Secure key replacement system, replacement device, and replacement method

Abstract

The invention provides a secure key replacement system, a replacement device and a replacement method, comprising an active signature server comprising a secure storage and processing unit and an interface. The secure storage and processing unit is configured to store a first private key, generate a signature using the first private key for authentication by a device storing a first public key forming a key pair with the first private key, and sign a replacement command using the first private key, the replacement command is configured to instruct the device to replace the first public key with a second public key forming a key pair with a second private key. The interface is configured to provide a signature to the device and a replacement command to at least one entity remote from the active signing server and the device for storage, the at least one entity including a coordinating server and / or at least one other entity signing server.

Description

Technical Field

[0001] The present invention relates to a computer system, particularly but not limited to a secure key replacement system, a replacement device, and a replacement method. Background Art

[0002] A signing server or other centralized entity may provide a signature generated based on data signed using the signing server's private key to a device (such as a secure flash device). Each device has a corresponding public key, so the public key can be used to authenticate the data against the signature. Among them, preventing the public key in the device from being overwritten by an attacker who wants to impersonate the signing server is an important issue.

[0003] In terms of the signing server, since the private key may be lost, damaged, or become unusable, the private key can no longer be used to generate signatures for the device to use the corresponding public key for authentication. One solution is to make a backup copy of the private key and store the private key in one or more secure locations when needed. Summary of the Invention

[0004] The present invention is directed to a secure key replacement system, including an active signing server that includes a secure storage and processing unit configured to store a first private key, generate a signature using the first private key for a device storing a first public key to authenticate, the first public key and the first private key forming a key pair, and sign a replacement command using the first private key, the replacement command being configured to instruct the device to replace the first public key with a second public key, the second public key and a second private key forming a key pair, and an interface configured to provide the signature to the device and provide the replacement command to at least one entity that is stored away from the active signing server and the device, the at least one entity including a coordination server and / or at least one other signing server.

[0005] According to an embodiment of the present invention, there is also provided a secure key replacement device, including a secure storage configured to securely store a first public key, the first public key and a first private key stored in an active signing server forming a key pair, and a secure processor configured to reject a replacement command for the first public key that is not authorized by a signature formed by the active signing server using the first private key, receive a replacement command signed by the first private key, the replacement command being configured to instruct the device to replace the first public key with a second public key, the second public key and a second private key stored in a new active signing server forming a key pair, authenticate the replacement command using the first public key, and, after authenticating the replacement command using the first public key, be responsible for replacing the first public key with the second public key.

[0006] According to another embodiment of the present invention, a security key replacement method is also provided, including storing a first private key, generating a signature by an in-use signing server using the first private key for authentication by a device storing a first public key that forms a key pair with the first private key, signing a replacement command by the in-use signing server using the first private key, the replacement command being configured to instruct the device to replace the first public key with a second public key, the second public key forming a key pair with a second private key, and providing the signature to the device, providing the replacement command to at least one entity for storage, the at least one entity being remote from the in-use signing server and the device, and the at least one entity including a coordination server and / or at least one other signing server.

[0007] According to another embodiment of the present invention, a security key replacement method is also provided, including securely storing a first public key that forms a key pair with a first private key stored by an in-use signing server, receiving a replacement command signed by the first private key, the replacement command being configured to instruct the device to replace the first public key with a second public key that forms a key pair with a second private key stored by a new in-use signing server, authenticating the replacement command using the first public key, and replacing the first public key with the second public key after authenticating the replacement command using the first public key. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present invention and, together with the description, are used to explain the principles of the present invention.

[0009] Figure 1 is a block diagram of a security key replacement system constructed and operated according to an embodiment of the present invention;

[0010] Figure 2 is included Figure 1 a flowchart of the steps of a method for operating the system;

[0011] Figure 3 is included Figure 1 a flowchart of the steps of a method for a device in the system;

[0012] Figure 4 is Figure 1 a block diagram view of the system, illustrating a situation where the in-use signing server or the active private key becomes unavailable;

[0013] Figure 5 is included Figure 1 a flowchart of the steps of a method for operating the system when the in-use signing server or the current private key becomes unavailable;

[0014] Figure 6 is Figure 1 a block diagram view of the system, illustrating the allocation of a new in-use signing server;

[0015] Figure 7 It is a flowchart of the method steps after the device in the system signs the server allocation in the new role. Figure 1 System in the new role after the device signs the server allocation method step flowchart.

