JP4709987B2 - Data transmission method, portable storage device and device - Google Patents

Description

  The present invention relates to digital rights management, and more particularly to mutual authentication between a device for digital rights management and a portable storage device.

  Recently, research on digital rights management (hereinafter referred to as “DRM”) has been active, and commercial services to which DRM is applied have already been introduced or are being introduced. The reason why DRM has to be introduced can be derived from various characteristics of digital data. Unlike analog data, digital data has the characteristics that it can be copied without loss, the reusability and ease of processing, and the characteristics that it can be easily distributed to third parties. It can be copied and distributed. Digital content, on the other hand, requires a lot of cost, effort and time to produce. Therefore, when unauthorized copying and distribution of digital content is permitted, this infringes on the interests of digital content producers, and the digital content producers' willingness to create is reduced, which greatly contributes to the activation of the digital content industry. It becomes an impediment factor.

  There have been efforts to protect digital content in the past, but in the past, the focus was mainly on preventing unauthorized access of digital content. In other words, access to digital content was only allowed for some people who paid for it. Therefore, the person who paid the price could access the digital content that was not encrypted, and the person who did not could not access the digital content. However, if the person who paid the price intentionally distributes the approaching digital content to the third party, the third party can use the digital content without paying the price. In order to solve such problems, the concept of DRM was introduced. The DRM allows unlimited access to predetermined encrypted digital content, but if the encrypted digital content is to be decrypted and played back, it is called a rights object (Rights Object). I need a license. Therefore, if DRM is applied, digital contents can be effectively protected unlike existing ones.

  The concept of DRM will be described with reference to FIG. How DRM handles content protected in a manner like encryption or scrambling (hereinafter referred to as “encrypted content”) and rights objects that allow access to the protected content Is about.

  Referring to FIG. 1, including users 110 and 150 who desire access to content protected by DRM, content providers 120 that supply content protected by DRM, and the right to access content. A rights object issuer (Rights Issuer) 130 that issues a right object and a certificate authority 140 that issues a certificate are shown.

  In operation, the user 110 obtains desired content from the content supplier 120, but obtains encrypted content protected by DRM. The user 110 is obtained from a rights object that has received a license to play back the encrypted content from the rights object issuing institution 130. A user 110 with a rights object can play back the encrypted content. Since the encrypted content can be freely distributed or distributed, the user 110 can freely transmit the encrypted content to the user 150. The user 150 needs a rights object in order to reproduce the transmitted encrypted content. Such a rights object is obtained from the rights object issuing institution 130. On the other hand, a certification authority issues a certificate (Certificate) indicating that the content supplier 120, the user 110, and the user 150 are valid users. The certificate is entered into the device from the time of device creation of the users 110 and 150, but the certificate can be reissued from the certificate authority 140 if the validity period of the certificate has expired.

  As described above, the DRM can contribute to the activation of the digital content industry by protecting the interests of producers or suppliers of digital content. However, although it is possible to exchange rights objects and encrypted contents between the user 110 and the user 150 using the mobile device as shown, it is inconvenient in practice. It is necessary to make it convenient to move rights objects or encrypted content between devices, but when using a portable storage device, it is convenient to move rights objects and encrypted content between devices. . Accordingly, mutual authentication is necessary as a premise that secure data transmission / reception can be performed between the portable storage device serving as a mediator between devices and the device.

  An object of the present invention is to provide a secure mutual authentication method between a portable storage device and a device. Another object is to provide a device having such a function and a portable storage device.

  The objects of the present invention are not limited by the objects described above, and other objects not mentioned will be clearly understood by those skilled in the art from the following.

  According to an embodiment of the present invention for achieving the above object, a method for mutual authentication of a device with a portable storage device includes: a device sending a first key to the portable storage device; If the first encrypted random number obtained by encrypting the first random number with one key and the third key are sent, the first encrypted random number is received, and the first encryption is performed using the second key corresponding to the first key. Decrypting the generated random number; sending a second encrypted random number obtained by encrypting the second random number with the third key to the portable storage device; and the first random number and the second random number Generating a session key with a random number.

  In order to achieve the above object, a method for mutual authentication with a device of a portable storage device according to an embodiment of the present invention includes receiving a first key and encrypting a first random number with the first key. Obtaining an encrypted random number and sending the first encrypted random number and a third key to the device; and a second encrypted result obtained by the device encrypting the second random number with the third key. Receiving the received random number, decrypting the second encrypted random number using a fourth key, and generating a session key using the first random number and the second random number. In addition.

