JP2004039036A - Contents utilization method using recording medium provided with two recording layers, and utilization system therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent contents from being erased erroneously and completely even due to any erroneous operations of a user, and to bill the charges according to the use of contents to the user. <P>SOLUTION: In the contents reception and distribution system that uses an IT home electric device incorporating an HDD, contents encrypted not to be changed or erased are recorded on the second layer of a two-layer recording medium, the contents are decoded by using a secret key provided from a contents manager when a user makes contents use contact with the manager, and a contents use right is provided. <P>COPYRIGHT: (C)2004,JPO

Description

【００２４】
但し、各変数は下記の通りである。
Ｌ：ヘッド，媒体間の結合インピーダンス
Ｖ：媒体の速度
Ｗ：記録されているトラックの幅
ｄ：ヘッド・媒体間の隙間
Ｍｒ：媒体の磁化成分
δ：媒体の磁性層の厚み
ａ_ｘ：減磁場の遷移パラメータ
２ｇ：磁気ヘッドのギャップ長さ
【００２５】
図４の（ｂ）は磁性層と磁気ヘッドの位置関係を示し、磁性層の上層部１３の厚みは１０ｎｍで、磁気ヘッド４１と磁性層上部とのギャップは１０ｎｍとし、磁性層の下層部１５の厚みは２０ｎｍで、磁気ヘッド４１と磁性層下層部とのギャップは２０ｎｍとし、それ以外のことは同一とする。この条件で、上記の式に当てはめると、ｘ＝０での位置での出力電圧において、下層部１５の残留磁化による電圧は、上層部１３の残留磁化による電圧の約２倍となる。この様子を図５の（ａ）および（ｂ）に示す。
【００２６】
図５の（ｃ）は、上層部１３と下層部１５とのパターンが重なる位置では、上層部１３の残留磁化による再生信号の電圧と下層部１５の残留磁化による電圧とが重畳されて出力されることを表している。予め、各層の残留磁化による出力電圧が判っているので、磁気ヘッド４１で読み取った再生信号を高周波でサンプリングし、波形解析を行うことにより、再生信号が何れの層によるのかを把握することが出来る。磁気記録媒体が２層記録媒体の場合には、上述のようにして、信号の記録，再生が行われる。
【００２７】
（第１の実施形態）
前述したように、２層記録媒体の下層部１５では、磁気ヘッド４１の接触などによる物理的な破壊を除いて、ユーザーによる書き込み、削除が出来ない。このことを利用して、ハードディスクを出荷する前にユーザーの大多数が使用する主なコンテンツを、そのままでは利用出来ないように、一部を除いて暗号化を行い、ハードデイスクの下層部１５に記録する。
【００２８】
次に、図６に示すように、ユーザーがこの下層部１５に記録されたコンテンツを利用するには、コンテンツの暗号化されていないコンテンツ情報（コンテンツ名称，コンテンツ管理者，契約先アドレス，契約条件，暗号化など）を読みとり、読み取った情報を用いて、まず情報の秘守に必要な公開鍵と秘密鍵とを作成し、その次にユーザーが希望するパスワードと公開鍵とを添えてコンテンツ管理者に対して、契約を申し込む（ステップ６０１）。
【００２９】
コンテンツ管理者は、本来、下層部１５の暗号化されたコンテンツを復号化する為のコンテンツ鍵は１種類であるが、ユーザーから提示されたパスワードと組み合わせて、パスワードが１種の鍵となるように、新たに契約したユーザー向けに暗号鍵を生成し、この暗号鍵をさらに上記公開鍵で暗号化してユーザーに配布する（ステップ６０２）。
【００３０】
ユーザーは、上記秘密鍵で暗号鍵を復号化して、復号化した暗号鍵を書き込みが出来る上層部１３に記録し保存する（ステップ６０３）。
【００３１】
その後、出荷前に２層記録媒体の下層部１５にあらかじめ記録されている暗号化されたコンテンツの中で、そのユーザにとって真に利用価値のある部分を利用する際において、ユーザがパスワードを入力すると、上層部１３に記録・保存された上記の暗号鍵がそのパスワードで復号化されて、コンテンツ鍵が生成され（ステップ６０４）、このコンテンツ鍵により下部層１５のコンテンツの中の暗号化された部分が復号化され（ステップ６０５）、ユーザーはコンテンツを利用することが出来るようになる（ステップ６０６）。
