JP2002290395A - Information terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem of a conventional reproduction device in which all contents are decoded and illegally distributed when a key used to encrypt a contents key is leaked because the key to encrypt the contents key used to encrypt contents is constant. SOLUTION: The information terminal (2) of this invention is provided with a particular key basic data generating means (12) that obtains particular key basic data depending on information other than particular information of the information terminal (2), a particular key generating means (16) that generates a particular key from the particular key basic data and the particular information and a contents key encryption means (7) that uses the particular key to encrypt the contents key.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a content distribution system for distributing digital data contents such as music data, image data, application programs, and game programs to an information terminal device, thereby preventing illegal distribution of the distributed contents. The present invention relates to an information terminal device capable of performing such operations.

[0002]

2. Description of the Related Art In a conventional content distribution system, for example, as disclosed in JP-A-2000-209169,
The content key at the time of encrypting the content is encrypted using the identification number unique to the playback device that plays back the content as a key. When decrypting the encrypted content, the playback device decrypts the encrypted content key using the identification number unique to the playback device as a key, and further decrypts the content with the content key. By encrypting the content key at the time of encrypting the content using the identification number unique to the playback device as a key, the playback of the content on playback devices other than the desired playback device is prohibited, and the illegal distribution of the content is prevented. .

[0003]

In the above prior art, since the key for encrypting the content key when encrypting the content in a certain playback apparatus is constant, the content key is encrypted. If the key to be encrypted is leaked, there is a problem that all contents are decrypted and illegally leaked. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to prevent illegal outflow of contents and further improve security.

[0004]

An information terminal device according to the present invention encrypts a content, which is distributed digital data, with a content key, which is a first encryption key, and encrypts the content key with a second encryption key. An information terminal device that encrypts with a unique key that is a key and stores the encrypted content and the encrypted content key; and a unique information storage unit that stores unique information of the information terminal device; Means for generating unique key basic data that is data for generating a unique key and that depends on information other than the unique information, and a unique key that generates the unique key from the unique key basic data and the unique information Generating means for generating digital data of a predetermined length and using the generated digital data as the content key; and Content key encryption means for encrypting the content key, content encryption means for encrypting the content with the content key, and a data storage unit for storing the encrypted content and an encrypted unique key. It is provided with.

The information terminal device according to the present invention further comprises a unique key basic data management table for associating the unique key basic data with a unique key basic data ID unique to each unique key basic data; Unique key basic data ID generating means for generating a key basic data ID, wherein the unique key basic data generating means refers to the unique key basic data management table; The unique key basic data corresponding to the generated unique key basic data ID is obtained.

Further, in the information terminal device according to the present invention, the unique key basic data ID generating means generates the unique key basic data ID from the distributed content.

Further, in the information terminal device according to the present invention, the unique key basic data ID generating means generates a random number and generates the unique key basic data ID from the generated random number.

Further, in the information terminal device according to the present invention, the unique key basic data generating means obtains the unique key basic data using the attribute value of the distributed content and arbitrary digital data. is there.

Further, an information terminal device according to the present invention provides a numerical value converting means for numerically converting the attribute value of the distributed content according to a predetermined procedure and outputting it as a conversion attribute value, and for encrypting the conversion attribute value. A conversion attribute encryption key management table for associating the conversion attribute encryption key with a conversion attribute encryption key ID unique to each conversion attribute encryption key, and the conversion attribute encryption key ID from the arbitrary digital data A conversion attribute encryption key ID generating means for generating a conversion attribute encryption key from the conversion attribute encryption key ID generated by the conversion attribute encryption key ID generation means with reference to the conversion attribute encryption key management table. Conversion attribute encryption key generation means,
The unique key basic data generation means obtains the unique key basic data by encrypting the conversion attribute value output by the numerical value conversion means with the conversion attribute encryption key generated by the conversion attribute encryption key generation means. Things.

Further, the information terminal device according to the present invention provides a unique key basic data ID of the unique key basic data management table.
And the unique key basic data corresponding to the unique key basic data ID. The unique key basic data corresponding to the distributed unique key basic data ID in the unique key basic data management table is stored in the distributed unique key. This is to replace the basic data.

In the information terminal device according to the present invention, the unique key basic data of the unique key basic data management table is updated based on time-dependent data unique to the information terminal device.

Further, in the information terminal device according to the present invention, the information terminal device is a mobile phone, and the unique information is a telephone number of the mobile phone.

Further, in the information terminal device according to the present invention, the data storage section is formed of a non-volatile memory, and is detachable from the information terminal device.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1. Embodiment 1 is shown in FIG.
This will be described with reference to FIGS. Referring to FIG.
FIG. 2 is a configuration diagram of a content distribution system according to the present embodiment, FIG. 2 is an internal configuration diagram of a unique key management unit, FIG. 3 is a diagram of a unique key code management table, and FIG. 5 is a flowchart showing an operation of generating a unique key in FIG. 4, FIG. 6 is a flowchart showing an operation of loading a capsule and decrypting contents, and FIG. 7 is a flowchart showing an operation of generating a unique key in FIG.

In FIG. 1, reference numeral 1 denotes a content distribution server that distributes digital data content such as music data, image data, application programs, and game programs, and 2 denotes a mobile phone that receives the content distributed by the content distribution server 1. The terminal 3 is a data communication path for transmitting and receiving data between the content distribution server 1 and any mobile phone terminal 2.