  In order to achieve the above object, a secure data transmission method between a device and a portable storage device according to an embodiment of the present invention includes a step of setting an initial value of a transmission sequence counter and data to be sent to the portable storage device. A transmission sequence counter value included in each APDU to be sequentially added from the initial value, and an APDU carrying data from the portable storage device, and a transmission sequence counter value included in the received APDU Including the step of determining whether or not there is an abnormality.

  According to another embodiment of the present invention for achieving the above object, a secure data transmission method between a device and a portable storage device sets an initial value of a transmission sequence counter and loads data to be sent to the device. Incrementing the transmission sequence counter value in each APDU sequentially from the initial value, and receiving the APDU carrying data from the device, and determining whether the transmission sequence counter value included in the received APDU is abnormal Including the steps of:

  To achieve the above object, the portable storage device according to an embodiment of the present invention includes an interface for connecting to a device and a first key obtained from a device certificate sent by the device connected through the interface. Using a public key encryption module that encrypts a first random number, decrypts the encrypted second random number sent by the device through the interface with a fourth key, and obtains a second random number, and the first and second random numbers A session key generation module for generating a session key is provided.

In order to achieve the above object, a device according to an embodiment of the present invention includes an interface for connection with a portable storage device, and a second encrypted first random number transmitted by the portable storage device through the interface. Public key encryption that obtains the first random number by decrypting with the key and encrypts the second random number with the third key obtained from the certificate of the portable storage device sent by the portable storage device connected through the interface And a session key generation module for generating a session key using the first and second random numbers.
According to one aspect of the present invention, a data transmission method used in a device that communicates with a portable storage device includes:
The device sends a first key to the portable storage device;
Receiving a first random number encrypted by the portable storage device using the first key from the portable storage device together with a second key, and decrypting the encrypted first random number using the first key; When,
Sending a second random number encrypted with the second key to the portable storage device;
Generating a session key from the first random number and the second random number;
Initializing a transmission sequence counter with a combination of at least some of the bits representing the first random number and at least some of the bits representing the second random number;
And when the APDU is transmitted between the device and the portable storage device, the value of the transmission sequence counter is counted.
According to one aspect of the present invention, a data transmission method used in a portable storage device that communicates with a device includes:
Receiving a first key from the device;
Encrypting a first random number with the first key and sending the encrypted first random number together with a second key to the device;
Receiving a second random number encrypted by the device with the second key, and decrypting the encrypted second random number with the second key;
Generating a session key from the first random number and the second random number;
Initializing a transmission sequence counter with a combination of at least some of the bits representing the first random number and at least some of the bits representing the second random number;
And a transmission sequence counter value is counted when an APDU is transmitted between the portable storage device and the device.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  Prior to the explanation, the meaning of terms used in this specification will be briefly explained. By the way, the explanation of the term is for the purpose of helping the understanding of the present specification, and is used as a meaning for limiting the technical idea of the present invention when not explicitly described as a matter limiting the present invention. It must be noted that this is not the case.

-Public-key cryptography (Public-key Cryptography)
Also referred to as asymmetric encryption (cryptographic), this means that the key used to decrypt the data is different from the key that encrypted the data. Since the encryption key, also called the public key, does not need to be kept secret, the encryption key can be exchanged over an insecure general channel. Such public key encryption algorithms are open to the public, and public key encryption can be used to determine whether a third party has the encryption algorithm, the encryption key, and the encrypted text. It has difficult characteristics. Examples of public key encryption systems include Diffie-Hellman encryption systems, RSA encryption systems, ElGamal encryption systems, and elliptic curve encryption systems. Since public key encryption is about 100 to 1000 times slower than symmetric key encryption, it is used for key exchange, electronic signature, etc. rather than encryption of content itself.

-Symmetric key encryption (Symmetric-key Cryptography)
Also referred to as secret key encryption, this means that the key used for data encryption and the key used for data decryption are the same. As an example of such symmetric key encryption, DES is most commonly used, and recently, applications employing AES are increasing.

-Certificate
A certification authority (Certification Authority) means that a public key has been authenticated to a user in connection with public key cryptography. The certificate signed the identity of the specific subscriber and the public key with the personal key of the certification authority. Means a message. Accordingly, if the public key of the certification authority is applied to the certificate, the integrity of the certificate can be easily grasped, and thus an attacker can prevent the attacker from arbitrarily modifying the public key of the specific user.

