JP2005229382A - Encryption device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encryption device which can surely protect information data which exist in an information device or in a network from an unfair action. <P>SOLUTION: The device comprises a receiving part which receives an encryption key and information data, an encryption part which enciphers the information data using the encryption key, a data padding part which embeds enciphered information data in container data and forms steganography data, and a storing device which stores the steganography data. Moreover, the device comprises a data extractor which extracts embedded enciphered information data in the steganography data from the steganography data stored in the storing device, and a decoder which performs decoding of the extracted enciphered information data using the received encryption key. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an encryption device, and more particularly to an encryption device that performs encryption and / or decryption for concealing information data.

  With the progress of the Internet, companies and personal PCs (personal computers) and private networks connected to the Internet are exposed to dangers due to fraudulent acts such as intrusion from the outside. In order to protect information data existing on PCs and networks from such unauthorized acts, various security technologies and measures such as firewalls that prevent unauthorized intrusion, encryption such as RSA, authentication, and digital signatures are taken. ing.

  In recent years, steganography (see, for example, Patent Document 1) has been studied as a technique for protecting information data. Steganography is also referred to as “image deep encryption”, “information invisibility”, and the like, and is a technique for concealing information data. In other words, it is a technique for embedding information data to be concealed in other information data so that others do not notice it. The other information data is called container data, vessel data, or the like, and for example, image data, audio data, or other digital data is used.

  Further, when performing cryptographic communication, an encryption algorithm and a key management algorithm are required, but there is KPS (Key Predistribution System) as a key management algorithm for securely exchanging keys. Here, KPS was devised by Professor Tsutomu Matsumoto of Yokohama National University and Professor Hideki Imai of the University of Tokyo (see Patent Document 2).

  However, it has been difficult to realize extremely strong security by the above-described various conventional techniques. For example, it is practically impossible to realize a complete firewall or software having complete security. For example, unauthorized intrusion and unauthorized operation to a computer are performed through a software security hole. In addition, such fraudulent acts and the advancement of security technologies are precious, and even new security technologies will eventually be broken by analysis and the like.

Therefore, it is an important issue to securely protect information data existing on an information device such as a PC or a network from such illegal acts.
Japanese Patent Laid-Open No. 2003-298732 Japanese Patent No. 1984390

  The present invention has been made in view of the above points, and is an encryption that can reliably protect information data existing in computers, information devices, and networks such as PCs, servers, database devices, etc. from unauthorized acts. The object is to provide a device.

  An encryption apparatus according to the present invention includes a receiving unit that receives an encryption key and information data, an encryption unit that encrypts information data using the encryption key, and embedding the encrypted information data in container data to store steganographic data. A data embedding unit to be generated and a storage device for accumulating steganography data are provided.

  In addition, the encryption device according to the present invention uses the data extraction unit that extracts the encryption information data embedded in the steganography data from the steganography data stored in the storage device, and the extracted encryption information using the received encryption key. And a decryption unit for decrypting data.

  The encryption device according to the present invention includes an access command detection unit that detects that an access command to steganography data stored in the storage device is issued, and an encryption key related to the access command received by the reception unit. A verification unit that verifies whether or not the encrypted information data embedded in the steganographic data is supported, and when the encryption key is verified not to correspond to the encrypted information data embedded in the steganographic data. And a controller that issues a modification command for commanding modification of the computerized information data.

  In the encryption apparatus according to the present invention, the controller controls the data embedding unit and the data extraction unit to execute modification of the encrypted information data.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments described below, equivalent components are denoted by the same reference numerals.

[Configuration of encryption device]
FIG. 1 is a block diagram schematically showing the configuration of an encryption device 10 that is Embodiment 1 of the present invention. The encryption device 10 includes an encryption / decryption processing unit (hereinafter referred to as an encryption / decryption processing unit) 11 that encrypts and / or decrypts information data, a steganography processing unit 12 that performs data steganography processing, and a random number generator 13. , A storage device 14, a controller (CPU) 15, and a host interface 16. These constituent circuits are connected to a controller (or CPU) 15 via a signal bus 17. That is, the controller 15 controls the entire encryption device.