【００３２】
（第２の実施形態）
上記のように、コンテンツを利用する都度、ユーザーはパスワードを入力し、暗号化されたコンテンツを復号化する工程を用いても良いが、ユーザーに負担が掛かるので、図７に示すように、暗号化されたコンテンツが、コンテンツ鍵で復号化された時点で、上層部１５に復号化されたコンテンツが記録されるようにして、この時点から上層部１５の復号化済みコンテンツを利用出来るようにし（ステップ７０５）、以降パスワードを入力しなくてもユーザーがコンテンツを利用することが出来るようにしても良い（ステップ７０６）。（なお、その他の工程は図６の第１の実施形態と同様である。）
【００３３】
この場合、万が一に上層部１３に記録の復号化されたコンテンツが削除または改竄されたとしても、上記のように下層部１５の暗号化されたコンテンツをコンテンツ鍵で復号化すれば良いことになるので、問題は生じない。
【００３４】
（第３の実施形態）
また、コンテンツ管理者がコンテンツの利用制限に厳しくない場合には、下層部１５に記録するコンテンツを圧縮化した形式にし、ユーザーがコンテンツ管理者と利用契約を結ぶと、ユーザはコンテンツ管理者から解凍するソフトの供給を受け、下層部１５に記録されている圧縮化されたコンテンツをその解凍するソフトにより解凍し、その解凍されたコンテンツを上層部１３に記録し、上層部１３に書き込まれたコンテンツを以後、自由に利用出来るようにしても良い。
【００３５】
（他の実施形態）
以上、本発明の実施形態を詳述したが、本発明は、前述した実施形態の機能を実現するソフトウエアのプログラム（本実施形態では、図６と図７に示すフローチャートに対応したプログラム）を、システム或いは装置に直接或いは遠隔から供給し、そのシステム或いは装置のコンピュータがその供給されたプログラムを読み出して実行することによっても達成される場合を含む。その場合、プログラムの機能を有していれば、形態は、プログラムである必要はない。プログラムを供給するための記録媒体としては、例えばハードディスク、光ディスク、光磁気ディスク、ＭＯ、ＣＤ−ＲＯＭ、ＣＤ−Ｒなどがある。
【００３６】
【発明の効果】
以上説明したように、本発明によれば、記録層が２層で構成された記録媒体において、ユーザー側では書き込みや消去が不可能な片側の高Ｈｃの層に、コンテンツ管理者が供給する暗号化されたコンテンツを、所定の磁気転写方式で予め書き込みを行い、ユーザーがコンテンツ管理者とコンテンツ利用契約を結んだ後に、ユーザはコンテンツ管理者から復号用の鍵の供給を受けて、暗号化されたコンテンツを復号化し、復号化されたコンテンツをユーザが書き込み自在の他方の層に記録し、次回以降のコンテンツ利用の際は、その他方の層に新たに記録されたコンテンツを実行することで、ユーザーの如何なる誤操作に対しても、コンテンツが誤って完全に抹消されることが防止されると共に、コンテンツの利用に応じた課金をユーザーに対して行うことが可能となる効果を奏する。
【図面の簡単な説明】
【図１】本発明で用いる磁気記録媒体の２層構成を示す模式的断面図である。
【図２】本発明で用いる２層構成の磁気記録媒体の各層の磁気特性を示す線グラフ図である。
【図３】本発明で用いる２層構成の磁気記録媒体の下層部に対する磁気転写のための（ａ）は初期化工程、（ｂ）は転写工程を示す模式的断面図である。
【図４】（ａ）は本発明で用いる２層構成の磁気記録媒体における残留磁化の様子を示す線グラフ図、（ｂ）はその２層構成の磁気記録媒体と磁気ヘッドとの位置関係を示す模式的断面図である。
【図５】本発明で用いる２層構成の磁気記録媒体から磁気ヘッドにより読み出された再生信号の波形を示し、（ａ）は上層部の再生信号の波形を、（ｂ）は下層部の再生信号の波形を、（ｃ）は両２層の再生信号の波形をそれぞれ示す波形図である。
【図６】本発明の第１の実施形態において２層構成の磁気記録媒体の下層部に予め記録され暗号化されたコンテンツを復号化してユーザが利用するまでに至る手順を示す模式的流れ図である。
【図７】本発明の第２の実施形態において２層構成の磁気記録媒体の下層部に予め記録され暗号化されたコンテンツを復号化してユーザが利用するまでに至る手順を示す模式的流れ図である。
【符号の説明】
１１　磁気記録媒体の記録層
１３　上層部（上の記録層）：保磁力Ｈｃ１
１５　下層部（下の記録層）：保磁力Ｈｃ２
３１　マスターディスク
３３　軟磁性パターン
４１　磁気ヘッド[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of using content using a recording medium having two recording layers, and a system for using the content, and more particularly to a technique for enabling content to be used with security without erasing content even if a user performs an erroneous operation. .