-Digital signature (DigitalSignature)
It is generated to indicate that a document has been created by the signer. Examples of such electronic signatures include RSA electronic signatures, ElGamal electronic signatures, DSA electronic signatures, Schnorr electronic signatures, and the like. In the case of an RSA electronic signature, the encrypted message sender encrypts the message with its own private key and sends it, and the receiver decrypts the message encrypted with the sender's public key. In such a case, it is proved that the message encryption is by the sender.

-Random number means a number or character string having arbitraryness, and in order to actually generate a complete random number, a pseudo-random number (Pseudo-Random) number may be used because it requires high cost.

-Portable storage device The portable storage device used in the present invention includes a nonvolatile memory having a readable, writable, and erasable property such as a flash memory, and means a storage device that can be connected to a device. . Examples of such a storage device include a smart media, a memory stick, a CF card, an XD card, a multimedia card, and the like, and a multimedia card (Multi Media Card: MMC) will be described below as an example.

  FIG. 2 is a diagram for briefly explaining the concept of digital copyright according to an embodiment of the present invention.

  The user 210 can obtain encrypted content from the content supplier 220. Encrypted content means content protected by DRM, but in order to reproduce it, a rights object for the content is required. A rights object includes a definition of content rights and a right constraint, and may also include rights for the rights object itself. An example of the right to content is reproduction, and examples of limitations include the number of reproductions, reproduction time, and reproduction period. Rights for the rights object itself include movement and copying. That is, a right object having a transfer right can be moved to another device or a secure multimedia card, and a right object having a copy right can be copied to another device or a secure multimedia card. In the former case, the original rights object is deactivated (concept including deletion of the rights object itself or deletion of the rights contained in the rights object) while moving, while the latter uses the original rights object in the activated state. It can be broken.

  The user 210 who has obtained the encrypted content requests the rights object issuing organization 230 for the rights object in order to obtain the reproduction authority for the content. If the rights object is received together with the rights object response from the rights object issuing institution 230, the encrypted content can be reproduced using the rights object. On the other hand, when the right object is transmitted to the user 250 having the encrypted object, the user 210 may transmit using the portable storage device. In one embodiment, the portable storage device may be a secure multimedia card 260 having a DRM function. In such a case, the user 210 performs mutual authentication with the secure multimedia card 260. The right object is moved to the security multimedia card 260. If the user 210 is to play back the encrypted content, the user can request the playback right from the secure multimedia card 260 and then receive the playback right from the secure multimedia card 260 to play back the encrypted content. On the other hand, the security multimedia card 260 can move the rights object to the user 250 after authenticating with the user 250, or the user 250 can reproduce the encrypted content. I have to go through. The operation between the device of the user 210 and the secure multimedia card 260 will be described with reference to FIGS. In this embodiment, in order for the device to use the secure multimedia card, mutual authentication is performed between the two. The mutual authentication process will be described with reference to FIG. In a draft of an object, H means that it is owned by the host (device) or created by the device, and S means that it is owned by the secure multimedia card or created by the secure multimedia card. To do.

FIG. 3 is a diagram illustrating a mutual authentication process according to an exemplary embodiment of the present invention. The mutual authentication process is a process of confirming that the device 310 and the secure multimedia card 320 are valid devices and exchanging random numbers for generating a session key between the two, and obtained through the mutual authentication process. A session key may be generated using a random number. In FIG. 3, the stage above the arrow means a command for requesting the partner apparatus to perform a predetermined operation, and the bottom of the arrow means a parameter or data to be moved by the command. In one embodiment, all commands in the mutual authentication process are performed by the device 310, and the secure multimedia card 320 operates according to the commands. For example, when the device 310 sends a command of mutual authentication response (S320) to the secure multimedia card 320, the secure multimedia card 320 receives the command and encrypts the device with its own ID (ID _S ), certificate S, and encryption. And sent random number _S. In other embodiments, the instructions can be issued by either the device 310 or the secure multimedia card 320. In this case, the mutual authentication response (S320) can be sent together with its own ID (ID _S ), the certificate _S and the encrypted random number _S while the secure multimedia card 320 sends it to the device 310. Hereinafter, a detailed mutual authentication process will be described.