  The case where the above-described encryption device 10 is configured as a so-called USB (Universal Serial Bus) memory will be described below as an example. That is, the encryption device 10 includes, for example, a USB interface 16 and a RAM (Random Access Memory) having a predetermined capacity, and is configured to be connected to a computer such as a PC or a server to operate. The present invention is not limited to a USB memory, and can be applied to various memory devices such as a compact flash (registered trademark of SanDisk Corporation, USA) and a memory stick (trademark of Sony Corporation). That is, the interface 16 conforms to a predetermined communication protocol.

  The encryption device 10 of the present embodiment will be described in detail with reference to FIGS. FIG. 2 is a diagram schematically illustrating the configuration of the encryption device 10.

  The encryption device 10 has a USB connector (not shown) and, for example, a USB ver2.0 interface 16, and can be operated by connecting the USB connector to a computer, a portable information terminal, or the like. In addition, a storage device 14 having a predetermined capacity and made of, for example, a semiconductor RAM (for example, 256 MB, 1 GB, etc.) is mounted. The controller 15 of the encryption device 10 is configured on an LSI together with the encryption / decryption processing unit 11 and the steganography processing unit 12. The controller 15 sends various commands including an encryption key (that is, an encryption key and a decryption key) to be described later, various data such as information data, and an access command such as an encryption / decryption command and a storage / read command to the interface 16. Receive via.

  The cryptographic device 10 is provided with a physical random number (true random number) generator 13. The physical random number generator 13 generates a 1-bit random number sequence. This random number sequence is digitally processed based on white noise such as thermal noise, and is a uniform genuine random number sequence without reproducibility.

  Further, the encryption device 10 includes a power supply circuit 21 such as a regulator that converts a supply voltage supplied from the outside via a connector into a voltage used inside the encryption device 10, and a clock signal used inside the encryption device 10. May be provided. These circuits are connected to the controller 15 by a signal bus or the like.

  As described above, the controller 15 is configured on an LSI including the encryption / decryption processing unit 11 and the steganography processing unit 12 as a module circuit. Further, on the LSI, a register that operates under the control of the controller 15, A memory and a flash ROM (not shown) in which various data and software are stored are mounted. For example, in the LSI, an input / output value and an encryption key (encryption key, decryption key) in various processes, a calculation value generated from these, a source key, a common key, a register storing a session key, a memory Has been implemented. Alternatively, in the encryption / decryption processing, a buffer memory for temporarily storing plaintext and ciphertext is mounted.

  The software stored in the flash ROM includes software that controls the operation of the controller 15 based on a command from a computer such as a PC to which the encryption device 10 is connected. For example, software that performs data exchange with the connected computer, processing in the encryption / decryption processing unit 11 and steganography processing unit 12, access to the storage device 14, and the like is included.

  In addition, an encryption algorithm, a steganography processing algorithm, data and software for exchanging data and control signals with the outside are stored. Such an algorithm or the like may be configured by software, hardware, or firmware.

[Operation of cryptographic device]
As described above, the encryption / decryption processing unit 11 encrypts the information data input to the encryption device 10 and also decrypts the encrypted data. Here, encryption means that normal data (plain text) is converted into data that cannot be decrypted by anyone other than the owner of the encryption key using an encryption algorithm and an encryption key (encryption key). Encrypting means decrypting encrypted data using an encryption key (decryption key). As the encryption algorithm, using a common key encryption algorithm (or secret key encryption or symmetric key encryption algorithm) that uses the same key for encryption and decryption, and two pairs of keys (public key and secret key) There is a public key encryption algorithm (or an asymmetric encryption algorithm) that encrypts and decrypts data.