[0016] Explanation of the attached figure numbers

[0017] 10: System;

[0018] SS: Signing server;

[0019] 14, 14': Signing server in use;

[0020] 16: Secure storage and processing unit;

[0021] 18: Coordination server;

[0022] 20: Device;

[0023] 202 - 220, 302 - 308, 502 - 524, 702 - 710: Steps;

[0024] 22: Secure processor;

[0025] 24: Secure storage;

[0026] 26, 28: Interfaces;

[0027] 30: Private key;

[0028] 32: Public key;

[0029] 34, 36, 40, 42, 44, 46, 48: Blocks;

[0030] 38: Signature;

[0031] 200, 300, 500, 700: Flowcharts;

[0032] 222, 310, 526, 712: Arrows. Detailed implementation manners

[0033] Now, reference will be made in detail to the exemplary embodiments of the present invention, and examples of the exemplary embodiments are illustrated in the accompanying drawings. Whenever possible, the same component symbols are used in the drawings and the description to represent the same or similar parts.

[0034] Overview

[0035] As mentioned above, the signing server can back up the private key in use in one or more secure locations to recover in case the private key in use becomes unavailable (e.g., lost, damaged, or unusable). However, in some situations, backing up the private key may not provide a solution, and one such situation is described below.

[0036] The National Institute of Standards and Technology (NIST) recommends the use of hash-based signatures (i.e., stateful signatures), which are one-time signatures that increment an index each time a signature is generated. It has the advantage of being unbreakable by quantum computers. Among them, it is crucial that the same index cannot be used twice, otherwise the signature will be broken. Therefore, simply backing up the private key is not enough, and the index also needs to be backed up, but there is no practical solution for this. Therefore, NIST recommends always storing the index and the key together in a hardware module (such as a hardware security module (HSM)). Since the index is incremented each time the key is used, the key cannot be backed up because the backed-up key does not have a link with the index and cannot ensure the security of the signature scheme. The signing server is an entity that contains an HSM and is used to securely store the private key and execute cryptographic programs (such as generating signatures) using the private key.

[0037] If the private key cannot be backed up, then when the private key is lost, damaged, or unusable, it is recommended that a new key pair be generated by the signing server or another signing server to sign data for device authentication. However, simply generating a new key does not completely solve the problem because each device has already installed the public key corresponding to the lost private key in a protected manner, making the public key irreplaceable. Therefore, the device has become useless in this regard because it cannot overwrite the old public key with the new public key, and the signing server's ability to provide signatures for all devices is permanently lost.

[0038] Embodiments of the present invention solve the above disadvantages by providing a system that can use a replacement command pre-generated by the original private key and send it to the device to replace the original public key with a new public key when the current private key is no longer available (such as lost, damaged, or unusable), thereby recovering from the situation where the private key is no longer available.

[0039] System Description

[0040] Please refer to Figure 1 , which is a block diagram of a secure key replacement system (hereinafter referred to as the system) 10 constructed and operated according to an embodiment of the present invention. The system 10 includes N signing servers SS, including 1 active signing server and N - 1 standby signing servers. N can be any suitable number greater than or equal to 2. As Figure 1 shown, the signing server 0 is the active signing server 14 at this time, and the signing servers 1 to N - 1 are standby signing servers. The system 10 also includes a coordination server 18 and a device 20, and the device 20 is, for example, a secure flash storage device.

[0041] Each signing server SS includes a secure storage and processing unit 16 (e.g., a hardware security module (HSM)) and an interface 26 for sharing data with other signing servers SS, the coordination server 18, and the devices 20 (e.g., via the coordination server 18). In Figure 1 the example of, signing server 0 includes a secure storage and processing unit 16 (HSM 0), signing server 1 includes a secure storage and processing unit 16 (HSM 1), and signing server N-1 includes a secure storage and processing unit 16 (HSM N-1). The secure storage and processing unit 16 (HSM) is a physical computing device for protecting and managing secrets, performing encryption and decryption functions for digital signatures, strong authentication, and other cryptographic functions. Each secure storage and processing unit 16 is configured to store one or more private keys (PRVK) 30 and may optionally store an index associated with the private key 30. In Figure 1 the example of, the secure storage and processing unit 16 (HSM 0) stores the private key 30 (PRVK_0), the secure storage and processing unit 16 (HSM 1) stores the private key 30 (PRVK_1), and the secure storage and processing unit 16 (HSM N-1) stores the private key 30 (PRVK_N-1), as described in more detail with reference to Figure 2 below.