  The device 310 and the secure multimedia card 320 use corresponding key pairs when exchanging important information such as random numbers. That is, the device 310 and the secure multimedia card 320 each include a key pair, but one key pair is composed of two corresponding keys. The device 310 includes a first key and a second key, but can be decrypted with the second key when encrypted with the first key and decrypted with the first key when encrypted with the second key. Of these, one key can be disclosed to other devices and security multimedia cards for use. That is, the first key is a public key that is used as a key that can be read by other devices, and the second key is a personal key that cannot be read by other devices, and only the device 310 can be read. . Similarly, the security multimedia card 320 includes a third key and a fourth key, but the third key is open and readable by other devices, and the fourth key is readable only by the security multimedia card 320. is there.

The device 310 requests mutual authentication to the secure multimedia card 320 (S310). While requesting mutual authentication, the device 310 sends the device public key PuKey _H to the secure multimedia card. In one embodiment, the device public key PuKey _H is sent to the device 310 through a device certificate Cert _H issued by a certification authority in step S310. The device certificate Cert _H includes a device public key PuKey _H and has an electronic signature of a certification authority. The secure multimedia card 320 that has received the device certificate Cert _H confirms whether the device 310 is a legitimate device and can obtain the device public key PuKey _H. The device certificate Cert _H and the device ID _H can be sent together.
Secure MMC 320 determines the expiration whether the valid period of the device certificate Cert _H, certificate revocation list (Certificate Revocation List: The following, "CRL" hereinafter) enabled device certificate Cert _H using (S312). If the validity period of the device certificate (Cert _H ) has elapsed or if it is a certificate of a device registered in the CRL, the secure multimedia card 320 may refuse mutual authentication with the device 310. In this case, the secure multimedia card 320 reports the result to the device 310, and the device 310 stops the DRM procedure. On the other hand, if the validity period of the device certificate Cert _H has passed or has been discarded, the device 310 may also proceed with a procedure for obtaining the device certificate Cert _H. In the case of a certificate of a device not registered in the CRL, the secure multimedia card 320 obtains the device public key PuKey _H through the device certificate Cert _H. Then, the DRM procedure is continued.

Next, the secure multimedia card 320 generates a random number _S (S314). The generated random number _S is encrypted with the device public key (PuKey _H ). Next, the mutual authentication response command by the device 310 is received or the secure multimedia card 320 sends the mutual authentication response command to the device 310 to perform the mutual authentication response process (S320). In the mutual authentication response process, the secure multimedia card 320 sends the secure multimedia card public key (PuKey _S ) and the encrypted random number _S to the device. In one embodiment, the secure multimedia card certificate CERT _S is sent instead of the secure multimedia card public key PuKey _S. In another embodiment, the multimedia card 320 sends the secure multimedia card certificate (CERT _S ), the encrypted random number _S, and the CRL issue time information of the secure multimedia card 320 to the device 310. This is because the device 310 and the secure multimedia card 320 can share the latest CRL with each other. On the other hand, the reason why the CRL issuance time information is sent without immediately transmitting the CRL is to reduce the overhead generated in the mutual authentication process because the CRL update does not frequently occur in most cases. When transmitting the CRL issue time information, it is transmitted together with the random number _S or separately. In addition, the security multimedia card ID (ID _S ) may be additionally transmitted together.

The device 310 receives the secure multimedia card certificate Cert _S and the encrypted random number _S , confirms that the secure multimedia card 320 is correct through the certificate confirmation, and obtains the secure multimedia card public key PuKey _S. The obtained and encrypted random number S is decrypted with the device personal key PrKey _H to obtain the random number _S (S322). It is determined whether or not the certificate is registered in the certificate validity period and the CRL in the certificate confirmation process. Next, the device 310 generates a random number _H (S324). The generated random number _H is encrypted with the secure multimedia card public key (PuKey _S ) (S326). Next, a final mutual authentication request process (S330) is performed. In the final mutual authentication request process (S330), the device 310 transmits the encrypted random number _H to the secure multimedia card 320. In one embodiment, the device 310 further includes the CRL issue time information of the device 310 along with the encrypted random number _H and sends it to the secure multimedia card 320. In this case, the CRL issue time information is encrypted together with the random number _H or separately.

