Abstract: According to a first aspect disclosed herein there is provide a device comprising: a PUF module, and one or more outer layer components providing at least part of an unsecured channel for inputting a challenge to the PUF module and receiving back a response. Internal logic of the PUF module comprises a logging mechanism arranged to automatically log a record of the challenge and/or response in a log medium, e.g. a blockchain. According to a second aspect, there is provided a method comprising: sending a first message to be recorded on a blockchain, submitting a query to check that the first message has been recorded on the blockchain without manipulation, on condition thereof, sending a second messaging transaction to be recorded on the blockchain. The first and second aspects may be used together or independently.

Abstract: A method is provided by which payments for assets are recorded using blockchain transactions, and verified based on immutable logs associated with the transactions.

Abstract: A method for enabling a verifying party to verify an identity of a target party or device. The method comprises, in a set-up phase: storing, in a data store, a respective piece of response data for each of a set of one or more responses resulting from a setting-up party inputting a respective set of one or more challenges into a PUF module comprising a physically unclonable function, PUF, to generate the one or more responses based on the PUF; and storing an indication of the set of challenges in the data store. The indication does not comprise a value of each of the challenges in the set, but rather a master challenge from which the set of challenges is derivable by applying a derivation function to the master challenge.

Abstract: A computer-implemented method of generating keys of a hierarchical key structure, wherein the method is performed by a key generator and comprises: obtaining a child key derivation path, wherein the child key derivation path comprises a sequence of elements, wherein the sequence of elements comprises one or more sets of one or more elements, each set of elements being generated based on a respective data item of a data path, and wherein each element in the sequence corresponds to a respective position of key in a respective level of the key structure; and generating one or more child keys based on the child key derivation path, wherein each respective child key is generated based on a respective element in the sequence at the respective position and of the respective level corresponding to that respective element.

Abstract: A computer-implemented method of providing proof that a data item of a blockchain transaction exists on a blockchain, wherein the method comprises: obtaining, from a requesting party, target data item of a target blockchain transaction; obtaining the target blockchain transaction; obtaining a target Merkle proof for the target blockchain transaction, wherein a corresponding target Merkle root is contained within a block of the blockchain, and wherein obtaining the target Merkle proof comprises calculating an index of a target transaction identifier of the target blockchain transaction within a leaf layer of a corresponding target Merkle tree; and outputting at least the target Merkle proof for use by the requesting party as proof that the target data item exists as part of the target blockchain transaction on the blockchain.

Abstract: A computer-implemented method of providing proof that a blockchain transaction exists on a blockchain, wherein the method is performed by a Merkle proof entity configured to store a set of transaction identifiers of respective blockchain transactions but not to publish new blockchain blocks to the blockchain network, and wherein the method comprises: obtaining a target transaction identifier of a target blockchain transaction, wherein the target transaction identifier forms part of the stored set of transaction identifiers; obtaining a target Merkle proof for the target blockchain transaction, wherein a corresponding target Merkle root is contained within a blockheader of the blockchain; and outputting the target Merkle proof for use by the requesting party as proof that the target blockchain transaction exists on the blockchain.

Abstract: A computer-implemented method comprising one or more instances of a challenge-response mapping operation. The challenge-response mapping operation comprises: from a submitting party, receiving challenge data comprising a secondary challenge, from among a set of multiple possible secondary challenges; inputting a primary challenge into a physically unclonable function, PUF, to generate a corresponding primary response; inputting the received secondary challenge and the generated primary response into a deterministic transform function in order to generate a secondary response, being a response to the secondary challenge, the transform function being a function of the secondary challenge and the primary response; and outputting response data comprising the secondary response or data derived therefrom.

Abstract: A method for enabling a verifying party to verify an identity of a target party or device. The method comprises, in a set-up phase: inputting of each of a set of one or more challenges into a PUF module comprising a physically unclonable function, PUF, to generate a respective one of a set of responses from each challenge; and causing to be stored, on a blockchain, a respective piece of response data for each of the set of one or more responses generated by the PUF module. The piece of response data for each response comprises the respective response or data derived therefrom. The pieces of response data are stored in one or more storage transactions recorded on the blockchain, thereby making at least one of the pieces of response data available to the verifying party for verifying the identity of the target in a subsequent verification phase.

Abstract: A computer-implemented method of authorising a payment by a target party to a verifying party. The method comprises, by the verifying party: performing a payment verification to verify a source of funds of the target party; and performing an identity verification to verify an identity of the target party. The identity verification comprises accessing response data stored in a data store in association with the identity of the target party, the data store being implemented in third party computer equipment of a trusted third party or on a peer-to-peer publication medium, wherein the response data comprises either a) a stored instance of a response to a challenge, or b) an attestation comprising a transformation of the response. The payment is authenticated on condition that the outputs of both the payment verification and identity verifications is true.

Abstract: A method for enabling a verifying party to verify an identity of a target comprising a target party or device. The method comprises, in a set-up phase, by a party other than the verifying party: inputting a set of one or more challenges into a PUF module comprising a physically unclonable function, PUF, in order to generate a respective set of one or more responses based on the PUF; and storing a respective response data record for each of the set of responses in a data store external to any equipment of the target party or verifying party, the data store either being part of third party computer equipment or being a public peer-to-peer publication medium. The response data records are thus made available to the verifying party to verify the identity of the target in a subsequent verification phase.