[0042] Each device 20 includes an interface 28 for sharing data with the coordination server 18 and each signing server SS. Each device 20 also includes a secure processor 22 and a secure storage 24. The secure storage 24 of each device 20 is configured to store a public key (PUBK) 32 (e.g., the public key 32 (PUBK_0) that forms a key pair with the private key 30 (PRVK_0) of the active signing server 14 (signing server 0)).

[0043] Figure 2 is a flowchart 200 of the method steps for operating the system 10 included in Figure 1 Please also refer to Figure 1 and Figure 2。The coordination server 18 is configured to assign the signing server 0 as the active signing server 14 (step 202). The secure storage and processing unit 16 of the active signing server 14 (signing server 0) is configured to generate a key pair and store the generated private key 30 (PRVK_0) and optionally store an index associated with the private key 30 (not shown). The secure storage and processing unit 16 of the active signing server 14 (signing server 0) is further configured to distribute the generated public key 32 (PUBK_0) to each device 20. The public key 32 (PUBK_0) of the active signing server 14 (signing server 0) is then stored in the secure storage 24 of each device 20 (step 204). In one embodiment, the secure storage and processing unit 16 of the active signing server 14 (signing server 0) is further configured to distribute the generated public key 32 (PUBK_0) to all signing servers SS and / or the coordination server 18 (not shown).

[0044] The secure storage and processing units 16 (HSM 1 to HSM N-1) of each standby signing server (signing servers 1 to signing server N-1) are configured to generate key pairs including public keys 32 (PUBK_1 to PUBK_N-1) and private keys 30 (PRVK_1 to PRVK_N-1) and store the generated private keys 30 and optionally store an index associated with the private key 30 (not shown) (step 206). In other words, the secure storage and processing units 16 of the N-1 signing servers are configured to generate N-1 corresponding key pairs, each key pair including its respective public key and its respective private key. As shown in the example of Figure 1 , HSM 1 generates a key pair including public key PUBK_1 and private key PRVK_1 and stores the generated private key PRVK_1, HSM N-1 generates a key pair including public key PUBK_N-1 and private key PRVK_N-1 and stores the generated private key PRVK_N-1, and so on. In one embodiment, optionally, the secure storage and processing units 16 of the standby signing servers SS are configured to distribute the generated public keys 32 to all signing servers SS, and / or the coordination server 18 (step 210).

[0045] The secure storage and processing unit 16 of the active signing server 14 (signing server 0) is configured to sign the replacement commands corresponding to each standby signing server SS using its private key 30 (PRVK_0) (step 212). Each replacement command may include: the public key of each standby signing server, and a signature signed using the private key 30 of the active signing server 14 on the data including the public key. For example, "replacement command 0>1" may include the public key 32 (PUBK_1) of standby signing server 1 and a signature signed using the private key 30 (PRVK_0) of the active signing server 14 (signing server 0).

[0046] The replacement command is configured to instruct the device 20 to replace the public key 32 (PUBK_0) of the active signing server 14 (signing server 0) with the public key 32 corresponding to this replacement command. For example, the secure storage and processing unit 16 of the active signing server 14 (signing server 0) may use its private key 30 (PRVK_0) to sign the "replacement command 0>1" corresponding to standby signing server 1 ( Figure 1 block 34), and "replacement command 0>1" is used to instruct the device 20 to replace the stored public key PUBK_0 with the public key PUBK_1; the secure storage and processing unit 16 of the active signing server 14 (signing server 0) may use its private key PRVK_0 to sign the "replacement command 0> N-1" corresponding to signing server N-1 ( Figure 1 block 36), and "replacement command 0>N-1" is used to instruct the device 20 to replace the stored public key PUBK_0 with the public key PUBK_N-1.

