Information processing device and control method

Abstract

To provide an information processing device or the like capable of securely acquiring an encryption key even in the case that the encryption key stored outside a device cannot be acquired.SOLUTION: An information processing device includes a first storage part for storing data, a second storage part for storing an encryption key, a control part for encrypting the first storage part by the encryption key, and a communication part for communicating with a server device storing the encryption key. The control part decrypts the encryption of the first storage part by using the encryption key acquired from the server device in the case of being able to acquire the encryption key from the server device through the communication part, and requests authentication, acquires the encryption key from the second storage part after performing authentication, and decrypts the encryption of the first storage part in the case of being unable to acquire the encryption key from the server device through the communication part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an information processing device and the like. [Background technology]

[0002] 2. Description of the Related Art In information processing devices and multifunction peripherals (such as image forming devices and image processing devices) incorporating information processing devices, storage (storage device, storage unit) is encrypted using a storage key (encryption key).

[0003] Furthermore, technologies for obtaining and managing encryption keys have also been proposed. For example, a technology has been proposed in which a second encryption key stored in a non-secure storage device is decrypted using a first encryption key stored in a secure memory within the device, and the resulting key is stored outside the device as a backup key, and when the first encryption key cannot be used, data encrypted with the second encryption key is decrypted using the backup key, and a password must be entered when using the backup key (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-236091 Summary of the Invention [Problem to be solved by the invention]

[0005] When the storage of an information processing device is encrypted, it is necessary to ensure the security of the storage while also increasing its availability. The technology described in Patent Document 1 stores the second encryption key in a non-secure storage device, and decrypts the storage without requiring the user to enter a password for using the encryption key when the device is turned on. Therefore, measures against theft of the device are insufficient. Furthermore, the technology described in Patent Document 1 does not address the case where the backup key stored outside the device cannot be obtained.

[0006] In view of the above-mentioned problems, the present disclosure aims to provide an information processing device or the like that is capable of securely acquiring an encryption key even when the encryption key stored outside the device cannot be acquired. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the information processing device of the present disclosure comprises a first memory unit that stores data, a second memory unit that stores an encryption key, a control unit that encrypts the first memory unit using the encryption key, and a communication unit that communicates with a server device that stores the encryption key, and is characterized in that, if the encryption key can be obtained from the server device via the communication unit, the control unit decrypts the first memory unit using the encryption key obtained from the server device, and if the encryption key cannot be obtained from the server device via the communication unit, the control unit requests authentication, and after authentication is performed, obtains the encryption key from the second memory unit and decrypts the first memory unit.

[0008] In addition, the control method disclosed herein is a control method for a device having a first memory unit that stores data and a second memory unit that stores an encryption key, and is characterized by including the steps of: encrypting the first memory unit using the encryption key; communicating with a server device that stores the encryption key; and, if the encryption key can be obtained from the server device that stores the encryption key, decrypting the first memory unit using the encryption key obtained from the server device; and, if the encryption key cannot be obtained from the server device, requesting authentication, and after authentication is performed, obtaining the encryption key from the second memory unit and decrypting the first memory unit. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide an information processing device or the like that is capable of securely acquiring an encryption key even when the encryption key stored outside the device cannot be acquired. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram for explaining the overall configuration of a system in a first embodiment. [Figure 2] FIG. 2 is a diagram showing the functional configuration of the information processing device according to the first embodiment. [Figure 3] FIG. 3 is a diagram showing an example of a parameter table of the information processing device in the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of a waiting time table in the first embodiment. [Figure 5] FIG. 2 is a diagram illustrating a functional configuration of a server device according to the first embodiment. [Figure 6] FIG. 4 is a diagram showing the data configuration of storage key information in the first embodiment. [Figure 7] FIG. 4 is a diagram illustrating an example of a parameter table of the server device in the first embodiment. [Figure 8] FIG. 2 is a flowchart showing a main processing flow of the information processing device in the first embodiment. [Figure 9] FIG. 10 is a flowchart showing the flow of a storage key acquisition process in the first embodiment. [Figure 10] FIG. 2 is a flowchart showing a main processing flow of the information processing device in the first embodiment. [Figure 11] FIG. 3 is a flowchart showing a main processing flow of the server device in the first embodiment. [Figure 12] FIG. 3 is a diagram illustrating an example of operation in the first embodiment. [Figure 13] FIG. 3 is a diagram illustrating an example of operation in the first embodiment. [Figure 14] FIG. 3 is a diagram illustrating an example of operation in the first embodiment. [Figure 15] FIG. 4 is a diagram illustrating a comparison of the operations of the first embodiment and the second embodiment. [Figure 16] FIG. 10 is a diagram illustrating an example of operation in the third embodiment. [Figure 17] FIG. 10 is a perspective view showing the appearance of an image processing device according to a fourth embodiment. [Figure 18]FIG. 10 is a diagram showing the functional configuration of an image processing device according to a fourth embodiment. [Figure 19] FIG. 11 is a flowchart showing the flow of main processes performed by an image processing device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment for carrying out the present disclosure will be described with reference to the drawings. Note that the following embodiment is an example for explaining the present disclosure, and the technical scope of the invention described in the claims is not limited to the following description.

[0012] [1. First embodiment] [1.1 Overall structure] A system 1 according to this embodiment will be described with reference to Fig. 1. As shown in Fig. 1, the system 1 according to this embodiment includes an information processing device 10 and a server device 20. The information processing device 10 and the server device 20 are connected via a network NW. The network NW may be any network such as a LAN (Local Area Network), a WAN (Wide Area Network), or the Internet (external network) as long as devices can exchange information with each other. In addition, various server devices such as a file server and an authentication server, as well as devices such as terminal devices and network equipment may be connected to the network NW.

[0013] The information processing device 10 is a computer (information processing device) such as a PC (Personal Computer) that is used by a user, but may be any device equipped with a computer. For example, the information processing device 10 may be a digital multifunction peripheral (MFP; Multi-Function Peripheral / Printer) such as an image processing device or an image forming device, or may be an automated teller machine, a machine tool, or the like.

[0014] The server device 20 is an information processing device that provides a service. In this embodiment, as an example of a service, the server device 20 manages (stores) a storage key of the information processing device 10, and provides a service of transmitting the managed storage key to the information processing device 10 in response to a storage key inquiry from the information processing device 10. The storage key is key data (encryption key) used to encrypt and decrypt (decrypt) the storage (storage device) of the information processing device 10. The server device 20 is also called a key server. The server device 20 is installed in a server room or the like, and is installed in a state protected from theft and the like.