[0002]
[Prior art]
In the current terminal equipment such as personal computers (personal computers) and workstations, regardless of whether the user needs it, various contents are pre-installed on the hard disk and occupy a large amount of the hard disk capacity. It is. One of the main reasons why the capacity of various contents has increased is that after the operating system (OS) became Windows (registered trademark) by Microsoft, a huge amount of data corresponding to graphic display was displayed. It is said that it became capacity.
[0003]
Currently, although hard disks are relatively inexpensive, they cost around tens of thousands of yen, and they are installed as additional units, making them inconvenient for portable use such as mobile devices. Attempt to secure a possible area. For this reason, the user tries to delete unnecessary items in the pre-installed contents, but there is a problem that mistaken deletion procedures delete other contents or delete shared files. Maybe. For this restoration, generally a backup disk supplied by the manufacturer can be used, but since all data etc. will be initialized, save the environment and data constructed by the user first on another recording medium. Therefore, there is a troublesome and troublesome trouble for the user that the setting for restoration has to be reset. Furthermore, a user who has poor storage of a backup disk needs to re-contract a contract to supply the contents properly and pay again.
[0004]
Also, the fact that the content is pre-installed at the time of shipment means that the usage fee of the content is included in the price of the product, and even if individual users are paid for the content they do not use, That would be unfair.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above points in the prior art, and its object is to prevent the content from being accidentally and completely deleted by any user's erroneous operation, and to prevent the content from being deleted. It is an object of the present invention to allow a user to be charged for use.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 provides a recording medium having two recording layers. Of these two layers, the first layer on one side on which writing and erasing cannot be performed on the user side is provided. This is a method of using the content using a medium in which the compressed content supplied by the content manager is recorded in advance at the time of shipment, and the user decompresses the content according to the content usage contract with the content manager. And a decompressing step of decompressing the content compressed on the first layer of the medium by the decompressing software, and decompressing the content decompressed in the decompression step to the other one of the media. In the recording step of recording on the layer, and when the user subsequently uses the content, the content written on the second layer of the medium is read and executed. Characterized in that it comprises a processing step.
[0007]
According to a second aspect of the present invention, the recording layer of the recording medium is composed of two layers. Of the two layers, the first layer on one side on which the user cannot write or erase is supplied by the content manager. This is a method of using content using a medium in which encrypted content is recorded in advance at the time of shipment, and when a user enters a content usage contract with a content manager, the content is set according to a password set by the user. A distribution step in which a secret key is distributed from an administrator; a recording step of recording the secret key distributed in the distribution step on the other second layer of the medium; Using the secret key written in the second layer of the medium and a user password, the encrypted content recorded in the first layer of the medium is used. A decoding step for decoding, characterized in that it comprises a processing step of executing the content that has been decrypted by the decoding step.
[0008]
According to a third aspect of the present invention, the recording layer of the recording medium is composed of two layers. Of these two layers, the first layer on one side which cannot be written or erased by the user is supplied by the content manager. This is a method of using content using a medium in which encrypted content is recorded in advance at the time of shipment, and when a user enters a content usage contract with a content manager, the content management is performed according to a password set by the user. A distribution step in which a secret key is distributed from a user, and, when a user first uses the content, the first layer of the medium using the secret key distributed in the distribution step and a user password. A decrypting step of decrypting the encrypted content recorded in the medium, and transmitting the content decrypted in the decrypting step to the other of the medium. A recording step of recording in the layer eyes, when the content use of the next time the user, characterized in that it comprises a processing step of reading and executing the content recorded the the second layer of the medium.