Further, the configuration inside the portable telephone terminal 2 will be described. 4 is a content receiving means for receiving the contents distributed by the content distribution server 1 via the data communication path 3, and 5 is unique to the portable telephone terminal 2. A unique key managing unit that manages a unique key that is a common key of the content key; a content key generating unit that generates a content key that is a common key for encrypting the content; and a content that encrypts the content key with the unique key. Key encrypting means, 8 is an encrypted content key storing means for storing the encrypted content key encrypted with the unique key in the form of a file in the memory card, 9 is content encrypting means for encrypting the content with the content key, 10 is a capsule generating means for generating a capsule in which the above-mentioned encrypted content is stored. Capsules storage means for storing in the storage unit 50. In this embodiment, the capsule storage unit 50 is a memory card provided with a nonvolatile memory such as a flash memory, and is detachable from the mobile phone terminal 2. Further, reference numeral 19 denotes capsule loading means for loading the capsules stored in the capsule storage means 11 into a main storage memory (not shown) of the mobile phone terminal 2, and reference numeral 20 denotes encrypted content stored in the capsule storage means 11. An encrypted content key loading means for loading a key,
21 is an encrypted content key decrypting means for decrypting the encrypted content key with the unique key, and 22 is an encrypted content decrypting means for decrypting the encrypted content with the content key.

FIG. 2 is a block diagram showing the detailed configuration of the unique key management unit 5. Reference numeral 12 denotes a unique key code which is a search key used when searching for a unique key code from a unique key code management table 14 to be described later. Unique key code ID for generating ID
Generating means, 13 is a unique key code searching means for searching a unique key code from a unique key code management table 14, and 14 is a unique key code management managing one or more records composed of a unique key code ID and a unique key code A table 15 is a telephone number extracting means for extracting the telephone number of the mobile telephone terminal 2 from a telephone number storage means (not shown), and 16 is a common key unique to the mobile telephone terminal 2 based on the unique key code and the telephone number. And a unique key generating means for generating a unique key.

FIG. 3 shows an example of the unique key management table 14. The unique key code ID 17 is a search key for searching the unique key code 18 to be described later from the unique key code management table 14, and 18 is the unique key code ID. This is a unique key code uniquely determined by the key code ID 17. Here, all the mobile phone terminals 2 that receive the content distributed by the content distribution server 1 need to have the same unique key code management table 1.
4 is assumed.

The portable telephone terminal 2 is an information terminal device according to the present invention. Similarly, the telephone number is unique information, the telephone number storage means is unique information storage means, the unique key code ID.
Reference numeral 17 denotes a unique key basic data ID, unique key code 18 denotes unique key basic data, and capsule storage unit 50 denotes a data storage unit. Further, the unique key code ID generating means 12 is a unique key basic data ID generating means in the present invention. Similarly, the unique key code search means 13 is a unique key basic data generating means, and the unique key code management table 14 is a unique key basic data It is a management table.

The operation will be described. First, the mobile phone terminal 2
Will be described with reference to the flowchart of FIG. 4 when the content is received from the content distribution server 1 and stored in the capsule storage unit 11. First, the mobile phone terminal 2 is connected to the content distribution server 1 by the content receiving means 4.
(ST11). At this time, the content distribution server 1 may distribute the encrypted content to the mobile phone terminal 3 in order to prevent eavesdropping on the data communication path 3, or may distribute the plain text content. is there. When receiving the encrypted content, the content receiving means decrypts the content, and stores the content in the main memory of the mobile phone terminal 2 in plain text. Next, the unique key management unit 5 generates a unique key that is a common key unique to the mobile phone terminal 2 (ST12). This step ST12
5 is shown in the flowchart of FIG.

When the operation of generating the unique key is started, the unique key code ID generating means 12 generates the unique key code ID using some or all of the attribute values of the content received by the content receiving means 4 as seeds. (ST12-1). Here, the attribute value of the content includes an ID of the content (an attribute value for uniquely identifying the content), a name of the content, and a type of the content (for example, an attribute value for indicating a type of music data, image data, and the like). ), Content data itself, data size, content creation date / time, content update date / time, and the like. However, all of these attribute values need not necessarily be information included in the content data itself, and may be extracted from information associated with the content data. For example, the name of the content is not information included in the content data itself but information associated with the content managed by the operating system of the mobile phone 2. In this step, for example, a unique key code ID is generated from the data size of the content, which is one of the content attribute values. Here, the unique key code ID generating means 12 divides the data size of the content by n, which is the number of unique key code IDs, and regards the remainder as the unique key code ID. n is, for example, about 20, but is not particularly limited. Note that the logic when the unique key code ID generating means 12 generates the unique key code ID 17 is secret including the content attribute value to be used as a seed, and the user of the mobile phone terminal 2 is required to use the unique key code ID 17.
Is difficult to generate. When generating the unique key code ID from an attribute other than the data size of the content, for example, a known hash function SHA-1 is used, the content data itself is input to the hash function SHA-1, and the output is divided by n. The remainder may be used as the unique key code ID. Date data such as the content creation date and time and the content update date and time may be expressed in a suitable binary number and input to the hash function SHA-1, and the remainder obtained by dividing the output by n may be used as the unique key code ID. In any case, the unique key code ID depends on information other than the telephone number, which is unique information of the mobile phone terminal 2.

