JP2006238307A - Encryption and decryption method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encryption and decryption method and device for preventing a third party from detecting the timing of key exchange. <P>SOLUTION: An encryption device 11 is provided with an information processor 13 for generating contents data, a hash processor 14 for generating summary data, a key selection processor 15 for selecting an arbitrary key from a key list storage and an encryption processor 16 for encrypting the summary data and the contents data. A decryption device 12 is provided with a key selection processor 17 for selecting an arbitrary key from the key list storage, a decryption processor 18 for decrypting the encrypted data, a hash processor 19 for generating the summary data from the decrypted contents data, and a comparison processor 20 for comparing the decrypted summary data with the summary data generated by the hash processor 19. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an encryption / decryption method and apparatus for distributing and receiving video and the like using streaming technology.

In recent years, network environments have been improved, and various information can be acquired via a network (for example, the Internet).
In addition, with the spread of streaming technology that plays back video data acquired from a network in real time, video content including video and audio can be viewed not only on lines with high communication speed but also on low lines. ing.

  When distributing paid video content, content targeted for a specific device, or the like, it is common to encrypt and distribute streaming data to prevent unauthorized viewing.

For example, Patent Document 1 discloses an authentication method that counts the number of times an encryption key is used and switches to another encryption key when the number of times the number is used. Further, Patent Document 2 discloses an authentication method in which authentication methods are switched periodically or irregularly in parallel with periodic authentication when reproducing encrypted content.
JP 2000-295209 A JP 2004-342046 A

  However, when streaming data is distributed and received using an open architecture platform such as a PC (personal computer), all of the distribution data is impersonated by a third party when playing the streaming data such as encrypted video content. In principle, it is possible to record, detect the key exchange timing, and extract the key by analysis by software to illegally decrypt the encrypted content.

  That is, by detecting the timing of key exchange, it is possible to analytically extract a key from distribution data obtained illegally, and there is a problem that unauthorized decryption can be performed using this key. .

  The present invention has been made in view of the above-mentioned problems, and the problem to be solved is to provide an encryption and decryption method and apparatus in which a third party cannot illegally detect the timing of key exchange. is there.

  In order to solve the above problems, an encryption method according to the present invention is an encryption method for encrypting and distributing content data, and a key for storing a list of keys used for encryption periodically or irregularly. Key selection processing for selecting a key from a list storage unit, summary data generation processing for generating summary data by irreversibly compressing the content data, and selecting the summary data and the content data by the key selection processing At least an information processing device includes an encryption process that encrypts data using a key to generate encrypted data, and a distribution process that distributes the encrypted data without distributing information about the key used in the encryption process. It is made to perform.

  According to the present invention, a key is selected periodically or irregularly by the key selection process without notifying the encryption data reception side (decryption device side) of the key switching timing, and encryption is performed using this key. Since this process is performed, there is an effect that it becomes impossible for a third party (including a legitimate recipient) to acquire the timing for switching the key illegally.

  The decryption method according to the present invention is a decryption method for decrypting encrypted content data, wherein a key is selected from a key list storage unit that stores a list of keys used for decryption. Processing and decrypting the encrypted content data using the key selected in the key selection processing, and irreversibly compressing the content data, which is content data and summary data attached to the content data Generated by the decryption process for generating the summary data, the summary data generation process for generating the summary data by irreversibly compressing the content data decrypted by the decryption process, and the summary data generation process. A comparison process that compares the summary data and the summary data generated by the decoding process, and determines whether or not the comparison results match. Characterized in that to be executed by the information processing apparatus until fruit match.

  According to the present invention, the summary data is generated from the decrypted content data by the summary data generation process, the summary data is compared with the summary data decrypted by the decryption process, and the comparison results match. Therefore, even if the encrypted data is encrypted by switching the key periodically or irregularly, the decryption can be normally performed.

  Further, the decryption processing according to the present invention is a decryption device for decrypting encrypted content data, and selects a key from a key list storage unit that stores a list of keys used for decryption. The encrypted content data is decrypted using a processing unit and a key selected by the key selection processing unit, and the content data and summary data attached to the content data are irreversibly compressed. A summary processing unit for generating summary data, a summary data generation processing unit for generating summary data by irreversibly compressing the content data decrypted by the decryption processing, and the summary data generation A comparison processing unit that compares the summary data generated by the process and the summary data generated by the decoding process, and determines whether or not the comparison results match; Provided, until the comparison result matches, the key selection processing section, the decoding processing unit, summary data generation section, and performing the comparison processing unit may be performed by the decoding apparatus according to claim.