[0009]
According to a fourth aspect of the present invention, the recording layer of the recording medium is composed of two layers. Of these two layers, the first layer on one side which cannot be written or erased by the user is supplied by the content manager. A content utilization system using a medium in which compressed content is recorded in advance at the time of shipment, wherein a user uses a decompression system supplied from the content manager in accordance with a content usage contract with the content manager. Decompressing means for decompressing the content recorded on the first layer of the medium by the software of the above, recording means for recording the decompressed content on the other second layer of the medium, and subsequent user use of the content In this case, there is provided processing means for reading and executing the content written in the second layer of the medium.
[0010]
According to a fifth aspect of the present invention, the recording layer of the recording medium is composed of two layers. Of these two layers, the first layer on one side on which writing and erasing cannot be performed by the user is supplied by the content manager. A content usage system using a medium in which encrypted content is recorded in advance at the time of shipment, wherein the user manages the content in accordance with a password set by the user at the time of a content usage contract with a content manager. Receiving means for receiving a secret key distributed from a user, recording means for recording the received secret key in the other second layer of the medium, and the second means of the medium when the user subsequently uses the content. Decryption for decrypting the encrypted content recorded on the first layer of the medium using the secret key and the user password written on the layer. And having a processing means for executing means, the content that has been decrypted.
[0011]
According to a sixth aspect of the present invention, the recording layer of the recording medium is composed of two layers. Of these two layers, the first layer on one side on which writing and erasing cannot be performed by the user is supplied by the content manager. A content usage system using a medium in which encrypted content is recorded in advance at the time of shipment, wherein the user manages the content in accordance with a password set by the user at the time of a content usage contract with a content manager. Receiving means for receiving a secret key distributed from a user, and when the user first uses the content, records on the first layer of the medium using the received secret key and the password of the user. Decrypting means for decrypting the encrypted content, and recording means for recording the decrypted content on the other second layer of the medium; When content usage subsequent users, and having a processing means for reading and executing the content recorded the the second layer of the medium.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Basic configuration)
In the present invention, as a recording medium for a hard disk, as shown in FIG. 1, a two-layer recording medium in which a recording layer indicated by reference numeral 11 is composed of two layers indicated by reference numerals 13 and 15 is employed. The magnetic characteristics of each layer of the two-layer recording medium are shown by an upper recording layer (hereinafter referred to as an upper layer) 13 having a low coercive force Hc1 as shown by a broken line curve in FIG. 2 and a solid line curve in FIG. And two lower recording layers (hereinafter referred to as lower layer portions) 15 having a high coercive force Hc2.
[0013]
The configuration in FIG. 1 is schematically shown schematically for easy understanding. Actually, for example, a medium substrate, a first underlayer, a lower recording layer (lower layer 15), a separation layer, 2 is a structure in which an underlayer, an upper recording layer (upper layer 13), and a carbon protective layer are sequentially laminated.
[0014]
Since the coercive force of the two recording layers 13 and 15 has a relationship of Hc1≪Hc2, the lower layer portion 15 has a high coercive force. Data cannot be written to the lower layer 15 and writing to the lower layer portion 15 is performed only by a hard disk manufacturer using a magnetic transfer technique.
[0015]
Please refer to Japanese Patent Application Laid-Open No. 2001-34939 for the basic contents of this magnetic transfer technique. The details of the above-described transfer technology to a two-layer recording medium are described in Japanese Patent Application No. 2001-279907 (filed on Sep. 14, 2001) proposed by the present applicant, and are referred to. I want to.
[0016]
Hereinafter, only the magnetic transfer method to the lower layer portion of the two-layer recording medium directly related to the present invention will be described. FIG. 3 shows an outline of the magnetic transfer technique.
[0017]
First, in the initialization step shown in FIG. 3A, a magnetic field in the horizontal direction with respect to the magnetic recording medium (hard disk), which is larger than Hc1 and Hc2, is applied to the recording layer. Numeral 11 indicates that the upper layer 13 and the lower layer 15 are both initially magnetized (black arrows indicate the direction in which the magnetic field is applied; the same applies hereinafter).
[0018]
Next, in a transfer step to the lower layer portion 15 shown in FIG. 3B, a non-magnetic substrate in which a soft magnetic layer (soft magnetic pattern) 33 processed into a linear or island pattern is embedded in the surface portion. An external magnetic field Hex is applied to the magnetic recording medium in a horizontal direction in a state where the magnetic transfer master disk 31 made of is in close contact with or close to the magnetic recording medium. At this time, the external magnetic field Hex is a magnetic field in a direction opposite to the initial magnetic field, and the magnitude satisfies Hc1≪Hex and Hc2 ≒ Hex.
