KR20230068144A - Method for Key Management Service And System Therefor - Google Patents

Abstract

The present disclosure provides a key management service providing method and a system therefor. According to one aspect of the present disclosure, when a client apparatus requests the use of a client key to an enclave, the enclave communicates with a security module to use the client key in a secure way provide a system for

Description

Key management service providing method and system therefor {Method for Key Management Service And System Therefor}

The present disclosure relates to a method for providing a key management service and a system therefor.

The contents described in this part merely provide background information on the present embodiment and do not constitute prior art.

A Hardware Security Module (HSM) is hardware for security that is located physically separate from a computing system and generates, stores, and manages keys. HSMs are physically independent hardware, secure cryptographic key operations such as signing certificates, and allow limited access through network interfaces. HSM is a physical security element, and may include tamper-evident and tamper-resistant functions. Tamper-evident is a function that leaves evidence of tampering that occurs in the HSM. Tamper-resistance is a function that deletes internal data when an attack on the HSM is detected.

Although the HSM has strong security, there is a problem in that it is difficult to scale up due to the characteristics of hardware equipment. As an alternative to these on-premises HSMs, a key management service (Cloud KMS) based on HSMs provided by the cloud is being used. Cloud KMS is based on multiple HSMs deployed on a cloud platform, allowing users to use HSMs remotely without purchasing HSMs themselves. Cloud KMS has wide scalability and is economical because one HSM can be used by multiple users. When one HSM is shared by several users, keys of the HSM are managed and isolated for each user by a cloud instance that operates the HSM.

However, Cloud KMS has a problem in that insider threats by malicious insiders can occur. For example, when a malicious insider possesses credential to access the HSM, the malicious insider may leak keys inside the HSM using the credential. Even if the HSM specifies a key as a non-extractable key, a malicious insider can still misuse the key. In addition, in the case of Cloud KMS, due to the environmental characteristics of cloud service, communication between the user and the HSM is hacked, and the HSM execution result or plain-text key requested by the user can be leaked to the outside or forged.

According to an aspect of the present disclosure, a secure channel between a secure module and a client device may be formed based on a master key pair.

According to an aspect of the present disclosure, it is possible to provide a security module that generates a key encryption key, encrypts a client key, and deletes the plaintext client key and the plaintext key encryption key.

According to one aspect of the present disclosure, a security module may obtain a key encryption key from a client device and decrypt and use the encrypted client key.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

According to one aspect of the present disclosure, a method for establishing a security channel to provide a key management service includes: generating a master key pair by a security module; and forming, by the security module, a secure channel with a client device based on the master key pair.

According to one aspect of the present disclosure, in the above-described secure channel establishment method, after the process of generating the master key pair, the process of providing the master public key to the client device through the enclave by a security module; and receiving, by the security module, a shared key encrypted by the master public key from the client device through the enclave.

According to an aspect of the present disclosure, a method for generating a client key to provide a key management service includes: generating, by a security module, the client key and a key encryption key (hereinafter referred to as KEK); the security module encrypting and storing the client key using the KEK; and deleting, by the security module, the plaintext client key and the plaintext KEK.

According to one aspect of the present disclosure, in a method of decrypting a client key to provide a key management service, the process of generating a one-time pad (OTP) by a security module; obtaining, by a security module, a key encryption key (hereinafter referred to as KEK) from a client device; and decrypting, by the security module, the encrypted client key based on the KEK.

According to one aspect of the present disclosure, in the above-described client key decryption method, the security module forms a security channel with the client device through an enclave; and providing, by the security module, the OTP to the client device.

According to one aspect of the present disclosure, in the above-described client key decryption method, after performing an operation related to the decrypted client key, the security module further includes deleting the decrypted client key, the OTP, and the KEK. Characterized in that, it provides a client key decryption method.

According to one aspect of the present disclosure, there is an effect of forming a security channel by sharing a public key between a client device and a security module based on a master key pair.

According to one aspect of the present disclosure, there is an effect of forming a secure channel without an offline process.

According to one aspect of the present disclosure, the client key can be protected against attacks by malicious insiders by the security module encrypting and storing the client key and deleting the plain text client key.

According to one aspect of the present disclosure, the operation requested by the client is transmitted to the security module through the enclave, and the decryption and use of the client key are performed only in the security module, so that the client key can be protected against attacks on the communication channel with the client device, It has the effect of preventing incorrect operation.