  In this embodiment, a case where DES (Data Encryption Standard) is used as an encryption algorithm will be described as an example. Triple DES (T-DES) and other secret key encryption algorithms can also be used. Alternatively, a public key encryption algorithm such as RSA encryption can be used, and the present invention is not limited to a specific encryption algorithm. When performing encryption communication, an encryption algorithm and a key management algorithm or a key exchange algorithm are required. As the key management algorithm, it is preferable to use an algorithm having information-theoretic security that cannot be attacked in principle due to a lack of information amount. In this embodiment, a case where KPS (Key Predistribution System) is used will be described as an example, but other key management algorithms may be used.

  In such encrypted communication using KPS, it is possible to automatically and safely exchange the encryption key between the sender and the receiver simply by inputting the other party's public key (Public-ID). In other words, there is no need to keep in touch or access a public key file or the like before communication to share the encryption key. Public-ID can use public information such as name, phone number and Internet ID, so there is no need to keep the other party's code secret. Moreover, if a Public-ID is set for each individual, person-to-person communication is performed. Therefore, even when a single device is used by a plurality of persons, individual confidentiality can be maintained.

  In the present embodiment, a case where information data to be kept secret is stored in the storage device 14 and shared between users will be described.

  Accordingly, the user who stores the information data to be kept secret in the storage device 14 is the first user (corresponding to the sender in the encrypted communication), and the user who decrypts the secret information data stored in the storage device 14 is the second user (encryption). This will be described as “corresponding to a recipient in communication”.

[Encryption and decryption]
Hereinafter, the encryption procedure in this embodiment will be described with reference to FIG. In FIG. 3, the processing executed in the encryption / decryption processing unit 11 is surrounded by a broken line.
(1.1) First, the encryption / decryption processing unit 11 receives an encryption key for encryption under the control of the controller. That is, more specifically, in the processing step S1 in the encryption / decryption processing unit 11, the KPS encryption key exchange algorithm determines that the secret of the first user from the first user (that is, the user storing the information data to be concealed). The key (Private-ID) K1 is received. The KPS encryption key exchange algorithm receives the public key (Public-ID) K2 of the second user (that is, the user who decrypts the information data to be concealed) input by the first user.

The KPS encryption key exchange algorithm generates a KPS common key K3 from the secret key of the first user and the public key of the second user.
(1.2) The random number generator 13 generates a genuine random number K4. The encryption / decryption processing unit 11 generates a session key K5 using the genuine random number K4.
(1.3) In process step S2 in the encryption / decryption processing unit 11, the session key K5 is encrypted by an encryption algorithm using the KPS common key K3 as an encryption key to generate an encrypted session key K6.
(1.4) In process step S3 in the encryption / decryption processing unit 11, the information data K7 input by the first user using the session key K5 as an encryption key is encrypted by an encryption algorithm to generate encrypted data K8.
(1.5) In process step S4 in the encryption / decryption processing unit 11, the encrypted session key K6 and the encrypted data K8 are combined to generate a communication text (communication data) K9.
(1.6) The communication sentence K9 is concealed by embedding the communication sentence K9 in the container data in the steganography processing unit 12 (data embedding). Image data, audio data, text data, and other digital data can be used as container data for embedding the communication text K9. As the container data, data stored in the encryption device 10 in advance can be used. Or you may make it produce | generate in the encryption apparatus 10 suitably, when performing a steganography process.
(1.7) The controller 15 stores (accumulates) the data generated in the steganography processing unit 12 (hereinafter referred to as steganography data) in the storage device 14.

Next, the procedure for decoding the steganographic data stored in the storage device 14 will be described with reference to FIG. In FIG. 4, processing executed in the encryption / decryption processing unit 11 is surrounded by a broken line.
(2.1) First, in process step S11 in the encryption / decryption processing unit 11, the second user (that is, the user who intends to decrypt the confidential information data) stores the first user (that is, the information data to be confidential). The user's public key (Public-ID) K11 is input to the KPS encryption key exchange algorithm. Further, the second user inputs the second user's private key (Private-ID) K12 to the KPS encryption key exchange algorithm.