Next, the unique key code search means 13 searches the unique key code management table 14 for a unique key code using the unique key code ID generated by the unique key code ID generation means 12 as a search key (ST12-2). As described above, the unique key code ID depends on information other than the telephone number, which is the unique information of the mobile phone terminal 2. Therefore, the unique key code is also changed to information other than the phone number, which is the unique information of the mobile phone terminal 2. Dependent. Here, the unique key code management table 14
Is managed in a place where it cannot be accessed from the outside, and the user can use a unique key code 18
Suppose it is difficult to find. In ST12-3, the telephone number extracting means 15 extracts the telephone number of the mobile telephone terminal 2 from the telephone number storing means (not shown),
In step 12-4, the unique key generation unit 16 generates a unique key using the unique key code retrieved by the unique key code search unit 13 and the telephone number extracted by the telephone number extraction unit 15 as seeds. At this time, the unique key generation means 16 generates a unique key uniquely determined from the telephone number and the unique key code. Therefore,
The unique key generated by a certain mobile phone terminal 2 has a different telephone number and a different value from the unique key generated by another mobile phone terminal 2. In this step, for example, the unique key generation unit 16
Will generate a unique key from the logical sum of the telephone number and the unique key code. However, at this time, the data length of the unique key code is equal to the key length of the unique key, and is, for example, 128 bits. The logic when the unique key generating means 16 generates the unique key is secret, and it is assumed that it is difficult for the user of the mobile phone terminal 2 to generate the unique key.

Referring to FIG. 4 again, ST13 is a step in which the content key generation means 6 generates a content key. In this step, a content key that is a random value having no dependency on the information (for example, telephone number) unique to the mobile phone terminal 2 or the content is generated. If this content key has a dependency relationship with information and content unique to the mobile phone terminal, the security of content protection encrypted using this key is reduced, and there is no dependency relationship with information and content unique to the mobile phone terminal. It is desirable. Therefore, the content key generation means 6 generates a random number having a number of digits corresponding to the algorithm for encrypting the content, that is, digital data having a predetermined length, and uses the digital data as a content key.

The next step ST14 is a step in which the content key encryption means 9 encrypts the content key generated by the content key generation means 6 with the unique key generated by the unique key generation means 16. In this step, the content key is exchanged with an arbitrary common key cryptosystem (for example, DES, MIST).
Y etc.). Therefore, the content key encrypted with a certain unique key cannot be decrypted unless it is the same unique key as the encrypted unique key. ST15
Is a step in which the capsule storage unit 11 stores the encrypted content key encrypted by the content key encryption unit 7 in the capsule storage unit 50 in the form of a file. At this time, from among a plurality of encrypted content keys stored in the capsule storage unit 50, an encrypted content key obtained by encrypting a content key used for decrypting one encrypted content can be extracted. It is necessary to store the encrypted content key in the capsule storage unit 50. For this purpose, a certain encrypted content key is associated with the name of the content encrypted by the encrypted content key and stored in the capsule storage unit 50.

In step ST15, the content encryption means 9 executes
This is a step of encrypting the content with the content key generated by the content key generation means 6. In this step,
The content is encrypted by the common key encryption method. Therefore, the content encrypted with a certain content key cannot be decrypted unless the content key is the same as the content key at the time of encryption. ST15 is a step in which the capsule generation means 10 generates a capsule in which the encrypted content encrypted by the content encryption means 9 and the content attribute value are stored. At this time, the content attribute value stored in the capsule is one or more arbitrary content attribute values including the content attribute value that is a seed when the unique key generation unit 16 generates the unique key. For example, when the unique key generation unit 16 generates a unique key using the data size of the content as a seed, the capsule generation unit 10
The data size of the content and any other content attribute value are stored in the capsule. Here, the capsule is an object that logically stores the content attribute value and the encrypted content, and it is not always necessary that the encrypted content and the content attribute value are physically integrated. For example, when storing the encrypted content in the form of a file, it is sufficient if the content attribute value can be extracted based on the file name. At this time, the capsule contains a content key that is a key for decrypting the encrypted content stored in the capsule among the plurality of encrypted content keys stored in the memory card by the encrypted content key storage unit 8. It is necessary to store information for extracting the encrypted content key. For example, the information required to retrieve an encrypted content key is:
The name of the content, which is stored in the capsule as described above.

Step ST18 is a step of storing the capsules generated by the capsule generation means 10 by the capsule storage means 11 in the capsule storage section 50 in the form of a file. By the above operation, the encrypted content, the encrypted content key, and the attribute of the content are stored in the capsule storage unit 50. The capsule storage unit stores at least the encrypted content key, the name of the content encrypted by the encrypted content key, the encrypted content, and the attribute value of the content.

Next, the mobile phone terminal 2 of the first embodiment
The operation when decrypting the content stored in the capsule storage unit 50 will be described. FIG. 6 is a flowchart showing this operation. When the decryption of the content is started, in ST21, the capsule loading means 19
The capsules stored in the capsule storage unit 50 in the form of a file are stored in the main storage memory (not shown) of the mobile phone terminal 2.
To load. At this time, the capsule loading means 19
Each of the encrypted content and the content attribute value stored in the capsule is extracted. The next step ST22 is a step in which the unique key management unit 5 generates a unique key that is a common key unique to the mobile phone terminal 2. Details of the operation of the unique key generation step are shown in FIG.

In FIG. 7, ST 22-1 is a process in which the unique key code ID generating means 12 extracts the content attribute values extracted from the capsule loaded by the capsule loading means 19.
This is a step of generating a unique key code ID using one or more content attribute values as a seed. In this step, the unique key code ID is generated using the same content attribute value as the seed when the unique key code ID is generated when storing the content. ST22-2, ST22-
3 and ST22-4 are ST12-2 and ST22, respectively.
This is the same operation as 12-3 and ST12-4.