Abstract: A comprising, by target computer equipment of a target party: obtaining a cryptographic key derived from a response generated by PUF module comprising a physically unclonable function, PUF, the response having been generated by the PUF module based on the PUF in response to a corresponding challenge input to the PUF module, wherein key information comprising the cryptographic key or a corresponding public key is also made available to a verifying party; from an issuing party, receiving a computation request specifying the computation to be performed; in response to the computation request, performing the computation in order to generate a computation result; signing a message comprising the computation result with the cryptographic key; and making the signed message available to the verifying party by sending the signed message to be recorded on a blockchain.

Abstract: A computer-implemented method of pseudo-randomly selecting a data element using blockchain transactions, wherein the method is performed by a first party and comprises: obtaining an ordered list of data elements and a plurality of seed inputs; generating a first transaction; and causing the first transaction to be made available to one or more blockchain nodes for inclusion in the blockchain, wherein the first transaction comprises a first output script, and wherein when executed alongside an input script of a second transaction, the first output script is configured to: output a re-ordered list of the data elements; output a pseudorandom number generated based on the plurality of seed inputs; and output, as a selected data element, the data element positioned at a position in the re-ordered list of data elements corresponding to the pseudorandom number.

Abstract: A computer-implemented method of accepting blockchain transactions, wherein the method is performed by a blockchain node of a blockchain network and comprises: generating a first transaction comprising a first output, the first output comprising a first output script; causing the first transaction to be published on the blockchain; receiving a second transaction comprising a second output, the second output comprising a second output script; and accepting the second transaction based on one or more conditions being met, wherein a first condition of said one or more conditions is that the second output script corresponds to the first output script.

Abstract: A computer-implemented method of recording an agreement between a requesting party and a confirming party on a blockchain, wherein the method is performed by the requesting party and comprises: generating a request transaction, wherein the request transaction comprises an input signed by the requesting party, and at least a first output comprising a cryptographic puzzle based on a first data item known to both the requesting and confirming parties, wherein the first data item represents the agreement; and causing the request transaction to be transmitted to one or more blockchain nodes.

Abstract: A computer-implemented method of generating a blockchain address based on a corresponding template output script of a blockchain transaction, wherein the blockchain address comprises a prefix component and a data component, and wherein the method is performed by a first party and comprises: generating a first blockchain address based on a first template output script, the first blockchain address comprising a first prefix component for identifying a first template output script, and a first data component representing one or more data items required to populate the first template output script; wherein the first prefix component is greater than one byte, and/or wherein the first data component is generated based on a plurality of data items required to populate the first template output script.

Abstract: A computer-implemented method for connecting to a layered network. The layered network comprises a plurality of nodes arranged in an ordered set of layers. The ordered set of layers comprises, in order, a core layer comprising a set of core nodes, a second layer comprising a set of second nodes, and one or more outer layers each comprising a respective set of outer nodes. Each core node is connected to at least one other core node. The method is performed by a connecting node and comprises connecting to the network according to a connection protocol. The connection protocol requires that each node must connect to at least one node of a preceding layer, and each outer node must also connect to at least one core node.

Abstract: A computer-implemented method for adapting connections between nodes of a layered network. The layered network comprises a plurality of nodes arranged in an ordered set of layers. The ordered set of layers comprises, in order, a core layer comprising a set of core nodes, a second layer comprising a set of second nodes, and one or more outer layers each comprising a respective set of outer nodes. Each core node is connected to at least one other core node. The method is performed by an adapting node, the adapting node being a node of the layered network that is connected to one or more second nodes and multiple core nodes. The method comprises, based on one or more network properties of the layered network, disabling a respective connection between the adapting node and at least one but not all of the multiple core nodes.

Abstract: A method performed in a layered network. The layered network comprises a core layer comprising one or more core nodes, one or more intermediate layers each comprising one or more intermediate layer nodes, and one or more outer layers each comprising one or more outer layer nodes. Each core node is a node of a blockchain network. At least some intermediate layer nodes are database nodes. At least some outer layer nodes are client nodes. Each database node stores at least part of a distributed database. The method includes, at a database node: receiving one or more update requests from one or more client nodes requesting to update a database entry; and for each update request, applying the update locally and/or forwarding to another database node.

Abstract: A computer-implemented method of pseudo-randomly selecting game elements for use in playing a game. An oracle obtains: a set of seed data items, the set of seed data items comprises one or more user seed data items generated by a respective user; a sequence of public keys; and a list of game elements. A total number of public keys corresponds to a total number of game elements. The oracle generates a first output of a game transaction. The first output comprises the sequence of public keys and a script configured to generate at least one pseudorandom number based on the set of seed data items. The script is configured to generate a list of the public keys based on the at least one pseudorandom number. An order of public keys in the list of public keys differs compared to an order of public keys in the sequence of public keys.

Abstract: A data structure embodied in one or more blockchain transactions has a plurality of nodes, each node embodied as a hash value contained in a blockchain transaction of the one or more blockchain transactions; and a plurality of directional edges plurality of nodes comprises leaf nodes and non-leaf nodes. In a first aspect, at least one of the non-leaf nodes has at least one child leaf node and at least one child non-leaf node, the hash value of the at least one non-leaf node being a hash of a concatenation of the respective hash values of the child leaf node and the child non-leaf node. In a second aspect, a first of the non-leaf nodes has a different number of child nodes than a second of the non-leaf nodes. In a third aspect, a first of the leaf nodes has a different level than a second of the leaf nodes.