JP2000076789A - Encoded sound reproducing system for cd linear pcm data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use the copied CD musical data only for a CD owner by providing a means encoding the CD linear PCM data with an optical storage and decoding the data with a sound reproducing device, and also providing a setting means of an encoding/decoding key and a storage means of a key in respective devices. SOLUTION: The linear PCM data in a musical CD 10 are read out by a CD-ROM drive 11, and are compressed/encoded to be transferred onto a main memory of a personal computer main body. The encoded CD data are copied onto a flash memory card 12 in a regular file form by a card drive loaded on the personal computer. The card 12 is used by being loaded on a portable type card type player 13. In the card type player 13, the data are read out from the card 12, and are decoded, and expanded further to be returned to the linear PCM data. The linear PCM data are made an audio analog signal by a digital analog converter to be outputted as music by an earphone, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to handling of CD linear PCM data in an audio reproduction system having a personal computer as a core.

[0002]

2. Description of the Related Art A CD-ROM drive or a DVD which is a peripheral device of a personal computer (hereinafter referred to as a personal computer).
An optical storage device such as a drive (hereinafter simply abbreviated as “drive”) can also play a music CD. However, music data recorded on a CD is linear PCM digital data, but is handled differently from digital data recorded on a general CD-ROM disc or DVD disc. Is restricted. This is to protect the copyright of CD music (prevent unauthorized copying).

[0003] Therefore, in the current reproduction of a music CD on a personal computer, an analog signal directly output from a drive is heard from a speaker via a mixing circuit of a sound card, or a sound arranged on a front panel of the drive. A method of listening through an earphone or an external speaker from an output terminal has been adopted.

In a CD-ROM drive with a built-in personal computer, it is not necessary to remove the CD-ROM drive, so that there is no problem in connecting an analog signal line directly to a sound card. However, a so-called external drive such as a portable CD-ROM drive for a notebook personal computer requires an analog signal line in addition to a standard digital signal cable such as SCSI. Alternatively, a dedicated cable in which an analog signal is added to a standard digital signal is required.

[0005] Although CD linear PCM data is the same digital data, it cannot be copied as a data file to another recording / reproducing device such as a hard disk. However, in a drive having a function of reading CD linear PCM data as digital data, the data can be read using a dedicated application program and stored as a sound file on a hard disk or the like. It takes the form of recording rather than duplication of data.

On the other hand, a component stereo or a dedicated C
D player, VCD player or DV capable of playing CDs
In a dedicated AV system such as a D player, linear PCM data is serially digitally output to the outside. This output format is also EIAJ standard. This is converted into an analog signal via an amplifier unit and output to a speaker or digitally recorded on a portable player.

[0007] The owner is allowed to make and use a primary copy only for personal use by the owner, and an example of digitally copying and using CD music data in a portable MD player is used. There is.

The personal computer has a graphical user interface, so that digital data can be copied and recorded on another medium very easily, and can be transferred to another personal computer via a network. System. On the other hand, a dedicated AV system is a closed system in which digital data does not go outside and is completed inside the system.

Although a personal computer is an open system that can easily copy and transfer digital data, various restrictions are imposed on the handling of copyrighted work data. Examples of playback of copyrighted works on personal computers include DVD drive and M
There is reproduction of DVD video stream data between PEG decoder cards.

[0010] The DVD video stream is originally MPEG2
The stream data is partially encrypted in sector units and recorded on a disk.

A decryption key for decrypting the encrypted sector is recorded in the disk, but cannot be read as normal data.

When the key is transferred from the drive to the decoder, the decryption key itself is encrypted and passed through an "authentication" procedure described below. This decryption key is structured so that even the operating system cannot know it.

In the authentication, the same encryption conversion means is provided on the DVD drive side and on the MPEG decoder side, and the random number generated by one of them is sent to the other side, and the converted value is returned. This is done by confirming the match with the converted value of. This procedure is mutually performed, and the two conversion values used in the authentication procedure are combined to use the decryption key of the stream data to be originally passed as the key for encrypting on the data bus. All of these encryption algorithms are private.

Further, if the authentication is not established, the drive does not output the stream data itself.

Since the decryption key exists only in the drive and the MPEG decoder, normal reproduction cannot be performed even if the stream data can be copied to the hard disk. Note that the authentication and the transfer of the decryption key are performed each time one title is reproduced.

