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Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
  • H04L9/32—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials
  • H04L9/3247—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials involving digital signatures
  • H04L9/3252—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials involving digital signatures using DSA or related signature schemes, e.g. elliptic based signatures, ElGamal or Schnorr schemes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
  • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
  • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
  • H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
  • H04L9/0825—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
  • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
  • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
  • H04L9/0838—Key agreement, i.e. key establishment technique in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these
  • H04L9/0841—Key agreement, i.e. key establishment technique in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these involving Diffie-Hellman or related key agreement protocols
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
  • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
  • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
  • H04L9/085—Secret sharing or secret splitting, e.g. threshold schemes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
  • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
  • H04L9/0891—Revocation or update of secret information, e.g. encryption key update or rekeying
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
  • H04L9/30—Public key, i.e. encryption algorithm being computationally infeasible to invert or user's encryption keys not requiring secrecy
  • H04L9/3066—Public key, i.e. encryption algorithm being computationally infeasible to invert or user's encryption keys not requiring secrecy involving algebraic varieties, e.g. elliptic or hyper-elliptic curves
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W12/00—Security arrangements; Authentication; Protecting privacy or anonymity
  • H04W12/02—Protecting privacy or anonymity, e.g. protecting personally identifiable information [PII]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W12/00—Security arrangements; Authentication; Protecting privacy or anonymity
  • H04W12/03—Protecting confidentiality, e.g. by encryption
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L2209/00—Additional information or applications relating to cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
  • H04L2209/56—Financial cryptography, e.g. electronic payment or e-cash
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/18—Self-organising networks, e.g. ad-hoc networks or sensor networks

Definitions

• the present disclosure relates to a method, a system and a device for encrypting data stored on an electronic device.
• the present disclosure further relates to a method, a system and a device for decrypting the encrypted data.
• Cryptography involves techniques for protecting data on a hard disk of an electronic device, for example in the event that the electronic device is lost or stolen.
• An electronic device may include a laptop computer, a desktop computer, a tablet computer, a mobile communication device and any other form of computing device.
• the electronic device may be associated with a natural person, a group of people such as employees of a company, a system such as a banking system, etc.
• the data on a hard disk of the electronic device may be protected by a password, passphrase or a PIN.
• short codes such as 4-8 character PINs can easily be determined by trialling different combinations of characters.
• Passwords and passphrases may be more secure than PINs.
• the level of security depends on the user memorising a lengthy set of code words or a sentence.
• a cryptographic key may be used to protect the data on the hard disk of the electronic device.
• the cryptographic key may be stored on a USB drive which needs to be physically connected to the electronic device to transmit the cryptographic key. However, due to electromagnetic signals that are generated during the transmission of the cryptographic key from the USB drive to the electronic device, the transmitted key may still be obtained by a third party.
• the method may further comprise storing, at the key device, the information indicative of the deterministic key (DK).
• DK deterministic key
• the deterministic key (DK) may be based on a message (M).
• the method may comprise a step of generating the message (M) at the electronic device.
• the method may further comprise determining the deterministic key (DK) based on determining a hash of the message (M).
• the step of storing information indicative of the deterministic key on the key device may comprise storing the message (M) on the key device.
• the method may comprise determining a second electronic device public key (P 2S ) based on at least the first electronic device public key (P 1S ) and the deterministic key (DK).
• the method may also comprise: sending from the electronic device to the key device, a notice indicative of using a common elliptic curve cryptography (ECC) system with a common generator (G).
• ECC elliptic curve cryptography
• G common generator
• the first electronic device public key (P 1S ) and the first key device public key (P 1C ) may be based on elliptic curve point multiplication of the respective first electronic device private key (V 1S ) and first key device private key (V 1C ) and the common generator (G).
• the method may comprise generating the first electronic device private key (V 1S ) and the first electronic device public key (P 1S ).
• the second electronic device public key (P 2S ) may be based on at least the first electronic device public key (P 1S ) with elliptic curve point addition to the deterministic key (DK).
• the second key device public key (P 2C ) may be based on at least the first key device public key (P 1C ) with elliptic curve point addition to the deterministic key (DK).
• the method may comprise determining the encryption key based on the determined secret.
• the encryption key may be based on the secret and identification information of the electronic device.
• the identification information may comprise a serial number of the electronic device.
• the method may comprise connecting the electronic device with the key device to be in communication with each other.