Referring again to FIG. 6, ST23 is a step in which the encrypted content key loading means 20 loads the encrypted content key stored in the capsule storage means. ST24 is an encrypted content key decryption means 21,
This is a step of decrypting the encrypted content key loaded by the encrypted content key loading means 20 with the unique key generated by the unique key generating means 16. ST25 is a step in which the encrypted content decrypting means 21 decrypts the encrypted content stored in the capsule loaded by the capsule loading means 19 with the content key decrypted by the encrypted content key decrypting means 21.

As described above, according to the first embodiment, the content stored in the capsule storage unit 50 by a certain mobile phone terminal 2 cannot be reproduced by another mobile phone terminal having a different telephone number. In addition, illegal outflow of contents can be more reliably prevented. In addition, since the content key for encrypting the content and the unique key for encrypting the content key for each content are different for each mobile phone terminal or for each content, illegal outflow of the content is more reliably prevented. Will be able to do it.

Second Embodiment In the first embodiment, at the time of storing a content, the unique key code ID generating means 12 sets the unique key code ID to one or more arbitrary content attribute values as a seed.
In the second embodiment, the unique key code ID generating unit 12 generates a random number and generates a random unique key code ID based on the generated random number.

The configuration of the content distribution system in this embodiment is the same as that of FIG. 1 described in the first embodiment, and the configuration of the unique key management unit 5 is also the same as that of FIG.
At this time, the unique key code ID generation means 12 changes the value from 0 to (n-
A random number which is an integer between 1) is generated, and this random number is used as a unique key code ID. This unique key code ID does not depend on the attribute value of the mobile phone terminal 2 or the content. This unique key code ID is the unique key basic data ID in the present invention.

Also, in the first embodiment, the capsule generating means 10 generates a capsule storing the content attribute value. In the second embodiment, the capsule generating means 10 A capsule is generated in which the unique key code ID, which is the generated random number, is stored in the capsule. Furthermore, in the first embodiment, when loading the content, the unique key code search unit 13 searches for the unique key code using the unique key code ID generated by the unique key code ID generation unit 12 as a search key. On the other hand, in the second embodiment, the unique key code ID search unit 12 searches for a unique key code using the unique key code ID stored in the capsule loaded from the capsule storage unit 50 by the capsule loading unit 19 as a search key. . Other operations are the same as those in the first embodiment.

In the first embodiment, when the same content is stored in a capsule storage unit such as a memory card in two different mobile phone terminals, the unique key for encrypting the content key is the same as the unique key code. , And are the same in the two mobile phone terminals. On the other hand, according to the second embodiment, if the unique key code ID is generated each time the content is encrypted, the unique key code can be made different for each mobile phone terminal and for each content. Therefore, the probability that the unique keys generated using the unique key codes as seeds are the same can be extremely reduced.
As described above, according to the second embodiment, since the unique key is not uniquely determined for each content to be stored, the encrypted content key is less likely to be illegally decrypted, and the unauthorized leakage of the content is more reliably performed. Can be prevented.

Embodiment 3 FIG. The third embodiment is different from the first embodiment or the second embodiment in that the configuration of the unique key management unit when the content is stored or when the content is loaded,
And the operation is improved. The configuration of the content distribution system in this embodiment is the same as that in FIG. 1 described in the first embodiment. However, the internal configuration of the unique key management unit 5 in FIG. 1 is different from that of the first embodiment, and is as shown in FIG. The operation when the mobile phone terminal 2 in this embodiment receives the content from the content distribution server 1 and stores it in the capsule storage unit 11 is the same as that in FIG. 4 described in the first embodiment. However, the operation of step ST12 for generating a unique key is different, as shown in FIG.

First, the content storage function according to the third embodiment will be described. FIG. 8 is a block diagram showing the configuration of the unique key management unit 5 according to the third embodiment. The same or corresponding parts as in FIG. In FIG. 8, reference numeral 23 denotes a hash key ID generation unit that generates a hash key ID that is a search key for searching for a hash key that is a common key used in a keyed hash function described later. A hash key search unit 25 for searching for a hash key that is a common key to be used is a hash key ID table that is a search key for the hash key, and a hash key management table that manages one or more records composed of hash keys. is there. Here, a hash function with a key is a function in which output data (hash value) when arbitrary data is input has a certain length of data, and it is difficult to calculate input data from the hash value in terms of computational complexity. (Unidirectionality), and it is computationally difficult to find two different input data so as to have the same hash value (collision avoidance).
It has two characteristics. Further, the keyed hash function includes a hash function and an encryption means, and encrypts an output of a predetermined hash function using a hash key which is a predetermined common key. As this hash function, for example, SHA-
1 is well known, and the output of SHA-1 is 160 bits, regardless of the length of the input. In this embodiment, SHA-1 is used as a hash function. Further, the hash function with a key is characterized in that when hash keys are different, different hash values are output even if input data is the same.

FIG. 9 shows an example of a hash key management table 25 for managing a record composed of a hash key ID, which is a search key for a hash key, and a hash key. In FIG. 9, reference numeral 26 denotes a hash key ID which is a search key used when searching for a hash key from the hash key management table 25;
Numeral 27 denotes a hash key used in the keyed hash function, which is assumed to be 128 bits as an example here.

