Methods, module and blockchain for distributed public keystore

Disclosed is a universal plug-in Distributed Public Keystore (DPK) module provided on a user equipment. The DPK module approves its identifier with a Public Key Manager (PKM) and obtains cryptocurrency from the PKM. The APPs on the user equipment generate and transmit user public keys to the DPK module. The DPK module generated its own user public key as well. After a storage transaction requirement by the DPK module is approved by a blockchain, the DPK module sends obtained user public keys to the blockchain so that the user public keys are stored in the blockchain. The user public keys are never stored outside the blockchain or in a third part server. The stored user public keys are retrieved to the DPK module when necessary, such as when a P2P communication is performed by any of the APPs.

TECHNICAL FIELD

The present disclosure relates generally to methods, module and blockchain for distributed public keystore. The present disclosure further relates to computer programs corresponding to the above methods, modules and blockchain.

BACKGROUND

Nowadays, real-time communication is widely used by all kinds of communication devices, hereinafter called user equipment (UE). For example, Voice over Internet Protocol (VOIP) or Voice over Long-Term Evolution (VOLTE) are utilized by communication applications (APPs) on the user equipment to perform real-time Person-To-Person (P2P) communications.

Information on security and privacy are critical issues facing the P2P communications. In prior art methods, user public keys/certificates generated by the communication applications are stored in a Certificate Authority (CA). CA is a public/third party infrastructure that is positioned in the communication network. The CA must be secure and trusted. However, such methods require a large infrastructure to manage all the public keys/certificates. The capacity and robustness requirement of the CA is very high. Once the CA is down for some reason, the communications for a large number of applications are affected. Further, the security of the CA is of high importance as the public keys/certificates are secret data needed to be well-protected from any fraudulent users.

Furthermore, if the applications store the user public keys/certificates to the CA, the storage transactions must be approved, otherwise a malicious user can also get access to the infrastructure and perform write/rewrite operation on the stored user public keys/certificates.

Therefore, there is need for a solution which helps P2P communication applications on user equipment performing in a more secure way. Another need may be for a solution that can handle user public keys/certificates robustly and securely. There is also a need for a solution that can efficiently handle large amount of user public keys/certificates.

SUMMARY

It is an object of the invention to address at least some of the problems and issues outlined above. It is possible to achieve these objects and others by using methods, modules and wireless devices as defined in the attached independent claims.

According to one aspect, a method performed by a Distributed Public Keystore module operated on a user equipment is provided. The method comprising: transmitting a Token of the DPK module to an external device having cryptocurrency so the external device can approve the DPK module and obtaining cryptocurrency from the external device to a wallet of the DPK module, in response to an approval of the Token by the external device. The method further comprises obtaining one or more user public keys generated by one or more Applications on the user equipment and transmitting the cryptocurrency in the wallet of the DPK module to a blockchain. The method further comprises sending a storage transaction requirement to the blockchain relating to the cryptocurrency and receiving a first information from a user of the user equipment, the first information originating from a message received from the blockchain, the message being received via the communication network to the user equipment, the first information being related to approval by the blockchain of the storage transaction requirement. The method further comprises sending a second information to the blockchain for approval and receiving from the blockchain, a public key storage allowance, relating to an approval by the blockchain for the sent storage transaction requirement based on the sent second information. The method further comprises sending the one or more user public keys to the blockchain for storage in the blockchain, based on the public key storage allowance. The method further comprises retrieving the one or more stored public key from the blockchain when the one or more public key is needed by the DPK module.

According to another aspect, a method performed by a blockchain connected to a user equipment is provided. The method comprising: receiving cryptocurrency from a wallet in a Distributed Public Keystore module operated on the user equipment and receiving a storage transaction requirement from the DPK module relating to the cryptocurrency. The method further comprises sending a message for approving the DPK module via a communication network to the user equipment, the message comprising a first information being sent to the DPK module via the user equipment. The method further comprises receiving a second information from the DPK module, the second information is based on the first information. The method further comprises approving the DPK module using the received second information. The method further comprises sending a public key storage allowance to the DPK module, based on the approving. The method further comprises receiving one or more user public key from the DPK module and storing the received one or more user public key. The method further comprises transmitting the stored one or more public key to the DPK module in response to a retrieving requirement from the DPK module.