• the electronic device may be connected to the key device via a wireless protocol, such as Bluetooth or a communications network, for example the internet, or a local communications network.
• the electronic device may be connected to the key device by virtue of a wire, for example via cable or a suitable port of the electronic device.
• the method may further comprise storing, at a data storage associated with the electronic device, the first key device public key (P 1C ).
• a computer implemented method of decrypting data at an electronic device, the data being encrypted in accordance with the method of encrypting data as described above, the method of decrypted the data comprising:
• the method may comprise authenticating the key device.
• the method may comprise generating, at the electronic device, an authentication message (M A ) and sending the authentication message (M A ) to the key device.
• the method may comprise generating, at the key device, a second asymmetric cryptography pair having a second key device private key (V 2C ) and a second key device public key (P 2C ).
• the second key device private key (V 2C ) may be based on a deterministic authentication key (DK A ) and the first key device private key (V 1C ).
• the second key device public key (P 2C ) may be based on the deterministic authentication key (DK A ) and the first key device public key (P 1C ).
• the method may comprise determining the deterministic authentication key (DK A ).
• the deterministic authentication key (DK A ) may be determined based on the authentication message (M A ), such as by determining a hash of the message (M A ).
• the method may include generating, at the key device, a signed authentication message (SM A ) based on the deterministic authentication key (DK A ) and the second key device private key (V 2C ).
• SM A signed authentication message
• the method may further include: receiving, at the electronic device, the signed authentication message (SM A ) from the key device; validating the signed message (SM A ) with the second key device public key (P 2C ); and authenticating the key device based on the result of validating the signed authentication message (SM A ).
• the method of decrypting the data may comprise requesting, at the electronic device, the information indicative of the deterministic key (DK) from the key device.
• the information indicative of the deterministic key (DK) comprises the message (M)
• the key device in response to receiving the request at the key device, the key device may generate a signed message (SM) based on the message (M) and send the signed message (SM) to the electronic device.
• the signed message (SM) may be generated based on the message (M) and the first or second key device private key.
• the method of decrypting the data may further comprise validating, at the electronic device, the signed message (SM) and retrieving the message (M) such that the secret can be determined, at the electronic device, for decrypting the data.
• a computer system for encrypting data at an electronic device comprising:
• the deterministic key (DK) may be based on a message (M).
• the processor may be configured to generate the message (M).
• the processor may further be configured to determine the deterministic key (DK) based on determining a hash of the message (M).
• the processor may be configured to determine a second electronic device public key (P 2S ) based on at least the first electronic device public key (P 1S ) and the deterministic key (DK).
• the electronic device may comprise an interface and the key device may comprise a key device interface to establish communication between the electronic device and the key device.
• the electronic device may be connected to the key device via a wireless protocol, such as Bluetooth or a communications network, for example the internet, or a local communications network.
• the electronic device may be connected to the key device by virtue of a wire, for example via cable or a suitable port of the electronic device.
• the interface of the electronic device may be configured to send a notice indicative of using a common elliptic curve cryptography (ECC) system with a common generator (G) to the key device interface of the associated key device.
• ECC elliptic curve cryptography
• G common generator
• the first electronic device public key (P 1S ) and the first key device public key (P 1C ) may be based on elliptic curve point multiplication of respective first electronic device private key (V 1S ) and first key device private key (V 1C ) and a generator (G).
• the processor may be configured to generate the first electronic device private key (V 1S ) and the first electronic device public key (P 1S ).
• the second electronic device public key (P 2S ) may be based on at least the first electronic device public key (P 1S ) with elliptic curve point addition to the deterministic key (DK).
• the second key device public key (P 2C ) may be based on at least the first key device public key (P 1C ) with elliptic curve point addition to the deterministic key (DK).
• the processor may be configured to determine the encryption key based on the determined secret.
• the encryption key may be based on the determined secret and identification information of the electronic device.
• the identification information may comprise a serial number of the electronic device.
• the electronic device may comprise a data storage in which the first key device public key (P 1C ) may be stored.
• the key device may comprise a key device data storage for storing at least the information indicative of the deterministic key.
• the computer system as described above further configured to decrypt data
• the processor of the electronic device being configured to:
• DK deterministic key
• DK deterministic key
• the processor may be configured to authenticate the key device. For this, the processor may generate an authentication message (M A ) and send the authentication message (M A ) to the key device.