The secure multimedia card 320 receives and decrypts the encrypted random number _H (S310). As a result, the device 310 and the secure multimedia card 320 generate a session key using the random number generated by itself and the random number generated by the other party (S340, S342). In the present embodiment, random numbers are generated and used by both the device 310 and the secure multimedia card 320, so that arbitraryness is greatly enhanced and secure mutual authentication is possible. That is, even if the optionality is weak on either side, the optionality can be supplemented on the other side.

Through this process, the device 310 and the secure multimedia card 320 can authenticate each other and share a session key. On the other hand, it is necessary for both parties to confirm whether or not the session key that the other party has is the same as the session key that the other party has, but this is performed in the final mutual authentication response process (S350). In other words, if one side encrypts and transmits the information that the other party knows with the generated session key, the other party decrypts it with its own session key and checks whether the session keys are the same as each other. Can do. In one embodiment, the secure multimedia card 320 transmits to the device that the random number _H generated by the device 310 has been encrypted with the session key. In this case, the device 310 receives the random number _H encrypted with the session key, decrypts it with its own session key, determines whether or not the random number _H has been restored, and determines whether or not the session key generation is correct. Is confirmed (S352). In another embodiment, the device 310 waits for an appropriate time after the final mutual authentication request (S330), and then encrypts the random number _S generated by the secure multimedia card 320 with the session key generated by the device 310, thereby securing the secure multimedia card. 320. In this case, the secure multimedia card 320 can confirm whether or not the session key generation is correct by decrypting the random number _S encrypted with its own session key. In one embodiment, if the session key generation is not correct, the mutual authentication process is performed from the beginning. In other embodiments, if the session key generation is not correct, the DRM procedure between the device 310 and the secure multimedia card 320 is terminated.

  In the present embodiment, the random number can be generated through a random number generation module (not shown) as described above, but any one selected from a plurality of numbers already generated and stored in the device or the security multimedia card can be selected. It can be a single number or a combination of numbers. The random number may simply mean a number, but may be a character string including characters other than numbers. Therefore, the meaning of random numbers as used herein is either interpreted to include numbers, combinations of numbers or strings generated through a random number generation module, or selected from stored numbers or strings. It may be interpreted to include one number or character string or a combination of a plurality of numbers or character strings.

  The embodiment of the present invention enables a more secure DRM by using two random numbers between the device 310 and the secure multimedia card 320 in the mutual authentication process, and the mutual authentication process in the session key confirmation process. It is possible to determine whether or not has been performed correctly. According to the embodiment of the present invention, a secure DRM operation between the device 310 and the secure multimedia card 320 is possible with the session key generated in the mutual authentication process, but a more secure DRM operation is enabled. Therefore, a confirmation process after the mutual authentication process can be further included. This will be described with reference to FIG.

  FIG. 4 is a diagram illustrating a DRM process using a transmission sequence counter according to an embodiment of the present invention.

  Various operations are possible between the device 410 and the secure multimedia card 420 during the DRM process. There may be a DRM for the rights object such as movement, copying or deletion of the rights object, and a DRM for the contents such as playback. Such a DRM process is premised on mutual authentication between the device 410 and the secure multimedia card 420. That is, in order to perform the DRM process, the device 410 and the secure multimedia card 420 first perform mutual authentication (S400). As a result of mutual authentication, the device 410 and the secure multimedia card 420 generate the same session key with each other (S410, S412). After sharing the session key, the DRM process can be performed, but a transmission sequence counter (Send Sequence Counter) is used for DRM with higher security. The transmission sequence counter is included in an APDU (Application Protocol Data Unit) and increases each time an APDU is transmitted. For example, if someone intercepts one or more APDUs, a discontinuity in the transmission sequence counter included in the APDU occurs. In addition, even when someone inserts an APDU, discontinuity of the transmission sequence counter occurs. An APDU is a unit for transmitting data such as a command word, a rights object, or content, and has a certain size. If the data size is smaller than the APDU, the data is transmitted by one APDU, and if the data size is larger than the APDU, the data is transmitted by a plurality of APDUs. A DRM process using a transmission sequence counter will be described with reference to FIG.

The device 410 and the secure multimedia card 420 initialize a transmission sequence counter for the DRM process after mutual authentication (S400) (S420, S422). In one embodiment, the transmission sequence counter is initialized with a combination of a random number _H and a random number _S. For example, when the size of the transmission sequence counter is 2 bytes in total, the subsequent byte of the random number _H and the random number _S are combined to initialize the transmission sequence counter. For example, when the last one byte of the random number _H and the random number _S ends with “01010101” and “11111110”, the transmission sequence counter is initialized to “0101010111111110”. By obtaining the initialization value of the transmission sequence counter using the random number _H and the random number _S , it is possible to increase the arbitraryness compared with the case of initializing to “0000000000000”, and thus a safer DRM process is possible.