According to one aspect of the present disclosure, since the storage in plain text is limited only while the actual user is using the corresponding client key, when an attacker tries to extract/misuse the client key, the log generated by the security module Based on this, it has the effect of immediately detecting an attack.

According to one aspect of the present disclosure, there is an effect of managing a multi-tenancy function capable of storing and using keys of several clients in the same security module while guaranteeing the integrity of client keys.

The effects of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

1 is a conceptual diagram illustrating a key management system according to an embodiment of the present disclosure.
2 is a conceptual diagram illustrating an implementation example of a key management system according to an embodiment of the present disclosure.
3 is a flowchart illustrating a method for establishing a secure channel according to an embodiment of the present disclosure.
4 is a flowchart illustrating a method for generating a client key according to an embodiment of the present disclosure.
5 is a flowchart illustrating a client key decryption method according to an embodiment of the present disclosure.
6 is a graph showing performance of a key management system according to an embodiment of the present disclosure.
7 is a graph showing the performance of a key management system according to an embodiment of the present disclosure according to simultaneous requests for client key use.

Hereinafter, some embodiments of the present disclosure will be described in detail through exemplary drawings. In adding a reference code to the components of each drawing, it should be noted that the same components have the same numbers as much as possible even if they are displayed on different drawings. In addition, in describing the present disclosure, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present disclosure, the detailed description will be omitted.

In addition, in describing the components of the present disclosure, terms such as first and second may be used. These terms are only used to distinguish the component from other components, and the nature, order, or order of the corresponding component is not limited by the term. Throughout the specification, when a part 'includes' or 'includes' a certain component, it means that it may further include other components without excluding other components unless otherwise stated. . In addition, the '... Terms such as 'unit' and 'module' refer to a unit that processes at least one function or operation, and may be implemented as hardware, software, or a combination of hardware and software.

The detailed description set forth below in conjunction with the accompanying drawings is intended to describe exemplary embodiments of the present disclosure, and is not intended to represent the only embodiments in which the present disclosure may be practiced.

In the key management system of the present disclosure, when a client apparatus requests the enclave to use a client key, the enclave communicates with a security module to secure the client key. It is a system for providing a key management service that allows keys to be used.

In the present disclosure, a security module is security hardware for generating, storing, and managing a key of a client, and may be a Hardware Security Module (HSM).

A security module according to an embodiment of the present disclosure may be implemented as a device having one or more programmable processors and a computer readable storage connected to the one or more programmable processors to store an encrypted client key, but some components It can be added, deleted, or changed. One or more programmable processors may perform all or part of a secure channel establishment method, a client key generation method, and a client key decryption method described below according to a command transmitted from an enclave.

In the present disclosure, an enclave is an instance or memory area located inside a processor, and means a trusted memory area for providing a Trusted Execution Environment (TEE). The enclave ensures data integrity because it performs security procedures whenever data is exchanged with external devices. The enclave may ensure data integrity by, for example, using encrypted memory and performing cryptographic operations using a hardware random number generator. Enclaves perform cryptographic operations for data protection key management and can ensure the integrity of data protection even if the kernel is compromised. The enclave operates as a secondary processor or instance fabricated within a System-on-Chip (SoC).

Such an enclave may be, for example, an enclave of Intel Software Guard Extension (SGX). Intel SGX is a software security technology based on Intel's microarchitecture, and is a security-related instruction set embedded in the CPU. SGX provides a trusted execution environment by providing an enclave in which access is restricted even by systems with high privileges. By using such an SGX enclave, it is possible to prevent forgery/falsification of enclave codes by malicious insiders.

An enclave according to an embodiment of the present disclosure includes a request unit for receiving a request from a client device and transmitting a command related to key management to a security module, and a master public key generated by the security module. It may be implemented as a device including all or part of an authentication unit that performs authentication, but some components may be added, deleted, or changed. When receiving a request for using a client key from a client device, the requesting unit may read an encrypted client key from the security module and provide the read encrypted client key to the security module.

A client device in the present disclosure is a device that provides a user interface for requesting a key management service (KMS) from a server including an enclave and a security module.

1 is a conceptual diagram illustrating a key management system according to an embodiment of the present disclosure.

The key management system 10 according to an embodiment of the present disclosure includes an enclave receiving a request from a client device, and a security module in which a client key is stored and stored. The key management system 10 is a server providing a key management service, and may be a system built in a cloud platform environment. In the key management system 10 according to an embodiment of the present disclosure, the client device and the security module communicate only through an enclave, the client device does not directly access the security module, and the security module provides a key management service through the enclave. The risk of communication hacking between the client device and the security module can be prevented by being requested to perform.