[0015] [1.2 Functional Configuration] [1.2.1 Information processing device] The functional configuration of the information processing device 10 will be described with reference to Fig. 2. As shown in Fig. 2, the information processing device 10 is configured to include a control unit 100, a display unit 120, an operation unit 125, a connection unit 130, a TPM (Trusted Platform Module) 140, a main memory unit 150, a read-only memory unit 160, a non-volatile memory unit 170, a storage 180, and a communication unit 190.

[0016] The control unit 100 is a functional unit for controlling the entire information processing device 10. The control unit 100 realizes various functions by reading and executing various programs stored in the read-only memory unit 160 and the storage 180, and is configured by one or more arithmetic units (e.g., CPUs (Central Processing Units)). The control unit 100 may be configured as an SoC (System on a Chip) having multiple functions among those described below.

[0017] The control unit 100 reads out the program stored in the read-only storage unit 160 to realize the functions of the waiting time acquisition unit 102 and the storage encryption unit 104 .

[0018] The waiting time acquisition unit 102 acquires the waiting time until the process of determining whether the password entered by the user is correct or incorrect is executed. For example, the waiting time acquisition unit 102 acquires the waiting time corresponding to the number of incorrect inputs, which will be described later, from the waiting time table 176. Note that the waiting time acquisition unit 102 may calculate (acquire) the waiting time by determining in advance a formula for calculating the waiting time and substituting the number of incorrect inputs into the formula.

[0019] The storage encryption unit 104 encrypts and decrypts the storage 180 using the storage key.

[0020] The display unit 120 displays various types of information. The display unit 120 is configured by a display device such as an LCD (Liquid Crystal Display), an organic EL (Electro-Luminescence) display, or a micro LED (Light Emitting Diode) display.

[0021] The operation unit 125 accepts operations from the user who uses the information processing device 10. The operation unit 125 is made up of various operation devices such as a mouse and a keyboard.

[0022] The connection unit 130 connects to other devices such as an external storage device, a terminal device, etc. The connection unit 130 is configured by a terminal such as a USB port.

[0023] The TPM 140 is a security module (security chip, semiconductor component) that implements various security functions and includes a storage means (secure memory) with excellent tamper resistance. The TPM 140 may be included in the information processing device 10 as a chip independent of the control unit 100, or may be built into the control unit 100. The control unit 100 may also have the functions of the TPM.

[0024] The TPM 140 implements a security function (encryptor) that performs encryption and decryption using a public key cryptosystem (e.g., RSA or DSA). Public key cryptosystems (e.g., RSA encryption) use two encryption keys (key pairs) to encrypt and decrypt data. One of the keys is called a private key and is strictly managed to prevent leakage. The other key is called a public key and is provided to the communication partner in advance. A sender of secret information encrypts the secret information using the recipient's public key and sends the resulting ciphertext to the recipient. The recipient decrypts the ciphertext received from the sender using its own private key. This allows the recipient to restore the secret information that the sender had in their possession. In this embodiment, the TPM 140 is described as encrypting and decrypting information using RSA encryption, a public key cryptosystem.

[0025] The TPM 140 of this embodiment stores an endorsement key as a key pair used in public key cryptography. The key pair consists of an endorsement private key 142 and an endorsement public key 144. The endorsement key is an RSA 2048-bit key pair that is written (embedded) into the TPM 140 when it is manufactured. Therefore, the endorsement key is different for each TPM 140. RSA cryptography is an encryption method that encrypts information using the public key of a key pair and decrypts information encrypted using the private key. Because there is no way to read or take out the endorsement private key 142 from the TPM 140, only the TPM 140 into which the endorsement private key 142, which is paired with the endorsement public key, is written can correctly decrypt data encrypted with the endorsement public key 144.

[0026] The TPM 140 also includes a secure memory 146 as a storage means (storage area) for storing data. The secure memory 146 of this embodiment stores a storage key 1462 used for encrypting and decrypting the storage 180, which will be described later. The secure memory 146 is a secure storage means (storage area). For example, the secure memory 146 protects data by encrypting it, and requires authentication such as a password to read the data. In this way, the storage key 1462 is strictly managed within the information processing device 10.

[0027] Password information 148 is information based on a password set for TPM 140, and is used when data stored in secure memory 146 is read, etc. Password information 148 stores a password predetermined by a user, a hash value of the password, and a key derived based on the password. Note that password information 148 may also store additional information related to the password.

[0028] The main memory unit 150 is a so-called RAM (Random Access Memory), and is a storage device (storage module) that can be read and written by the control unit 100.

[0029] The read-only storage unit 160 is a so-called ROM (Read Only Memory), and is a storage device (storage module) that can only read out stored data.

[0030] The nonvolatile storage unit 170 is a nonvolatile memory (storage module) and is configured, for example, by an EEPROM (Electrically Erasable Programmable Read-Only Memory).

[0031] The nonvolatile storage unit 170 stores various setting values ​​of the information processing device 10. For example, the nonvolatile storage unit 170 stores a server setting 172, a parameter table 174, and a waiting time table 176.

[0032] The server settings 172 are information about the server device 20, such as information about the server device 20 itself, such as the name of the server device 20 (key server name), and information necessary for communication with the server device 20, such as an IP (Internet Protocol) address and port number.

[0033] The parameter table 174 is a table in which parameters of the information processing device 10 are stored. For example, as shown in FIG. 3, the parameter table 174 is a table of data in which parameter names are associated with parameter values. In this embodiment, the parameter table 174 stores a parameter value of a counter value (for example, "0") and a parameter value of the number of incorrect inputs (for example, "0"). The counter value of the information processing device 10 is an integer value used to verify the validity of information received from the server device 20. The counter value of the information processing device 10 is, for example, a sequential number with an initial value of 0. The number of incorrect inputs is an integer value indicating the number of incorrect inputs of a password used to read data stored in the secure memory 146, and the initial value is 0.

[0034] As shown in FIG. 4, the waiting time table 176 is a table in which the number of incorrect inputs (for example, "0") is associated with the waiting time (for example, "0 seconds").

[0035] The storage 180 is a storage device (storage module) that stores various programs, including a control program, and various data required for the operation of the information processing device 10. The storage 180 is a so-called auxiliary storage device, and is configured by a storage device such as a semiconductor memory, such as an SSD (Solid State Drive) or an HDD (Hard Disk Drive).