[0019]
As a result, since the external magnetic field Hex is sufficiently larger than the coercive force Hc1 of the upper layer portion 13, regardless of the presence of the soft magnetic pattern 33 of the master disk 31, the upper layer portion 13 moves in the direction of the magnetic field of the external magnetic field Hex (ie, It is uniformly magnetized in the direction opposite to the initial magnetization (indicated by an arrow). On the other hand, in the lower layer portion 15, since the leakage magnetic field below the soft magnetic pattern 33 is not so large as to reverse the magnetization, the initial magnetization is kept under the soft magnetic pattern 33, but the external magnetic field is not provided in the portion without the soft magnetic pattern 33. The magnetization is reversed by the magnetic field Hex (indicated by black arrows). Thus, the transfer of the soft magnetic pattern 33 of the master disk 31 is performed on the lower layer portion 15.
[0020]
In this manner, the lower layer 15 of the magnetic recording medium corresponding to the first layer on one side, on which writing and erasing is not possible on the user side, is performed by using the above-described magnetic transfer technology, for example, as described below. The compressed content supplied by the administrator is recorded in advance at the time of shipment. On the other hand, in the upper layer portion 13 of the magnetic recording medium corresponding to the other second layer, data or the like is recorded on the user side using a normal magnetic head (see 41 in FIG. 4).
[0021]
Since the signal recorded on the magnetic recording medium is reproduced by one magnetic head, the signals of the lower layer 15 and the upper layer 13 are superposed and detected. For example, there is a method using a difference in amplitude of a reproduced signal, and FIG. 4 shows a separation method based on the difference in amplitude of the reproduced signal.
[0022]
FIG. 4A shows the magnetic characteristics of the magnetic material. Once the magnetic material experiences a large magnetic field, a constant residual magnetization remains even when the magnetic field is zero. When the residual magnetization remains inside the magnetic field, a magnetic field is generated in a direction to cancel the magnetization, and this is called a demagnetizing field. The reproduction signal of the magnetic head is expressed by the following equation.
[0023]
(Equation 1)

[0024]
However, each variable is as follows.
L: coupling impedance between head and medium V: speed of medium W: width of recorded track d: gap between head and medium Mr: magnetization component of medium δ: thickness of magnetic layer of medium a _x : demagnetizing field Transition parameter 2g: gap length of magnetic head
FIG. 4B shows the positional relationship between the magnetic layer and the magnetic head. The thickness of the upper layer 13 of the magnetic layer is 10 nm, the gap between the magnetic head 41 and the upper part of the magnetic layer is 10 nm, and the lower layer 15 of the magnetic layer is formed. Has a thickness of 20 nm, the gap between the magnetic head 41 and the lower part of the magnetic layer is 20 nm, and the other things are the same. Under this condition, when applied to the above equation, at the output voltage at the position of x = 0, the voltage due to the residual magnetization of the lower layer portion 15 is about twice as large as the voltage due to the residual magnetization of the upper layer portion 13. This situation is shown in FIGS. 5A and 5B.
[0026]
In FIG. 5C, at the position where the patterns of the upper layer portion 13 and the lower layer portion 15 overlap, the voltage of the reproduction signal due to the residual magnetization of the upper layer portion 13 and the voltage due to the residual magnetization of the lower layer portion 15 are superimposed and output. It represents that. Since the output voltage due to the residual magnetization of each layer is known in advance, the reproduction signal read by the magnetic head 41 is sampled at a high frequency, and the waveform analysis is performed, so that it is possible to grasp which layer the reproduction signal belongs to. . When the magnetic recording medium is a two-layer recording medium, signal recording and reproduction are performed as described above.
[0027]
(1st Embodiment)
As described above, the lower layer 15 of the two-layer recording medium cannot be written or deleted by the user except for physical destruction due to contact with the magnetic head 41 or the like. Taking advantage of this, the main contents used by the majority of users before shipping the hard disk are encrypted except for a part so that they cannot be used as they are, and are recorded in the lower layer 15 of the hard disk. I do.
[0028]
Next, as shown in FIG. 6, in order for the user to use the content recorded in the lower layer portion 15, the content information (content name, content manager, contractor address, contract condition) , Encryption, etc.), and using the read information, first create a public key and a private key necessary for confidentiality of the information, and then attach the password and public key desired by the user to manage the contents. Apply for a contract with the person (step 601).