The KPS encryption key exchange algorithm generates a KPS common key K13 from the public key of the first user and the secret key of the second user. The KPS common key K13 is the same as the KPS common key K3 in encryption.
(2.2) The steganography processing unit 12 reads the steganographic data stored in the storage device 14, and extracts the communication text K14 embedded in the steganography data (that is, the same as the communication text K9 at the time of encryption). (Data extraction)
(2.3) In process step S12 in the encryption / decryption processing unit 11, the encrypted session key K15 and the encrypted data K17 are separated from the communication text K14.
(2.4) In the processing step S13 in the encryption / decryption processing unit 11, the encrypted session key K15 is decrypted by the decryption algorithm using the common key K13 as an encryption key to generate a session key K16.
(2.5) In process step S14 in the encryption / decryption processing unit 11, the encrypted data K17 is decrypted by the decryption algorithm using the session key K16 as an encryption key, and the original data K18 (that is, the information data K7 before encryption) Take out the same).

  According to the encryption device 10 of the present invention described above, data to be kept secret even when the encryption device 10 is connected to a public network such as an IP network or a private network such as a LAN via a computer, a gateway, or the like. The data can be safely concealed in the encryption device 10 without knowing the existence of the.

  As described above, according to the encryption device 10 of the present invention, the information data to be concealed is encrypted by an encryption algorithm based on the information security, and is extremely difficult to break even if a quantum computer is used. It has strong safety. In addition, deep encryption and information invisibility are made possible by steganography. Therefore, even if the data is taken out, it is invisible, and the data is encrypted by an encryption algorithm based on information security, so it has extremely strong security.

  In particular, it is preferable that the steganography processing unit 12 is provided with a tamper resistant device. The tamper resistant device has software tamper resistant capabilities such as protection against the analysis of the steganography processing unit 12 and destruction of the data so that it cannot be read automatically when copying or moving data. It is preferable.

  Furthermore, tamper resistant devices are provided in all or part of the other components of the encryption device 10, such as the encryption / decryption processing unit 11, the random number generator 13, the storage device 14, the controller (or CPU) 15, and the like. Also good. The tamper resistant device may be a device that can withstand physical tampering or destruction of the IC or the like, or various protections such as protection against analysis of each component from the outside, protection against copying and movement of data, etc. It may have hardware and software tamper resistance.

  Further, although the case where the encryption device 10 is configured as a USB memory has been described, the present invention is not limited to this, and the present invention can be applied to various storage media such as a compact flash card, a memory stick, an IC card, and an IC chip. .

  5 and 6 are block diagrams for explaining encryption and decryption of the encryption device 10 according to the second embodiment of the present invention. The encryption device 10 includes an encryption / decryption processing unit 11, a steganography processing unit 12, a random number generator 13, a storage device 14, and a controller (or CPU) 15, and each of these components operates under the control of the controller 15. The point is the same as in the above-described embodiment.

  In the present embodiment, a case where a public key cryptosystem (asymmetric key cryptosystem) that encrypts and decrypts data using two pairs of keys (a public key and a secret key) will be described as an example. In this embodiment, one encryption key (public key, secret key) is assigned to the storage device 14 in order to encrypt information data to be concealed and decrypt the concealed data.

  More specifically, in the case of encrypting information data, as shown in FIG. 5, the user storing the information data to be kept secret is stored in the user's private key (Private-ID) J1 and the storage device 14. The assigned public key (Public-ID) J2 is input to the encryption / decryption processing unit 11. Further, a genuine random number is input from the random number generator 13 to the encryption / decryption processing unit 11. The encryption / decryption processing unit 11 encrypts the received confidential information data J3 using the input (received) user private key J1 and the public key J2 of the storage device 14 to generate encrypted data J4. . In the encryption / decryption processing unit 11, the KPS encryption key exchange algorithm is used as in the above-described embodiment. Other encryption key exchange algorithms can also be used. It is preferable to use an encryption key exchange algorithm having information security. Further, the present invention is not limited to a specific encryption algorithm, and various encryption algorithms can be applied.

