Abstract: A computer-implemented method of using a multi-level, ML, blockchain protocol to reach consensus on a data chain using a core blockchain, wherein the method comprises: obtaining a target data block associated with the data chain; generating a target ML block of the ML blockchain, wherein the target ML block is a respective core blockchain transaction and comprises a) the target data block, and b) a target chain output, wherein the target chain output is configured to be spent by a respective chain input of a subsequent ML block and comprises a locking script configured to implement a respective consensus-based locking mechanism, wherein the respective consensus-based locking mechanism of each respective ML block is a function of the respective data block of that respective ML block, and c) a target chain input that references the respective chain output of a previous ML block.

Abstract: Contributions to a work by contributors having respective levels in a defined hierarchy are recorded in one or more blockchain transactions. One or more lower-level contributors provide, to a higher-level contributor, one or more lower-level contributions respectively, and the higher-level contributor provides a higher-level contribution responsive to the one or more lower-level contributions. A higher-level contributor transaction comprises one or more inputs, which in turn comprise: one or more pointers to one or more spendable outputs of one or more lower-level contributor transactions and one or more transaction signatures. The transactions contain contributions commitments which, together with the one or more pointers, represent the relationship between the higher-level contributor and the lower-level contributors within the defined hierarchy. The one or more transaction signatures prove that relationship.

Abstract: A computer-implemented method that may be implemented using a blockchain network including monitoring a computational task distribution system to detect a challenge to a proposer string provided by a proposer computer system in response to a request made by a requester computer system, and as a result of detecting the challenge, at least: resolving the challenge using a first blockchain network by at least selecting a solution from a set of solutions provided to the first blockchain network, the set of solutions at least including the proposer string; and distributing digital assets from the first digital asset and the second digital asset to one or more parties of the computational task distribution system based at least in part on the solution.

Abstract: A method of generating a blockchain transaction comprising: generating a transaction comprising a locking script comprising a first shared hash value (HV) generated by applying a hash function (HF) to a second shared HV, wherein the second shared HV is generated by applying a HF to a combination of the respective public keys, and wherein the locking script is configured to require an unlocking script to comprise a target public key, a target signature, and an intermediate HV generated based on all but one of the respective public keys, apply the HF to the target public key to generate a target HV, combine the target HV and the intermediate HV to generate a target second shared HV, apply the HF to the target second shared HV to generate a target first shared HV, an verify that the target first HV matches the first shared HV, and verify the target signature.

Abstract: A solution for controlling access to a resource such as a digital wallet implemented using a blockchain. Use of the invention during set-up of the wallet can enable subsequent operations to be handled in a secure manner over an insecure channel. An example method comprises splitting a verification element into multiple shares; determining a common secret at multiple nodes in a network; and using the common secret to transmit a share of the verification element between nodes. The shares can be split such that no share is sufficient to determine the verification element and can be stored at separate locations. Upon share unavailability, the share can be retrieved a location accessibility. For safe transmission of the share(s), the common secret is generated at two different nodes independently and used to generate an encryption key for encrypting at least one share of the verification element to be transmitted securely.

Abstract: Methods and devices for propagating transactions in a network of nodes, each node having one or more connections to other nodes. The method includes determining that one of the nodes is a bottleneck for propagation of transactions; receiving, over a first time period, a plurality of new transactions from one or more first nodes in the network of nodes; combining the plurality of new transactions using network coding and a local encoding vector to generate a message; and sending the message and a global encoding vector to one or more second nodes in the network of nodes instead of sending the plurality of new transactions to the one or more second nodes. The network may be a blockchain network.

Abstract: A computer implemented method for generating a multisignature transaction for a blockchain comprising: receiving a first output and a non-signature portion of a first input, the first input comprising an outpoint to a first spendable transaction output encoding a multisignature requirement; electronically signing the first output and the non-signature portion of the first input, thereby generating a signature for satisfying the multisignature requirement when included with: (i) an associated sighash single flag, and (ii) at least one other signature; receiving a second output and a non-signature portion of a second input, the second input comprising an outpoint to a second spendable transaction output encoding a signature requirement requiring at least one signature; and electronically signing the second output and the non-signature portion of the second input, thereby generating a signature for at least partially satisfying the signature requirement when included in a signature portion with an associated sig

Abstract: Techniques are provided to implement the functionality of a logic gate by blockchain transaction. A method includes providing a locking script in a first transaction, comprising an instruction to process Boolean input; providing a further transaction having an unlocking script; processing an input signal to provide a Boolean input; and using the Boolean input to execute the locking and unlocking scripts of the first and further transactions, wherein the computing resource or agent influence the behaviour of a device or process based upon the validity of the further transaction; transmitting the further transaction and/or first transaction to a blockchain network for validation; interpreting the detecting of the further transaction within the blockchain or blockchain network as the TRUE output of a logic gate; and interpreting the failure to detect the further transaction within the blockchain or blockchain network as the FALSE output of the logic gate.

Abstract: A method of managing an overlay network overlaid on data-storage transactions of a blockchain, whereby data content of the overlay network is stored in payloads of the data-storage transactions and overlay-layer links are defined between the data-storage transactions. The method comprises identifying a graph structure of the overlay network, wherein nodes corresponds to different ones of the data-storage transactions and edges correspond to the links. Each node is associated with a respective first key for signing an input of a child data-storage transaction to authorise writing the child to the blockchain. The method further comprises using a child key derivation, CKD, function to determine a hierarchical set of second keys having the same graph structure as the overlay network, wherein the second keys enable an additional function other than signing inputs of the data-storage transactions.

