US 20050180289 A1
A digital information recording apparatus to record digital information to protect copyright of digital information that includes at least first digital information and first copy control information. The digital information recording apparatus records the digital information based upon the first copy control information, which denotes one of: a copy inhibition prohibiting copying of said first digital information; a limited copy permission authorizing a predetermined number of times of copying of said first digital information; and an unlimited copy permission authorizing unlimited copying of said first digital information.
1. A digital information recording apparatus to record a digital information, comprising:
separation means for separating first digital information and first copy control information from an inputted digital information signal including at least said first digital information and said first copy control information;
decrypt means for decrypting said first digital information outputted from said separation means;
select means for selecting one of said first digital information and a decrypted second digital information outputted from said decrypt means;
recording means for recording a selected one of said first digital information and said decrypted second digital information from said select means; and
control means for controlling at least said select means and said recording means in response to said first copy control information outputted from said separation means.
This is a continuation of application Ser. No. 10/210,107 filed 2 Aug. 2002, allowed, which is a continuation of application Ser. No. 09/201,757 filed 1 Dec. 1998 and issued 17 Sep. 2002 as U.S. Pat. No. 6,453,304 B1, the contents of both of which applications are incorporated herein by reference in their entirety.
This invention relates to an apparatus for protecting a copyright of digital information that is digitally transmitted between an information apparatus for home use and personal computers.
Recently, there have been significant advances in data compression for video and audio signals using digital technologies, so that an accumulation and/or transmission of data can be easily performed. Correspondingly, digitalization in the field of broadcasting has also advanced rapidly. For example, a broadcasting system in which an analog video and/or audio signals are digitally compressed and encoded with high efficiency, using an MPEG (Moving Picture Experts Group) standard, and are transmitted through a satellite and/or cable system has been developed. In general, a digital-broadcasting receiver called a set-top-box has been used for receiving and decoding a digital-broadcast signal.
Furthermore, a digital VCR (Video Cassette Recorder) that can record and reproduce video and audio information, such as a digital TV broadcast signal on magnetic type by employing a compression-encoding method has been developed as an apparatus for home use to record and/or reproduce video and audio signals.
One technology by which a requested program can be selected from received digital signals and in which plural information is multiplexed and transmitted is disclosed in the Japanese published unexamined patent application No. 118-56350. Moreover, a digital VCR that uses rotating magnetic heads is shown, for example, in the Japanese published unexamined patent application No. 5-174496. Furthermore, in the publication Newly Developed D-VHS Digital Tape Recording System for the Multimedia Era (IEEE Transactions on Consumer Electronics, Vol. 42, No. 3, August 1996, pp. 617-622), a digital broadcast recording system is disclosed in which a digital broadcast receiver and a digital VCR are connected with a transmission line, such as a digital interface. Japanese published unexamined patent application No. H2-7269 is technology describes a method for protecting a copyright of transmitted information in a case where a digital device is connected to a digital interface. In a case where copying of the digital content of an output from a digital interface is prohibited, the digital content is changed (scrambled) to different codes, and then the different codes are outputted on the digital interface. Therefore, the copyright of the digital contents are somewhat protected, because a digital recording apparatus, which receives the different codes doesn't have the ability to decode the different codes.
When a digital broadcasting signal is recorded and reproduced by using a digital VCR, etc., there is a first disadvantage in that, in transmitting copyrighted information externally between apparatuses through a digital interface, unauthorized interception of and/or tampering with the copyrighted information can occur, even if the copyrighted information is scrambled.
As one example, copyrighted information can be intercepted during transmission between apparatuses, and copy control information included therein can be modified (i.e., tampered with) so as to record the copyrighted information with unauthorized copy control information, e.g. allowing unlimited (i.e., piracy) copying. Accordingly, there is a problem that the pirated copyrighted information can be used again by transmitting the information to a device with a descramble function through another digital interface, even though further use should be prohibited. Accordingly, external transmission and recording of copyrighted information with prohibitive copy control information is disadvantageous in that it is susceptible to copyright piracy.
Accordingly, it is an object of the present invention to provide a digital information recording apparatus which is able to record digital information in such a way as to protect the digital information, including copy control information, transmitted on a digital transmission line.
Further, it is an object of the present invention to protect a copyright of the digital contents on a digital interface.
In view of the foregoing objects of the invention for solving the problems explained above, a digital information recording apparatus to record digital information, comprises: separation means for separating first digital information and first copy control information from inputted digital information, including at least the first digital information and the first copy control information; decrypt means for decrypting the first digital information outputted from the separation means to produce decrypted second digital information; select means for selecting the first digital information or the decrypted second digital information from the decrypt means; recording means for recording the selected one of the first digital information or the decrypted second digital information; and control means for controlling at least the select means and the recording means in response to the first copy control information received from the separation means.
According to a preferred embodiment, a digital information recording apparatus to record digital information, comprises: separation means for separating first digital information and first copy control information from inputted digital information, including at least the first digital information and the first copy control information; process means for processing the first digital information outputted from the separation means and for outputting second digital information in response to control information; recording means for recording the second digital information; and control means for controlling at least the process means and the recording means in response to the first copy control information; wherein the control means controls the process means using the control information.