  The obtained encrypted data J4 is embedded in the container data in the steganography processing unit 12 and concealed as steganography data. The controller 15 controls the storage device 14 to store (accumulate) the steganographic data in which the encrypted information data is embedded.

  When decrypting steganographic data in which encrypted information data is embedded, as shown in FIG. 6, the user storing the information data to be kept secret is assigned to the public key J11 and the storage device 14 of the user. The secret key J12 is input to the encryption / decryption processing unit 11. In response to the input of the encryption key or the reception of a user command or the like, the steganography processing unit 12 reads the steganography data from the storage device 14 and extracts the encrypted data J13 embedded in the steganography data. The encryption / decryption processing unit 11 decrypts the encrypted data J13 by using the input public key J11 of the user and the secret key J12 of the storage device 14, and extracts the original information data J14.

  With this configuration, the storage device 14 can be shared by a plurality of users, and information data to be kept secret can be safely stored and read.

  Further, as described above, according to the encryption device 10 of the present invention, the information data to be concealed is encrypted by the encryption algorithm based on the information security. In addition, it is invisible by steganography. Therefore, even if the data is taken out, it is invisible, and the data is encrypted by an encryption algorithm based on information security, so it has extremely strong security.

  Note that the encryption device 10 in the first and second embodiments described above may be provided in a computer such as a PC, a server, or a database device and configured to operate. In this case, the interface 16 is not necessarily required, but the encryption device 10 is configured to operate via various external buses, expansion buses, and the like such as an IDE bus, a PCI bus, and a USB of the computer.

  FIG. 7 is a block diagram schematically illustrating the configuration of the encryption device 10 according to the third embodiment of the present invention.

  The encryption device 10 includes an encryption / decryption processing unit 11, a steganography processing unit 12, a storage device 14, and a controller (or CPU) 15, and further includes a verification unit 15A described in detail later. Each of these components is connected to the controller 15 via the signal bus 17. That is, the controller 15 controls the entire encryption device. The encryption device 10 is provided in a computer such as a PC, a server, or a database device, and is configured to operate. For example, the storage device 14 may be connected to the IDE bus of the computer, and may be connected to other components of the encryption device 10 described above via an interface circuit.

  The encryption device 10 may be configured to operate based on commands from the processor of the computer via various external buses, expansion buses, such as the IDE bus, PCI bus, and USB of the computer. .

  In this embodiment, the encryption / decryption processing unit 11 receives an encryption key. The encryption / decryption processing unit 11 encrypts the information data to be concealed that is input (received) using the received encryption key. In the encryption / decryption processing unit 11, a secret key encryption (symmetric key encryption) method, a public key encryption (asymmetric key encryption) method, and other various encryption algorithms can be used. That is, it is not limited to a specific encryption algorithm. As in the above-described embodiment, it is preferable to use an encryption key exchange algorithm having information security, such as a KPS encryption key exchange algorithm.

  The encrypted data obtained by the encryption is embedded in the container data (data embedding) in the steganography processing unit 12 and is concealed as steganography data. The controller 15 controls to store the steganographic data in which the encrypted information data is embedded in the storage device 14.

  Below, when a command (hereinafter referred to as an access command) for accessing (reading, using, copying, moving, etc.) the data stored (accumulated) in the storage device 14 is issued, it is executed in the encryption device 10. The procedure of the processing operation will be described with reference to the flowchart shown in FIG. In the following, a case where an access command (read command) for reading data from the storage device 14 is described as an example, but the operation performed in the case of other access commands is the same.