[0029]
Although the content manager originally has only one type of content key for decrypting the encrypted content of the lower layer unit 15, the content manager combines the password with the password presented by the user so that the password becomes one type of key. Then, an encryption key is generated for the newly contracted user, and this encryption key is further encrypted with the public key and distributed to the user (step 602).
[0030]
The user decrypts the encryption key with the secret key, and records and stores the decrypted encryption key in the writable upper layer 13 (step 603).
[0031]
Thereafter, when the user inputs a password when using a portion of the encrypted content pre-recorded in the lower layer portion 15 of the double-layer recording medium that is truly useful for the user before shipping. The above-mentioned encryption key recorded and stored in the upper layer unit 13 is decrypted with the password to generate a content key (step 604), and the encrypted portion of the content of the lower layer 15 by this content key. Is decrypted (step 605), and the user can use the content (step 606).
[0032]
(Second embodiment)
As described above, every time the content is used, the user may enter a password and use a process of decrypting the encrypted content. However, since a burden is imposed on the user, as shown in FIG. When the decrypted content is decrypted with the content key, the decrypted content is recorded in the upper layer unit 15 so that the decrypted content of the upper layer unit 15 can be used from this point ( Step 705), the user may be allowed to use the content without inputting a password thereafter (step 706). (The other steps are the same as those of the first embodiment in FIG. 6)
[0033]
In this case, even if the decrypted content recorded in the upper layer unit 13 is deleted or falsified, the encrypted content in the lower layer unit 15 may be decrypted with the content key as described above. Therefore, no problem arises.
[0034]
(Third embodiment)
If the content manager is not strict about the usage restrictions on the content, the content to be recorded in the lower layer part 15 is compressed and when the user enters into a usage contract with the content manager, the user decompresses the content from the content manager. Receiving the supplied software, decompresses the compressed content recorded in the lower layer section 15 by the decompressing software, records the decompressed content in the upper layer section 13, and writes the content written in the upper layer section 13. May be made freely available thereafter.
[0035]
(Other embodiments)
As described above, the embodiment of the present invention has been described in detail. In the present invention, a software program (a program corresponding to the flowcharts shown in FIGS. 6 and 7 in the present embodiment) for realizing the functions of the above-described embodiment is used. This is also achieved by directly or remotely supplying a system or device, and a computer of the system or device reading and executing the supplied program. In that case, the form need not be a program as long as it has the function of the program. Examples of the recording medium for supplying the program include a hard disk, an optical disk, a magneto-optical disk, an MO, a CD-ROM, and a CD-R.
[0036]
【The invention's effect】
As described above, according to the present invention, in a recording medium having two recording layers, the encryption provided by the content manager is applied to one high-Hc layer that cannot be written or erased on the user side. After the content is written in advance by a predetermined magnetic transfer method and the user signs a content usage contract with the content manager, the user receives a decryption key from the content manager and By decrypting the decrypted content, recording the decrypted content on the other writable layer by the user, and executing the newly recorded content on the other layer the next time the content is used, In response to any user's erroneous operation, the content is prevented from being completely deleted by mistake, and the user is charged for the use of the content. An effect that it is possible to perform with.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a two-layer structure of a magnetic recording medium used in the present invention.
FIG. 2 is a line graph showing magnetic properties of each layer of a magnetic recording medium having a two-layer structure used in the present invention.
FIGS. 3A and 3B are schematic cross-sectional views showing an initialization step and a transfer step for magnetic transfer to a lower layer portion of a two-layer magnetic recording medium used in the present invention.
4A is a line graph showing the state of residual magnetization in a magnetic recording medium having a two-layer structure used in the present invention, and FIG. 4B is a diagram showing a positional relationship between the magnetic recording medium having the two-layer structure and a magnetic head; It is a typical sectional view shown.
5A and 5B show a waveform of a reproduction signal read by a magnetic head from a magnetic recording medium having a two-layer structure used in the present invention, wherein FIG. 5A shows a waveform of a reproduction signal of an upper layer portion, and FIG. FIG. 3C is a waveform diagram showing a waveform of a reproduced signal, and FIG.
FIG. 6 is a schematic flow chart showing a procedure from decryption of content pre-recorded and encrypted in a lower layer portion of a magnetic recording medium having a two-layer structure to use by a user in the first embodiment of the present invention; is there.