The key management system 10 according to an embodiment of the present disclosure includes all or part of the following three features.

1. Establish a secure channel

The secure module and the client device form a secure channel by sharing the same cryptographic key, that is, by sharing a shared key.

2. Client's Key Generation and Encryption

The security module generates a client key and a key encryption key (KEK) used to encrypt the client key. Here, the key encryption key may be delivered to the client device through the created secure channel.

3. Decryption and use of client's key

When the client device intends to use the client's key, it obtains a key encryption key from the client device and decrypts the encrypted client key. The security module can ensure the integrity of the client key by obtaining the encrypted client key from the enclave. The client device transmits the KEK to the security module through the enclave, and the security module can use it to restore the encrypted client key in plain text. When the client key is used, the security module deletes the plain text client key from memory to prevent leakage of the client key when the security module is attacked.

Meanwhile, the key management system may use all or part of a master key pair, the aforementioned shared key, a client key, a key encryption key, and a one-time pad (OTP).

A master key pair is a key pair used to share a shared key between a security module and a client device. The master key pair may include a master public key delivered to the client device and a master private key possessed only by the security module. Here, the master secret key is stored and managed in the security module with a non-extractable attribute and/or an attribute used only for decryption set as an attribute value. This is to form a secure channel between the secure module and the client device. The master key pair may be a Rivest-Shamir-Adleman (RSA) based master key pair.

A shared key is a key shared between the secure module and the client device. The shared key is an attribute value, and a non-extractable attribute and/or an attribute used only for encryption may be set.

The client key is the key of the client stored and managed in the security module.

A key encryption key is a key used to encrypt a client key.

The OTP is a one-time key used to provide the KEK to the security module.

On the other hand, in the key management system 10, the client device may perform remote attestation on the enclave to confirm code integrity of the enclave and then transmit a command. Remote verification allows the host to verify the code and data integrity of the enclave's domain and remotely verify that the enclave was created in a specific environment (e.g. a real SGX CPU).

2 is a conceptual diagram illustrating an implementation example of a key management system according to an embodiment of the present disclosure.

The key management system 10 according to an embodiment of the present disclosure may be implemented in a cloud platform environment. Such a cloud platform may create a client instance to run a virtual security module, for example, a virtualized HSM (HSM). Such a client instance may be driven by a virtual machine (VM) within a cloud platform. This virtual security module functions as an enclave. Accordingly, a client device supporting access to the cloud platform requests a key management service from the client instance (KMS request in FIG. 2), and this request is secured as security module commands (HSM commands in FIG. 2) in the virtual security module. It is passed to the module server (HSM server in FIG. 2). The secure module server includes a secure module (HSM in FIG. 2) including a memory (HSM memory in FIG. 2).

Meanwhile, keyless SSL, JSON Web Token (JWT), DB key provisioning service, and Key encryption at rest service may be used as the cloud platform of the key management system 10, but this is exemplary and is not limited to these platforms. In FIG. 6, performance evaluation results performed by applying Keyless SSL, JWT, DB key provisioning service, and Key encryption at rest service as a cloud platform will be described later.

3 is a flowchart illustrating a method for establishing a secure channel according to an embodiment of the present disclosure.

The security module generates a master key pair (S300). The security module may set an unextractable attribute and an attribute used only for decryption of the master secret key of the master key pair. Meanwhile, the security module may set an attribute that cannot be extracted and an attribute used only for encryption with respect to a key decrypted by the master secret key.

The security module receives authentication against the master public key from the enclave. This authentication task may be performed by steps S302 and step S304, but this is an example and the authentication task is not performed only for this example.

The security module provides the certificate of the master public key to the enclave (S302). This can be done at the request of the enclave. The security module provides the master public key along with the certificate to the enclave.

The enclave performs certificate verification to confirm that the master public key has been generated in the security module based on the certificate (S304).

Meanwhile, this authentication work may be omitted.

Through the enclave, the master public key is delivered to the client device (S306). The enclave may deliver the master public key received from the security module to the client device in order to perform authentication. The enclave may deliver the master public key to the client device when authentication is complete, that is, authentication is complete. Alternatively, the enclave may deliver the master public key to the client device at the request of the security module.

The client device generates a shared key (S308). The shared key may be a symmetric key. The client device may set non-extractable attributes in the shared key.

The client device encrypts the shared key using the master public key (S310).

The security module receives an encrypted shared key from the client device (S312). This is done through enclaves.