According to another aspect, a Distributed Public Keystore module operable on a user equipment is provided. The DPK module is configured for two-way communication with a blockchain, the DPK module comprising a processing unit and a memory, the memory containing instructions executable by the processing unit, whereby the DPK module is operative for: transmitting a Token of the DPK module to an external device having cryptocurrency so the external device can approve the DPK module and obtaining cryptocurrency from the external device to a wallet of the DPK module, in response to an approval of the Token by the external device. The DPK module is further operative for obtaining one or more user public keys generated by one or more Applications on the user equipment and transmitting the cryptocurrency in the wallet of the DPK module to a blockchain. The DPK module is further operative for sending a storage transaction requirement to the blockchain relating to the cryptocurrency and receiving a first information from a user of the user equipment, the first information originating from a message received from the blockchain, the message being received via the communication network to the user equipment, the first information being related to approval by the blockchain of the storage transaction requirement. The DPK module is further operative for sending a second information to the blockchain for approval and receiving from the blockchain, a public key storage allowance, relating to an approval by the blockchain for the sent storage transaction requirement based on the sent second information. The DPK module is further operative for sending the one or more user public keys to the blockchain for storage in the blockchain, based on the public key storage allowance. The DPK module is further operative for retrieving the one or more stored public key from the blockchain when the one or more public key is needed by the DPK module.

According to another aspect, a blockchain is provided. The blockchain is configured for two-way communication with a number of user equipment and communication networks, the blockchain comprising a processing unit and a memory, the memory containing instructions executable by said processing unit, whereby the blockchain is operative for: receiving cryptocurrency from a wallet in a Distributed Public Keystore module operated on the user equipment and receiving a storage transaction requirement from the DPK module relating to the cryptocurrency. The blockchain is further operative for sending a message for approving the DPK module via a communication network to the user equipment, the message comprising a first information being sent to the DPK module via the user equipment. The blockchain is further operative for receiving a second information from the DPK module, the second information is based on the first information. The blockchain is further operative for approving the DPK module using the received second information. The blockchain is further operative for sending a public key storage allowance to the DPK module, based on the approving. The blockchain is further operative for receiving one or more user public key from the DPK module and storing the received one or more user public key. The blockchain is further operative for transmitting the stored one or more public key to the DPK module in response to a retrieving requirement from the DPK module.

According to other aspects, computer programs and carriers are also provided, the details of which will be described in the claims and the detailed description.

Further possible features and benefits of this solution will become apparent from the detailed description below.

DETAILED DESCRIPTION

Briefly described, a universal plug-in Distributed Public Keystore (DPK) module is provided on a user equipment. The DPK module approves its identifier with a Public Key Manager (PKM) and obtains cryptocurrency from the PKM. The APPs on the user equipment generate and transmit user public keys/user information to the DPK module. The DPK module generated its own user public key as well. After a storage transaction requirement by the DPK module is approved by a blockchain, the DPK module sends received user public keys/user information to the blockchain so that the user public keys/user information are stored in the blockchain. The user public keys/user information are never stored outside the blockchain or in a third part server. The stored user public keys/user information are retrieved to the DPK module when necessary, e.g., when a P2P communication is performed by any of the APPs.

FIG.1shows a system comprising a DPK module106and a blockchain114that is arranged to communicate with a communication device aka user equipment102on which the DPK module106is arranged.

A blockchain114is a distributed data where copies are stored on multiple nodes simultaneously. There is no single controlling computer in charge of maintaining the data, or what is referred to as the ledger. Blockchain is more than just a decentralized digital ledger; It may also contain data and transaction records. The use of the blockchain technology deals with confirming the integrity of data associated with the transaction. This feature is key for securing the integrity of networked devices. Examples of blockchain114are public blockchains like Bitcoin and Ethereum™, private blockchains like Hyperledger™ and R3 Corda™ and hybrid blockchains like Dragonchain™.