[0036] The storage 180 stores an operating system 182 and the like. To read the operating system 182 stored in the encrypted storage 180, it is necessary to decrypt the storage 180. A storage key 1462 is required to encrypt or decrypt the storage 180.

[0037] The communication unit 190 communicates with external devices such as the server device 20. The communication unit 190 is configured by, for example, a communication device such as a network interface card (NIC) used in a wired / wireless LAN, a communication module, a LAN adapter, or the like.

[0038] [1.2.2 Server device] The functional configuration of the server device 20 will be described with reference to Fig. 5. The server device 20 includes a control unit 200, a display unit 210, an operation unit 220, a storage unit 260, and a communication unit 290, as shown in Fig. 5.

[0039] The control unit 200 is a functional unit for controlling the entire server device 20. The control unit 200 realizes various functions by reading and executing various programs stored in the storage unit 260, and is configured with one or more arithmetic units (e.g., CPUs). The control unit 200 may be configured as an SoC (System on a Chip) having multiple functions among those described below.

[0040] The display unit 210 displays various types of information. The display unit 210 is configured with a display device such as an LCD, an organic EL display, or a micro LED display. The operation unit 220 accepts operations by a user who uses the server device 20. The operation unit 220 is configured with various operation devices such as a mouse and a keyboard.

[0041] The storage unit 260 is a storage device (storage module) that stores various programs and various data, including a control program required for the operation of the server device 20. The storage unit 260 is configured by a storage device such as an SSD, which is a semiconductor memory, or an HDD, for example.

[0042] The storage unit 260 secures a storage key information storage area 262 as a storage area, and further stores a parameter table 264.

[0043] The storage key information storage area 262 stores information related to the storage key (storage key information). Fig. 6 is a diagram showing the storage key information stored in the storage key information storage area 262. For example, as shown in Fig. 6, the storage key information includes an endorsement public key (e.g., "PubEK1") and a corresponding storage key (e.g., "9D215EB90560C18D...").

[0044] The storage key information is stored in advance. The storage key information storage area 262 may be a database (key database). The server device 20 uses the storage key information storage area 262 to manage the storage keys of the information processing device 10.

[0045] The parameter table 264 is a table that stores parameters of the server device 20. For example, as shown in FIG. 7, the parameter table 264 is a table of data in which parameter names are associated with parameter values. In this embodiment, the parameter table 264 stores a parameter value of a counter value (for example, "1"). The counter value of the server device 20 is an integer value used to verify the validity of information transmitted by the server device 20, and is, for example, a sequential number with an initial value of 1.

[0046] The communication unit 290 communicates with external devices such as the information processing device 10. The communication unit 290 is configured by, for example, a communication device such as a NIC used in a wired / wireless LAN, a communication module, a LAN adapter, or the like.

[0047] The above-described functional configuration is an example, and necessary functional units may be added or unnecessary functional units may be omitted as appropriate in the information processing device 10 and the server device 20. For example, the connection unit 130 may be omitted from the information processing device 10, and the display unit 210 and the operation unit 220 may be omitted from the server device 20.

[0048] [1.3 Processing flow] The processing flow of this embodiment will be described. It is assumed that the information processing device 10 stores information about the server device 20 as server settings 172. It is also assumed that the storage 180 (first storage unit) is encrypted and that a storage key 1462 for decrypting the encryption of the storage 180 is stored in the secure memory 146 (second storage unit). It is also assumed that the server device 20 stores storage key information that associates the storage key 1462 of the information processing device 10 with the endorsement public key 144 of the information processing device 10.

[0049] [1.3.1 Information processing device] The flow of main processes executed by the information processing device 10 will be described with reference to Figures 8 to 10. The processes shown in Figures 8 to 10 are executed by the control unit 100 that reads out a program stored in the read-only storage unit 160 when the information processing device 10 is powered on (when the power is turned on). That is, the processes in Figures 8 to 10 are processes in the boot process of the information processing device 10.

[0050] First, a description will be given of the process shown in Fig. 8. The control unit 100 (waiting time acquisition unit 102) acquires the waiting time based on the number of incorrect inputs stored in the parameter table 174 (step S100).

[0051] Next, the control unit 100 assigns the waiting time acquired in step S100 to the locking timer, and operates the locking timer in parallel with the processing shown in FIG. 8, to start counting down the waiting time (step S102).

[0052] Next, the control unit 100 reads the settings of the server device 20 and determines whether the settings of the server device 20 have been set (step S104 → step S106). For example, the control unit 100 determines that the settings have been set if the server settings 172 are stored in the nonvolatile storage unit 170 and the server settings 172 include information necessary for communication with the server device 20. On the other hand, the control unit 100 determines that the settings have not been set if the server settings 172 are not stored in the nonvolatile storage unit 170 or the server settings 172 do not include information necessary for communication with the server device 20.

[0053] If the setting of the server device 20 has been completed, the control unit 100 executes a storage key acquisition process to determine whether or not the storage key of the storage 180 can be acquired from the server device 20 (step S106; Yes→step S108). The storage key acquisition process will be described with reference to FIG. 9.

[0054] First, the control unit 100 transmits the guaranteed public key 144 to the server device 20 via the communication unit 190 (step S130). At this time, the control unit 100 may obtain the IP address of the server device 20 from the name of the server device 20 based on the information stored in the server setting 172.

[0055] Next, the control unit 100 receives the ciphertext encrypted by the endorsement public key 144 from the server device 20 (step S132). Furthermore, the control unit 100 decrypts the ciphertext received from the server device 20 using the endorsement private key 142 via the TPM 140 (step S134). Note that in this embodiment, the ciphertext transmitted from the server device 20 is assumed to be information (for example, a character string) obtained by encrypting a counter value and a storage key.

[0056] Next, control unit 100 acquires a counter value from the ciphertext (plaintext) decrypted in step S134 (step S136), and determines whether or not the counter value is appropriate (step S138). For example, if the counter value acquired in step S136 is greater than the counter value stored in parameter table 174, control unit 100 determines that the counter value is appropriate; otherwise, it determines that the counter value is inappropriate.

[0057] If the counter value is appropriate, the control unit 100 determines that valid information has been received from the server device 20 and that the storage key can be acquired from the server device 20 (step S138; Yes -> step S140). In this case, the control unit 100 updates the counter value stored in the parameter table 174 by substituting the counter value acquired in step S136 for the counter value (step S142).

[0058] On the other hand, if the counter value is not appropriate, the control unit 100 determines that invalid information has been received from the server device 20, and determines that the storage key cannot be acquired from the server device 20 (step S138; No -> step S144). In this case, the control unit 100 may discard the received information without using it.