Next, the operation when a unique key is generated in this embodiment will be described with reference to FIG. ST32-1 is a step in which the hash key ID generating means 23 generates a random number (arbitrary digital data) and generates a random hash key ID based on the generated random number.
ST32-2 is a hash key searching means 24,
This is a step of searching for a hash key from the hash key management table 25 using the hash key ID generated by the ID generation unit 23 as a search key. Here, hash key management table 0
Is managed in a location that cannot be accessed from the outside, and it is difficult for a user to find a hash key corresponding to an arbitrary hash key ID. ST32-3 is Embodiment 1
The telephone number extracting means 15 extracts the telephone number of the mobile phone terminal 2 from a telephone number storing means (not shown).

ST32-4 is a unique key generation means 16,
Output data when one or more arbitrary content attribute values are input data of a hash function with a key, and ST32-3
Is a step of generating a unique key using the telephone number extracted by the telephone number extracting means 15 as a seed. At this time, the hash key search means 24
Use the hash key retrieved by. In this step, for example, the content data itself, which is one of the content attribute values, is used as the input value of the keyed hash function, and a 160-bit output is first obtained by the hash function SHA-1.
The upper 128 bits of the 160 bits are encrypted by using a 128-bit hash key retrieved by the hash key retrieval means 24 as an encryption key using a cryptographic algorithm such as MISTY or DES. The output data of the function. This keyed hash function output is 128 bits. Next, the sum of the output of the keyed hash function and the telephone number is obtained, and this sum is used as a unique key. This unique key is also 128 bits.

In the first embodiment, the capsule generating means 10 generates a capsule storing the content attribute value. In the third embodiment, the capsule generating means 10 Generate a capsule that stores the generated unique key code ID in the capsule.

Next, the mobile phone terminal 2 of the third embodiment
The operation (content loading) when decrypting the content stored in the capsule storage unit 50 will be described. This operation is the same as that of FIG. 6 described in the first embodiment, except for the unique key generation step in ST22, and the operation is as shown in FIG. In FIG. 11, ST42-
Reference numeral 1 denotes a hash key search unit 24, which refers to a hash key management table 25 and stores a hash key stored in a capsule.
This is a step of searching for a hash key using the ID as a search key. Here, the hash key ID serving as a search key when searching for a hash key is obtained by extracting the hash key ID stored in the capsule loaded by the capsule loading means. The next steps ST42-2 and ST42-3 are the same as ST32-3 and ST32-4, respectively.

In the above description, the hash value is the conversion attribute value in the present invention. Similarly, the hash key is the conversion attribute encryption key, the hash key ID is the conversion attribute encryption key ID, and the hash key ID generation means 23 is the same. The conversion attribute encryption key ID generation unit and the hash key generation unit 24 are the conversion attribute encryption key generation unit, and the hash key management table 25 is the conversion attribute encryption key management table. Further, the numerical value conversion means in the present invention is the hash function in the above description, and this hash function is included in the unique key generation means 16.

In the first and second embodiments,
Since the unique key is generated using the unique key code as one of the seeds, the number of unique keys that can be generated is the number of unique key codes (for example, about 20) managed in the unique key code management table.
And the number was a very small number compared to the total number of possible values of a key having the same length as the unique key. (The total number of values that can be taken by a key having a length of 128 bits is 2 to the 128th power.) On the other hand, according to the third embodiment, a different content attribute value for each content is assigned to a hash function with a key. Is more secure because the number of unique keys used when storing content can be expected to be equal to the total number of content keys. Furthermore, a hash key ID that does not depend on the content is generated,
Since the hash key is searched by using the hash key ID and the hash key management table, the encrypted content key is difficult to be decrypted because different unique keys are assigned to the same content. It is possible to more reliably prevent illegal outflow of contents.

Embodiment 4 FIG. In the first and second embodiments, the unique key code management table for managing the unique key which is a seed when the unique key is generated is not changed. The security of the content in the content distribution system largely depends on the security of the unique key for encrypting the content key. In order to manage the unique key more safely, for example, the unique key code managed in the unique key code management table may be updated every certain period. In the fourth embodiment, the unique key code managed in the unique key code management table can be updated.

The configuration of the content distribution system in this embodiment is the same as that in FIG. 1 described in the first embodiment. FIG. 12 is a block diagram showing an internal configuration of the unique key management unit 5 according to the fourth embodiment. The same or corresponding parts as those in FIG. 2 are denoted by the same reference numerals and description thereof is omitted. Figure 1
2, reference numeral 28 denotes a unique key code receiving unit that receives a pair of a unique key code ID and a unique key code distributed by the content distribution server 1, 29 denotes a version number of the unique key code received by the unique key code receiving unit 28, Version number verification means 30 for comparing and verifying the version numbers of the unique key codes managed in the unique key code management table 14, 30 searches for the number of times the unique key codes managed in the unique key code management table 14 have been used, and A unique key code usage count verifying means for verifying whether or not there is a unique key code updating means for updating the current unique key code in the unique key code management table to a new unique key code received by the unique key code receiving means. Means.

FIG. 13 is an example of the unique key code management table 14 according to the fourth embodiment. In FIG. 13, reference numeral 32 denotes the number of times the unique key code is used when the content is stored in the memory card, and 33 denotes the unique key code version number which is the version number of each unique key code. It is.

The operation of updating the unique key code 18 in the unique key code management table 14 in the content distribution system according to the fourth embodiment will be described below. FIG. 14 is a flowchart showing an operation when the unique key code 18 managed in the content management table 14 is updated. ST51 is a unique key code receiving means 28
The new unique key code ID 17 and unique key code 18 distributed by the content distribution server 1 via the data communication path 3
This is a receiving step of receiving a pair of. The unique key code ID received here is the same as any unique key code ID in the unique key code management table 14. In this step, for example, the content distribution server 1 updates the new unique key code ID 17 and the unique key code 1
8 is distributed to the mobile phone terminal 2. The mobile phone 2 also receives the version number 33 of the unique key code. In addition, the mobile phone terminal 2 may receive a plurality of unique key codes ID17 different from each other at one time, or one unique key code ID 17 at a time.
Only the unique key code may be received. When the unique key code or the unique key code ID and the unique key code pair are encrypted for security in the data communication path 3, the unique key code receiving means 28 outputs the encrypted unique key code. Or, a pair of the unique key code ID and the unique key code is decrypted.