Abstract: A method (300) and system (1) of determining a common secret for two nodes (3, 7). Each node (3, 7) has a respective asymmetric cryptography pair, each pair including a master private key and a master public key. Respective second private and public keys may be determined based on the master private key, master public key and a deterministic key. A common secret may be determined at each of the nodes based on the second private and public keys. In one example, a node (3, 7) may determine the common secret based on (i) a second private key based on the node's own master private key and the deterministic key; and (ii) a second public key based on the other node's master public key and the deterministic key. The invention may be suited for use with, but not limited to, digital wallets, blockchain (e.g. Bitcoin) technologies and personal device security.

Abstract: A computer-implemented method (900) and system (1) for verifying the integrity of a computer software for installation using a distributed hash table (13) and a peer-to-peer distributed ledger (14). This may be the Bitcoin blockchain or an alternative implementation. The method includes determining (910) a metadata associated with a transaction record stored on the peer-to-peer distributed ledger (14). An indication of an entry stored on the distributed hash table (13) may be determined (920) from the metadata. The method further includes determining (930) a third hash value based on the computer software and determining (940) a fourth hash value from the entry on the distributed hash table (13). The method further includes comparing (950) the third hash value and the fourth hash value and verifying (960) the integrity of the computer software based on the comparing of the third hash value and the fourth hash value.

Abstract: At least one proof transaction for recording on a blockchain comprises at least an s-part for an Elliptic Curve Digital Signature Algorithm, ECDSA, signature. The s-part is computed from a set of signature components, each provided by a participant of a signing subset of a set of keyshare participants. Each of keyshare participant holds an ephemeral keyshare of an unknown ephemeral key, and each of the signing components is provided by the participant of the signing subset based on their ephemeral keyshare. The at least one proof transaction indicates an r-challenge of at least one challenge transaction, and a node of a blockchain network applies signature verification to: (i) the s-part of the at least one proof transaction, and (ii) one of: (iia) an r-part of the r-challenge, (iib) an r-part of the at least one proof transaction, and in that event checks that that r-part satisfies the r-challenge.

Abstract: A method of generating a blockchain transaction, wherein each second party is associated with a public key, each public key is associated with a index, and wherein the method comprises: generating a first transaction comprising a locking script comprising a plurality of sub-scripts, each sub-script being associated with a respective index and comprising a expected hash value of the public key associated with the index associated with that sub-script, and wherein the locking script is configured to require a first unlocking script to comprise a target index, a target public key, and a target signature, and execute the sub-script associated with the target index, wherein each sub-script is configured to generate a hash of the target public key and require the generated hash value to match the respective expected hash value included in that sub-script, and verify that the target signature is a valid signature for the target public key.

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 challenge is input to a PUF device comprising a physically unclonable function, PUF. The device generates a corresponding response. A wallet application is instantiated to use a seed determined from the response, the instantiating comprising storing a transform of the seed or response in association with the wallet application. At a later time, a user supplies the wallet application with information demonstrating a right to use the seed, wherein the wallet application is configured so as in response to verify this information based on the transform as stored in association with the wallet application, and on condition that the information is thereby verified, to derive at least one child key from the seed. A blockchain transaction is then signed using the child key as derived by the wallet application in response to the verification.

Abstract: A method and system for controlling a flow execution of a generated script transaction according to a blockchain protocol are disclosed. The method comprises using a software resource to determine how a logic is to be controlled and stored as a portion of code, generate an input by a computing resource as a result of a computation, retrieve the stored portion of code, and insert, based on the input, the stored portion of code into a transaction script associated with a blockchain transaction such that, upon execution of the transaction script. Embodiments allow the generation of a more complex blockchain script, control how the script will execute when implemented on the blockchain, and control how or when an output of the transaction is unlocked.

Abstract: Techniques are presented for a blockchain-implemented method and system of controlling use of or access to a parking space. The method comprises generating a blockchain transaction indicative of a condition on use of, or access to, the parking space, the blockchain transaction comprising a multi-signature script requiring a plurality of signatures for completion of the blockchain transaction; providing a first subset of the plurality of signatures to the blockchain transaction to generate a partially signed signature script to partially complete the blockchain transaction; and responsive to the condition on use of or access to the parking space being satisfied, providing a second subset of the plurality of signatures to the blockchain transaction to fully complete the blockchain transaction.

Abstract: This invention relates generally to blockchain implementations and is suited for, but not limited to, use with the Bitcoin blockchain. A method of using a blockchain to control a process executing on a computing resource, the method comprising: executing a loop on the computing resource, and using a state of the blockchain to influence the execution of the loop, wherein the process: is an automated voting process; or comprises a distribution or an allocation of one or more tokens to a voter, wherein each token is associated with an amount of cryptocurrency.

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 of sharing a first common secret among a plurality of nodes for enabling secure communication for blockchain transactions. The method comprises determining, for at least one first node a plurality of second common secrets, wherein each second common secret is common to the first node and a respective second node, is determined at the first node based on a first private key of the first node and a first public key of the second node and is determined at the second node based on the first private key of the second node and the first public key of the first node. The method further comprises exchanging encrypted shares of the first common secret among the plurality of nodes to enable each of the plurality of nodes to reach a threshold number of shares of the first common secret to access the first common secret.