  As described above, according to the present invention, it is possible to provide an encryption / decryption method and apparatus in which a third party cannot detect the key exchange timing illegally.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
FIG. 1 shows a principle diagram of an encryption apparatus according to the present invention.
The encryption device shown in FIG. 1 encrypts summary data and content data, a key selection processing unit 2 that selects a key from the key list storage unit 1, a summary data generation processing unit 3 that generates summary data from content data, and the like. And an encryption processing unit 4 that generates one encrypted data, and a distribution processing unit 5 that distributes encrypted data without distributing information about a key used for encryption.

The content data is content data encoded into streaming data, and the same applies to the following description.
The key list storage unit 1 stores a list of keys used in the encryption processing unit 4, and the key selection processing unit 2 selects a key from the key list storage unit 1 periodically or irregularly (hereinafter referred to as a key list). The selected key is referred to as “encryption key”) and notifies the encryption processing unit 4.

On the other hand, when the summary data generation processing unit 3 receives the content data, the summary data generation processing unit 3 performs, for example, hash processing on the content data to generate irreversibly compressed summary data.
Here, irreversibly compressing means that content data once compressed is compressed so that it cannot be restored to the original state or is extremely difficult.

The encryption processing unit 4 encrypts content data and summary data with an encryption key, and generates one encrypted data.
Then, the distribution processing unit 5 supplies (distributes) encrypted data to the requested platform via, for example, a network. However, information relating to the key used in the encryption processing unit 3 (for example, information relating to the key exchange timing and the key used for the encrypted data) is not distributed (notified) to the requested platform.

FIG. 2 shows a principle diagram of a decoding apparatus according to the present invention.
The decryption apparatus shown in FIG. 2 includes a key selection processing unit 7 that selects a key from the key list storage unit 6, a decryption processing unit 8 that decrypts the received encrypted data and generates summary data and content data. The summary data generation processing unit 9 that generates summary data from the decrypted content data, and the comparison processing unit that compares the summary data generated by the decryption processing unit 8 with the summary data generated by the summary data generation processing unit 9 10.

  As with the key list storage unit 1 shown in FIG. 1, the key list storage unit 6 stores a list of keys used in the decryption processing unit 8, and the key selection processing unit 7 receives an arbitrary key from the key list storage unit 6. (Hereinafter, the selected key is referred to as “decryption key”) and notifies the decryption processing unit 8 of the selected key.

The decryption processing unit 8 decrypts the received encrypted data with the decryption key, and generates summary data and content data.
On the other hand, the summary data generation processing unit 9 performs the same processing as the summary data generation processing unit 3 shown in FIG. 1, for example, hash processing, on the content data decrypted by the decryption processing unit 8, and is irreversible. To generate automatically compressed summary data.

  The comparison processing unit 10 compares the summary data decrypted by the decryption processing unit 8 with the summary data generated by the summary data generation processing unit 9, and if the comparison results do not match, the key selection processing unit 7 is instructed to select a new key.

  The key selection processing of the key selection processing unit 7, the decryption processing of the decryption processing unit 8, the summary data generation processing of the summary data generation processing unit 9, and the comparison processing of the comparison processing unit 10 are repeated until the comparison results match. Do.

  If the comparison results match, it is determined that the decryption process has been normally performed using the decryption key, and the content data decrypted by the decryption processing unit 8 is transmitted to an upper processing unit (not shown).

  Here, the encryption device 11 and the decryption device 12 according to the present embodiment described below can be realized by a general information processing device. Namely, a CPU for performing data processing such as generation, reproduction, display, encryption or decryption of streaming data, a non-volatile memory for storing data necessary for data processing, and an input device for inputting data And an output device for outputting data, an external recording device for recording programs and key data, and a network connection device for connecting to a network. .

  Therefore, the information processing units 13 and 21, the hash processing units 14 and 19, the key selection processing units 15a and 17a, the encryption processing unit 16, the decryption processing unit 18, and the comparison processing unit 20 illustrated in FIG. This can be realized by causing a CPU included in the system to execute a program describing a predetermined process.

Therefore, each processing unit in FIG. 3 described below is mainly processed by the CPU provided in the information processing apparatus. However, in order to clarify the processing of each processing unit, each processing unit will be described as the main.
The key list storage units 15b and 17b referred to by the key selection processing units 15a and 17a are a volatile memory (for example, RAM, hereinafter simply referred to as “memory”) provided in the information processing apparatus or an external storage device (for example, magnetic field). Disk).