ST52 is the version number verification means 29
And the unique key code version number corresponding to the unique key code ID received by the unique key receiving means 28, and the unique key identical to the unique key code ID received by the unique key receiving means 28 in the unique key management table 14. This is a comparison verification step of comparing and verifying two unique key code version numbers with a unique key code version number corresponding to the code ID. At this time, if the version numbers of the two unique key codes match, it is determined that the unique key code has already been updated, and the unique key code in the unique key code management table 14 is not updated. Also, the unique key code receiving means 28
If the received unique key code version number is newer (larger number), the process proceeds to the next step ST53.

In ST53, the unique key code usage count verifying means 30 searches the unique key code usage count 32 of the unique key code management table 14 using the unique key code ID received by the unique key code receiving means 28 as a search key. Verify the number of times the retrieved unique key code is used. At this time, if the searched number of times of use of the unique key code is 1 or more, it is determined that there is content stored in the memory card using the current unique key code, and the process proceeds to step ST54.
At this time, if the searched number of times of use of the unique key code is 0, it is determined that there is no content stored in the memory card using the current unique key code, and step ST
Go to 55.

In ST54, the unique key code usage count is 1 in order to enable the update of the unique key code which cannot be updated as it is because the unique key code usage count is 1 or more. The content stored using the unique key code described above is stored in a new unique key code received by the unique key code receiving unit 28 or another unique key code in the unique key code management table 14, particularly, the version number. Is a step of saving to a memory card using a new (large version number) unique key code.

In this step, it is necessary to load the encrypted content stored in the memory card, and to store the encrypted content in the memory card. The operation at the time of saving is described in Embodiment 1,
2 when loading the content in, and
This is the same as the operation when saving content. However, when loading the encrypted content, the encrypted content key stored at the same time as encrypting the content is also loaded and used to generate the encrypted content key (encrypt the content key). The content key must be decrypted using the same unique key as Therefore, the unique key code I is stored in the unique key code management table.
The correspondence between D and the unique key code must be the same as when this content was encrypted. Then, the encrypted content is decrypted using the decrypted content key.

Next, when storing the encrypted content, a unique key code ID other than the received unique key code ID can be applied.
A new unique key is generated using the unique key code corresponding to D, and the content key is encrypted using the new unique key. The method of determining the applicable unique key code ID is as follows. For example, if the unique key code ID at the time of encrypting the content is C (0 ≦ C ≦ n−1), the unique key code ID is stored in the unique key code management table. Change the code ID from (C + 1) → (C + 2) →
.. → (n−1) → 0 → 1 →... Cyclically, and adopts the latest applicable unique key code ID. In the first embodiment, the method of determining the unique key code ID is determined by setting the data size of the content to n, which is the number of unique key code IDs.
, And the remainder is regarded as the unique key code ID. Here, a certain number is increased or decreased with respect to the remainder to become the unique key code ID. This fixed number is simultaneously stored in the capsule and used when determining the unique key code ID at the time of decryption.

However, here, the unique key code receiving means 28
Can store the content using the new unique key code received when the current unique key code does not need to be stored in the unique key code management table 14, that is, the current unique key code can be stored. Will be able to save all of the content saved using the new unique key code, or will be unable to load the content saved using the current unique key code. Only if permitted by the user who owns the content. In order to confirm this permission, a display indicating that the unique key code is to be changed is displayed on a display unit (not shown) of the mobile phone terminal 2, and the user inputs from the input unit (not shown) whether or not to permit the change. Further, in this step, it is assumed that the content can be saved using the new unique key code for one or more contents at the same time. At this time, the field value of the number of times the unique key code is used in the unique key code management table 14 is reduced by the number of unused unique key codes. When step ST54 is completed, the process returns to step ST53.

ST55 is a process for updating the unique key code means 31.
The unique key code received by the unique key code receiving means 28
The unique key code corresponding to the ID and the unique key code version number are replaced with the current record of the unique key code management table 14. At this time, if there is already a content stored on the memory card using the new unique key code received by the unique key code receiving means, the number of unique key code management tables 14
To the value of the unique key code usage count field.

As described above, according to the fourth embodiment, the unique key code can be updated, for example, every certain period, so that the unique key code can be updated as compared with the case where the same unique key code is continuously used. Become more secure. In addition, even if a certain unique key code is leaked, the existing unique key code can be invalidated by updating the existing unique key code with a new unique key code. You will be able to minimize it.

The content distribution server 1 may distribute the pair of the unique key code ID and the unique key code at predetermined time intervals.

Also, in order to reduce the processing time for updating the unique key code management table, it is determined that there is no need to update a unique key code that has never been used at any one time, and is not updated. Is also good. Here, the reason why the unique key code that has never been used need not be updated is that the risk of the value of the unique key code being leaked is smaller than that of the unique key code that is frequently used. . For example,
At this time, after a certain unique key code is used several times, the field value of the number of times of use is currently 0, and the field value of the number of times of use is changed because the unique key code has never been used. A field for managing the maximum value of the number of times of use up to the present is added to the unique key code management table in order to distinguish the case from zero. At this time, when the field value of the number of times of use is 0 and the field value of the maximum value of the number of times of use is 0, that is, since the unique key code has never been used, the field of the number of times of use is If the value is 0, it may be determined that there is no need to update the unique key code, and the unique key code may not be updated.