[0047] The interface 26 of the active signing server 14 (signing server 0) is configured to provide (e.g., send) the replacement command to one or more entities (e.g., to the coordination server 18 and / or standby signing servers (e.g., signing servers 1 to signing server N-1)), and these entities are away from the active signing server 14 and the device 20 to store the replacement command (step 214). In one embodiment, the coordination server 18 may store all the replacement commands, and / or each replacement command may be stored by the corresponding signing server SS. For example, "replacement command 0>1" ( Figure 1 block 34) may be stored by signing server 1, and "replacement command 0>N-1" ( Figure 1 block 36) may be stored by signing server N-1.

[0048] The secure storage and processing unit 16 of the active signing server 14 (signing server 0) is configured to generate a signature 38 using its private key 30 (PRVK_0) for authentication by the device 20 (step 216). In one embodiment, the secure storage and processing unit 16 of the active signing server 14 (signing server 0) is configured to generate a hash-based signature 38 for authentication by the device 20 using its private key PRVK_0 and a stored index (stored in the secure storage and processing unit 16 of the active signing server 14). In an embodiment where a hash-based signature is generated, the secure storage and processing unit 16 of the active signing server 14 is configured to update (e.g., increment) the index in response to generating each hash-based signature (step 218, optional). The interface 26 of the active signing server 14 is configured to provide the signature 38 to the device 20 (e.g., via the coordination server 18) for the device 20 to authenticate using its stored public key 32 (PUBK_0) (corresponding to the active signing server 14 (signing server 0)) (step 220). Steps 216 - 220 may be repeated (arrow 222).

[0049] Figure 3 A flowchart 300 of method steps for a device 20 in the system 10. Please also refer to Figure 1 and Figure 3 . The secure storage 24 is configured to securely store the public key 32 (PUBK_0) corresponding to the private key 30 (PRVK_0) stored by the active signing server 14 (signing server 0) (step 302). The secure processor 22 is configured to authenticate a received replacement command using its stored public key 32 (PUBK_0) and, in response to successful authentication, accept the replacement command containing the signature signed by the active signing server 14 (signing server 0); and, in response to unsuccessful authentication, reject the replacement command that does not contain the signature signed by the active signing server 14 (signing server 0) (step 304). The secure processor 22 is configured to receive one or more signatures 38 (step 306). The secure processor 22 is configured to authenticate whether the received signature 38 is a signature signed by the active signing server 14 (signing server 0) using its stored public key 32 (PUBK_0) (step 308). Steps 306 - 308 may be repeatedly executed (arrow 310).

[0050] Figure 4 is a block diagram of the system 10 illustrating the situation when the original active signing server (signing server 0) and / or its private key 30 (PRVK_0) becomes unavailable (block 40). Figure 5 is a flowchart 500 illustrating the method steps of operation of the system 10 when the original active signing server (signing server 0) and / or the current private key 30 (PRVK_0) becomes unavailable.Figure 6 Block diagram of system 10, illustrating the situation where system 10 assigns a new active signing server 14' (block 42).

[0051] Please refer to Figures 4 to 6 , the coordination server 18 can be configured to detect the situation where the active signing server 14 (signing server 0) and / or its private key 30 (PRVK_0) become unavailable (step 502).

[0052] The coordination server 18 is configured to assign a standby signing server (e.g., signing server 1) as the new active signing server 14' (step 504). The coordination server 18 is configured to provide a replacement command corresponding to the new active signing server 14' (signing server 1) (e.g., "replacement command 0>1" ( Figure 6 block 34)) to the device 20 (in response to the situation where the original active signing server 14 (signing server 0) and / or its private key 30 (PRVK_0) become unavailable), so that the device 20 replaces its originally stored public key 32 (PUBK_0) with the public key 32 (PUBK_1) corresponding to the replacement command (replacement command 0>1) (step 506). The step of the device 20 replacing PUBK_0 with PUBK_1 is as Figure 7 detailedly described.

[0053] The coordination server 18 can be configured to add a signing server SS with a secure storage and processing unit 16 to the system ( Figure 6 block 48) as a standby signing server (step 508). The secure storage and processing unit 16 (HSM N) of the newly added standby signing server (signing server N) is configured to generate a key pair including a public key 32 (PUBK_N) and a private key 30 (PRVK_N) and store the generated private key 30 (PRVK_N) and optionally store an index associated with the private key 30 (not shown), as Figure 6 shown (step 510). In one embodiment, optionally, the secure storage and processing unit 16 of the newly added signing server SS is configured to distribute the generated public key 32 (PUBK_N) to all signing servers SS, and / or the coordination server 18 (step 514).