FIG. 7 is a schematic flow chart showing a procedure from decrypting pre-recorded and encrypted content in a lower layer portion of a two-layered magnetic recording medium to using it by a user in the second embodiment of the present invention. is there.
[Explanation of symbols]
11 Recording layer 13 of magnetic recording medium Upper layer (upper recording layer): coercive force Hc1
15 Lower layer (lower recording layer): coercive force Hc2
31 Master Disk 33 Soft Magnetic Pattern 41 Magnetic Head

Claims (6)

The recording layer of the recording medium is composed of two layers. Of these two layers, compressed contents supplied by the contents manager are shipped in advance to the first layer on one side which cannot be written or erased by the user side. Sometimes a method of using content using a recorded medium,
A user receives supply of decompression software from the content manager in accordance with a content usage contract with the content manager, and decompresses the content compressed on the first layer of the medium by the decompression software. Decompression step,
A recording step of recording the content decompressed in the decompression step on the other second layer of the medium;
A step of reading and executing the content written in the second layer of the medium when the user subsequently uses the content, wherein the recording medium includes two recording layers. How to use the content used. The recording layer of the recording medium is composed of two layers. Of the two layers, the encrypted content supplied by the content manager is shipped in advance to the first layer on which the user cannot write or erase. Sometimes a method of using content using a recorded medium,
A distribution step in which a secret key is distributed from the content manager according to the password set by the user when the user has a content usage contract with the content manager;
A recording step of recording the secret key distributed in the distribution step on the other second layer of the medium;
At the time of subsequent use of the content of the user, the encrypted key recorded on the first layer of the medium is used by using the secret key and the user password written on the second layer of the medium. Decrypting the decrypted content;
And a processing step of executing the content decrypted in the decrypting step. A method of using content using a recording medium having two recording layers. The recording layer of the recording medium is composed of two layers. Of the two layers, the encrypted content supplied by the content manager is shipped in advance to the first layer on which the user cannot write or erase. Sometimes a method of using content using a recorded medium,
A delivery step in which a secret key is delivered from the content manager according to the password set by the user when the user enters into a content usage contract with the content manager;
When the user first uses the content, the encrypted content recorded in the first layer of the medium is encrypted using the secret key and the user password distributed in the distribution step. A decoding step for decoding;
A recording step of recording the content decrypted in the decrypting step on the other second layer of the medium;
And a processing step of reading and executing the content recorded on the second layer of the medium when the user uses the content from the next time on, the recording medium having two recording layers. How to use content using. The recording layer of the recording medium is composed of two layers. Of these two layers, compressed contents supplied by the contents manager are shipped in advance to the first layer on one side which cannot be written or erased by the user side. Sometimes a content usage system using a recorded medium,
A decompression means for a user to decompress the content recorded on the first layer of the medium by decompression software supplied from the content manager in accordance with a content usage contract with the content manager;
Recording means for recording the decompressed content on the other second layer of the medium; and reading and executing the content written on the second layer of the medium when the user subsequently uses the content. A content utilization system using a recording medium having two recording layers, comprising: a processing unit. The recording layer of the recording medium is composed of two layers. Of the two layers, the encrypted content supplied by the content manager is shipped in advance to the first layer on which the user cannot write or erase. Sometimes a content usage system using a recorded medium,
Receiving means for receiving a secret key distributed from the content manager according to a password set by the user when the user has made a content usage contract with the content manager;
Recording means for recording the received secret key in the other second layer of the medium;
At the time of subsequent use of the content of the user, the encrypted key recorded on the first layer of the medium is used by using the secret key and the user password written on the second layer of the medium. Decryption means for decrypting the content,
Processing means for executing the decrypted content. A content utilization system using a recording medium having two recording layers. The recording layer of the recording medium is composed of two layers. Of the two layers, the encrypted content supplied by the content manager is shipped in advance to the first layer on which the user cannot write or erase. Sometimes a content usage system using a recorded medium,
Receiving means for receiving a secret key distributed from the content manager according to a password set by the user when the user has made a content usage contract with the content manager;
When the user uses the content for the first time, decrypting the encrypted content recorded on the first layer of the medium using the received secret key and the user's password. Means,
Recording means for recording the decrypted content on the other second layer of the medium;
Processing means for reading and executing the content recorded in the second layer of the medium when the user uses the content from the next time on, the recording medium having two recording layers Content usage system using.

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