[0016]

It is conceivable to add an audio reproducing function to a general-purpose digital information recording / reproducing apparatus and use it as a portable player. For example, CD music data is copied to a general-purpose digital data recording medium such as a floppy disk having a storage capacity of several tens to several hundreds of megabytes, a flash memory card, or a magneto-optical disk (MO), and each recording / reproducing apparatus is used. To play music.

In the near future, personal computers will be the core of AV
Component systems are expected to become widespread. For example, it is conceivable to edit and record CD music data in a large-capacity recording / reproducing device such as an MO drive, a DVD-RAM drive, or a hard disk drive.

In the current system, the responsibility for creating and managing a copy of copyrighted work data is left to the individual.
However, due to the open nature of personal computers that can be copied to portable media and connected to a network, it is necessary to be careful in copying and managing copyrighted data.

If CD music data can be copied as a file on a recording medium of a portable player using a graphical user interface of a personal computer, editing work becomes simple and very convenient.

However, if the copying of the raw data of the CD is unconditionally permitted, the data borrowed from the rental store can be digitally copied and kept as it is, copied to an acquaintance's friend and distributed, or published on a network. Illegal activities such as

That is, if the copy is made too easily, the consciousness of the copyright is reduced and the sense of responsibility is lost, but on the other hand, there is a contradiction that simple operation is desirable in actual use.

The problem to be solved by the present invention is to provide a means for a simple digital copy of CD music data, while at the same time making the data unusable only to authorized CD owners. .

[0023]

In an environment where a user can freely copy, store, and transfer digital data, C
This is to encrypt and store D linear PCM data. For this purpose, means for encrypting CD linear PCM data on the optical storage device side and means for decrypting the data on the audio reproducing device side are provided, and means for setting encryption / decryption keys and means for storing keys in each device. Is provided. Key settings are basically stored only once when the system is established.
It is not always performed in real time every time data is transmitted.

In other words, a relationship of sharing an encryption / decryption key is provided between the optical storage device and the audio playback device in the system owned by the individual, and the data exchanged between them is This means that data can be used only within the system, and data can be copied, stored, or transferred.

The purpose of the DVD video encryption system is to prevent the information contained on a disc from being copied onto another medium. For this reason, reproduction cannot be performed at all without a DVD disk.

An object of the present invention is to provide a system capable of fulfilling the management responsibility of the duplicate data of a CD even if the user is not particularly conscious of it. And this point is DV
Different from D-Video encryption system.

Since CD data is not originally recorded in an encrypted form, raw data can be intentionally read by a drive having an appropriate function.
Therefore, there is no need for strict encryption. Therefore,
The encryption / decryption algorithm may be simple or completely public.

There are two means depending on where the encryption is performed, as follows.

The first method is a method in which the hardware microcomputer or the firmware microcomputer performs software encryption inside the optical storage device.

The second method is that the optical storage device uses a CD
This is a method in which linear PCM data is output as it is and encrypted by software in a device driver section of an operating system (OS) of a personal computer. in this case,
The key is managed by the OS.

In any method, the data file is encrypted in the form of a data file that can be freely operated by a user on a personal computer.

Similarly, depending on where the decoding is performed, there are two types as follows.

The first method is a method in which a hardware microcomputer or a firmware microcomputer performs software decoding inside the audio reproducing apparatus.

The second method is a method in which when an audio reproducing device is provided inside a personal computer, decoding is performed by software using a device driver of the OS.

The CD data may be encrypted in the linear PCM data format as it is, but it is also possible to compress the data before encryption and to decompress the data after decryption. This is more practical for recording and storing data. In this case, as in the above-described method, there are a method of performing compression / decompression inside the apparatus and a method of performing compression / decompression using a device driver of an OS of a personal computer.

As a method for distributing the encryption / decryption key, there is the following method.

(1) If the optical storage device and the audio reproduction device can be physically connected directly and have communication means, the devices communicate with each other, determine a key, and share the key.

(2) If the optical storage device and the sound reproducing device are directly connected to the personal computer and have a communication means, the personal computer mediates communication between the devices and distributes the determined key.

(3) When the optical storage device is connected to a personal computer and the audio reproducing device is a portable player and is indirectly incorporated into the system via a data recording medium, key information is transferred through the recording medium. Means are provided, and keys are distributed by a recording medium.

As a problem caused by providing a simple digital copying means, there is a need to prohibit long-term storage of digital copies of rental CDs.

For this purpose, a method of invalidating the stored data by periodically updating the key is effective.

