claim 1, wherein the second selecting means uses the content data for which the processing for copyright protection is requested for the content data other than the content data for which the processing for copyright protection is requested. The transmission device according to claim 5, wherein an error correction code having a stronger strength than the error correction code is selected. 7. The method according to claim 1, wherein the second selecting means is a content data other than the content data requesting the copyright protection processing, the error data being a content data requesting the copyright protection processing. Selects an error-correcting code that has stronger strength than the error-correcting code to be used for data with In response to this, it is necessary to select an error correction code that has a stronger strength than the error correction code used for content data other than content data that requires copyright protection processing and has error tolerance. The transmitting device according to claim 5, wherein 8. The method according to claim 1, wherein the second selection unit is configured to execute the copyright protection processing when the encryption method applied to the content data requiring the copyright protection processing does not have an error resilience capability. 8. The method according to claim 6, wherein an error correction code having a stronger strength than an error correction code used when an encryption method applied to content data requiring processing has an error resilience capability is selected. The transmitting device according to the above. 9. The transmitting apparatus according to claim 7, wherein at least MPEG4 data is handled as said error-resistant content data. 10. The method according to claim 1, wherein when the copy restriction is imposed on the content data, the first selection means treats the content data as requesting a process for copyright protection. The transmitting device according to claim 5, wherein 11. The wireless network according to claim 1, wherein said wireless network is
6. The transmitting apparatus according to claim 5, wherein the transmitting apparatus is based on "th". 12. A transmitting apparatus for transmitting content data requesting processing for copyright protection or other content data via a wireless network, and transmitting the content data transmitted from the transmitting apparatus to the wireless network. A content data transfer method in a wireless communication system including a receiving device that receives content via a wireless communication device, wherein the transmitting device requests the content data to be transmitted / received for a process for copyright protection. Based on whether or not to select whether or not to encrypt the content data, at least based on whether the content data is a request for processing for copyright protection, A code used for the content data is selected from among error correction codes of a plurality of intensity levels, When encrypting the content data is selected, an encryption key is exchanged between the transmitting device and the receiving device via the wireless network, and the transmitting device performs When encryption is selected, the content data is encrypted using the encryption key exchanged with the reception device, and the transmission device encrypts the content data. For the encrypted content data when encryption is selected or for the unencrypted content data when it is selected not to encrypt the content data, The transmission device obtains and adds an error correction code of the strength level, and the transmission device has information for specifying the error correction code and the strength level of the error correction code. To the receiving device via the wireless network, the receiving device transmits the content data, the error correction code, and the error correction received from the transmitting device via the wireless network. Based on the code strength level, the content data is subjected to error correction processing, and the receiving device is subjected to encryption by receiving the content data, which requests processing for copyright protection. And decrypting the content data by using the encryption key exchanged with the transmitting device. 13. A content data transfer method in a transmitting device for transmitting content data requesting a process for copyright protection or other content data to a receiving device via a wireless network, wherein the content data is transmitted and received. Based on whether or not the content data requires processing for copyright protection, whether or not to encrypt the content data is selected. Based on at least whether or not a request for protection processing is required, a code to be used for the content data is selected from among a plurality of strength-level error correction codes, and encryption of the content data is performed. When the application is selected, an encryption key is exchanged with the receiving device via the wireless network, When encrypting the content data is selected, the content data is encrypted using the encryption key exchanged with the receiving device, and the content data is encrypted. Is selected for the encrypted content data when it is selected to perform the encryption or for the unencrypted content data when the encryption is not performed for the content data. A content data transfer method comprising: obtaining and adding an error correction code of the intensity level; and transmitting the content data to which the error correction code is added via the wireless network. 14. A computer-readable recording program for causing a computer to function as a transmitting device for transmitting content data requesting processing for copyright protection or other content data to a receiving device via a wireless network. Whether or not to encrypt the content data based on whether or not the content data to be transmitted / received requests processing for copyright protection. A first selection function for selecting a plurality of strength levels based on at least whether or not the content data to be transmitted / received requires processing for copyright protection. A second selection function of selecting a code to be used for the content data from the codes, and the first selection function When encrypting the content data is selected, a key exchange function for exchanging an encryption key with the receiving device via the wireless network; and When encrypting the content data is selected, an encryption function for encrypting the content data; and encrypting the content data by the first selecting function. To the encrypted content data when it is selected to apply or to the unencrypted content data when it is selected not to encrypt the content data by the first selection function. An error correction processing function for obtaining and adding an error correction code of an intensity level selected by the second selection function; Computer-readable recording medium a program for the added the content data No. to realize a radio interface processing function for transmission over the wireless network to the computer. 15. A program for causing a computer to function as a transmitting device for transmitting content data requesting a process for copyright protection or other content data to a receiving device via a wireless network, the program comprising: A first selection for selecting whether or not to encrypt the content data based on whether or not the content data that is required to be processed for copyright protection A function and a function to use the content data from among the error correction codes of a plurality of strength levels based on at least whether or not the content data to be transmitted / received requests processing for copyright protection. A second selection function for selecting an item to be encrypted; and encrypting the content data by the first selection function. When selected, a key exchange function for exchanging an encryption key with the receiving device via the wireless network, and encrypting the content data by the first selection function An encryption function for encrypting the content data when selected, and an encryption function for encrypting the content data by the first selection function. The second selection function selects the unencrypted content data when the content data or the first selection function selects not to encrypt the content data. An error correction processing function for obtaining and adding an error correction code of a given intensity level; and Program for realizing a radio interface processing function for transmitting via the line network to the computer.