The user equipment102may be any type of device capable of communicating with the blockchain114, mobile network and Internet. For example, the user equipment102may be a machine type UE or a UE capable of machine to machine (M2M) communication, a sensor, a tablet, a mobile terminal, a smart phone, a laptop embedded equipped (LEE), a laptop mounted equipment (LME), a USB dongle, a Customer Premises Equipment (CPE) etc.

Referring toFIG.1, a user equipment102is communicatively connected to a blockchain114so that a two-way communication can be performed between the user equipment102and the blockchain114. The blockchain114here is an Ethereum as an example. The user equipment102is also communicatively connected to a PKM128in the same way.

The user equipment102includes one or more APP104. The APP104can be common applications that the user of the user equipment102downloads from an application market, e.g. Apple APP Store™, Google Play™. The APP104can be e.g., real-time communication APPs. A DPK module106is also downloaded from an application market by the user. A DPK module106can be downloaded independently or as a module part of other APP. The DPK module106is a general plug-in module that can be embedded into any type of client devices aka user equipment (IoT sensors, mobile devices, SIM, SD card, eSIM, etc. . . . ), web-browser, and servers. The DPK module106can interact with the APP104and the blockchain114via different interfaces. When the APP104generate user public keys/user information, the user public keys/user information are transmitted to the DPK module106for further processing. Meanwhile, the DPK module106itself generates its own user public key.

The DPK module106includes a Token108, a wallet110and a blockchain protocol client, in this case a Light Ethereum Subprotocol (LES) Client112. The Token108operates as an identifier of the DPK module106when the DPK module106is approved by the PKM128. In a initialization step, the wallet110is empty. After the Token108is approved by the PKM128, the DPK module106obtains cryptocurrency e.g., Ether from the PKM128and stores into its wallet110. Generally speaking, the PKM128is not the only type of device that the DPK module106can get cryptocurrency from. The DPK module106can obtain cryptocurrency from all kinds of external devices which provide cryptocurrency as long as the Token108of the DPK module106can be approved by the external device and the cryptocurrency transmission is secure. The external device can be any server/equipment accessible via network and providing cryptocurrency. The LES client112is a blockchain client installed on all type of UEs (smart phones, IoT devices, laptops, etc.) which has a smaller size and needs less space than ordinary blockchain client.

A PKM128or any other external cryptocurrency providing device may also be included in the whole system. The PKM128receives a Token108of the DPK module. The Token108acts as an identifier of the DPK module106. When receiving the Token, the PKM128tries to approve the Token108. When the Token108is approved successfully by the PKM128, the PKM128transfers cryptocurrency, e.g., Ether to the wallet110so that the cryptocurrency can be sent to the blockchain114as payment in further interactions. This step is the1.1Approve step illustrated inFIG.1.

A blockchain114includes multiple smart contracts116which perform different functions, and a secure interface118. A smart contract is defined as a computer code running over blockchain, capable of exchanging any value (money, property, etc.) without the need of a third party. The smart contracts offer the following advantages over the existing computer programs:1. Autonomous: their execution is managed by the network,2. Trust-less: the blockchain ledger's version is validated with consensus among nodes,3. Data safe: the application's data remain permanently in the blockchain,4. Transparent: smart contract's code and storage are publicly available.

The blockchain114interacts with the DPK module106via interfaces of the blockchain114. The DPK module106obtains user public keys from the APPs104or from itself. The DPK module106can obtain not only user public keys, but also other crucial data that are related to the user public keys, e.g., APP identifications and user information related to an application, etc. The user information related to the applications is, e.g., information of the user to be transferred between the user equipment and other device using the application. These data can also be stored in the blockchain. The DPK module106transmits cryptocurrency to the blockchain114so that further interactions with the blockchain114are “paid”. Then the DPK module106sends a storage transaction requirement to the blockchain114, the storage transaction requirement is related to the cryptocurrency which has been “paid” before.