Embodiment 5 FIG. In the first and second embodiments, the unique key code management table for managing the unique key code, which is a seed when the unique key is generated, is common to all mobile phone terminals. In the fifth embodiment, an example is shown in which a higher security is provided by using a unique key code management table different between each mobile phone terminal.

The configuration of the content distribution system in this embodiment is the same as that in FIG. 1 described in the first embodiment. FIG. 15 is a block diagram showing the internal configuration of the unique key management unit 5 according to the fifth embodiment. 2 and 12 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 15, reference numeral 34 denotes a unique key code generation means for generating a unique key code unique to the mobile phone terminal for an arbitrary unique key code ID. In the fourth embodiment, the new unique key code for updating the current unique key code in the unique key code management table is the unique key code received by the unique key code receiving unit. On the other hand, in the fifth embodiment, a new unique key code is generated by the unique key code generation means by using information that should be unique to each mobile phone terminal, such as a call history and an incoming call history of each mobile phone terminal. This is a unique key code generated in. These call histories, incoming histories, and the like are time-dependent data unique to each mobile phone. This unique key code may be generated by generating a 160-bit hash value from the data of the call history and the incoming call history using, for example, a hash function SHA-1, and using the upper 128 bits as the unique key code. In addition, since the call history and the incoming call history change with time, a new unique key code may be generated at regular intervals (predetermined intervals). Here, the operation when updating the unique key code in the unique key management table after generating the new unique key code is the same as the operation in the fourth embodiment.

As described above, according to the fifth embodiment, since each mobile phone terminal can use a different unique key code, a case where the same unique key code is used in a plurality of mobile phone terminals It is extremely safe compared to. Further, when the mobile phone terminal is manufactured or shipped, the cost can be reduced as compared with a case where a unique key code management table different for each mobile phone terminal is written. Further, similar to the fourth embodiment, the unique key code can be updated at regular intervals, so that the same effects as in the fourth embodiment can be obtained.

[0061]

As described above, the information terminal device according to the present invention encrypts the content, which is the distributed digital data, with the content key, which is the first encryption key, and converts the content key into the second encryption key. In an information terminal device that stores the encrypted content and the encrypted content key, a unique information storage unit that stores unique information of the information terminal device; A unique key basic data generating means for obtaining unique key basic data which is data to be generated and which depends on information other than the unique information, and a unique key generation for generating the unique key from the unique key basic data and the unique information Means for generating digital data of a predetermined length and using the generated digital data as the content key; and the content key by the unique key. Content key encrypting means for encrypting the key, content encrypting means for encrypting the content with the content key, and a data storage unit for storing the encrypted content and an encrypted unique key. Since unique key basic data that depends on other than unique information is used for unique key generation, even if the unique information is leaked, the unique key cannot be generated and the security is high.

Further, the information terminal device according to the present invention includes: a unique key basic data management table for associating the unique key basic data with a unique key basic data ID unique to each unique key basic data; And a unique key basic data ID generating means for generating a basic data ID, wherein the unique key basic data generating means generates the basic data ID by referring to the unique key basic data management table. Since the unique key basic data corresponding to the obtained unique key basic data ID is obtained, there is an effect that the generation of the unique key basic data is easy.

In the information terminal device according to the present invention, the unique key basic data ID generating means generates the unique key basic data ID from the distributed content.
There is an effect that generation of the unique key basic data ID is easy.

In the information terminal device according to the present invention, the unique key basic data ID generating means generates a random number and generates the unique key basic data ID from the generated random number. There is an effect that it is difficult to do.

In the information terminal device according to the present invention, the unique key basic data generating means obtains the unique key basic data using the attribute value of the distributed content and arbitrary digital data. Has the effect of being difficult to leak.

Further, the information terminal device according to the present invention comprises a numerical value conversion means for numerically converting the attribute value of the distributed content according to a predetermined procedure and outputting the converted attribute value as a conversion attribute value, and for encrypting the conversion attribute value. A conversion attribute encryption key management table that associates a conversion attribute encryption key with a conversion attribute encryption key ID unique to each conversion attribute encryption key, and generates the conversion attribute encryption key ID from the arbitrary digital data. Conversion attribute encryption key ID generation means, and conversion for generating a conversion attribute encryption key from the conversion attribute encryption key ID generated by the conversion attribute encryption key ID generation means with reference to the conversion attribute encryption key management table Attribute encryption key generation means,
The unique key basic data generation means obtains the unique key basic data by encrypting the conversion attribute value output by the numerical value conversion means with the conversion attribute encryption key generated by the conversion attribute encryption key generation means. There is an effect that the key basic data is hard to leak.

Further, the information terminal device according to the present invention is characterized in that the unique key basic data ID in the unique key basic data management table
And the unique key basic data corresponding to the unique key basic data ID. The unique key basic data corresponding to the distributed unique key basic data ID in the unique key basic data management table is stored in the distributed unique key. The replacement with the basic data has an effect that the unique key basic data is hard to leak.

In the information terminal device according to the present invention, the unique key basic data in the unique key basic data management table is updated based on the time-dependent data unique to the information terminal device, so that the unique key basic data is not easily leaked. This has the effect.