This is, so to speak, to give life to the copied digital data. Since the data itself cannot be degraded and disappeared, the audio reproducing apparatus is provided with a means for recording the number of times of reproduction or the total time of reproduction, and when the predetermined number of times or time is reached, a key update request is made. I do. At this point, the key stored in the apparatus is invalidated by deleting it. Thereafter, all data recorded and accumulated on the medium cannot be used.

If the data file has date information,
An expiration date is set and stored in the audio reproducing apparatus, and the file is reproduced and compared with the expiration date to request a key update.

When an audio reproducing apparatus such as a portable player has only a recording medium reproducing function and distributes a key by using a recording medium, the audio reproducing apparatus has a passive function of only storing a given key. Key setting. It is conceivable that an unauthorized user who does not want to update the key keeps the medium for key distribution and resets the same key as the previous key.

In order to prevent this, there is a method in which the device stores the previous key and rejects the key update if the key is the same at the time of update. If the key is updated, this method has no effect. In addition, there is a method of storing all keys several times to several tens of times in the past, and rejecting key update if the same key is specified among them, but there is a method of rejecting key update that exceeds the stored number. If the update is performed sequentially using the distribution medium, it is possible to return to the original key.

Therefore, it is desirable that an audio reproducing apparatus having only a medium reproducing function has a means for directly communicating with a personal computer for updating a key. In order to prevent the unauthorized use, the key needs to be actively generated by the audio reproducing apparatus.

As an active key generation method, when the encryption key and the decryption key are the same, at least one of the random number bit sequence generated by the optical storage device and the random number bit sequence generated by the audio reproducing device. There is a method of using a random number bit string including a character as a common key. When setting a key for each device, the device does not recognize a random key bit string generated by itself as a correct key if the bit string is not included in the key bit string.

In a sound reproducing apparatus having a recording function on a medium, if this method is used when a key is transferred via a recording medium, even if the medium is replaced with a previously used key distribution medium, it is detected. Key update can be performed correctly.

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 shows an example of a CD-ROM drive, a flash memory card, and a card-type player. Here, it is assumed that the optical storage device is a CD-ROM drive 11 and is built in a personal computer. The audio reproducing device is a portable card-type player 13 using a flash memory card 12 as a recording medium. Linear PCM in music CD10
The data is read by the CD-ROM drive 11, compressed and encrypted inside the drive, and transferred to the main memory of the personal computer.

The personal computer is also equipped with a card drive, and copies the encrypted CD data to the flash memory card 12 in a normal file format. The flash memory card is a portable medium, and is used by being attached to a portable card type player 13. The card-type player 13 reads data from the flash memory card 12, decrypts the data, further decompresses the data, and restores the original linear PCM.
The data is converted back to data, converted into an analog audio signal by a digital / analog converter, and output as music through earphones or the like. The dotted lines in the figure indicate physical boundaries between the devices.

Second Embodiment FIG. 2 shows an example of a CD-ROM drive, a hard disk drive, and a sound card in a personal computer. It is assumed that all devices are built in a personal computer housing. Here, the optical storage device is a CD-ROM drive 21, and the audio reproducing device is a sound card 23.

In the operating system of the personal computer, the user issues an instruction to copy music files in the CD drive to the hard disk by dragging and dropping.

The linear PCM data in the music CD 20 is read by the CD-ROM drive 21 and sent to the main memory of the motherboard of the personal computer as it is. The operating system of the personal computer (the physical entity is the CPU of the personal computer) compresses this CD data,
The data is encrypted and recorded and stored on the hard disk 22 in the same manner as a normal data file.

Next, the user gives an instruction to play back music to the copied file on the hard disk by double-clicking or the like. The data file is once read into the main memory, and the operating system decodes and decompresses it to return to the original linear PCM data, and then transfers it to the sound card 23. Sound card 2
3 converts the data into an analog audio signal and sends the signal to an internal speaker of a personal computer or to an external audio device via an output terminal to reproduce the music. The dotted lines in the figure indicate physical boundaries between the devices.

In this example, the operating system performs encryption / decryption, compression / decompression processing by software, and has an advantage that an existing CD-ROM drive or sound card can be used as it is.

FIG. 3 shows an example of the encryption / decryption method.