[0054] The secure storage and processing unit 16 of the active signing server 14' (signing server 1) is configured to sign a replacement command (step 516) corresponding to each standby signing server SS using its private key 30 (PRVK_1). Each replacement command may include: the public key of each standby signing server, and a signature signed using the private key 30 of the active signing server 14' for the data including the public key. For example, "replacement command 1>N" may include the public key 32 (PUBK_N) of standby signing server N and a signature signed using the private key 30 (PRVK_1) of the active signing server 14' (signing server 1).

[0055] The replacement command is configured to instruct the device 20 to replace the public key 32 (PUBK_1) of the active signing server 14' (signing server 1) with the public key 32 corresponding to the replacement command. For example, the secure storage and processing unit 16 of the active signing server 14' (signing server 1) may use its private key 30 (PRVK_1) to sign the "replacement command 1> N-1" corresponding to standby signing server N-1 ( Figure 6 block 46), and "replacement command 1> N-1" is used to instruct the device 20 to replace the stored public key PUBK_1 with the public key PUBK_N-1; the secure storage and processing unit 16 of the active signing server 14' (signing server 1) may use its private key PRVK_1 to sign the "replacement command 1> N" corresponding to signing server N ( Figure 6 block 44), and "replacement command 1>N" is used to instruct the device 20 to replace the stored public key PUBK_1 with the public key PUBK_N.

[0056] The interface 26 of the active signing server 14' (signing server 1) is configured to provide (e.g., send) the replacement command to one or more entities (e.g., to the coordination server 18 and / or standby signing servers (e.g., signing servers 2 to signing server N)), and these entities are away from the active signing server 14' and the device 20 to store the replacement command (step 518). In one embodiment, the coordination server 18 may store all the replacement commands, and / or each replacement command may be stored by the corresponding signing server SS. For example, "replacement command 1> N-1" ( Figure 6 block 46) may be stored by signing server N-1, and "replacement command 1> N" ( Figure 6 block 44) may be stored by signing server N.

[0057] The secure storage and processing unit 16 of the active signing server 14' (signing server 1) is configured to generate a signature 38 using its private key 30 (PRVK_1) for authentication by the device 20 (step 520). In one embodiment, the secure storage and processing unit 16 of the active signing server 14' (signing server 1) is configured to generate a hash-based signature 38 using its private key PRVK_1 and a stored index (stored in the secure storage and processing unit 16 of the active signing server 14') for authentication by the device 20. In an embodiment where a hash-based signature is generated, the secure storage and processing unit 16 of the active signing server 14' is configured to update (e.g., increment) the index in response to generating each hash-based signature (step 522, optional). The interface 26 of the active signing server 14' is configured to provide the signature 38 to the device 20 (e.g., via the coordination server 18) for the device 20 to authenticate using its stored public key 32 (PUBK_1) (corresponding to the active signing server 14' (signing server 1)) (step 524). Steps 520 - 524 may be repeated (arrow 526).

[0058] Figure 7 For a system 10 including Figure 1 step flowchart 700 of a device 20 in the system after a new active signing server 14' (signing server 1) is allocated. Please also refer to Figure 6 and Figure 7 . The secure processor 22 is configured to receive a replacement command from a remote entity (e.g., "replacement command 0>1" ( Figure 6 block 34)) (step 702). The secure processor 22 is configured to authenticate the received replacement command using its originally stored public key 32 (PUBK_0) (corresponding to the private key 30 (PRVK_0) of the original active signing server 14 (signing server 0)) (step 704). The secure processor 22 is configured to replace the originally stored public key 32 (PRVK_0) with the public key 32 (PUBK_1) corresponding to the received replacement command (corresponding to the private key 30 (PRVK_1) of the new active signing server 14') in response to successfully authenticating the received replacement command (replacement command 0>1) (step 706). The secure processor 22 is configured to receive one or more signatures 38 (step 708). The secure processor 22 is configured to authenticate whether the received signature 38 is a signature signed by the active signing server 14' (signing server 1) using the new public key 32 (PUBK_1) (step 710). Steps 708 - 710 may be repeatedly executed (arrow 712).