• the key device may comprise a key device processor that may be configured to generate a second asymmetric cryptography pair having a second key device private key (V 2C ) and a second key device public key (P 2C ).
• the second key device private key (V 2C ) may be based on a deterministic authentication key (DK A ) and the first key device private key (V 1C ).
• the second key device public key (P 2C ) may be based on the deterministic authentication key (DK A ) and the first key device public key (P 1C ).
• the key device processor may further be configured to determine the deterministic authentication key (DK A ).
• the deterministic authentication key (DK A ) may be determined based on the authentication message (M A ), such as by determining a hash of the message (M A ).
• the key device processor may be configured to generate a signed authentication message (SM A ) based on the deterministic authentication key (DK A ) and the second key device private key (V 2C ).
• SM A signed authentication message
• DK A deterministic authentication key
• V 2C second key device private key
• the processor of the electronic device may be configured to: receive the signed authentication message (SM A ) from the key device; validate the signed message (SM A ) with the second key device public key (P 2C ); and authenticate the key device based on the result of validating the signed authentication message (SM A ).
• the processor of the electronic device may request the information indicative of the deterministic key (DK) from the key device.
• the information indicative of the deterministic key (DK) comprises the message (M)
• the key device processor in response to receiving the request at the key device, may generate a signed message (SM) based on the message (M) and send the signed message (SM) to the electronic device.
• the signed message (SM) may be generated based on the message (M) and the first or second key device private key.
• the processor of the electronic device may further be configured to validate the signed message and retrieving the message (M) such that the secret can be determined for decrypting the data.
• An electronic device for encrypting data the electronic device being associated with a key device, wherein the electronic device is associated with a first asymmetric cryptography pair having a first electronic device private key (V 1S ) and a first electronic device public key (P 1S ), and the key device is associated with a second asymmetric cryptography pair having a first key device private key (V 1C ) and a first key device public key (P 1C ); the electronic device comprising a processing device configured to:
• a computer program comprising machine-readable instructions to cause a processing device of an electronic device to implement any one of the methods described above.
• FIG. 1 is a schematic diagram of an example system to encrypt data
• FIG. 2 is a flow chart of computer-implemented methods for registering the electronic device and the key device of FIG. 1 ;
• FIG. 3 is a flow chart of a computer-implemented method for encrypting data at the electronic device of FIG. 1 using a secret;
• FIG. 4 is a flow chart of a computer-implemented method of authenticating the key device of FIG. 1 ;
• FIG. 5 is a flow chart of a computer implemented method of decrypting the encrypted data at the electronic device following authentication of the key device.
• FIG. 6 illustrates a schematic of an example processing device.
• FIG. 1 illustrates a computer system 1 that includes an electronic device 3 that is in communication with a key device 5 .
• the electronic device 3 has an associated first processing device 23 and the key device 5 has an associated second processing device 25 .
• the electronic device 3 may be a personal electronic device, such as a laptop computer, a desk computer, a tablet computer, a mobile communication device, a computer server or any other computing device capable of processing data.
• the electronic device 3 is represented by a laptop computer.
• the key device 7 may be a further personal electronic device, such as a mobile communication device, a portable memory device, such as a USB drive or the like.
• a mobile communication device such as a Wi-Fi device, a Wi-Fi device, or a Wi-Fi device.
• a portable memory device such as a USB drive or the like.
• the key device 5 is represented by a mobile communication device.
• the electronic device 3 may be in communication with the key device 5 via a wireless protocol, such as Bluetooth or a communications network, for example the internet or a local communications network.
• a wireless protocol such as Bluetooth or a communications network
• the electronic device 3 may be physically connected to the key device 5 , for example via a USB port of the electronic device or via a cable connection.
• the electronic device 3 is in communication with the key device 5 via Bluetooth 7 .
• the electronic device 3 is associated with a first asymmetric cryptography pair having an electronic device master private key (V 1S ) and an electronic device master public key (P 1S ).
• the key device 5 is associated with a second asymmetric cryptography pair having a key device master private key (V 1C ) and a key device master public key (P 1C ).
• the first and second asymmetric cryptography pairs may be generated during registration. Methods of registration 200 , 300 performed by the electronic device 3 and the key device 5 will be described in further detail below with reference to FIG. 2 .
• the public key for each device may be shared between the devices 3 , 5 publicly, for example via Bluetooth 7 .