According to another embodiment, a digital information recording apparatus having a digital information output means, comprises: separation means for separating first digital information and first copy control information from digital information including at least the first digital information and first copy control information outputted from the digital information output means; decrypt means for decrypting the first digital information outputted from the separation means to produce decrypted second digital information; select means for selecting the first digital information or the decrypted second digital information outputted from the decrypt means; recording means for recording the selected one of the first digital information or the decrypted second digital information; and control means for controlling at least the select means and the recording means in response to the first copy control information received from the separation means.
Various embodiments of the present invention will be explained with reference to the drawings.
A digital signal inputted from the input terminal 301 is supplied to the encryption circuit 303 and to one input of the selection circuit 305. A copy control information signal, which relates to the digital signal from the input terminal 301, is inputted to the input terminal 302. The copy control information, for example, in the form of 2-bit (or greater bit) digital data, indicates one of a prohibition against copying, a limited permission to allow copying a predetermined number of times (e.g., once) and no-limitation so as to allow unlimited copying of the digital signal, e.g., with copy control data (1, 1), (1, 0) and (0, 0), respectively.
The copy control information discrimination circuit 304 performs a discrimination procedure based on the copy control information received from the input terminal 302 and, if the copy control information is discriminated as (1, 1) or (1, 0) which denotes a prohibition or a limited permission, while the encryption circuit 303 is controlled to operate actively, the selection circuit 305 is switched to a terminal Cr so as to cause encrypted information to pass therethrough. If the copy control information is discriminated as (0, 0), which denotes no-limitation for copying, while the encryption circuit 303 is controlled to operate inertly, the selection circuit 305 is switched to a terminal Th.
The encryption circuit 303 encrypts the inputted digital signal with a predetermined encryption key which typically may be renewed minute by minute, and outputs the encrypted digital signal. To prevent an error in the propagation of the signal which influences the following data even if some errors like a bit-error are caused during transmission, for example, in the encryption circuit 303 a block encryption algorithm is employed by which a block unit, consisting of a plural number of bits, is used so that the encryption processing is realized with a simplified circuit.
One embodiment, the encryption circuit 303, is shown in
In the block processing unit 3035, a block sequence of the data Ya and Yb is converted to become the same as the original bit sequence, and the encrypted data Y is outputted from the block processing unit 3035. Moreover, although not illustrated, the above-mentioned processings can be suspended and consumption of electric power caused by the processings can be reduced in response to an external signal, by stopping supply of a clock signal used as a standard for processings, such as an add processing, or by setting to a hold-mode an enable signal which selects whether to latch or hold data inputted to a register for holding a processing result. In
With the above-mentioned encrypting operations, unless decryption processing is performed to reverse the encryption, any work can be protected from unauthorized use by an intercepting party and/or from tampering, since the digital signal regarding such copyrighted work can be encrypted. In addition, since encryption processing is not performed when the copy control information indicates that unlimited copying of the work is permitted, the work can be used freely in such case.
In addition, in this embodiment, although it is performed outside of the encryption circuit 303 to select whether or not the encryption processing is to be performed for the digital signal, switching and the same processing may be performed in the encryption circuit-303.
In the copy control information separation discrimination circuit 402, from the digital signal received from the input terminal 401, the copy control information added to the digital signal by the apparatus of
The decryption circuit 403 decrypts the inputted digital signal with a predetermined decryption key which is the same as the encryption key added by the encryption circuit 303 of the apparatus shown in
As a result of the above-mentioned procedures, the digital signal whose copyright has to be protected can be subjected to decryption by authorized persons and outputted, and if the copy control information indicates permission for copying, the digital signal can be outputted with no decryption. When the output terminal 307 in
The digital broadcast signal sent by a broadcasting station is inputted to the digital broadcast signal receiving unit 200 from the input terminal 201. The digital broadcast signal, for example, is sent through a digital broadcasting satellite, by terrestrial broadcasting or by cable broadcasting or any other suitable arrangement. Here, it is presupposed that a video signal and audio signal are compressed in a packet form using the MPEG system by a broadcasting station.
As shown in
The procedure carried out in the selection circuit 2023 is as follows. At first, a user specifies a logical channel of a desired audio-visual program. Here, the term logical channel refers to a collection of video and audio information constituting one program, and can, for example, correspond to a television channel used by an analog television broadcasting system. Moreover, in general, a frequency band in which a plural number of programs are multiplexed is called a logical channel in the digital broadcasting system.