  The controller 15 detects that an access command (read command) for reading data from the storage device 14 has been received (step S11). In response to the read command, the controller 15 determines whether the read command is a command for reading steganographic data (that is, a steganographic data file) in which encrypted information data is embedded (step S12). . When it is determined that an instruction to read steganography data has been issued, the following processing is executed under the control of the controller 15. If it is determined in step S12 that the command is not for reading steganographic data, that is, if it is determined that the data is not steganographic processed by the steganographic processing unit 12, this routine is terminated.

  The controller 15 instructs the storage device 14 to issue a transmission hold instruction for temporarily stopping (holding) the data transmission (step S13).

  The verification unit 15A detects whether the encryption / decryption processing unit 11 has received the encryption key related to the access command in response to the access command (read command) that instructs to read the steganography data. Then, it is verified whether or not the related encryption key corresponds to the encrypted data embedded in the steganographic data (step S14). More specifically, whether the detected encryption key (the encryption key associated with the access command) is an encryption key that can correctly decrypt the encrypted data embedded in the steganographic data to be accessed (ie, Whether it is a genuine decryption key or not. Note that it may be verified whether or not the encryption key when the steganography data is encrypted (that is, the encryption key) matches the detected encryption key. Further, it may be verified whether the access key is an encryption key or encryption key that can verify that the person who has accessed is authentic, such as a common key or a session key. If the encryption key does not correspond to the data embedded in the steganography data, the case where the encryption key is not detected may be included.

  When the encryption key does not correspond to the data embedded in the steganography data, the controller 15 sends a control signal (CS) to the steganography processing unit 12 based on the verification result of the verification unit 15A in the controller 15. .

  On the other hand, when it is verified in step S14 that the encryption key corresponds to the data embedded in the steganography data, this routine is terminated. That is, the restriction on data access is released, and access to the steganography data is permitted.

  The control signal (CS) described above is a signal that controls to prohibit reading of the steganographic data from the storage device 14 in a state where the encrypted information data is embedded when the authentic encryption key is not supplied.

  More specifically, when the verification unit 15A determines that the encryption key does not correspond to the data embedded in the steganographic data, the controller 15 modifies the steganographic data embedded in the steganographic data. A control signal (CS) commanded to the processing unit 12 is sent out (step S15).

  The controller 15 controls the steganography processing unit 12 to save the original steganography data (that is, the steganography data before modification) to the storage device 14 or another storage device (step S16).

  The steganography processing unit 12 modifies the encrypted information data embedded in the steganography data in accordance with the control signal (CS) (step S17). Examples of the modification of the embedded encrypted information data include removal of the encrypted information data from the steganography data, destruction of the encrypted information data, replacement with data that does not need to be concealed (dummy data), etc. Including changing the steganographic data to safe data.

  After the modification of the steganography data is completed, the controller 15 replaces the modified steganography data file with a file of steganography data (original steganography data) before modification. That is, the same file name is stored in the storage device 14.

  Thereafter, the controller 15 instructs the storage device 14 to send a transmission permission instruction for permitting transmission of the modified steganography data (step S18). The storage device 14 sends the modified data as data that has received a read command. In other words, data that does not include the encrypted information data and has been changed to data that is safe even if it is taken out is transmitted as a data file having a file name initially specified.

  In the encryption apparatus 10 of the present embodiment, when accessing steganographic data, a user having a legitimate access right extracts the data to be concealed from the container data (data extraction or steganographic decryption) and is encrypted. It is assumed that the information data is decrypted.

  Therefore, with the configuration and operation described above, it is possible to avoid access (data read, use, copy, move, etc.) to data that should be kept confidential except for a user who has the right access right to decrypt the encrypted information data. . In addition, a person who accesses a storage device on a LAN or other network by illegal or illegal means such as hacking and obtains data from the storage device 14 arranged on the network can obtain a plurality of acquired data It is impossible to know which data file of the file contains data to be kept secret, and even whether the accessed device (storage device 14) contains data to be kept secret. Moreover, since the data to be concealed is not included in the acquired data, the data to be concealed cannot be known even if steganographic decryption, decryption, or the like is attempted later by analysis or the like.