The security module decrypts and stores the encrypted shared key using the master secret key (S314). Since decryption is performed using the master secret key, the shared key possessed by the security module may be set to non-extractable attributes and attributes used only for encryption.

4 is a flowchart illustrating a method for generating a client key according to an embodiment of the present disclosure.

The client key generation method of FIG. 4 may be performed after the secure channel establishment method of FIG. 3 is performed. Alternatively, steps S404 and S406 of FIG. 4 may be performed after the secure channel establishment method of FIG. 3 is performed. This allows the client key to be safely stored within the secure module.

The security module generates a client key and KEK (S400). The client key will be a key of the type requested by the client device. KEK may be a symmetric key.

The security module encrypts the KEK using a shared key shared with the client device (S402). This is a key wrapping to provide to the client device, and the security module does not hold a separately encrypted KEK. The shared key may be a key obtained by performing the step of FIG. 3 . Key wrapping is a class of symmetric key cryptographic algorithms designed to encapsulate a key.

The security module provides the encrypted KEK to the client device (S404).

The client device decrypts and stores the encrypted KEK using the shared key (S406).

Meanwhile, steps S404 and step S406 of FIG. 4 are performed in parallel with the other steps of FIG. S406 may be performed.

The security module encrypts the client key using the KEK (S408).

The security module stores the encrypted client key (S410). The encryption in step S408 is key wrapping using KEK, and the security module does not store the encrypted client key but delivers it to the enclave, and the security module uses the enclave's CreateObject command to encrypt the encrypted client key (received by the enclave). can be stored as a key object.

The security module deletes the plaintext client key and the plaintext KEK generated in step S400 (S412). This ensures that the secure module holds only the encrypted client key and shared key in memory.

5 is a flowchart illustrating a client key decryption method according to an embodiment of the present disclosure.

The client key decryption method of FIG. 5 may be performed after the secure channel establishment method of FIG. 3 and/or the client key generation method of FIG. 4 are performed. In this way, the client device can ensure the integrity of the client key and safely use the client key.

The client device performs remote verification on the enclave (S500). The client device can verify the integrity of the enclave's code and data integrity, and whether the enclave is normally created. Step S500 may be performed at any step of FIGS. 3 to 5 before the client device transmits a command to the enclave.

The client device requests the use of a client key (S502). The enclave issues appropriate commands to the security module according to the request of the client device.

The security module generates an OTP (S504). OTP may be a symmetric key.

The security module encrypts the OTP using a shared key shared with the client (S506). This is a key wrapping to provide to the client device, and the security module does not hold a separately encrypted OTP. The shared key may be a key obtained by performing the step of FIG. 3 .

The security module provides the encrypted OTP to the client device (S508).

The client device decrypts the encrypted OTP using the shared key (S510).

The client device encrypts the KEK using OTP (S512).

The security module receives the KEK encrypted by OTP from the client device (S514).

The security module decrypts the encrypted KEK using the OTP (S516).

The security module obtains the encrypted client key read by the enclave (S518, S520). The enclave may read the encrypted client key from the security module and transmit the read encrypted client key to the security module again so that the security module decrypts and stores the encrypted client key. The enclave can issue GetValue commands to the secure module, pass the encrypted client key, and UnWrap commands.

The security module decrypts the encrypted client key using the KEK (S522).

The security module and the enclave perform tasks requested by the client device using the client key (S524). This may be a method in which the enclave issues a specific command to the security module according to a request of the client device, but is not limited thereto.

When the use of the client key is completed, the security module deletes the OTP, KEK, and the decrypted plaintext client key (S526). Since the OTP is a one-time key issued to use the client key, it is deleted, and the KEK and plaintext client key are deleted so that the client key cannot be decrypted even if the enclave or security module is attacked.

In FIGS. 3 to 5 , it is described that each process is sequentially executed, but this is merely an example of the technical idea of an embodiment of the present disclosure. In other words, those skilled in the art to which an embodiment of the present disclosure belongs may change and execute the order described in FIGS. 3 to 5 or perform one of each process within the range that does not deviate from the essential characteristics of an embodiment of the present disclosure. Since it will be possible to apply various modifications and variations by executing the above process in parallel, it is not limited to the time-sequential order of FIGS. 3 to 5.

6 and 7 show performance evaluation results when a key management system according to an embodiment of the present disclosure is applied. In Figures 6 and 7, the case of using only the HSM without an enclave as a conventional key management device (Stand-alone HSM in Figs. 6 and 7) and the case of using the Strawman method and the key management system according to the present disclosure (Fig. 6 and Fig. 7 proposed system) were compared. Here, the Strawman method is a method in which the enclave verifies commands for the HSM of the client device and their sequence using the log of the HSM.