After receiving the storage transaction requirement from the DPK module106, one of the multiple smart contracts116sends a Hypertext Transfer Protocol (HTTP) request to the secure interface118of the blockchain114. The secure interface118offers a secure connection between the smart contracts and external web application programming interfaces (APIs). In some embodiments, the secure interface118is an Oraclize contract. The Oraclize contract is a smart contract situated between the Blockchain network and the public Internet. It helps smart contracts issue requests to the Internet via HTTP(S) POST and GET methods to gather information or post data. The main challenge with oracles is trust. Fortunately, recent substantial research attempts succeeded in solving these trust issues by providing different trusted computing techniques.

The HTTP request is sent to a True Random Number Generator (TRNG) server122situated in the Internet120to get a random Personal Identification Number (PIN) code. Transport Layer Security Notary (TLSNotary) is considered as a TRNG. Oraclize for instance, provides an enhanced oracle network that uses the TLSNotary proof, which returns a cryptographic proof for the user showing that a certain HTTP request returned data from the right server at a specific time. Hence, Oraclize refers to their service as “provably-honest”. Other attestators building TRNG like Town Crier company uses Trusted Execution Environments (TEE) such as the Intel Software Guard Extensions (SGX) to guarantee that the returned data is not tampered with. Other hardware-based techniques include Qualcomm TEE, Android safetyNet, Ledger Nano S attestation, Samsung Knox™ etc.

When the PIN code is sent back to the smart contract116, the smart contract116again connects via the secure interface118to a Short Message Service (SMS) Gateway124and sends the PIN code to the SMS gateway. The SMS Gateway sends an SMS to the user equipment102containing the PIN as a payload via a Mobile Network Operator126. The PIN can be included in the message directly or indirectly.

If the PIN is contained in the message directly/explicitly, once the SMS is received by the user equipment102, a user of the user equipment102reads the SMS including the PIN code and inputs the PIN code to the DPK module106via a user interface, of the UE102. If the PIN is contained in the message indirectly, e.g., only an information related to the PIN is contained in the message, the user uses the information to generate the PIN. For example, the user uses a hardware “Authorization Token” to generate a PIN based on the information. Then the user inputs the PIN code to the DPK module106. Instructions to the user to input a PIN code can be displayed on the user equipment102. The DPK module106then transmits the inputted PIN code to the blockchain114. The blockchain114compares if the received PIN code from the DPK module106is consistent with the PIN code originating from the TRNG server122. If so, the storage transaction requirement from the DPK module106is approved by the blockchain114and a public key storage allowance is sent to the DPK module106. The whole process of storage transaction approvement is illustrated as step1.2inFIG.1.

The blockchain114keeps two tables, each table having entries containing user public key connected to user equipment and wallet address, one table is PendingList, the other table is ApprovedList. Once the storage transaction requirement from the DPK module106is approved by the blockchain114, the correspondent entry in the PendingList is entered into the ApprovedList. An example of the PendingList and the ApprovedList is shown in Table 1. In the embodiment of Table 1, the user equipment102is a mobile phone.

After receiving the public key storage allowance, the DPK module106sends the user public keys from the APPs104or its own user public key to the blockchain114for storage. Because the user public keys of the APPs104or DPK module106are stored in the blockchain114, and not in a centralized infrastructure, the security of the storage is improved. The user public keys are never stored outside the blockchain or in a third part server. Furthermore, since the storage transaction requirements are approved by the blockchain114, the stored user public keys cannot be overwritten by other malicious users. This storing step is illustrated step1.3inFIG.1.

When any one of the APPs104or the DPK module106itself needs the user public key stored at the blockchain114, the DPK module retrieves1.4the stored public key from the blockchain114. When transmitting cryptocurrency from the DPK module106to the blockchain114, the wallet address of the wallet110is the unique identifier of the DPK module106for the blockchain114. Furthermore, if the user equipment102is a mobile phone, the MSISDN number of the mobile phone is connected with the wallet address of the wallet110. This will block any malicious user with a new wallet address to change the transaction data for a spoofed phone number.