[0059] If there is no response from the server device 20 in step S130, the control unit 100 may retry transmitting the assurance public key 144 to the server device 20. If there is no response from the server device 20 a certain number of times, the control unit 100 may stop the retry attempts, determine that communication with the server device 20 has not been successful, and terminate the processing in Fig. 9. In this case, the control unit 100 determines that it is impossible to acquire the storage key from the server device 20.

[0060] 8, the control unit 100 determines whether the determination result in the storage key acquisition process indicates that the storage key can be acquired from the server device 20 (step S110). If the storage key can be acquired from the server device 20, the control unit 100 acquires the storage key based on the information received from the server device 20 (step S110; Yes→step S112). For example, the control unit 100 acquires the storage key from the ciphertext (plaintext) decrypted in step S134 of FIG. 9.

[0061] Next, the control unit 100 (storage encryption unit 104) uses the storage key acquired in step S112 to decrypt the storage 180 (step S114). The control unit 100 also reads and executes the operating system 182 from the decrypted storage 180, thereby starting up the operating system 182 (step S116).

[0062] On the other hand, if the control unit 100 cannot acquire the storage key from the server device 20, it displays an error message on the display unit 120 indicating that the storage key cannot be acquired from the server device 20 (step S110; No→step S118). Furthermore, the control unit 100 displays a screen on the display unit 120 for allowing the user to select a startup option for the information processing device 10, and allows the user to input the startup option (step S120). For example, the following three startup options are selectable: ·Restart Change settings Password entry Note that even if the control unit 100 determines in step S106 that the server device 20 has not been configured, it executes the process in step S120 (step S106; No→step S120).

[0063] Next, the control unit 100 determines the startup option input by the user (step S122). If the startup option is reboot, the control unit 100 reboots the information processing device 10 and starts over from the process in step S100 (step S122; reboot → step S100). If the startup option is setting change, the control unit 100 transitions to a BIOS (Basic Input Output System) setting mode (step S122; setting change → step S124). In this case, the control unit 100 displays a setting screen on the display unit 120. The setting screen may allow the settings of the server device 20 to be changed. When the user has completed the settings, the control unit 100 reboots the information processing device 10 and starts over from the process in step S100.

[0064] If the startup option is password input, the control unit 100 executes a process to acquire a storage key using the password (step S122; password input). That is, the control unit 100 requests the user for authentication to read data from the secure memory 146.

[0065] The process of obtaining a storage key using a password will be described with reference to Fig. 10. First, the control unit 100 displays a screen on the display unit 120 for prompting the user to enter a password used to read data stored in the secure memory 146, and requests the user to enter the password (step S150).

[0066] After the user inputs a password, the control unit 100 determines whether the waiting time of the lock timer is greater than 0 (step S152). If the waiting time of the lock timer is greater than 0, the control unit 100 waits until the waiting time of the lock timer reaches 0 (step S152; Yes→step S154). If the waiting time of the lock timer is 0, the control unit 100 omits the processing of step S154 (step S152; No).

[0067] Next, the control unit 100 determines whether the password entered in step S150 is the correct password (step S156). For example, if the password entered by the user matches the password stored in the password information 148, the control unit 100 determines that the entered password is correct.

[0068] If the password is correct, the control unit 100 authenticates the user who entered the password as a legitimate user of the information processing device 10, and resets the parameter value for the number of incorrect inputs in the parameter table 174 to 0 (step S156; Yes→step S158). In addition, the control unit 100 acquires the storage key 1462 stored in the secure memory 146 of the TPM 140 (step S160).

[0069] Next, the control unit 100 (storage encryption unit 104) decrypts the storage 180 using the storage key 1462 acquired in step S160 (step S162). The control unit 100 reads and executes the operating system 182 from the decrypted storage 180, thereby starting up the operating system 182 (step S164).

[0070] On the other hand, if the control unit 100 determines in step S156 that the password is incorrect, it adds 1 to the parameter value of the number of incorrect inputs in the parameter table 174 (step S156; No -> step S166). Furthermore, the control unit 100 (waiting time acquisition unit 102) acquires a waiting time based on the number of incorrect inputs (step S168). The control unit 100 assigns the acquired waiting time to the lock timer (step S170). After executing the process in step S170, the control unit 100 returns to step S150.

[0071] [1.3.2 Server device] The flow of main processes executed by the server device 20 will be described with reference to Fig. 11. The processes shown in Fig. 11 are executed by the control unit 200 of the server device 20 reading out a program stored in the storage unit 260.

[0072] First, the control unit 200 determines whether or not a certified public key has been received from another device via the communication unit 290 (step S180). If the control unit 200 has not received a certified public key from another device, the control unit 200 repeats the process in step S180 (step S180; No).

[0073] When the control unit 200 receives the guaranteed public key, it reads the storage key information including the guaranteed public key from the storage key information memory area 262 and obtains the storage key corresponding to the guaranteed public key (step S180; Yes → step S182).

[0074] Next, the control unit 200 adds the counter value stored in the parameter table 264 to the storage key acquired in step S182 (step S184). Furthermore, the control unit 200 implements an RSA encryption device and encrypts the information (character string) of the storage key to which the counter value has been added (step S186). At this time, the control unit 200 performs encryption using the guaranteed public key received in step S180 or the guaranteed public key included in the storage key information read in step S182.

[0075] Next, the control unit 200 updates the counter value acquired in step S184 by adding 1 to the counter value and storing the result in the parameter table 264 (step S188). Furthermore, the control unit 200 transmits the ciphertext generated in step S186 to the information processing device 10 that transmitted the guaranteed public key in step S180 (step S190).

[0076] The above-described process may be modified as needed. For example, the control unit 100 may execute the following process in step S156.

[0077] (1) Use of a password key derivation function The control unit 100 inputs the password input by the user as an argument of a password-based key derivation function (PBKDF), thereby deriving a key based on the password.

[0078] (2) Use of salt for password key derivation functions The salt is a non-secret random number value that is generated each time a password is set for the secure memory 146. When the control unit 100 uses a password derivation function, it inputs the salt along with the password as arguments to the password derivation function. This enables the control unit 100 to resist dictionary attacks.

[0079] (3) Key stretching When deriving a key from a password or the like, the control unit 100 applies a pseudo random function (PRF) consisting of a cryptographic hash function or the like within the password key derivation function not just once but multiple times (several thousand times or more). In other words, the control unit 100 inputs the output of the PRF back into the PRF to repeatedly derive the key. This enables the control unit 100 to improve resistance to brute force attacks. The number of repetitions may be predetermined or may be set by the user.