The enclave in FIGS. 6 and 7 used an Intel SGX enclave, and as a key management server including an enclave and an HSM, a Quad-core Intel Xeon E-2288 (370 GHz CPU, 8 physical cores) based environment , an environment based on a KMS client and an end client (i.e., an application server and an application client) was applied as a client device.

6 is a graph showing performance of a key management system according to an embodiment of the present disclosure.

6 is a graph showing end-to-end performance evaluation results using keyless SSL, JWT signing service, DB key provisioning, and key encryption at rest as a cloud platform that performs key management. As performance evaluation indicators, throughput (Fig. 6 (a)) and 95-percentile latency (Fig. 6 (b)) were used.

Referring to (a) of FIG. 6, it can be seen that throughput and latency are the best when using stand-alone HSM, but when using stand-alone HSM, there are limitations in security due to all the disadvantages of the conventional Cloud KMS. . In the case of using the key management system of the present disclosure, it can be confirmed that the enclave has a slightly lower level of throughput than the throughput of the stand-alone HSM while maintaining security. On the other hand, compared to Strawman, which uses an enclave like the key management system of the present disclosure, the key management system of the present disclosure has a slightly higher level (DB key provisioning, Key encryption at rest) or a very high level (Keyless SSL, JWT signing service In the case of ), it can be seen that it has a throughput of .

On the other hand, with respect to latency, it can be seen that when using the key management system of the present disclosure, it has a low latency similar to that of the stand-alone HSM (in the case of Keyless SSL, JWT signing service) and always has a low latency compared to Strawman. Stand-alone HSM has the lowest latency on all platforms because it does not use an enclave.

Accordingly, in the case of applying the key management system according to an embodiment of the present disclosure, it can be seen that in a specific platform, performance is similar to that of using a stand-alone HSM, and in all platforms, it shows superior performance compared to Strawman. .

7 is a graph showing the performance of a key management system according to an embodiment of the present disclosure according to simultaneous requests for client key use.

Stand-alone HSM has one partition, so it does not support multi-tenancy. On the other hand, the key management system according to an embodiment of the present disclosure can store and manage a plurality of client keys without limiting the number of partitions included in the security module. In the case of a general cloud-based HSM, multi-tenancy according to the capacity of HSM key storage may be supported, but, like the key management system of the present disclosure, there is a problem in not supporting security against insider threats.

7 shows throughput (FIG. 7(a)) and 95th percentile latency (FIG. 7(b)) according to the number of simultaneous requests.

Referring to (a) of FIG. 7 , it can be seen that the throughput of both the stand-alone HSM and the key management system of the present disclosure increases as the number of simultaneous requests increases. On the other hand, in the case of using Strawman, it can be seen that the change in throughput is insignificant. This is because in the case of Strawman, requests are performed serially.

Referring to (b) of FIG. 7 , as the number of simultaneous requests increases, it can be seen that the change in latency of both the stand-alone HSM and the key management system of the present disclosure gradually increases. On the other hand, in the case of using Strawman, it can be confirmed that the rate of increase in latency greatly increases as the number of requests increases as requests are performed serially.

Accordingly, it can be confirmed that the key management system of the present disclosure has high throughput and low latency while supporting secure multi-tenancy.

Various implementations of devices, units, processes, steps, etc. described herein may include digital electronic circuits, integrated circuits, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), computer hardware, firmware, software, and/or combinations thereof. These various implementations may include being implemented as one or more computer programs executable on a programmable system. A programmable system includes at least one programmable processor (which may be a special purpose processor) coupled to receive data and instructions from and transmit data and instructions to a storage system, at least one input device, and at least one output device. or may be a general-purpose processor). Computer programs (also known as programs, software, software applications or code) contain instructions for a programmable processor and are stored on a “computer readable medium”.

A computer-readable recording medium includes all kinds of recording devices that store data that can be read by a computer system. These computer-readable 　recording media include non-volatile or non-transitory storage devices such as ROM, CD-ROM, magnetic tape, floppy disk, memory card, hard disk, magneto-optical disk, and storage device. It may further include a medium. In addition, the computer-readable recording medium may be distributed in computer systems connected through a network, and computer-readable codes may be stored and executed in a distributed manner.