Further, in the information terminal device according to the present invention, the data storage section is formed of a non-volatile memory, and is detachable from the information terminal device, so that there is an effect that the convenience is high.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a content distribution system according to Embodiments 1 to 5 of the present invention.

FIG. 2 is an internal configuration diagram of a unique key management unit according to the first and second embodiments.

FIG. 3 is a diagram of a unique key code management table.

FIG. 4 is a flowchart showing an operation of storing a capsule in the mobile phone terminal.

FIG. 5 is a flowchart showing an operation of generating a unique key in FIG. 4;

FIG. 6 is a flowchart showing an operation of loading a capsule and decoding content.

FIG. 7 is a flowchart showing an operation of generating a unique key in FIG. 6;

FIG. 8 is an internal configuration diagram of a unique key management unit according to the third embodiment.

FIG. 9 is a diagram of a hash key management table according to the third embodiment.

FIG. 10 is a flowchart showing an operation of a step of generating a unique key according to the third embodiment.

FIG. 11 is a flowchart showing an operation of generating a unique key according to the third embodiment.

FIG. 12 is an internal configuration diagram of a unique key management unit according to the fourth embodiment.

FIG. 13 is a diagram of a unique key code management table according to the fourth embodiment.

FIG. 14 is a flowchart showing an operation when updating a unique key code according to the fourth embodiment.

FIG. 15 is an internal configuration diagram of a unique key management unit 5 according to the fifth embodiment.

[Explanation of symbols]

1 content distribution server, 2 mobile phone terminal, 3
Data communication path, 4 content receiving means, 5 unique key managing unit, 6 content key generating means, 7 content key encrypting means, 8 encrypted content key storing means,
9 content encryption means, 10 capsule generation means, 11 capsule storage means, 12 unique key code ID
Generating means, 13 unique key code searching means, 14 unique key code management table, 15 telephone number extracting means,
16 unique key generation means, 17 unique key code ID, 1
8 unique key code, 19 capsule loading means, 2
0 encrypted content key loading means, 21 encrypted content key decryption means, 22 encrypted content decryption means, 23 hash key ID generation means, 24 hash key search means, 25 hash key management table, 26
Hash key ID, 27 hash key, 28 unique key code receiving means, 29 version number verification means,
30 unique key code use count verification means, 31 unique key code update means, 32 unique key code use count, 3
3 unique key code version number, 34 unique key code generation means, 50 capsule storage unit.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J104 AA04 AA16 EA06 EA18 EA26 NA02 NA12 NA35 NA37 NA41

Claims (10)

[Claims] 1. A distributed digital data content is encrypted with a content key that is a first encryption key,
An information terminal device that encrypts the content key with a unique key that is a second encryption key and stores the encrypted content and the encrypted content key, stores unique information of the information terminal device. Unique information storage means; unique key basic data generating means for obtaining unique key basic data that is data for generating the unique key and depends on information other than the unique information; A content key generating means for generating digital data of a predetermined length and using the generated digital data as the content key; and a content for encrypting the content key with the unique key. Key encryption means, content encryption means for encrypting the content with the content key, and the encrypted content An information terminal device, comprising: a data storage unit for storing an encrypted unique key; 2. A unique key basic data management table for associating the unique key basic data with a unique key basic data ID unique to each unique key basic data, and a unique key for generating the unique key basic data ID in a predetermined procedure. A key basic data ID generating unit, wherein the unique key basic data generating unit refers to the unique key basic data management table to generate the unique key basic data ID generated by the unique key basic data ID generating unit. 2. The method according to claim 1, wherein the corresponding unique key basic data is obtained.
An information terminal device according to item 1. 3. The unique key basic data ID generation means,
From the distributed content, the unique key basic data I
The information terminal device according to claim 2, wherein D is generated. 4. The unique key basic data ID generation means,
The information terminal device according to claim 2, wherein a random number is generated, and the unique key basic data ID is generated from the generated random number. 5. The information terminal according to claim 1, wherein the unique key basic data generation means obtains unique key basic data using an attribute value of the distributed content and arbitrary digital data. apparatus. 6. Numerical conversion means for numerically converting the attribute value of the distributed content in a predetermined procedure and outputting the converted attribute value, a conversion attribute encryption key for encrypting the conversion attribute value, Conversion attribute encryption key ID unique to each conversion attribute encryption key
And a conversion attribute encryption key management table for associating
A conversion attribute encryption key ID generating means for generating D, and a conversion attribute encryption key from the conversion attribute encryption key ID generated by the conversion attribute encryption key ID generation means with reference to the conversion attribute encryption key management table And a conversion attribute encryption key generated by the conversion attribute encryption key generation unit. The unique attribute basic data generation unit generates the conversion attribute encryption key generated by the conversion attribute encryption key generation unit. 6. The information terminal apparatus according to claim 5, wherein the unique key basic data is obtained by encryption. 7. The unique key basic data ID of the unique key basic data management table and the unique key basic data corresponding to the unique key basic data ID are distributed, and the distributed unique data of the unique key basic data management table is distributed. Key basic data ID
3. The information terminal device according to claim 2, wherein the unique key basic data corresponding to the information terminal is replaced with the distributed unique key basic data. 8. The information terminal device according to claim 2, wherein the unique key basic data in the unique key basic data management table is updated based on time-dependent data unique to the information terminal device. 9. The information terminal device is a mobile phone,
The information terminal device according to any one of claims 1 to 8, wherein the unique information is a telephone number of the mobile phone. 10. The information terminal according to claim 1, wherein the data storage unit comprises a non-volatile memory, and is detachable from the information terminal device. apparatus.