  The above-described embodiments can be applied in appropriate combination. For example, in the case where the second embodiment is combined with the third embodiment, the verification unit 15A determines whether one or both of the user's private key and the storage device 14 corresponds to data embedded in the steganography data. Can be verified. Further, in the case where the first embodiment is combined with the third embodiment, the verification unit 15A corresponds to data in which one or both of the first and second user private keys or the session key is embedded in the steganography data. You may make it verify whether it does.

  As described above in detail, it is possible to provide an encryption device that can reliably protect information data existing in computers, information devices, and networks such as PCs, servers, and database devices from illegal activities.

It is a block diagram which shows typically the structure of the encryption apparatus which is Example 1 of this invention. FIG. 2 is a diagram schematically illustrating the configuration of the encryption device. It is a figure which shows the procedure of encryption of information data. It is a figure which shows the procedure which decodes the steganography data stored in the storage device. It is a block diagram for demonstrating encryption of the encryption apparatus which is Example 2 of this invention. It is a block diagram for demonstrating the decoding of the encryption apparatus which is Example 2 of this invention. It is a block diagram which shows typically the structure of the encryption apparatus which is Example 3 of this invention. It is a flowchart shown about the procedure of the processing operation performed in the encryption apparatus which is Example 3 of this invention.

Explanation of symbols

10 Encryption Device 11 Encryption / Decryption Processing Unit 12 Steganography Processing Unit 13 Random Number Generator 14 Storage Device 15 Controller 15A Verification Unit 16 Interface 17 Signal Bus

Claims (12)

An encryption device,
A receiving unit for receiving the information data and the encryption key;
An encryption unit that encrypts the information data using the encryption key;
A data embedding unit that embeds encrypted information data in container data to generate steganographic data;
And a storage device for storing the steganographic data.   A data extraction unit for extracting encrypted information data embedded in the steganographic data from the steganographic data stored in the storage device, and decryption of the extracted encrypted information data using the encryption key received by the receiving unit The encryption apparatus according to claim 1, further comprising:   The cryptographic apparatus according to claim 1, further comprising a random number generator for generating a genuine random number, wherein the encryption unit encrypts the information data using the genuine random number.   The encryption apparatus according to claim 2, wherein the encryption unit and the decryption unit encrypt the information data using a KPS encryption key exchange algorithm.   The encryption apparatus according to claim 2, further comprising an interface circuit that receives the encryption key and the information data and relays the data to the reception unit.   The encryption method according to claim 2, wherein the encryption method in the encryption unit and the decryption unit is a public key encryption method, and a pair of two public keys and a secret key is assigned to the storage device. apparatus. An access command detection unit for detecting that an access command to steganography data stored in the storage device is issued;
A verification unit that verifies whether the encryption key related to the access command received by the reception unit corresponds to the encrypted information data embedded in the steganography data;
And a controller that issues a modification command for commanding modification of the encrypted information data when it is verified that the encryption key does not correspond to the encrypted information data embedded in the steganography data. Item 3. The encryption device according to Item 2.   8. The encryption apparatus according to claim 7, wherein the controller controls the data embedding unit and the data extraction unit to modify the encrypted information data.   The modification of the encrypted information data includes any one of deletion of the encrypted information data from the steganographic data, destruction of the encrypted information data, and replacement of the encrypted information data with dummy data. The encryption device according to claim 7.   8. The encryption apparatus according to claim 7, wherein when the controller detects that the access command has been issued, the controller issues a hold command for holding access to the steganography data.   9. The encryption apparatus according to claim 8, wherein the controller saves the steganographic data prior to the modification of the encrypted information data embedded in the steganographic data when the modification instruction is issued. .   9. The encryption apparatus according to claim 8, wherein the controller permits the steganographic data after the modification of the encrypted information data as data responding to the access command.

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