[0080] When the above-described process is performed, information that can be compared with information derived by the above-described process (e.g., a key derived using a password key derivation function) is stored in password information 148. For example, password information 148 may include information on a key derived by applying the password key derivation function one or more times, and information on a salt.

[0081] Furthermore, the control unit 100 may reset the number of incorrect password inputs to 0 if the information processing device 10 has been continuously powered on for more than 24 hours since the last incorrect password input.

[0082] [1.4 Example of operation] [1.4.1 Storage key registration operation] An example of the operation of this embodiment will be described with reference to Fig. 12 to Fig. 14. First, a procedure in which the information processing device 10 registers an endorsement public key in the server device 20 will be described with reference to Fig. 12. First, the information processing device 10 generates a storage key ((1) in Fig. 12). The storage key may be a password entered by the user, or may be a key generated using a password key derivation function based on the password. The storage key is stored as a storage key 1462 in the secure memory 146 of the TPM 40 ((2) in Fig. 12).

[0083] The information processing device 10 also registers the generated storage key in the server device 20. At this time, the information processing device 10 transmits PubEK1, which is the endorsement public key 144, and the storage key to the server device 20 ((3) in FIG. 12). The server device 20 generates storage key information including the received storage key and endorsement public key PubEK1, and stores the information in the storage key information storage area 262 ((4) in FIG. 12). Note that communication between the information processing device 10 and the server device 20 may be protected by means such as Transport Layer Security (TLS). In this case, when starting communication for registration, the information processing device 10 verifies a digital certificate presented by the communication partner to confirm that the communication partner is the authentic server device 20. For this purpose, a digital certificate is stored in advance in the server device 20.

[0084] [1.4.2 Storage key transmission and reception behavior] The operation of transmitting and receiving a storage key will be described with reference to Fig. 13. First, the information processing device 10 makes an inquiry to the server device 20 to obtain the storage key of the information processing device 10. At this time, the information processing device 10 transmits PubEK1, which is the endorsement public key 144, to the server device 20 ((1) in Fig. 13).

[0085] The server device 20 receives the inquiry and searches the storage key information storage area 262 ((2) in FIG. 13). As a result, the server device 20 acquires the storage key (search result) corresponding to the PubEK1 received from the information processing device 10 ((3) in FIG. 13).

[0086] The server device 20 adds the counter value to the storage key ((4) in FIG. 13). At this time, the server device 20 updates the counter value by adding 1 to it. The server device 20 encrypts the counter value and the storage key using PubEK1 ((5) in FIG. 13), and returns the encrypted ciphertext to the information processing device 10 ((6) in FIG. 13).

[0087] The information processing device 10 obtains the counter value and the storage key by having the TPM 140 decrypt the received response ((7) in FIG. 13). At this time, if the counter value obtained from the server device 20 is greater than the counter value of the information processing device 10, the information processing device 10 adopts the response and updates the counter value of the information processing device 10 ((8) in FIG. 13). In this way, the information processing device 10 can obtain the storage key without reading the secure memory 146 ((9) in FIG. 13).

[0088] 1.4.3 Actions to deal with replay attacks In this embodiment, the information processing device 10 acquires a storage key from the server device 20, thereby omitting the process of inputting a password at startup to extract the storage key from the TPM 140. Here, there are concerns about eavesdropping on information transmitted from the server device 20 to the information processing device 10, and "spoofing" attacks in which an attacker acquires the information using a fake device different from the information processing device 10. Generally, technologies such as TLS are used to prevent such attacks. In this case, it is necessary to install a digital certificate in the information processing device 10 and present the digital certificate to the server device 20.

[0089] However, the storage key is required before the information processing device 10 starts the operating system. It is difficult for the information processing device 10 to use TLS or the like before the operating system starts. Another problem is that a digital certificate or the like must be separately prepared for the information processing device 10.

[0090] Therefore, the information processing device 10 of this embodiment uses the RSA key pair (endorsement keys) of the TPM 140 as a key (key distribution key) for encrypting the storage key. Specifically, the information processing device 10 decrypts a ciphertext, which has been encrypted by the server device 20 using the endorsement public key 144 of the information processing device 10, using the endorsement private key 142 of the information processing device 10. In other words, the information processing device 10 can use the endorsement public key before starting the operating system. This enables the information processing device 10 to communicate encrypted information with the server device 20, thereby ensuring security. As a result, in this embodiment, it is possible to send and receive the ciphertext of the storage key more easily than when the storage key is received by TLS.

[0091] Furthermore, in this embodiment, the ciphertext transmitted from the server device 20 to the information processing device 10 includes a counter value. This enables the information processing device 10 to respond to a replay attack. Here, with reference to Fig. 14, an operation of the information processing device 10 to respond to a replay attack will be described.

[0092] 14(a) shows a legitimate operating environment, and FIG. 14(b) shows an attacker's environment (attacker's base). First, in the legitimate operating environment, information processing device 10, whose counter value is "00000020", acquires a ciphertext whose counter value is "00000021" from server device 20. Information processing device 10 determines that the counter value received from server device 20 is appropriate, and updates the counter value of information processing device 10 to "00000021".

[0093] Here, the attacker connects his / her own PC to a network (such as a LAN) in a legitimate operating environment and eavesdrops on the response from the server device 20 to the information processing device 10 ((1) in FIG. 14). The attacker also steals the information processing device 10 and installs it at the attacker's base ((2) in FIG. 14).

[0094] Furthermore, the attacker connects a fake key server that transmits the intercepted response to the information processing device 10. In such an environment, the information processing device 10 queries the fake key server for a storage key and receives a response from the fake key server ((3) in FIG. 14). Here, the counter value included in the response is “00000021.” Meanwhile, the counter value of the information processing device 10 is “00000021.” Here, the counter value from the genuine server device 20 should be larger than the counter value of the information processing device 10, but the counter value acquired from the fake key server is smaller than that, so the information processing device 10 determines that the counter value is inappropriate ((4) in FIG. 14). As a result, the information processing device 10 realizes that the response is invalid (a replay attack = reuse of a past response), does not accept the response received from the fake key server, and requests entry of a password. Unless the attacker knows the password, he or she cannot steal information from the information processing device 10.

[0095] Note that there is a technique for replay attacks that uses the current time, but this requires time synchronization (clock synchronization) between the information processing device 10 and the server device 20. In contrast, the information processing device 10 of the present embodiment uses a counter value to effectively prevent information leakage due to unauthorized use outside the operating environment.