A 32-bit primitive polynomial, G (x) = x ^ 32 + x ^ 31
An M-sequence random number bit string is generated by + x ^ 4 + 1, and an exclusive OR 31 of the bit string with the input data bit string is taken as an output data bit string. Encryption and decryption are exactly the same procedure, and the key is the same. The random number generating means can be constituted by a feedback shift register 34 in which a 32-bit shift register 32 and exclusive ORs 33a and 33b are combined, and the key is 32 bits and used as an initial value of a random number sequence. As the key storage means 35, for example, a memory such as an EEPROM which does not disappear even when the power is turned off is used.

For music reproduction, a fast forward / fast reverse function is essential. Therefore, it is effective to divide a data file of one music into small blocks, for example, 32 Kbytes, and initialize a random value for each unit.

The purpose of the encryption is not to keep the data confidential, but to make it data that can be used only by a specific audio playback device. Such a simple encryption method may be used.

However, a key management method is important instead.

FIG. 4 shows an example of a method for generating and distributing an encryption / decryption key.

In the example of the sound reproducing device-A 41, the sound reproducing device-O 42 and the optical storage device 43, the key is a 32-bit common key.

When a key update request is issued from any device, automatically from the operating system (OS) 44, or from a user, the OS that centrally manages each device issues this key update request. Tell each device. Each device generates a random number (here, 8 bits) and
Return to S. The OS generates a 32-bit common key required by the system by connecting these random number bit strings. The OS adds a random number to the portion less than 32 bits. The key thus completed is distributed to each device, and the setting of the key, that is, the storage in the non-volatile memory is requested.

Each device confirms that the received 32-bit key contains an 8-bit random number bit string generated by itself. If it is included, it is rewritten with this new key and the normal termination is notified to the OS. If not included, the OS is notified of abnormal termination without rewriting the key. The OS confirms the normal end of all the devices, and ends the key generation and distribution processing.
If there is an abnormal termination, notify the user to that effect and prompt correct update procedure.

In order to prohibit long-term preservation of a digital copy of a rental CD, it is necessary for the audio reproducing apparatus to periodically request a key update, and the following methods are available.

When the file has date information, (1) the validity period of the key is fixedly determined. Since the computer can manage the date and time, the date information is also sent at the time of key distribution, the audio playback device also stores the date, and when playing the music file, it compares it with the date when the file was created,
If the validity period is exceeded, a key update is requested. In this method, a key update request is always made at regular intervals, and a user who follows a regular use method of not reproducing an old file is forced to perform a troublesome work of key update, which is not preferable. But the simplest and easiest way.

(2) According to the date of the file to be reproduced,
Automatically extend the expiration date.

When a music file is played back, the file creation date is checked, compared with the date stored in the audio playback device, and if it is newer, the internally stored date is updated to the latest file date. The date of the file designated to be reproduced is compared with the date stored therein, and if there is a gap longer than the validity period, a key update is requested.

Here, there is a method of taking an average value of the creation dates of some files instead of the latest value of the creation dates of the files. However, it is necessary to put restrictions so that the date does not go back in the past.

If there is no date information in the file, (3) the file is managed by the number of reproductions or the total reproduction time. The number of times of reproduction or the reproduction time is stored, and is updated successively. When a predetermined number of times or time is reached, a key update is requested. Although this method is as simple as (1), it is not preferable because it periodically requests a key update.

(4) Reproduction files are identified, and the number of reproductions is counted.

It is desired to limit the number of times of reproduction of a specific data file, and the object can be achieved by providing a file identification means.

For example, a 256-byte array variable area for storing the number of times of reproduction is secured in the audio reproducing apparatus, and is cleared to zero when the key is updated. The file is identified by a hash function (for example, exclusive OR of data bytes of a plurality of fixed addresses of the file data), and the function value is used as a subscript of the array to increment the counter variable by +1. At this time, if the variable value exceeds a specified value of the maximum number of reproduction times (for example, 100 times), a key update is requested.

However, the hash function returns the same value with a probability of 1/256 even in different files. It can be said that the discrimination ability deteriorates while many songs are being reproduced. For this reason, it is necessary to periodically correct the number of incorrect identifications. For example, if the number of non-zero-valued variables exceeds half of the total (ie, it is clear that at least 128 different songs have been played), the minimum value among the non-zero values is changed to the non-zero value. There is a method of subtracting from all variables.

In the above example, the key update request is made, but the reproduction may be simply refused.

In addition, the following examples can be applied to the embodiment of the present invention.

(1) Addition of header information In a personal computer, there is a utility program that can easily change the file creation date, and the date of the file management information may be easily falsified. For this reason, it is effective to add header information to the head of the data to be encrypted and put the creation date here. At the same time, to clarify data management responsibilities,
The name and login name can also be included in the header.