  When the device 410 issues a DRM command to the secure multimedia card 420, a transmission sequence counter is included in the APDU (S430). If a total of 10 APDUs are transmitted in the DRM command, the transmission sequence counter is incremented by 1 for each APDU from the initial value “0101010111111110”. Next, the security multimedia card (S420) checks the transmission sequence counter to determine whether an incorrect APDU has been inserted in the middle, or whether someone has intercepted the original APDU (S432).

  A transmission sequence counter is included in the APDU even when the secure multimedia card 420 issues a DRM command to the device 410 (S440). In one embodiment, the initial value of the transmission sequence counter uses the initial value that was initialized first. For example, if a total of 10 APDUs are transmitted in the DRM command, the transmission sequence counter is incremented by 1 for each APDU from the initial value “0101010111111110”. In another embodiment, the initial value of the transmission sequence counter is based on the final transmission sequence counter value. For example, when the final transmission sequence counter value is “1000000000000000”, the transmission sequence counter value of the next APDU starts from “1000000000000001”. Next, the device (S410) checks the transmission sequence counter to determine whether an incorrect APDU has been inserted in the middle or someone has intercepted the original APDU (S442).

  Increasing the transmission sequence counter sequentially is exemplary, and the technique of the present invention can be used even when the transmission sequence counter is sequentially decreased from the initial value or when the width of the increase or decrease of the transmission sequence counter is not 1. It must be interpreted as being included in the philosophy.

  FIG. 5 is a functional block diagram illustrating a configuration of a secure multimedia card according to an embodiment of the present invention.

  The term “module” used in the present embodiment means software or a hardware component such as FPGA or ASIC, and the module plays a predetermined role. However, the module is not limited to software or hardware. The module may be configured to reside on an addressable recording medium and may be configured to play one or more processors. Thus, by way of example, modules are components such as software components, object-oriented software components, class components and task components, and processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, micro-components. Includes codes, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided in the components and modules can be combined with fewer components and modules or further separated into additional components and modules. In addition, the components and modules may be implemented to play one or more CPUs in the device or secure multimedia card.

  In order to perform such a DRM process, the security multimedia card 500 needs a security function, a function for storing content or a right object, a function for exchanging data with a device, and a DRM management function. The security multimedia card 500 for this purpose includes an RSA module 540 having a security function, a session key generation module 550, and an AES module 560, and includes a content / right object storage module 530 having a storage function, and exchanges data with devices. And a control module 520 that controls each configuration module to perform a DRM process. Also, the transmission sequence counter storage module 570 is included to detect incorrect insertion or deletion of APDUs transmitted and received in the DRM process.

  The interface 510 connects the secure multimedia card 500 with the device. Basically, the fact that the secure multimedia card 500 is connected to the device means that the secure multimedia card and the interface of the device are electrically connected to each other, but this is exemplary. Thus, the meaning of “connected” must also be understood to mean that they are in a state of being able to communicate with each other through a wireless medium in a non-contact state. The APDU transmitted and received between the secure multimedia card 500 and the device through the interface 510 includes a transmission sequence counter to cope with malicious attacks.

  The RSA module 540 performs public key encryption, and performs RSA encryption at the request of the control module 520. In the embodiment of the present invention, RSA encryption is used for exchanging keys (random numbers) in the mutual authentication process. However, this is exemplary, and other public key encryption methods may be used.

  Session key generation module 550 generates a random number to be transmitted to the device and generates a session key using the random number received from the device and the random number generated by itself. The random number generated by the session key generation module 550 is encrypted through the RSA module and transmitted to the device through the interface 510. On the other hand, the generation of a random number by the session key generation module 550 is exemplary, and as described above, any one of a plurality of existing random numbers can be selected.

  The AES module 560 is a module that performs symmetric key darkening, and performs symmetric key encryption using the generated session key. It is mainly used to receive a content encryption key from a rights object and encrypt it with a session key, and to encrypt important information in the communication process with the device. The AES encryption scheme is also exemplary, and other symmetric key encryption may be used like DES.