• a secret is determined based on a technique similar to the technique described in the co-filed application no. GB1603117.1 (Feb. 23, 2016), and GB1619301.3 (filed Nov. 15, 2016), both entitled “Determining a common secret for two Blockchain nodes for the secure exchange of information” filed at the Intellectual Property Office by the applicant, which is herein incorporated by reference in its entirety.
• the secret is determined on a private cryptography key of the electronic device 3 and a public cryptography key of the key device 5 .
• data can be encrypted using an encryption key (E) that is based on the determined secret.
• the secret may be used as the encryption key (E).
• the method 400 is performed without communicating any of the private keys between the devices 3 , 5 which will be described in further detail with reference to FIG. 3 .
• the method of encrypting data performed by the electronic device 3 initially includes connecting the electronic device 3 with a key device 5 to communicate with the key device 5 .
• the communication may be established through a wired connection or a wireless connection, such as Bluetooth 7 .
• the method further includes determining a deterministic key (DK) which may be based on a message (M) created by the electronic device 3 .
• DK deterministic key
• the processing device 23 of the electronic device 3 may generate a message (M) and then uses a standard algorithm to create a hash of the message forming the deterministic key (DK).
• the method further includes determining a second electronic device private key (V 2S ) based on at least the electronic device master private key (V 1S ) and the deterministic key (DK), and determining a second key device public key (P 2C ) based on the key device master public key (P 1C ) and the deterministic key (DK).
• a secret is then determined based on the second electronic device private key (V 2S ) and the second key device public key (P 2C ).
• the method may include determining a second electronic device public key (P 2S ) based on at least the electronic device master public key (P 1S ) and the deterministic key (DK).
• data can then be encrypted using an encryption key (E) that is based on the determined secret.
• E an encryption key
• the determined secret itself may be used as encryption key (E), or the encryption key (E) may be determined based on the secret.
• the secret may be erased and only the deterministic key (DK) or the message (M) may be sent to the key device 5 where it can be securely stored.
• the deterministic key (DK) or the message (M) stored on the key device 5 can subsequently be used to decrypt the encrypted data.
• the data to be encrypted/decrypted may comprise one or more individual files, one or more folders comprising files or an entire hard drive of the electronic device.
• the method may comprise prompting a user to select the files and/or folders that are to be encrypted/decrypted.
• the key device 5 may store information indicative of a deterministic key for each file and folder and link them accordingly.
• method 200 is performed by the electronic device 3 and method 300 is performed by the key device 5 .
• This includes establishing the first and second asymmetric cryptography pairs for the respective devices 3 , 5 .
• the asymmetric cryptography pairs include associated private and public keys, such as those used in public-key encryption.
• the asymmetric cryptography pairs are generated using Elliptic Curve Cryptography (ECC) and properties of elliptic curve operations.
• ECC Elliptic Curve Cryptography
• Standards for ECC may include known standards such as those described by the Standards for Efficient Cryptography Group (www.sceg.org).
• Elliptic curve cryptography is also described in U.S. Pat. Nos. 5,600,725, 5,761,305, 5,889,865, 5,896,455, 5,933,504, 6,122,736, 6,141,420, 6,618,483, 6,704,870, 6,785,813, 6,078,667, 6,792,530.
• this includes the electronic device 3 and the key device 5 settling 210 , 310 to a common ECC system and using a common generator (G).
• the common ECC system may be based on secp256K1 which is an ECC system used by Bitcoin.
• the common generator (G) may be selected, randomly generated, or assigned.
• communications between the respective devices 3 , 5 are realised by an application programming interface (API) communicating with a dedicated application installed on the mobile communications device 5 .
• API application programming interface
• software may be downloaded and installed on the laptop computer which is compatible with the dedicated application installed on the mobile communication device.
• the key device 5 may be provided with not only the software application for the key device but also with the software for the electronic device. In this way, when the key device is connected to the electronic device, the software can be installed on the electronic device by executing the installation from the key device.
• the method 200 includes settling 210 on the common ECC system and common generator (G). This may include sending information indicative of the common ECC system and common generator from the electronic device 3 to the key device 5 , or receiving the information from a third device, such as remote server computer.
• the electronic device 3 may send, via Bluetooth 7 , a notice indicative of using the common ECC system with a common generator (G) to the key device 5 .
• the key device 5 may settle 310 by sending a notice indicative of an acknowledgment to using the common ECC system and common generator (G).