Referring toFIG.2, the layout of the whole system is similar toFIG.1. The blocks202,204,206,208,210,212,214,216,218,222and228have the same functions as the correspondent blocks102,104,106,108,110,112,114,116,118,122and128inFIG.1. The differences are instead of SMS gateway124and Mobile Network Operator126, the solution inFIG.2uses Application Server224and Cloud Messaging226. An example of cloud messaging is Google FCM. When the smart contract216receives the PIN code from the TRNG222via the secure interface218, the smart contract216sends a push notification including the PIN code to the Application Server224. The PIN code is included in the push notification directly or indirectly. The Application Server224transmits the push notification to the user equipment202via the Cloud Messaging226. The user of the user equipment202receives the push notification. The following steps in the solution ofFIG.2is the same as in the solution ofFIG.1.

Referring toFIG.3, it illustrates another embodiment of the invention. The layout of the whole system is similar toFIG.2. The blocks302,304,306,308,310,312,314,316,318,324,326and328have the same functions as the correspondent blocks202,204,206,208,210,212,214,216,218,224,226and228inFIG.2. The steps of “2.1Approve”, “2.3Store Public Keys” and “2.4Retrieve Public Keys” are similarly performed in this embodiment as performed in the embodiment ofFIG.2, and will not be described in details here. Only the step “2.2Approve Storage Transaction” is described here in details.

After receiving the storage transaction requirement from the DPK module306, one of the smart contracts316of the blockchain314contacts with the secure interface318of the blockchain314. The secure interface318generates a random number N1 and sends out a message comprising the random number N1 via an external communication network to an Application Server324. The message is transmitted through the Application Server324and a Cloud Messaging service or network326to the user equipment302. The random number N1 is also stored in the blockchain314. After receiving the message, the user equipment302transfers the random number N1 of the message to the DPK module306. When receiving the random number N1, the DPK module306generates another random number N2 itself, then calculates a function H (N1, N2) with the random numbers N1 and N2 as inputs. The function H is preinstalled in the DPK module306and can be any function that can be used for approvement, e.g., a Hash function.

When the function H (N1, N2) has been calculated, the DPK module306transmits the random number N2 and the function H (N1, N2) to the blockchain314simultaneously. However, the random number N2 and the function H (N1, N2) are transmitted to the blockchain314via different routes. The random number N2 is transmitted via an external communication network, that is, via the cloud messaging service/network326and the application server324, then received by the blockchain314via the secure interface318. The function H (N1, N2) is transmitted to the blockchain314directly via the interfaces between the DPK module306and the blockchain314.

After receiving the random number N2 and the function H (N1, N2), the blockchain314calculates a function H′ (N1, N2) with the inputs N1 and N2. The function H′ is preinstalled in the blockchain314and consistent with the function H in the DPK module306. After calculation, the blockchain314compares if the received H (N1, N2) is consistent with the calculated H′ (N1, N2). If consistent, the storage transaction requirement is approved by the blockchain314, and a public key storage allowance is sent to the DPK module306. The whole process of “2.2Approve storage Transaction” in this embodiment is accomplished.

FIG.4is a flow chart illustrating a procedure performed by a DPK module, according to further possible embodiments. The DPK module is operated on a user equipment. The steps can be understood in conjunction withFIG.1,FIG.2,FIG.3andFIG.6. The method comprising:

Step402: transmitting a Token of the DPK module106,206,306,606to an external device128,228,328having cryptocurrency so the external device128,228,328can approve the DPK module106,206,306,606. The token is a unique identifier for the DPK module106,206,306,606in the external device128,228,328. In a preferred embodiment, the cryptocurrency is Ether. In another preferred embodiment, the external device128,228,328is a Public Key Manager (PKM).

Step404: obtaining cryptocurrency from the external device128,228,328to a wallet110,210,310of the DPK module106,206,306,606, in response to an approval of the Token by the external device128,228,328.

Step406: obtaining one or more user public key on the user equipment102,202,302. In a preferred embodiment, the user public keys are obtained by the DPK module106,206,306,606from one or more Applications104,204,304. In another preferred embodiment, the user public keys are obtained from the DPK module106,206,306,606itself. That is, the user public keys are generated by the DPK module106,206,306,606. In another preferred embodiment, user information related to an application104,204,304is also obtained. The user information related to an application104,204,304is for example information of the user to be transferred between the user equipment102,202,302and other device using the application104,204,304.