(2) Encryption from the middle of the data If the CD linear PCM data is encrypted as it is, almost all the music data starts in a silent state. In the encryption method of the embodiment, the key value is visible as it is. In such a case, it is effective to perform the encryption not in the beginning of the file but in the middle of the file in which valid audio data surely exists.

(3) Check Before Reproduction If the keys of the encrypted file do not match, the file only produces noise sound. To prevent users from feeling uncomfortable, provide a means (such as a checksum) to confirm that the decryption was successful, check before actually playing the music, notify the user and do not play the audio Can also. When the data is compressed, the check can be performed by confirming the validity of the compression format.

[0080]

According to the present invention, the duplication, storage, and transfer of CD music data, which is a literary work, can be uniformly and easily handled as data files of a personal computer.

By removing the function of analog output from the optical disk device, there is also a secondary effect that the price of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system including a CD-ROM drive, a flash memory card, and a card-type player.

FIG. 2 is a diagram showing a system including a CD-ROM drive, a hard disk, and a sound card.

FIG. 3 is a diagram showing an encryption / decryption method.

FIG. 4 is a view for explaining a method of generating and distributing an encryption / decryption key.

[Explanation of symbols]

10 ... CD for music, 11 ... CD-R
OM drive, 12 ... flash memory card,
13: card-type player, 20: music CD,
21: CD-ROM drive, 22: Hard disk drive, 23: Sound card, 31
... Exclusive OR for encryption / decryption, 32 ... 32 bit shift register, 33a, 33b ... Exclusive OR for feedback shift, 34 ... M-sequence random number generating means by feedback shift register method, 35 ... Encryption / decryption Keys, 41 ... Sound reproducing device-A, 42 ... Sound reproducing device-
Otsu, 43: Optical storage device, 44: Key generation / distribution means (operating system).

Claims (9)

[Claims] 1. A CD (compact disk) linear PCM
In the relationship between an optical storage device (hereinafter referred to as an S device) from which data can be read and an audio reproducing device (hereinafter referred to as a D device) that converts digital data into an audio analog signal, data is transferred between these two devices. When there is a device capable of storing, transferring, and copying, and when CD linear PCM data is to be transferred through a route through the device (hereinafter, an open route), (1) the S device and the D device must be The encryption / decryption key is shared, this key information is stored in each device, (2) the linear PCM data is encrypted by the S device using the encryption key, and the data is output. (3) Open (4) Encrypted audio reproduction system for CD linear PCM data, characterized in that the data encrypted by the D device is converted into the original linear PCM data using a decryption key and output as an audio signal. Beam. 2. The system according to claim 1, wherein data compression is performed before encryption in the S device, and data expansion is performed after decryption in the D device. Compression-encrypted audio playback system. 3. An encrypted audio reproduction of CD linear PCM data according to claim 1, further comprising a key storage means and an encryption means for realizing the system function of claim 1 or 2. System device. 4. An apparatus for reproducing encrypted CD linear PCM data, comprising a key storage means and a decryption means for realizing the system functions of claim 1. 5. A system according to claim 1 or 2, wherein a key distribution system is used to directly transfer an S-device and a D-device by a cable when sharing an encryption / decryption key. An encrypted audio reproduction system for CD linear PCM data. 6. A system according to claim 1 or 2, wherein the operating system delivers a common encryption / decryption key to the S device and the D device connected to the personal computer. CD to do
A linear PCM data encrypted audio playback system. 7. A system according to claim 1 or 2, wherein a D device having a function of reproducing a digital information recording medium is connected to a personal computer by a recording / reproducing apparatus of the same type of digital information recording medium. An encrypted sound reproduction system for CD linear PCM data, which is a key distribution method for producing a recording medium including information and information requesting rewriting of a key, and distributing the key to a D device. 8. The system according to claim 1, wherein the D device counts and stores the reproduction time and the number of times of reproduction, and requests the key to be rewritten when the predetermined time or the number of times is reached. Characteristic CD linear P
CM data encrypted audio playback system. 9. A system according to claim 1, wherein at least S
A random number bit string including either the random number bit string generated by the device or the random number bit string generated by the D device is defined as a common key, and the S device or the D device stores its own device in the bit string of the distributed key. CD linear PCM characterized by a key generation method and a key authentication method characterized by rejecting the storage setting of a key in the case where the random number bit string generated by the key does not exist is regarded as an invalid key.
Data encryption audio playback system.