• the method 200 also includes generating 220 , at the electronic device 3 , a first asymmetric cryptography pair that includes the electronic device master private key (V 1S ) and the electronic device master public key (P 1S ).
• the electronic device master private key (V 1S ) is determined based, at least in part, on a random integer in an allowable range specified in the common ECC system.
• the first asymmetric cryptography pair includes:
• the electronic device 3 may store the first asymmetric cryptography pair in a first data storage 13 associated with the electronic device 3 .
• the electronic device master private key V 1S
• V 1S the electronic device master private key
• the method 200 includes sending 230 the electronic device public master key (P 1S ) to the key device 3 .
• P 1S public master key
• this step may not be necessary.
• the key device 5 receives 320 the electronic device master public key (P 1S ) and stores 330 the received electronic device master public key (P 1S ) within a storage element of the key device 5 .
• the method 300 at the key device 5 includes generating 340 a second asymmetric cryptography pair that includes the key device master private key (V 1C ) and the key device master public key (P 1C ).
• the key device master private key (V 1C ) is also a random integer within the allowable range specified in the common ECC system.
• the second asymmetric cryptography pair includes:
• the key device 5 may store the second asymmetric cryptography pair in a second data store 15 of the key device.
• the method 300 further includes sending 330 the key device master public key (P 1C ) to the electronic device 3 where it may be stored in storage 13 .
• the respective public master keys may be received and stored at a third data store associate with a third device, such as a trusted third party.
• a third device such as a trusted third party.
• This may include a third party that acts as a public directory, such as a certification authority.
• the key device master public key P 1C
• the electronic device 3 may be requested and received by the electronic device 3 only when determining the secret is required.
• the registration steps may only need to occur once as an initial setup. Afterwards, the master keys can be reused in a secure matter to determine the secret that is dependent, inter alia, on the deterministic key (DK).
• DK deterministic key
• An exemplary method 400 of encrypting data at the electronic device 3 by determining a secret that is based on a private key of the electronic device 3 and a public key of the key device 5 will now be described with reference to FIG. 3 .
• the secret may be used for one cycle only, each cycle being a full round of encryption and decryption of the data.
• new private and public keys may be determined for both the electronic device and the key device for each cycle of encryption and decryption.
• the new private and public keys may for example be determined by re-hashing the message (M) as described in further detail in the co-filed application as mentioned above which is herein incorporated by reference in its entirety.
• sub-keys may be created, wherein each sub-key is linked to the master key.
• the method 400 includes generating 410 a message (M) at the electronic device 3 .
• the message (M) may be random, pseudorandom, or user defined.
• the message (M) is based on Unix time and a nonce (and arbitrary value).
• the message (M) is arbitrary. However it is to be appreciated that the message (M) may have selective values (such as Unix Time, etc.) that may be useful in some applications.
• the method 400 includes sending 420 the message (M) via Bluetooth 7 , to the key device 5 where the message (M) will be stored.
• the message (M) may be sent to the key device 5 over an unsecure network as the message (M) does not include information on the private keys.
• the message (M) may be communicated to the key device 5 at any time.
• the message (M) may be sent to the key device 5 after the encryption of the data is completed.
• the method 400 further includes the step of determining 430 a deterministic key (DK) based on the message (M). In this example, this includes determining a cryptographic hash of the message.
• the selection of message may be arbitrary for the purpose of generating the encryption key (E) and will be newly selected for each encryption/decryption cycle.
• the message (M) is reduced to 160 bits by hashing in order to keep the message length short.
• hash algorithms may be used. This may include other hash algorithms in the Secure Hash Algorithm (SHA) family. Some particular examples include instances in the SHA-3 subset, including SHA3-224, SHA3-256, SHA3-384, SHA3-512, SHAKE128, SHAKE256. Other hash algorithms may include those in the RACE Integrity Primitives Evaluation Message Digest (RIPEMD) family. A particular example may include RIPEMD-160. Other hash functions may be based on Zémor-Tillich hash function and knapsack-based hash functions.
• SHA Secure Hash Algorithm
• RIPEMD RACE Integrity Primitives Evaluation Message Digest
• hash functions may be based on Zémor-Tillich hash function and knapsack-based hash functions.
• the method 400 then includes determining 440 , 450 , 460 the following second keys based on the deterministic key (DK), i.e. the hash of the message (M).