[0059] Based on the above, in certain embodiments of the present invention, the active signing server includes a secure storage and processing unit that generates a key pair including a public key and a private key, and stores the generated private key. The public key generated by the active signing server is sent to the device (e.g., via a coordination server) and stored in the secure storage and processing unit of the device for authentication. Each standby signing server includes a secure storage and processing unit for generating a key pair including a public key and a private key, and storing the generated private key. The secure storage and processing unit of the active signing server pre-signs the replacement commands corresponding to each standby signing server using its private key. Each replacement command may include the public key generated by the corresponding standby signing server and the signature signed by the active signing server. Each replacement command is used to instruct the device to replace the public key it originally stores with the public key corresponding to the replacement command when needed. Each replacement command is sent to be stored in a remote entity (e.g., a coordination server or the signing server corresponding to the replacement command). In the case where the active signing server or its private key is no longer available, the remote entity can provide the replacement command to the device. Each device authenticates the authenticity of the replacement command using the original public key and replaces the original public key with the public key corresponding to the replacement command in response to successful authentication. In this way, each device can protect the public key it currently stores by accepting the replacement command signed by the active signing server and rejecting the replacement command not signed by the active signing server. Then, the signing server corresponding to the replacement command becomes the new active signing server and can use its private key to generate signatures so that each device can authenticate data using the new public key.

[0060] In addition, the new active signing server can then use its private key to sign new replacement commands corresponding to each standby signing server for use in instructing the device to replace the public key it stores with the public key generated by another standby signing server when needed. Each new replacement command is sent to be stored in a remote entity (e.g., a coordination server or the signing server corresponding to the replacement command).

[0061] In practice, some or all of these functions may be combined in a single physical component, or alternatively, implemented using multiple physical components. These physical components may include hardwired or programmable devices, or a combination of both. In some embodiments, at least some of the functions of the processing circuit may be performed by a programmable processor controlled by appropriate software. This software can be downloaded to the device electronically via a network. Alternatively, the software can be stored in a tangible, non-transitory computer-readable storage medium, such as optical, magnetic, or electronic memory.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A secure key replacement system, characterized in that, Comprising: An in-operation signing server, the in-operation signing server comprising: A secure storage and processing unit for: Storing a first private key; Generating a signature using the first private key for authenticating a device for storing a first public key that forms a key pair with the first private key; and Signing a replacement command using the first private key, the replacement command being used to instruct the device to replace the first public key with a second public key, the second public key forming a key pair with a second private key; and An interface for providing the signature to the device and providing the replacement command to at least one entity, the at least one entity being remote from the in-operation signing server and the device for storing the replacement command, the at least one entity including a coordination server and / or at least one other signing server.

2. The security key replacement system according to claim 1, characterized in that, Further comprising: N signing servers, the N signing servers including the in-operation signing server and N-1 signing servers, wherein: The N-1 signing servers are used to generate N-1 corresponding key pairs, each key pair including a respective new public key and a respective new private key; The secure storage and processing unit of the in-operation signing server is used to sign N-1 replacement commands using the first private key, the N-1 replacement commands being used to instruct the device to replace the first public key with the respective new public keys; and The interface is used to provide the N-1 replacement commands to the coordination server and / or the N-1 signing servers.

3. The security key replacement system according to claim 1, wherein The secure storage and processing unit is used to: Store an index; Generate a hash-based signature using the first private key and the stored index for authenticating the device; And Updating the index in response to generating each of the hash-based signatures.

4. The security key replacement system according to claim 1, wherein The coordination server is used to provide the replacement command to the device to cause the device to replace the first public key with the second public key.

5. The security key replacement system according to claim 4, wherein The coordination server is used to provide the replacement command to the device in response to an interruption of the in-operation signing server, or the first private key being destroyed or unavailable for use by the in-operation signing server.

6. The security key replacement system according to claim 4, characterized in that Further comprising a new in-operation signing server, the new in-operation signing server comprising: A new secure storage and processing unit for: Storing the second private key; Generating a signature using the second private key for authenticating a device for storing the second public key; and Signing a new replacement command using the second private key, the new replacement command being used to instruct the device to replace the second public key with a third public key that forms a key pair with a third private key; and A new interface for providing the new replacement command to the at least one entity.