FIG. 3 is a diagram illustrating an outline of the encryption device and the decryption device according to the present embodiment.
The encryption device 11 shown in FIG. 3 includes an information processing unit 13 that generates content data, a hash processing unit 14 that performs hash processing on content data and generates summary data, and a key that stores a list of keys. A key selection processing unit 15a that selects an arbitrary key (encryption key) from the list storage unit 15b, and an encryption processing unit 16 that encrypts content data and summary data using the selected encryption key are provided.

  In the encryption device 11, the information processing unit 13 generates content data in response to an external request or the like. The generated content data is sent to the hash processing unit 14 for hash processing. In this embodiment, data obtained by hashing content data is used as summary data.

  Here, since there are various conventional techniques such as MD5 (Message Digest 5) and SHA-1 (Secure Hash Algorithm 1) for hash processing, explanation is omitted, but an appropriate algorithm may be used as necessary. .

  Further, the key selection processing unit 15a arbitrarily selects a key (encryption key) to be used for encryption from the key list storage unit 15b irregularly or periodically, and receives data of the selected encryption key from a storage unit (not shown). read out. At this time, for example, a random number generation function may be used to determine a time until a random number is generated and a next key is selected every time a key is selected.

The key selection order may be a predetermined key list order, or may be selected randomly from the key list stored in the key list storage unit 15b using the random number generation function.
The encryption processing unit 16 combines the summary data and the content data to generate one data, and encrypts this data to generate encrypted data.

When the encrypted data is generated by the above processing, the encryption device 11 transmits the encrypted data to the requested information processing device via, for example, a network connection device.
Here, the encryption apparatus 11 according to the present embodiment does not notify the requested information processing apparatus of any information such as the key switching timing and the key switching.

  Therefore, even when an unauthorized third party acquires content data (encrypted data) encrypted by impersonation or the like, it is impossible to recognize the timing for switching the key.

  Since it is impossible to detect the key switching timing, it becomes impossible to extract the key analytically by software or the like from the illegally acquired content data based on the key switching timing. It becomes possible to prevent unauthorized decryption of data.

  On the other hand, the decryption device 12 shown in FIG. 3 receives the key selection processing unit 17a that selects an arbitrary key from the key list storage unit 17b that stores a list of a plurality of keys, and the encrypted data sent from the encryption device 11. Decryption processing unit 18 that generates content data and summary data by decrypting, hash processing unit 19 that performs hash processing on the decrypted content data and generates summary data, and decryption by decryption processing unit 18 A comparison processing unit 20 that compares the summarized data and the summary data generated by the hash processing unit 19, and an information processing unit 21 that performs information processing for displaying or reproducing the decrypted content data. I have.

  When receiving the encrypted data from the encryption device 11, the decryption processing unit 18 requests the key selection processing unit 17a to select a key. The key selection processing unit 17a arbitrarily selects a key (decryption key) to be used for decryption from the key list storage unit 17b that stores a list of a plurality of keys, and notifies the decryption processing unit 18 of the selected key.

  Upon receiving the notification of the decryption key, the decryption processing unit 18 reads the decryption key data from a storage unit (not shown), decrypts the received encrypted data, and further generates summary data and content data from the decrypted data. .

  The hash processing unit 19 performs the same processing as the hash processing unit 14 (for example, hash processing using the same algorithm), performs hash processing on the content data decrypted by the decryption processing unit 18, and generates summary data.

  Then, the comparison processing unit 20 compares the summary data generated by the decryption processing unit 18 with the summary data generated by the hash processing unit 19. If the comparison results match, it is determined that the decryption has been performed normally, and the content data decrypted by the decryption processing unit 18 is transmitted to the information processing unit 21.

If the comparison results do not match, it is determined that the decryption has not been performed normally, and the key selection processing unit 17a is instructed to select another arbitrary key again.
Then, the decryption processing of the encrypted data by the decryption processing unit 18, the summary data generation processing by the hash processing unit 19, and the comparison processing of the summary data by the comparison processing unit 20 are repeated until the comparison results match.

  By the decryption process described above, even when the key switching timing is not notified, it is possible to automatically detect the key switching timing and detect and decrypt a key that can be normally decrypted.

In the encryption device 11 and the decryption device 12 according to the present embodiment, the encryption method may be a common (secret) key encryption method or a public key encryption method.
For example, in the case of the common key encryption method, a list of a plurality of common keys may be stored in the key list storage unit 15b of the encryption device 11 and the key list storage unit 17b of the decryption device 12. In this case, a plurality of public keys may be stored in the key list storage unit 15b of the encryption device 11, and a secret key that is paired with the public key may be stored in the key list storage unit 17b of the decryption device 12.