• DK deterministic key
• M hash of the message
• the second electronic device public key P 2S may not be necessary for the encryption of the data. It may not be necessary to determine the second electronic device public key P 2S . As will be described in further detail below, for determining the secret, the second electronic device public key P 2S may not be necessary.
• the electronic device 3 may then determine 470 the secret based on the determined second electronic device private key (V 2S ) and the determined second key device public key (P 2C ).
• Equation 8 The Secret and Encryption Key
• the secret may be used as asymmetric encryption key, or as the basis for determining a symmetric encryption key.
• the method 400 includes a further step of determining 480 an encryption key (E) based on the determined secret.
• the encryption key (E) is further based on the electronic device's serial number to ensure that the encryption key (E) is specific to the electronic device 3 .
• the concept of random salts is used to determine the encryption key (E). It will be appreciated that any suitable techniques to calculate an encryption key (E) based on the determined secret may be used (if any).
• the method 400 further includes encrypting 490 the data, at the electronic device 3 , using the determined encryption key (E). It will be appreciated that any suitable method for encrypting the data using the encryption key (E) may be used.
• the electronic device 3 does not need to store the encryption key (E) or the secret as this can be re-calculated based on the message (M) which is stored on a data storage of the key device 5 .
• the electronic device 3 re-calculates the secret which was previously determined when the data was encrypted.
• the electronic device 3 is connected to the key device 5 to be in communication with each other.
• the step of connecting the respective devices 3 , 5 may include determining whether the respective software running on the devices is compatible and synchronised.
• the key device 5 is initially authenticated by the electronic device 3 .
• a method of authenticating 500 the key device 5 will be described with reference to FIG. 4 .
• the method of authenticating 500 the key device 5 may be part of the decryption cycle of the data at the electronic device 3 .
• the method 500 includes generating 510 an authentication message (M A ) at the electronic device 3 which will be used to authenticate that the key device 5 is the key device 5 . It will be appreciated that the generated message (M A ) may solely be used for the authentication of the key device 5 . However, in some examples, the authentication message (M A ) may form the message (M) as described with reference to FIG. 3 used in the encryption process for the next encryption-decryption cycle.
• the method 500 includes receiving 520 the authentication message (M A ) at the key device 5 via Bluetooth 7 from the electronic device 3 .
• the key device 5 determines 530 a deterministic authentication key (DK A ) based on the message (M A ).
• the key device 5 determines anew asymmetric cryptography pair based on the deterministic authentication key (DK A ).
• the method 500 also includes determining 550 a second key device public key P 2C according to the following formula.
• P 2C P 1C +SHA-256( M A ) ⁇ G (Equation 12)
• the method 300 further includes generating 560 a signed message (SM A ) based on the authentication message (M A ) and the determined second key device private key (V 2C ).
• Generating a signed message includes applying a digital signature algorithm to digitally sign the authentication message (M A ). In one example, this includes applying the second key device private key (V 2C ) to the message in an Elliptic Curve Digital Signature Algorithm (ECDSA) to obtain the signed message (SM A ).
• ECDSA examples include those based on ECC systems with secp256k1, secp256r1, secp384r1, se3cp521r1.
• the signed authentication message (SM A ) is subsequently sent 570 to the electronic device 3 for authentication of the key device 5 .
• the method 500 includes receiving 580 the signed authentication message (SM A ) from the key device 5 .
• the electronic device 3 may then validate 590 the signature on the signed authentication message (SM A ) with the second key device public key (P 2C ) that was determined at step 550 .
• Verifying the digital signature may be done in accordance with an Elliptic Curve Digital Signature Algorithm (ECDSA).
• EDSA Elliptic Curve Digital Signature Algorithm
• the signed authentication message (SM A ) that was signed with the second key device private key (V 2C ) should only be correctly verified with the corresponding second key device public key (P 2C ), since V 2C and P 2C form a cryptographic pair. Since these keys are deterministic of the key device master private key (V 1C ) and the key device master public key (P 1C ) that were generated at registration of the key device, verifying the signed authentication message (SM A ) can be used as a basis of authenticating that an alleged key device 5 sending the signed message (SM A ) is the same key device 5 as during registration.
• the electronic device 3 decrypts the encrypted data by re-calculating the secret and thereby the encryption key (E).
• An exemplary method 600 of decrypting the encrypted data will now be described with reference to FIG. 5 .