[0096] In the above-described embodiment, the secure memory 146 is protected by a password, and the control unit 100 requests the user to input the password for authentication. However, the authentication method may be a method other than a password, such as biometric authentication (fingerprint authentication, voice authentication, face authentication, etc.), or possession authentication using an ID card, a mobile terminal device, etc., and any general authentication method can be used.

[0097] As described above, the information processing device of the present embodiment ensures security for the storage and, if a storage key cannot be acquired from the server device, acquires the storage key based on a password, thereby improving the availability of the information processing device. In particular, the information processing device of the present embodiment attempts to acquire a storage key from a key server (server device) when powered on (when powered on), and, if the storage key is acquired, decrypts the storage using the storage key acquired from the server device and operates. This eliminates the need for a user to enter a password when starting up the information processing device. As a result, the information processing device of the present embodiment can save the user the trouble of having to enter a storage protection password in daily use, thereby improving user convenience. Furthermore, by eliminating the need to enter a password, the information processing device of the present embodiment is expected to reduce security risks, such as writing a storage protection password on a sticky note and attaching it to a post-it note. This is effective when the information processing device is shared.

[0098] Furthermore, in this embodiment, when a storage key is transmitted from a server device, it is encrypted using the guaranteed public key of the information processing device. Generally, a storage key is required to start an operating system, so the storage key needs to be securely transmitted before the operating system starts. To perform encrypted communication using TLS or the like before the operating system starts, the mechanism for starting the device (boot process) also needs to include a cryptographic communication mechanism similar to that of the operating system, which increases the burden in terms of device design, number of components, and user management effort. However, this embodiment achieves transmission and reception of the storage key through encryption using the guaranteed public key, without requiring TLS or the like.

[0099] Furthermore, if the information processing device of this embodiment cannot obtain the storage key from the server device, it can obtain the storage key by entering a password, thereby preparing for network trouble and maintaining the availability of the device. For example, even if the storage key cannot be obtained due to a failure in the network (LAN, etc.) or the server device, or a change in the functional configuration, the information processing device of this embodiment can decrypt the storage. Here, the storage key is stored in a secure memory that is strictly managed within the information processing device, so the information processing device of this embodiment can securely obtain the storage key.

[0100] In addition, the information processing device of this embodiment stores the storage key in a secure memory to make it difficult to read, and further verifies information received from a server device using a counter value, thereby preventing information leakage and protecting confidentiality even if the information processing device is stolen.

[0101] [2. Second Embodiment] Next, a second embodiment will be described. The second embodiment differs from the first embodiment in that the storage key is stored in an external storage medium instead of in the secure memory. The following description will focus on the differences from the first embodiment.

[0102] In this embodiment, an external storage medium storing a storage key is connected to the connection unit 130 of the information processing device 10. In addition, in step S160 of Fig. 10, the control unit 100 acquires the storage key from the external storage medium connected to the connection unit 130. In the following description, it is assumed that the external storage medium storing the storage key is a USB memory.

[0103] Here, when the storage key is stored in the USB memory, it is necessary to prevent unauthorized use in the event that both the information processing device 10 and the USB memory are stolen by an unauthorized user. Therefore, in this embodiment, the following method may be implemented so that the information processing device 10 can securely obtain the storage key from the USB memory.

[0104] (1) Encrypting the storage key and storing it on a USB memory stick The method of encrypting the storage key and storing it in the USB memory is a method in which the encrypted storage key is stored in the USB memory, and the information processing device 10, upon acquiring the encrypted storage key, decrypts the storage key to acquire the storage key. An encryption key (key encryption key) for decrypting the storage key is stored, for example, in the secure memory 146 of the TPM 140. In this case, the control unit 100 requests the user for a password for the TPM 140 (a password for the secure memory 146) in step S140. At this time, if the user enters the correct password, the control unit 100 retrieves the key encryption key from the TPM 140 (secure memory 146). The control unit 100 reads the encrypted storage key from the USB memory and decrypts the encrypted storage key using the key encryption key. Note that the key encryption key may be generated by a means for generating a key encryption key from a password (a password-based key derivation function). In this case, the control unit 100 may request the user to enter the password that was entered when the key encryption key was generated in step S140, and may decrypt the storage key using the key encryption key if the correct password is entered.

[0105] (2) Using a USB memory stick with built-in encryption functionality A method of using a USB memory with built-in encryption function is, for example, to use a USB memory that operates an attached application program on the host (information processing device 10) side and accepts password input. Alternatively, a USB memory that has numeric input keys and accepts a personal identification number, or a USB memory that has a fingerprint sensor and performs fingerprint authentication, may be used. After the encryption is decrypted in such a USB memory with built-in encryption function, the control unit 100 acquires the storage key stored in the USB memory in step S140.

[0106] Fig. 15 is a diagram showing the difference between the first embodiment and the present embodiment. Fig. 15(a) is a diagram showing the operation of the first embodiment, in which the storage key is stored in the information processing device 10 and the server device 20. On the other hand, Fig. 15(b) is a diagram showing the operation of the present embodiment, in which the storage key is stored in an external storage medium and the server device 20. When the information processing device 10 of the present embodiment is unable to acquire the storage key from the server device 20, it acquires the storage key from the external storage medium.

[0107] In addition, in step S160 of Figure 10, the control unit 100 may determine whether the storage key 1462 is stored in the secure memory 146, and if the storage key 1462 is not stored in the secure memory 146, the control unit 100 may obtain the storage key from an external storage device.

[0108] In the above description, the external storage medium is described as a USB memory, but the external storage medium may be any device that can securely exchange data with the information processing device 10. For example, the external storage device may be a hard disk or an SD card that can be protected against information leakage. The external storage device may also be connected via short-range wireless communication such as Bluetooth (registered trademark).

[0109] In this way, the information processing device of this embodiment can obtain the storage key from the external storage medium. By implementing measures to prevent unauthorized use of this external storage medium, the information processing device can securely obtain the encryption key even when the storage key is not stored in the security module and the encryption key cannot be obtained from the server device.

[0110] 3. Third Embodiment Next, a third embodiment will be described. The third embodiment differs from the first embodiment in that the storage key is stored in a terminal device (e.g., a mobile terminal) instead of being stored in a secure memory. The following description will focus on the differences from the first embodiment.