  In the encryption device 11 and the decryption device 12 described above, summary data is generated by hash processing, but the present invention is not limited to this. For example, a checksum generation processing unit that generates a checksum from content data may be used instead of the hash processing units 14 and 19.

  Further, the hash processing units 14 and 19, the encryption processing unit 16, and the decryption processing unit 18 illustrated in FIG. 3 are realized by causing a CPU included in the information processing apparatus to execute a program describing a predetermined process. However, it is not intended to limit this.

  For example, the processing of the hash processing units 14 and 19 may be executed by a circuit dedicated to hash processing, and the encryption processing unit 16 may be realized by a circuit dedicated to encryption processing. The decryption processing unit 18 may also be realized by a circuit dedicated to decryption processing.

  (Supplementary note 1) An encryption method for encrypting and distributing content data, wherein a key selection process for selecting a key from a key list storage unit that stores a list of keys used for encryption periodically or irregularly; Summary data generation processing for generating summary data by irreversibly compressing the content data, and generating the encrypted data by encrypting the summary data and the content data using the key selected in the key selection processing An encryption method characterized by causing an information processing apparatus to execute at least an encryption process to be performed and a distribution process to distribute the encrypted data without distributing information relating to a key used in the encryption process.

  (Additional remark 2) The said key selection process is further provided with the random number generation process which produces | generates a random number, The key is selected from the said key list memory | storage part by the space | interval determined based on this random number, The additional remark 1 characterized by the above-mentioned. Encryption method.

  (Supplementary note 3) The encryption method according to supplementary note 2, wherein the summary data generation processing generates summary data by performing a hash process on the content data.

(Supplementary Note 4) The encryption method according to Supplementary Note 2, wherein the summary data generation process generates summary data by calculating a checksum from the content data.
(Supplementary Note 5) A decryption method for decrypting encrypted content data, wherein a key selection process for selecting a key from a key list storage unit that stores a list of keys used for decryption, and the key selection process The encrypted content data is decrypted using the key selected in Step 1, and content data and summary data attached to the content data, which is obtained by irreversibly compressing the content data, are generated. A decryption process for generating the summary data by irreversibly compressing the content data decrypted by the decryption process, the summary data generated by the summary data generation process, and the decoding The summary data generated by the digitization process is compared with each other, and the comparison process for determining whether or not the comparison results match is performed until the comparison results match. A decoding method, characterized by causing a processing device to execute.

  (Additional remark 6) The said summary data generation process produces | generates summary data by performing a hash process with respect to the said content data, The decoding method of Additional remark 5 characterized by the above-mentioned.

(Supplementary note 7) The decoding method according to supplementary note 5, wherein the summary data generation process generates summary data by calculating a checksum from the content data.
(Additional remark 8) It is the encryption apparatus which encrypts and distributes content data, Comprising: The key selection process part which selects a key from the key list memory | storage part which memorize | stores the list | wrist of the key used for encryption regularly or irregularly A summary data generation processing unit that irreversibly compresses the content data to generate summary data, and encrypts the summary data and the content data using a key selected by the key selection processing unit An encryption apparatus comprising: an encryption processing unit that generates data; and a distribution processing unit that distributes the encrypted data without distributing information related to a key used in the encryption process.

  (Supplementary note 9) The key selection processing unit further includes a random number generation processing unit that generates a random number, and selects a key from the key list storage unit at an interval determined based on the random number. The encryption device described in 1.

  (Supplementary Note 10) The encryption apparatus according to supplementary note 9, wherein the summary data generation processing unit generates summary data by performing a hash process on the content data.

  (Supplementary note 11) The encryption device according to supplementary note 9, wherein the summary data generation processing unit generates summary data by calculating a checksum from the content data.

  (Supplementary note 12) A decryption device for decrypting encrypted content data, a key selection processing unit for selecting a key from a key list storage unit for storing a list of keys used for decryption, and the key selection Decrypting the encrypted content data using a key selected by the processing unit, content data and summary data attached to the content data, the summary data obtained by irreversibly compressing the content data; A decryption processing unit that generates the summary data by irreversibly compressing the content data decrypted by the decryption processing, and the summary data generated by the summary data generation processing And a summary processing unit that compares the summary data generated by the decryption process and determines whether or not the comparison results match. Until but matches, the key selection processing section, the decoding processing unit, summary data generation processing unit, and the decoding apparatus characterized by performing the comparison processing unit.