Next, a program association table PAT, which is contained in the present received PS, is received. The PAT represents a table in program specific information (PSI), specified by the MPEG2 standard. A packet identification (PID), which indicates an identification number of a packet in which a specified logical channel of video and audio information is contained, is described in a program map table (PMT). The PMT is also a table of the PSI. Described in the PMT are the PID of the packet, such as a video and audio signal, which constitutes each logical channel included in the received TS, and a program clock reference (PCR) that indicates the time information timed by a reference clock signal used at the time of the compression of the video and audio signal. Moreover, the copy control information of each logical channel is stored in the PMT. If the PAT is obtained, the PID is taken out from the PAT, and the PMT including the PID is received. As shown in
As mentioned above, in order to discriminate which information, such as video, audio and PCR information which constitute a logical channel, is stored in each packet, it is required to acquire the PID. The selection circuit 2023 supplies a packet-stream in which a video and audio signal are stored at the MPEG decoder 2024. The MPEG decoder 2024 expands the compressed video signal and audio signal and restores them. The restored video signal and audio signal are outputted from the output terminal 203. A user can view and listen to the information carried on these signals using a television monitor.
Hereafter, the process of recording information in the recording and reproducing unit 100 will be explained using
The discrimination circuit for copy control information 506 switches the encryption and decryption circuit 503 and selectors 502 and 504 according to the copy control information. For example, if the copy control information is 11 or 10, which means that copying is forbidden or is permitted only once, as a first example, selectors 502 and 504 are switched to the Cr side and the encryption and decryption circuit 503 is enabled for coding or decoding signals. If the copy control information is 00, which means that copies are permitted without any limitation, the encryption and decryption circuit 503 is inhibited, while switches 502 and 504 are turned to the Th side.
In the encryption and decryption circuit 205 shown in
The digital interface circuit 102 of the recording and reproducing unit 100 or the digital interface circuit 206 of the recording/reproducing device 200 is able to realize a protocol of a fast digital bus interface, such as IEEE 1394. It simultaneously has a function of transmitting a fast signal, while keeping the time interval of the transmitted packet stream constant. In
The packet stream to which time stamps were added is stored in the buffer circuit 603. These packets are processed as bus-packets and are sent out on a digital bus interface. The header processing circuit 604 adds copy control information received from controller 204, an indication of the size of the packet, error correction symbols and other information to the packets, which are original packets received by the buffer 603 itself, an unified (i.e. combined) packet made up of some of the packets received by the buffer 603, or a partial divided packet derived from a received packet. After that, they are sent to the digital bus interface.
On the other hand, signal processing in the digital interface circuit 102 is performed as follows. Header processing circuit 604 reads out the copy control information of the packet received from the input and output terminal 605, which was added by the header processing circuit 604 in the digital interface circuit 206, and sends the information to controller 108 via external interface circuit 606. At the same time, the header processing circuit 604 reads out packet size information, error information and other information of the received packet and sends the same to the buffer circuit 603. Divided packets are constructed into their original form and are outputted from this block with a timing corresponding to the time stamps that are added at the top of each packet.
As shown in
The signal processing performed by the recording/reproducing device 100 will be explained using
Servo circuit 107 controls the rotary phase of rotating drum 1051, and signals are recorded on the proper recording tracks on magnetic tape 106 by the magnetic heads 1052 mounted on the rotating drum 1051. A program that a user selects can be recorded on the magnetic tape by using the above-mentioned processing. Because enciphered information is transmitted on the digital bus interface, an unauthorized interception and a falsification of the data can be prevented.
Next, a reproducing process will be explained. Servo circuit 107 controls the rotary phase of rotating drum 1051. Magnetic heads 1052 that scan the signal track of the magnetic tape 106 read out a reproduced signal, and this signal is transmitted to recording/reproducing signal processing circuit 1041 after being amplified by reproducing amplifier 1043. The recording/reproducing signal processing circuit 1041 performs error correction processing on the reproduced signal, and then recreates packets. In this process, the copy control information stored on the magnetic tape during the recording process is reproduced and transmitted to the controller.
The reproduced packet stream is encoded by encryption and decryption circuit 103, depending upon the copy control information, and is sent to the digital bus interface 102, after the copy control information is added thereto by the digital interface circuit 102. The digital interface circuit 206 separates the copy control information, while maintaining the time interval. Then, the packets are decoded in the circuit 205, depending upon the copy control-information, and are transmitted to selector 2023 These signals can be used by the user as the received broadcast signal. With such an arrangement, a processed signal on the digital bus interface is encoded so as to be protected from unauthorized interception and falsification.
This example of the invention has been directed to a magnetic recording device with a helical scanning head as a recording/reproducing device. However, the invention is not restricted to such an arrangement, but can be applied to other devices, for example, those with an optical disk memory or a semiconductor memory. Furthermore, IEEE 1394 provides an example of a digital interface circuit, but the invention is not limited to this digital interface circuit, since other interface standards or arrangements are likewise applicable. In the described example of the invention, one tuner for digital broadcast is connected to one recording/reproducing device, however, this invention is not to be restricted to such a case, but can be applied to any other possible connection. For example, a connection between a tuner for digital broadcast and a computer, a connection between a computer and a recording/reproducing device, and a connection using a daisy chain between a digital tuner and several devices are possible.
As explained above, this invention makes it possible to protect the digital contents of proprietary data transmitted through a digital transmission line.