[0111] In this embodiment, a terminal device that stores a storage key is connected to the connection unit 130 of the information processing device 10. In addition, in step S160 of FIG. 10, the control unit 100 acquires the storage key from the terminal device connected to the connection unit 130.

[0112] Here, if the terminal device that stores the storage key of the information processing device 10 is appropriately protected so that it cannot be misused by anyone other than a legitimate user, the terminal device may behave in the same manner as the server device 20. In this case, the terminal device stores the endorsement public key and the storage key in association with each other. The control unit 100 transmits the endorsement public key 144 to the terminal device in step S160 of FIG. 10 . The terminal device transmits the storage key 1462 corresponding to the received endorsement public key 144 to the information processing device 10. This allows the information processing device 10 to obtain the storage key 1462 from the terminal device. Note that an appropriate protection is when a password is required or authentication such as biometric authentication is performed when the terminal device is used.

[0113] On the other hand, if there is a risk that the terminal device may be fraudulently used by someone other than a legitimate user, it is insufficient to behave in the same manner as the server device 20. In such a case, when the storage key is acquired by the information processing device 10, a password is to be input into the terminal device.

[0114] The password input to the terminal device may be the TPM 140 password set in the TPM 140, or a password other than the TPM 140 password, or both may be used together (in this case, both passwords must be input). Inputting the TPM 140 password and a password other than the TPM 140 password is effective when it is necessary to increase the security level against acquisition of the storage key.

[0115] 16(a) is a diagram showing an example of operation of this embodiment. The storage key is stored in a mobile terminal (terminal device) and the server device 20. When the information processing device 10 of this embodiment cannot acquire the storage key from the server device 20, it acquires the storage key from the mobile device.

[0116] In addition, in step S160 of Figure 10, the control unit 100 may determine whether the storage key 1462 is stored in the secure memory 146, and if the storage key 1462 is not stored in the secure memory 146, obtain the storage key from the terminal device.

[0117] 16(b), the storage key may be stored in the TPM 140 and the mobile terminal, and the TPM 140 and the mobile terminal may be used in combination. For example, suppose that a first administrator (e.g., a primary administrator) and a second administrator (e.g., a sub-administrator) are assigned as users who have the role of starting up the information processing device 10. The primary administrator manages the password for the TPM 140 in the information processing device 10. When the server device 20 is unavailable, the primary administrator starts up the information processing device by entering the password for the TPM 140. The sub-administrator manages the mobile terminal that stores the storage key. When the server device 20 is unavailable and the primary administrator is absent, the sub-administrator starts up the device using the mobile terminal.

[0118] In this way, the information processing apparatus of this embodiment can acquire a storage key from a terminal device connected to the information processing apparatus. In this case, compared to storing the storage key in the information processing apparatus or a USB memory, storing the storage key in the terminal device requires a password in addition to the TPM password, thereby enhancing security. In this way, a security level can be set according to the storage location of the storage key. A user can flexibly set the storage location and security level of the storage key according to the method of operating the information processing apparatus. Furthermore, the image processing apparatus can securely acquire an encryption key from a terminal device even when it is unable to acquire the encryption key from a server device.

[0119] [4. Fourth Embodiment] Next, a fourth embodiment will be described. In the fourth embodiment, the information processing device described in the first embodiment is applied to an image processing device, and a predetermined function is provided to the user even when the encryption of storage cannot be decrypted. In this embodiment, FIG. 2 of the first embodiment is replaced with FIG. 18. Note that the same functional units are assigned the same reference numerals, and descriptions thereof will be omitted.

[0120] [4.1 Functional Configuration] The functional configuration of the image processing device 12 of this embodiment will be described with reference to Figs. 17 and 18. Fig. 17 is an external perspective view of the image processing device 12, and Fig. 18 is a functional configuration diagram of the image processing device 12. The image processing device 12 is a device having a copy function, a print function, a scan function, an email sending function, etc., and is generally called a digital multifunction peripheral. Note that the image processing device 12 may also be an image forming device equipped with means for forming an image on recording paper such as paper or OHP film using means such as an electrophotographic method.

[0121] The image processing device 12 further includes an image input unit 110 and an image forming unit 112 in addition to the components of the information processing device 10 in the first embodiment.

[0122] The image input unit 110 is a functional unit that reads an image of a document and generates image data. For example, the image input unit 110 is configured by a scanner device that converts an image into an electrical signal using an image sensor such as a CCD (Charge Coupled Device) or a CIS (Contact Image Sensor), and generates digital data by quantizing and encoding the electrical signal.

[0123] Image forming unit 112 is a functional unit that forms image data on a recording medium (e.g., recording paper). For example, image forming unit 112 feeds recording paper from paper feed tray 114 in Fig. 17, forms an image on the surface of the recording paper, and discharges the recording paper with the image formed from discharge tray 116. Image forming unit 112 is configured, for example, by a laser printer that uses an electrophotographic system.

[0124] The operation unit 125 of this embodiment may be configured with hard keys (for example, a numeric keypad), buttons, etc. The image processing device 12 may also include a touch panel in which the display unit 120 and the operation unit 125 are integrally formed. The method for detecting input to the touch panel may be any common detection method, such as a resistive film method, an infrared method, an electromagnetic induction method, or a capacitance method.

[0125] In this embodiment, the read-only storage unit 160 stores an operating system 162 and an operation program 164. The operation program 164 is a program that is executed to operate each function of the image processing device 12. On the other hand, the image processing device 12 does not store an operating system in the storage 180.

[0126] [4.2 Processing flow] The flow of main processes executed by the image processing device 12 will be described with reference to Fig. 19. The processes shown in Fig. 19 are executed by the control unit 100 of the image processing device 12 reading out the operation program 164 stored in the read-only storage unit 160.

[0127] First, the control unit 100 acquires a storage key for the storage 180 (step S400). The control unit 100 executes the processes of FIGS. 8 to 10 of the first embodiment as the process in step S400. Here, if the correct password is not entered a predetermined number of times in the process shown in FIG. 10, the control unit 100 determines that the storage 180 cannot be restored, and ends the processes of FIGS. 8 to 10 of the first embodiment. Furthermore, the control unit 100 omits the processes in step S116 in FIG. 8 and step S164 in FIG. 10.

[0128] Next, the control unit 100 reads and executes the operating system 162 stored in the read-only memory unit 160, thereby starting up the operating system 162 (step S402). The control unit 100 also reads and executes the operating program 164, thereby enabling functions such as a copy function and a scan function to be executed (step S404).