• the method 600 includes requesting 610 the message (M) that was previously used in the encryption cycle and stored on the key device 5 as described in step 420 of method 400 .
• the method 600 then includes receiving 630 message (M).
• the message (M) is signed 620 by the key device 5 using the second key device private key (V 2C ) before the message (M) is sent to the electronic device 3 .
• the method 600 further includes verifying 650 the signed message (SM). This may be done by independently determining the second key device public key (P 2C ) and then performing applying an Elliptic Curve Digital Signature Algorithm (ECDSA) to SM and P 2C .
• the method 600 then includes retrieving 660 the message (M) from the signed message (M) so that the electronic device 3 can re-calculate 670 the secret following steps 430 to 470 as described with reference to FIG. 3 .
• the encryption key (E) is re-determined based on the secret and the electronic device's serial number as described with reference to step 480 of method 400 . Once the encryption key (E) is determined, the data can be decrypted 690 .
• the electronic device 3 and the key device 5 may be personal electronic devices, such as a laptop computer, tablet computer, mobile communication device, computer server etc.
• the electronic device may include a processing device 23 , 25 , a data store 13 , 15 and a user interface 14 .
• FIG. 6 illustrates an example of a processing device 23 , 25 .
• the processing device 23 , 25 may be used at the electronic device 3 , or the key device 5 .
• the processing device 23 , 25 includes a processor 1510 , a memory 1520 and an interface device 1540 that communicate with each other via a bus 1530 .
• the memory 1520 stores instructions and data for implementing the method 200 , 300 , 400 , 500 and 600 described above, and the processor 1510 performs the instructions from the memory 1520 to implement the method 200 , 300 , 400 , 500 and 600 .
• the interface device 1540 may include a communications module that facilitates communication with the communications network, such as Bluetooth 7 and, in some examples, with the user interface 14 and peripherals such as data store 13 , 15 .
• processing device 1501 may be independent network elements, the processing device 1501 may also be part of another network element. Further, some functions performed by the processing device 1501 may be distributed between multiple network elements.
• the electronic device 3 may have multiple processing devices 23 to perform method 200 , 400 and parts of method 500 , 600 in a secure local area network associated with the electronic device 3 .
• Signing may comprise executing a cryptographic function.
• the function has an input for a clear text and an input for a key, such as a private key.
• a processor may execute the function to calculate a number or string that can be used as a signature.
• the signature is then provided together with the clear text to provide a signed text.
• the signature changes completely if the message text or the key changes by a single bit. While calculating the signature requires little computational power, recreating a message that has a given signature is practically impossible. This way, the clear text can only be changed and accompanied by a valid signature if the private key is available. Further, other entities can easily verify the signature using the publicly available public key.
• encrypting and decrypting comprises a processor executing a cryptographic function to calculate an output string representing the encrypted message or the clear text message respectively.
• Keys, tokens, metadata, transactions, offers, contracts, signatures, scripts, metadata, invitations, and the like refer to binary data represented as numbers, text or strings stored on data memory, such as variables in program code of type “string” or “int” or other types or text files.
• An example of the peer-to-peer ledger is the Bitcoin Blockchain. Transferring funds or paying fees in bitcoin currency comprises creating a transaction on the bitcoin Blockchain with the funds or fees being output from the transaction.
• An example of a bitcoin transaction includes an input transaction hash, a transaction amount one or more destinations, a public key of a payee or payees and a signature created by using the input transaction as the input message and a private key of a payer to calculate the signature. The transaction can be verified by checking that the input transaction hash exists in a copy of the bitcoin Blockchain and that the signature is correct using the public key. To ensure that the same input transaction hash has not been used elsewhere already, the transaction is broadcast to a network of computing nodes (‘miners’). A miner accepts and records the transaction on the Blockchain only if the input transaction hash is not yet connected and the signatures are valid. A miner rejects the transaction if the input transaction hash is already linked to a different transaction.
• miners computing nodes
• identifiers for the two items may be stored in the same records to make the two items associated with each other.
• identifiers for the two items may be included in the transaction string to make the two items associated with each other.
• Authorising another entity may comprise calculating a signature string of a transaction using a private key and providing the signature string to the entity to allow the entity to use the signature to verify the transaction.
• a user having an account with another entity may comprise the entity storing information about the user, such as email address, name and potentially public keys.
• the entity may maintain a database, such as SQL, OrientDB, MongoDB or others.
• the entity may also store one or more of the user's private keys.

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