(Additional remark 13) The said summary data production | generation process part produces | generates summary data by hashing the said content data, The decoding apparatus of Additional remark 12 characterized by the above-mentioned.
(Supplementary note 14) The encryption device according to supplementary note 12, wherein the summary data generation processing unit generates summary data by calculating a checksum from the content data.

  (Supplementary note 15) An encryption program for encrypting content data, the key selection processing for selecting a key from a key list storage unit that stores a list of keys used for encryption periodically or irregularly; Summary data generation processing for irreversibly compressing content data to generate summary data, and encryption for generating encrypted data by encrypting the summary data and the content data using the key selected in the key selection processing An encryption program that causes at least an information processing apparatus to execute an encryption process and a distribution process that distributes the encrypted data without distributing information related to a key used in the encryption process.

  (Supplementary note 16) A decryption program for decrypting encrypted content data, and a key selection process for selecting a key from a key list storage unit that stores a list of keys used for decryption, and the key selection process The encrypted content data is decrypted using the key selected in Step 1, and content data and summary data attached to the content data, which is obtained by irreversibly compressing the content data, are generated. A decryption process for generating the summary data by irreversibly compressing the content data decrypted by the decryption process, the summary data generated by the summary data generation process, and the decoding The comparison result is compared with the summary data generated by the digitization process, and the comparison process for determining whether or not the comparison result matches. Decoding program for causing execute the information processing apparatus to.

It is a figure which shows the principle of the encryption apparatus which concerns on this invention. It is a figure which shows the principle of the decoding apparatus which concerns on this invention. It is a figure which shows the outline | summary of the encryption apparatus and decryption apparatus which concern on a present Example.

Explanation of symbols

1 Key List Storage Unit 2 Key Selection Processing Unit 3 Summary Data Generation Processing Unit 4 Encryption Processing Unit 5 Key List Storage Unit 6 Key List Storage Unit 7 Key Selection Processing Unit 8 Decryption Processing Unit 9 Summary Data Generation Processing Unit 10 Comparison Processing Unit 11 Encryption Device 12 Decryption Device 13 Information Processing Unit 14 Hash Processing Unit 15 Key Selection Processing Unit 16 Encryption Processing Unit 17 Key Selection Processing Unit 18 Decryption Processing Unit 19 Hash Processing Unit 20 Comparison Processing Unit 21 Information Processing Device

Claims (5)

An encryption method for encrypting and distributing content data,
A key selection process for selecting a key from a key list storage unit that stores a list of keys used for encryption periodically or irregularly;
Summary data generation processing for irreversibly compressing the content data to generate summary data;
An encryption process for generating the encrypted data by encrypting the summary data and the content data using the key selected in the key selection process;
A delivery process for delivering the encrypted data without delivering information about the key used in the encryption process;
An encryption method characterized by causing an information processing apparatus to execute at least. The key selection process further includes a random number generation process for generating a random number,
2. The encryption method according to claim 1, wherein a key is selected from the key list storage unit at an interval determined based on the random number.   3. The encryption method according to claim 2, wherein the summary data generation processing generates summary data by performing hash processing on the content data. A decryption method for decrypting encrypted content data,
A key selection process for selecting a key from a key list storage unit that stores a list of keys to be used for decryption; and
The encrypted content data is decrypted using the key selected in the key selection process, and the summary is obtained by irreversibly compressing the content data and the summary data attached to the content data. Decryption processing for generating data,
Summary data generation processing for generating summary data by irreversibly compressing the content data decrypted by the decryption processing;
A comparison process for comparing the summary data generated by the summary data generation process with the summary data generated by the decoding process and determining whether or not the comparison results match;
The decoding method is characterized in that the information processing apparatus is executed until the comparison results match. A decryption device for decrypting encrypted content data,
A key selection processing unit that selects a key from a key list storage unit that stores a list of keys used for decryption; and
The encrypted content data is decrypted using the key selected by the key selection processing unit, and is obtained by irreversibly compressing the content data and summary data attached to the content data A decryption processing unit for generating summary data;
A summary data generation processing unit that irreversibly compresses the content data decrypted by the decryption processing to generate summary data;
A comparison processing unit that compares the summary data generated by the summary data generation process with the summary data generated by the decoding process, and determines whether or not the comparison results match;
With
A decryption apparatus that executes a key selection processing unit, a decryption processing unit, a summary data generation processing unit, and a comparison processing unit until the comparison results match.

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