[0129] Next, the control unit 100 determines whether the encryption of the storage 180 has been released (step S406). If the encryption of the storage 180 has been released, the control unit 100 operates the image processing device 12 using the storage 180 (step S406; Yes → step S408). In this case, for example, the control unit 100 does not limit the number of images input via the image input unit 110, and executes copying or scanning of multiple pages. In other words, the image processing device 12 performs normal operation.

[0130] On the other hand, if the encryption of the storage 180 has not been decrypted, the control unit 100 operates the image processing device 12 without using the storage 180 (step S406; No → step S410). In this case, for example, the control unit 100 stores image data input via the image input unit 110 in the main memory unit 150 and performs copying or scanning based on the data stored in the main memory unit 150. Therefore, the control unit 100 limits the number of images input via the image input unit 110 to the number that can be stored in the main memory unit 150. In this case, the control unit 100 may limit the number of images that can be input at one time to one, allowing single-page copying or scanning. Furthermore, the size of data stored in the main memory unit 150 may be reduced by limiting the resolution and image quality of the read image. As a result, in the copy function, the number of images formed (output) via the image forming unit 112 may be reduced or the quality of the images may be lower than in the normal case. Furthermore, the number of images stored in the external storage device or transmitted to the outside may be smaller than usual, and the quality of the images may be lower.

[0131] In this way, the image processing device of this embodiment can switch the operation method of the image processing device depending on whether the storage has been decrypted. In this case, even if the storage cannot be decrypted, the image processing device can ensure user convenience by enabling the operation of predetermined functions.

[0132] [5. Modifications] The present invention is not limited to the above-described embodiments and various modifications are possible. In other words, embodiments obtained by combining technical means that are appropriately modified within the scope of the present invention are also included in the technical scope of the present invention. For example, in the above-described embodiments, the device that acquires the storage key from the server device is described as an information processing device or an image processing device, but the device may also be a server or a virtual machine.

[0133] Although the above-described embodiments are described separately for convenience of explanation, they may be combined within the scope of technical feasibility. For example, the second embodiment and the fourth embodiment may be combined. In this case, if the image processing device cannot obtain the storage key from the server device, it obtains the storage key stored in the external storage medium.

[0134] In addition, the programs that run on each device in the embodiments are programs that control the CPU, etc. (programs that make a computer function) so as to realize the functions of the above-described embodiments. Information handled by these devices is temporarily stored in a temporary storage device (e.g., RAM) during processing, and then stored in various storage devices such as ROMs (Read Only Memories) and HDDs, and is read, modified, and written by the CPU as needed.

[0135] Here, the recording medium for storing the program may be any of semiconductor media (e.g., ROM, non-volatile memory card, etc.), optical recording media / magneto-optical recording media (e.g., DVD (Digital Versatile Disc), MO (Magneto Optical Disc), MD (Mini Disc), CD (Compact Disc), BD (Blu-ray (registered trademark) Disc), etc.), magnetic recording media (e.g., magnetic tape, flexible disk, etc.), etc. Furthermore, not only are the functions of the above-described embodiments realized by executing the loaded program, but the functions of the present invention may also be realized by processing in cooperation with an operating system or other application programs, etc., based on instructions from the program.

[0136] Furthermore, when distributing the program on the market, the program can be stored on a portable recording medium and distributed, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is of course included in the present invention. [Explanation of symbols]

[0137] 10. Information processing equipment 12 Image processing device 100 control section 102 Waiting time acquisition unit 104 Storage Encryption Unit 110 Image input unit 112 Image forming unit 120 Display section 125 Operation section 130 Connection 140 TPM 142 Endorsement Private Key 144 Endorsement Public Key 146 Secure Memory 1462 Storage Key 148 Password Information 150 Main memory 160 Read-only memory 170 Non-volatile memory unit 172 Server Settings 174 Parameter Table 176 Waiting Time Table 180 Storage 190 Communications Department 20 Server device 200 control section 210 Display section 220 Operation section 260 Storage section 262 Storage key information storage area 264 Parameter Table 290 Communications Department

Claims

1. A first storage unit that stores data encrypted using an encryption key; a second storage unit that stores the encryption key; a communication unit that communicates with a server device that stores the encryption key; A control unit; Equipped with The control unit When decrypting the first storage unit, acquiring the counter value together with the encryption key via the communication unit; If the acquired counter value is greater than a pre-stored counter value, the encryption key acquired from the server device is used to decrypt the first storage unit; If the encryption key cannot be obtained via the communication unit or if the counter value is equal to or less than the pre-stored counter value, the device requests authentication from the user, and after the authentication is performed, the device obtains the encryption key from the second storage unit and decrypts the encryption of the first storage unit.

1. An information processing device comprising:

2. The information processing apparatus according to claim 1 , wherein the control unit requests authentication using a password set in the second storage unit.

3. 3. The information processing apparatus according to claim 1, wherein the second storage unit is protected by a TPM (Trusted Platform Module).

4. The control unit receiving, from the server device, the encryption key encrypted by a public key embedded in the TPM; The encrypted encryption key is decrypted using a private key embedded in the TPM.

4. The information processing apparatus according to claim 3,

5. An information processing device described in any one of claims 1 to 4, characterized in that the control unit registers the encryption key in the server device via the communication unit.

6. 5. The information processing device according to claim 1, wherein the control unit, if the encryption key is not stored in the second storage unit, acquires the encryption key from another connected device.

7. 2. The information processing apparatus according to claim 1, wherein the control unit acquires the encryption key from the server device after power is turned on and before an operating system is started.

8. The control unit When the encryption of the first storage unit is decrypted, the device operates using the first storage unit; If the authentication is not performed, the device operates without using the first storage unit.

8. The information processing device according to claim 1, wherein the information processing device is a computer.

9. further comprising an image input unit for inputting an image of a document; 9. The information processing device according to claim 8, wherein the control unit, when operating without using the first storage unit, limits the number of images input by the image input unit or reduces the data size of the input images.

10. A method for controlling a device having a first storage unit that stores data encrypted using an encryption key and a second storage unit that stores the encryption key, comprising: communicating with a server device that stores the encryption key; When decrypting the first storage unit, acquiring a counter value together with the encryption key via the communication; If the acquired counter value is greater than a pre-stored counter value, decrypting the first storage unit using the encryption key acquired from the server device; If the encryption key cannot be obtained through the communication or if the counter value is equal to or less than the pre-stored counter value, requesting authentication from a user, and after the authentication is performed, obtaining the encryption key from the second storage unit and decrypting the first storage unit; A control method comprising:

Images