Various implementations of the systems and techniques described herein may be implemented by a programmable computer. Here, the computer includes a programmable processor, a data storage system (including volatile memory, non-volatile memory, or other types of storage systems, or combinations thereof) and at least one communication interface. For example, a programmable computer may be one of a server, network device, set top box, embedded device, computer expansion module, personal computer, laptop, personal data assistant (PDA), cloud computing system, or mobile device.

The above description is merely an example of the technical idea of the present embodiment, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of the present embodiment, but to explain, and the scope of the technical idea of the present embodiment is not limited by these embodiments. The scope of protection of this embodiment should be construed according to the claims below, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of rights of this embodiment.

10: Key management system

Claims (19)

A method for establishing a secure channel to provide a key management service,
The process of the security module generating a master key pair (master key pair); and
Forming, by the security module, a secure channel with a client device based on the master key pair
Characterized in that it comprises a, secure channel forming method. According to claim 1,
The master key pair includes a master public key and a master private key,
The process of the security module receiving authentication for the master public key from the enclave
Characterized in that it further comprises a secure channel forming method. According to claim 2,
After the process of generating the master key pair, the security module providing the master public key to the client device through the enclave; and
Process of receiving, by the security module, a shared key encrypted by the master public key from the client device through the enclave
Characterized in that it further comprises a secure channel forming method. According to claim 3,
The process of forming the secure channel,
characterized in that the encrypted shared key is decrypted using the master secret key and stored. According to claim 4,
Characterized in that, the attribute value of the master secret key and the attribute value of the stored shared key are set to be non-extractable. A method for generating a client key to provide a key management service,
a step of generating, by a security module, the client key and key encryption key (hereinafter referred to as KEK);
the security module encrypting and storing the client key using the KEK; and
Process of deleting the plaintext client key and plaintext KEK by the security module
Characterized in that it comprises a, client key generation method. According to claim 6,
Forming, by the security module, a secure channel with a client device through an enclave; and
The security module providing the KEK to the client device
Characterized in that it further comprises, the client key generation method. According to claim 7,
The process of forming the secure channel,
Characterized in that the security module generates a master key pair including a master public key and a master secret key, and obtains a shared key shared with the client device based on all or part of the master key pair, the client key creation method. According to claim 7,
The process of providing the KEK,
A method for generating a client key, characterized in that the KEK is key-wrapped using a shared key shared with the client device, and the wrapped KEK is provided to the client device. A method for decrypting a client key to provide a key management service,
Process of generating OTP (One-Time Pad) by security module;
obtaining, by a security module, a key encryption key (hereinafter referred to as KEK) from a client device; and
The process of the security module decrypting the encrypted client key based on the KEK
Characterized in that it comprises a, client key decryption method. According to claim 10,
Forming, by the security module, a secure channel with the client device through an enclave; and
Process of the security module providing the OTP to the client device
Characterized in that it further comprises, the client key decryption method. According to claim 11,
The process of providing the OTP,
A method for decrypting a client key, characterized in that the OTP is key-wrapped using a shared key shared with the client device, and the wrapped OTP is provided to the client device. According to claim 11,
The process of obtaining the KEK,
Characterized in that it is performed by receiving the KEK encrypted by the OTP from the client device, the client key decryption method. According to claim 13,
The process of decrypting the encrypted client key,
Decrypting the encrypted KEK using the OTP to obtain the KEK, and decrypting the encrypted client key using the KEK. According to claim 10,
Prior to the process of decrypting the encrypted client key, the process of obtaining the encrypted client key from the enclave by the security module
Characterized in that it further comprises, the client key decryption method. According to claim 15,
The process of obtaining the encrypted client key,
Characterized in that the enclave is performed by reading the encrypted client key from the security module and providing it to the security module, the client key decryption method. According to claim 10,
Deleting, by the security module, the decrypted client key, the OTP, and the KEK after performing an operation related to the decrypted client key
Characterized in that it further comprises, the client key decryption method. As a security module device for providing a key management service,
one or more programmable processors; and
a computer readable storage coupled to the one or more programmable processors for storing an encrypted client key;
The one or more programmable processors perform each process of the client key generation method according to any one of claims 6 to 9 according to a command transmitted from the enclave, a security module device. In the enclave device for providing a key management service,
a request unit that receives a request from a client device and transmits a command related to key management to a security module; and
Including an authentication unit that performs authentication of a master public key generated by the security module,
When receiving a request for using a client key from the client device, the requesting unit,
Characterized in that, the enclave device reads the encrypted client key from the security module and provides the read encrypted client key to the security module.

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