7. The security key replacement system according to claim 1, wherein Further comprising a giving device in the device, the giving device comprising: Secure storage for securely storing the first public key; and A secure processor for: Rejecting a replacement command for replacing the first public key that is not authorized by a signature formed using the first private key; Receiving the replacement command signed by the first private key; Authenticating the replacement command using the first public key; and In response to authenticating the replacement command using the first public key, replace the first public key with the second public key.

8. The security key replacement system according to claim 7, wherein The security processor of the giving device is configured to: Authenticate the signature signed by the active signing server using the first public key; and After the first public key is replaced with the second public key, authenticate the signature signed by the new active signing server using the second public key.

9. A security key replacement device, characterized in that, Comprises: A secure storage for securely storing a first public key, the first public key forming a key pair with a first private key stored by an active signing server; And A security processor configured to: Reject a replacement command for replacing the first public key, the replacement command not authorized by a signature formed by the active signing server using the first private key; Receive a replacement command signed by the first private key, the replacement command for instructing the device to replace the first public key with a second public key, the second public key forming a key pair with a second private key stored by a new active signing server; Authenticate the replacement command using the first public key; And In response to authenticating the replacement command using the first public key, replace the first public key with the second public key.

10. The security key replacement device according to claim 9, characterized in that, The security processor is configured to: Authenticate the signature signed by the active signing server using the first public key; and After the first public key is replaced with the second public key, authenticate the signature signed by the new active signing server using the second public key.

11. A security key replacement method, characterized in that, Comprises: Store a first private key; Generate a signature by the active signing server using the first private key for authenticating a device that stores a first public key forming a key pair with the first private key; Sign a replacement command by the active signing server using the first private key, the replacement command for instructing the device to replace the first public key with a second public key, the second public key forming a key pair with a second private key; And Provide the signature to the device and provide the replacement command to at least one entity, the at least one entity being remote from the active signing server and the device to store the replacement command, the at least one entity including a coordination server and / or at least one other signing server.

12. The security key replacement method according to claim 11, wherein Further comprises: N - 1 signing servers generate N - 1 corresponding key pairs, each key pair including a respective new public key and a respective new private key; The secure storage and processing unit of the active signing server signs N - 1 replacement commands using the first private key, the N - 1 replacement commands for instructing the device to replace the first public key with respective new public keys; And Provide the N - 1 replacement commands to the coordination server and / or the N - 1 signing servers.

13. The security key replacement method according to claim 11, characterized in that, Further comprises: Store an index; Generate a hash - based signature using the first private key and the stored index for authenticating the device; And Update the index in response to generating each hash - based signature.

14. The security key replacement method according to claim 11, characterized in that Further comprises providing the replacement command to the device to cause the device to replace the first public key with the second public key.

15. The security key replacement method according to claim 14, wherein Providing the replacement command to the device is performed in response to an interruption of the signing server in operation, or the first private key being destroyed or unavailable to the signing server in operation.

16. The security key replacement method according to claim 14, characterized in that Further included are: Storing the second private key by a new signing server in operation; Generating a signature using the second private key for authenticating the device storing the second public key; Signing a new replacement command using the second private key, the new replacement command being used to instruct the device to replace the second public key with a third public key forming a key pair with a third private key; And Providing the new replacement command to the at least one entity.

17. The security key replacement method according to claim 11, wherein Further included are: Receiving the replacement command signed by the first private key; Authenticating the replacement command using the first public key; And Replacing the first public key with the second public key in response to authenticating the replacement command using the first public key.

18. The security key replacement method according to claim 17, wherein Further included are: Authenticating a signature signed by the signing server in operation using the first public key; And After the first public key is replaced with the second public key, authenticating a signature signed by the new signing server in operation using the second public key.

19. A security key replacement method, characterized in that, Included are: Securely storing a first public key forming a key pair with a first private key stored by a signing server in operation; Receiving a replacement command signed by the first private key, the replacement command being used to instruct the device to replace the first public key with a second public key, the second public key forming a key pair with a second private key stored by a new signing server in operation; Authenticating the replacement command using the first public key; And Replacing the first public key with the second public key in response to authenticating the replacement command using the first public key.

20. The security key replacement method according to claim 19, characterized in that, Further included are: Authenticating a signature signed by the signing server in operation using the first public key; And After the first public key is replaced with the second public key, authenticating a signature signed by the new signing server in operation using the second public key.

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