Step408: transmitting the cryptocurrency in the wallet110,210,310of the DPK module106,206,306,506to a blockchain114,214,314,614. In one preferred embodiment, the blockchain114,214,314,614is Ethereum. In a preferred embodiment, the wallet110,210,310in the DPK module106,206,306,606includes a wallet address, the wallet address is a unique identifier for the DPK module106,206,306,606relating to the transmission of the cryptocurrency from the wallet110,210,310to the blockchain114,214,314,614.

Step410: sending a storage transaction requirement to the blockchain114,214,314,614relating to the cryptocurrency.

Step412: receiving a first information from the user equipment102,202,302, the first information originating from a message received from the blockchain114,214,314,614, the message being received via a communication network to the user equipment102,202,302, the first information being related to approval by the blockchain114,214,314,614of the storage transaction requirement.

In a preferred embodiment, the first information can be a PIN or other unique password. The PIN/password can be explicitly included the message. In another embodiment, actual PIN/password cannot be obtained directly from the message. Instead, the user gets the actual PIN/password by using the information comprised in the message. For example, the user inputs the information comprised in the message into a hardware “Authorization Token” and the “Authorization Token” generates the actual PIN/password for the user. In another embodiment, the user reads the message and is instructed to input the PIN/password into the DPK module106,206,306,606. The instructions can be displayed on the user equipment102,202,303from the DPK module106,206,306,606or from the received message. In a preferred embodiment, the message sent from the blockchain114,214,314,614is sent as/via SMS or cloud messaging226. The user of the user equipment102,202,302reads the SMS/cloud messaging and inputs the PIN/password to the DPK module106,206,306,606.

In another embodiment, the first information is a random number N1. The random number N1 is comprised in a message sent from the blockchain114,214,314,614. The user equipment102,202,302obtains the random number N1 from the received message and sends the random number N1 to the DPK module106,206,306,606. In a preferred embodiment, the message sent from the blockchain114,214,314,614is sent as/via SMS or cloud messaging326.

Step414: sending a second information based on the first information to the blockchain114,214,314,614for approval.

In a preferred embodiment, if the first information is a PIN/password, the second information is also the PIN/password.

In a preferred embodiment, a step413is performed by the DPK module106,206,306,606prior to the step414. The step413generates the second information based on the received first information. In this embodiment, the first information is the random number N1. By receiving the random number N1, the DPK module106,206,306generates another random number N2 itself, then calculates a function H (N1, N2) having the random numbers N1 and N2 as inputs. The function H is preinstalled in the DPK module306and can be any function that used for approvement, e.g., Hash function. The second information is the random number N2 and the function H (N1, N2). In a preferred embodiment, in the step414, the random number N2 and the function H (N1, N2) are sent via different routes. The random number N2 is sent via a communication network, e.g., cloud messaging, application server etc. The function H (N1, N2) is sent directly via the interfaces between the DPK module106,206,306,606and the blockchain114,214,314,614.

Step416: receiving from the blockchain114,214,314,614, a public key storage allowance, relating to an approval by the blockchain for the sent storage transaction requirement based on the sent second information.

Step418: sending the one or more user public key to the blockchain114,214,314,614for storage in the blockchain114,214,314,614, based on the public key storage allowance. In a preferred embodiment, the sending418of the one or more user public key to the blockchain also includes sending user information related to an application104,204,304on the user equipment102,202,302, the user information related to an application104,204,304being for example information of the user to be transferred between the user equipment102,202,302and other device using the application104,204,304.

Step420: retrieving the one or more stored user public key from the blockchain114,214,314,614, when the public key is needed by the DPK module106,206,306,606. In a preferred embodiment, the stored user information related to an application104,204,304on the user equipment102,202,302is also retrieved.

FIG.5is a flow chart illustrating a procedure in a blockchain, according to further possible embodiments. The blockchain is communicatively connected to the DPK module. In a preferred embodiment, the blockchain is Ethereum. The method comprising:

Step502: receiving cryptocurrency from a wallet110,210,310in a Distributed Public Keystore module106,206,306,606operated on the user equipment102,202,302. In a preferred embodiment, the cryptocurrency is Ether.