  The content / right object storage module 530 stores the encrypted content and the right object. Although the rights object is stored in an encrypted state, the security multimedia card 500 encrypts the rights object by the AES method using a unique key that cannot be read from the other device, and the rights object is stored in the other device. When moving or copying, decrypt using the unique key. The use of right object encryption or symmetric key encryption using a unique key is exemplary, and it is encrypted with the personal key of the secure multimedia card and decrypted with the public key of the secure multimedia card when necessary May be used.

  FIG. 6 is a functional block diagram illustrating the configuration of a device according to an embodiment of the present invention.

  In order to perform the DRM process, the device 600 includes a security function, a function for storing content or a right object, a function for exchanging data with the device, a data transmission / reception function capable of communicating with a content provider and a right object issuing organization, and a DRM. There must be a management function. The device 600 includes an RSA module 640 having a security function, a session key generation module 650, and an AES module 660. The device 600 includes a content / right object storage module 630 having a storage function, and can exchange data with the security multimedia card. And a control module 620 for controlling each component module to perform the DRM process. In addition, the device 600 includes a transmission / reception module 690 for a data transmission / reception function and a display module 670 for displaying content to be reproduced. A transmission sequence counter storage module 680 is provided to store the transmission sequence counter value. The stored transmission sequence counter value is used to detect incorrect insertion or deletion of APDUs transmitted and received in the DRM process.

  The transmission / reception module 690 enables the device 600 to communicate with a content issuer or a rights object issuer. The device 600 can obtain the rights object and the encrypted content from the outside through the transmission / reception module 690.

Interface 610 allows device 600 to be coupled with a secure multimedia card. Basically, the fact that the device 600 is connected to the security multimedia card means that the interface of the security multimedia card and the device is electrically connected to each other. The meaning of “coupled” should also be interpreted as meaning that communication is possible with each other through a wireless medium in a non-contact state. The APDU transmitted and received between the device 600 and the secure multimedia card through the interface 610 includes a transmission sequence counter to cope with malicious attacks.
The RSA module 640 is a module that performs public key encryption, and performs RSA encryption at the request of the control module 620. In the embodiment of the present invention, RSA encryption is used for the exchange of keys (random numbers) and electronic signatures in the mutual authentication process, but this is only an example, and other public key encryption methods may be used. good.

  The session key generation module 650 generates a session key using a random number received from the device by generating a random number to be transmitted to the device and a random number generated by itself. The random number generated by the session key generation module 650 is encrypted through the RSA module and transmitted to the device through the interface 610. On the other hand, the generation of a random number by the session key generation module 650 is an example, and it is possible to select any one of a plurality of existing random numbers. As described above.

  The AES module 660 is a symmetric key encryption module, and performs symmetric key encryption using the generated session key. It is mainly used to receive the content encryption key from the rights object and encrypt it with the session key, and to encrypt other important information during the communication with the device. The AES encryption scheme is also exemplary, and other symmetric key encryption may be used like DES.

  The content / right object storage module 630 stores the encrypted content and the right object. Since the rights object is stored in an encrypted state, the device 600 encrypts the rights object by the AES method using a unique key that cannot be read by another device or the security multimedia card, and the other security multimedia card. Alternatively, when the right object is moved or copied to the device, it is decrypted using a unique key. Encrypting with the personal key of the device 600 and decrypting with the public key of the device 600 when necessary using the symmetric key encryption using a unique key is also an example of encryption of the rights object. Is also possible.

  The display module 670 displays so that the user can visually recognize that the content permitted to be played through the rights object is played. The display module 670 may be implemented by a liquid crystal display device such as a TFT LCD or an organic EL.

  According to the present invention, secure mutual authentication between a device and a portable storage device is possible as a basic premise of digital copyright management. According to the present invention, safe data transmission is possible through a transmission sequence counter.

  Those skilled in the art to which the present invention pertains will understand that the present invention can be embodied in other specific forms without altering its technical idea or essential features. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not limiting. The scope of the present invention is defined by the terms of the claims, and any changes or modifications derived from the meaning and scope of the claims and equivalents thereof must be construed as being included in the scope of the present invention. .

It is a figure explaining the concept of digital rights management. It is a figure explaining briefly the concept of the digital copyright by one Embodiment of this invention. FIG. 5 is a diagram illustrating a mutual authentication process according to an exemplary embodiment of the present invention. FIG. 6 is a diagram illustrating a DRM process using a transmission sequence counter according to an exemplary embodiment of the present invention. It is a functional block diagram which shows the structure of the security multimedia card by one Embodiment of this invention. It is a functional block diagram which shows the structure of the device by one Embodiment of this invention.

Claims (16)

A data transmission method used in a device that communicates with a portable storage device, comprising:
The device sends a first key to the portable storage device;
Wherein the first random number portable storage device is encrypted using the first key together with the second key received from the portable storage device, the first key before Symbol a first random number encrypted Decrypting, and
A step of sending a second random number encrypted with the second key to the portable storage device,
Generating a session key by the first random number and said second random number,
And a step of initializing the transmit sequence counter by the number that combines at least a part of bits representing at least a portion and the second random number of bits representing the first random number, the device and a portable storage device A data transmission method in which the value of the transmission sequence counter is counted when an APDU is transmitted between them . Wherein the first key is a public key of the device, the second key is a public key of the portable storage device, the data transmission method according to claim 1. The first key to be sent to the portable storage device sends through certificate of the device, the second key received from the portable storage device is received through certificate of the portable storage device, the data transmission method according to claim 1 . The data transmission method according to claim 1, wherein the first random number is generated by the portable storage device and the second random number is generated by the device. Together received the previous SL first random number that is encrypted issuing time information of certificate revocation list of the portable storage device, the second random number prior Symbol encrypted issuing time information of certificate revocation list that sent to the portable storage device, the data transmission method according to claim 1. Receiving information capable of grasping the session key generated by the portable storage device;
The data transmission method according to claim 1, further comprising: confirming whether a session key generated by the device is the same as a session key generated by the portable device. A data transmission method used in a portable storage device that communicates with a device, comprising:
Receiving a first key from the device,
A step of sending the first key of the first random number is encrypted together said device a first random number and the second key that is encrypted,
The method comprising the device before Symbol a second random number received encrypted with the second key, decrypts the second key and the second random number is encrypted,
Generating a session key by the first random number and said second random number,
And a step of initializing the transmit sequence counter by the number that combines at least a part of bits representing at least a portion and the second random number of bits representing the first random number, wherein the portable storage device and the device A data transmission method in which the value of the transmission sequence counter is counted when an APDU is transmitted between the two . Wherein the first key is a public key of the device, the second key is a public key of the portable storage device, the data transmission method of claim 7. The second key to send to the device sends through certificate of the portable storage device, a first key received from the device receives through the certificate of the device, the data transmission method of claim 7. The data transmission method according to claim 7, wherein the first random number is generated by the portable storage device, and the second random number is generated by the device. Ri feed issuance time information of certificate revocation list of the portable storage device before Symbol the device together with the first random number is encrypted, the was pre Symbol encrypted issuing time information of certificate revocation list of devices receiving both the 2 random number, the data transmission method of claim 7. The data transmission method according to claim 7, further comprising : sending information to the device that can grasp a session key of the portable storage device so that it can be confirmed whether or not the session key generated by the device is the same.   A device that communicates with a portable storage device,
  Sending a first key to the portable storage device;
  Receiving the first random number encrypted by the portable storage device using the first key from the portable storage device together with the second key, and decrypting the encrypted first random number using the first key;
  Transmitting the second random number encrypted with the second key to the portable storage device;
  Generating a session key from the first random number and the second random number;
  Performing a process of initializing a transmission sequence counter with a number combining at least part of the bits representing the first random number and at least part of the bits representing the second random number;
  A device in which a value of the transmission sequence counter is counted when an APDU is transmitted between the device and the portable storage device.   A portable storage device that communicates with the device,
  Receiving a first key from the device;
  Encrypting a first random number with the first key, sending the encrypted first random number together with a second key to the device;
  The device receives a second random number encrypted with the second key, decrypts the encrypted second random number with the second key;
  Generating a session key from the first random number and the second random number;
  Performing a process of initializing a transmission sequence counter with a number combining at least part of the bits representing the first random number and at least part of the bits representing the second random number;
  A portable storage device in which a value of the transmission sequence counter is counted when an APDU is transmitted between the portable storage device and the device. Recorded co Npyu data reading possible of record medium storing a program which causes perform the method according to the device in claim 1. Recorded co Npyu data reading possible of record medium storing a program which causes perform the method according to the portable storage device in claim 7.

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