Step504: receiving a storage transaction requirement from the DPK module106,206,306,606relating to the cryptocurrency.

Step506: sending a message for approving the DPK module106,206,506via a communication network to the user equipment102,202, the message comprising a first information being sent to the DPK module106,206,306,606via the user equipment102,202,302.

The first information can be a PIN or other unique password. In a preferred embodiment, The PIN/password can be explicitly included the message. In another embodiment, actual PIN/password cannot be obtained directly from the message. Instead, the actual PIN/password can be obtained by using the information comprised in the message. For example, the user inputs the information comprised in the message into a hardware “Authorization Token” and the “Authorization Token” generates the actual PIN/password for the user. In a preferred embodiment, the message is sent as/via SMS or cloud messaging. In a another preferred embodiment, the message is sent from the blockchain114,214,314,614via a secure interface118,218,318and a communication network to the user equipment102,202,302. The secure interface118,218,318provides a secure connection to an external network. In a preferred embodiment, the secure interface118,218,318is an Oraclize contract.

In another embodiment, the first information is a random number N1. The random number N1 is generated by the blockchain114,214,314,614and comprised in a message. The message is sent by the blockchain114,214,314,614to the user equipment102,202,302, preferably via cloud messaging and application server or via SMS. In a preferred embodiment, the random number is generated by the secure interface118,218,318, e.g., Oraclize contract.

Step508: receiving a second information from the DPK module106,206,306,606, the second information is based on the first information.

In a preferred embodiment, if the first information is a PIN/password, the second information is also a PIN/password which is exactly the same as the first information. In another embodiment, if the first information is the random number N1, the second information is the random number N2 and the function H (N1, N2), preferably sent via different routes.

Step510: approving the DPK module106,206,306,606using the received second information. In a preferred embodiment, the second information is a PIN/password, the blockchain114,214,314,614compares whether the received PIN/password is consistent with the sent PIN/password. If so, the DPK module106,206,306,606is approved. In another embodiment, the second information is a random number N2 and a function H (N1, N2), the blockchain114,214,314,614generates an own function H′ (N1, N2) based on the N1 generated earlier and the received N2. The function H′ is preinstalled in the blockchain114,214,314,614and is the same as the function H on the DPK module106,206,306,606. If the result of the H′ (N1, N2) is consistent with the received H (N1, N2), the DPK module106,206,306,606is approved.

Step512: sending a public key storage allowance to the DPK module106,206,306,606, based on the approving.

Step514: receiving one or more user public key from the DPK module106,206,306,606.

Step516: storing the received one or more user public key.

Step518: transmitting the stored one or more public key to the DPK module106,206,306,606in response to a retrieving requirement from the DPK module106,206,306,606.

FIGS.6aand6bare block diagrams illustrating a DPK module and a blockchain, respectively, in more detail, according to further possible embodiments.

According to embodiments, the DPK module106,206,306,606is operable on the user equipment102,202,302and configured for two-way communication with a blockchain114,214,314,614. The DPK module106,206,306,606may comprises a processing unit630and a memory632. The memory632contains instructions executable by the processing unit630, whereby the DPK module106,206,306,606is operative for performing any of the steps mentioned in relation toFIG.4.

The instructions executable by said processing unit630may be arranged as a computer program stored e.g., in said memory632. The processing unit630and the memory632may be arranged in a sub-arrangement. The sub-arrangement may be a micro-processor and adequate software and storage therefore, a Programmable Logic Device, PLD, or other electronic component(s)/processing circuit(s) configured to perform the methods mentioned above. The processing unit630may comprise one or more programmable processor, application-specific integrated circuits, field programmable gate arrays or combinations of these adapted to execute instructions.

The computer program in the memory632may be arranged such that when its instructions are run in the processing unit630, they cause the DPK module106,206,306,606to perform the steps described in any of the described embodiments of the DPK module106,206,306,606and its method. The computer program may be carried by a computer program product connectable to the processing unit630. The computer program product may be the memory632, or at least arranged in the memory. The memory632may be realized as for example a RAM (Random-access memory), ROM (Read-Only Memory) or an EEPROM (Electrical Erasable Programmable ROM). In some embodiments, a carrier may contain the computer program. The carrier may be one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or computer readable storage medium. The computer-readable storage medium may be e.g., a CD, DVD or flash memory, from which the program could be downloaded into the memory632. Alternatively, the computer program may be stored on a server or any other entity to which the DPK module106,206,306,606has access via a communication interface. The computer program may then be downloaded from the server into the memory632.

According to the embodiments, a blockchain114,214,314,614is configured for two-way communication with a number of user equipment102,202,302and communication networks, the blockchain114,214,314,614comprising a processing unit634and a memory636, the memory636containing instructions executable by said processing unit634, whereby the blockchain114,214,314,614is operative for performing any of the steps mentioned in relation toFIG.5.

The computer program in the memory636may be arranged such that when its instructions are run in the processing unit634, they cause the blockchain114,214,314,614to perform the steps described in any of the described embodiments of the blockchain114,214,314,614and its method. The instructions executable by said processing unit634may be arranged as a computer program stored e.g., in said memory636. The processing unit634and the memory636may be arranged in a sub-arrangement. The sub-arrangement may be a micro-processor and adequate software and storage therefore, a Programmable Logic Device, PLD, or other electronic component(s)/processing circuit(s) configured to perform the methods mentioned above. The processing unit634may comprise one or more programmable processor, application-specific integrated circuits, field programmable gate arrays or combinations of these adapted to execute instructions.

The computer program in the memory636may be arranged such that when its instructions are run in the processing unit634, they cause the blockchain114,214,314,614to perform the steps described in any of the described embodiments of the blockchain114,214,314,614and its method. The computer program may be carried by a computer program product connectable to the processing unit634. The computer program product may be the memory636, or at least arranged in the memory. The memory636may be realized as for example a RAM (Random-access memory), ROM (Read-Only Memory) or an EEPROM (Electrical Erasable Programmable ROM). In some embodiments, a carrier may contain the computer program. The carrier may be one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or computer readable storage medium. The computer-readable storage medium may be e.g., a CD, DVD or flash memory, from which the program could be downloaded into the memory636. Alternatively, the computer program may be stored on a server or any other entity to which the blockchain114,214,314,614has access via a communication interface. The computer program may then be downloaded from the server into the memory636.

FIG.7is a signaling diagram illustrating an example of a procedure when the solution is performed, according to further possible embodiments.

A Token7.1of the DPK module706is sent by the DPK module706to the PKM728. After the PKM728approves the Token, cryptocurrency7.2is sent by the PKM728to the DPK module706. The DPK module706generates or obtains user public keys7.3from one or more applications. The DPK module706transmits the cryptocurrency7.4to the blockchain714. The cryptocurrency is related to the storage transaction requirement7.5which is sent from the DPK module706to the blockchain714. The blockchain714sends a message7.6to the user equipment702. The message7.6relates to a future approval of the storage transaction requirement. On receiving the message7.6, the user equipment702obtains a first information from the message and transmits the first information7.7to the DPK module706. The DPK module706transmits a second information7.8to the blockchain714. The second information is based on the first information. After the second information7.8is approved by the blockchain714, a Public Key Storage Allowance7.9is transmitted to the DPK module706. Then the User Public Keys7.10are sent to the blockchain714for storing. The User Public Keys7.11are retrieved by the DPK module706when needed.

Although the description above contains a plurality of specificities, these should not be construed as limiting the scope of the concept described herein but as merely providing illustrations of some exemplifying embodiments of the described concept. It will be appreciated that the scope of the presently described concept fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the presently described concept is accordingly not to be limited. Reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Further, the term “a number of”, such as in “a number of wireless devices” signifies one or more devices. All structural and functional equivalents to the elements of the above-described embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed hereby. Moreover, it is not necessary for an apparatus or method to address each and every problem sought to be solved by the presently described concept, for it to be encompassed hereby. In the exemplary figures, a broken line generally signifies that the feature within the broken line is optional.