Abstract: A computer-implemented method of constructing a candidate block of a blockchain, wherein the method comprises: obtaining a set of blockchain transactions; obtaining a transaction representation by inputting each of the set of blockchain transactions to a Bloom filter that utilizes one or more hash functions; and constructing the candidate block, wherein the candidate block comprises the transaction representation.

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: The disclosure provides improved methods and systems for processing, storing, sharing, retrieving, writing, and accessing data (content) on a blockchain. In particular, improved efficiency and also enhanced access control permissions are provided. An embodiment of the present disclosure comprises the step of processing at least one blockchain transaction (Tx) comprising: a protocol flag; a discretionary public key (DPK); and a discretionary transaction ID (DTxID). These are discretionary in the sense that they are not required as part of the underlying blockchain protocol but in accordance with the present disclosure. This combination of features enables portions of data to be identified, retrieved, and shared on a blockchain, and also to be linked/associated with one another when provided in a plurality of transactions. It enables a graph or tree-like structure to be constructed, which reflects the hierarchical relationships between portions of data, facilitating their processing, searching, and sharing.

Abstract: A method of sharing a first common secret among a plurality of nodes (A, B, C) for enabling secure communication for blockchain transactions comprises: determining, a first node (A) a plurality of second common secrets (SAPC, SAPB), wherein each second common secret is common to first node and a second node (B), determined at first node based on a first private key of first node and a first public key of second node (PC, PB) determined at the second node based on the first private key of the second node (SB, SC) and the first public key of the first node (PA). A third common secret (SBPC, SCPB) common to the second node (B) and a third node (C) is determined for the second node. The method comprises encrypting, at the first node, shares of first common secret known to the first node, and sending encrypted shares to second nodes.

Abstract: A computer-implemented method of constructing a candidate block of a blockchain, wherein the method comprises: obtaining an ordered sequence of blockchain transactions comprising at least an initial blockchain transaction and a final blockchain transaction; obtaining a transaction representation, wherein the transaction representation is obtained by: i) hashing the final blockchain transaction to obtain a respective hash value, and ii) concatenating the respective hash value with a preceding blockchain transaction in the ordered sequence to obtain a respective intermediate result, and hashing the respective intermediate result to obtain a respective hash value, wherein ii) is repeated until the initial blockchain transaction has been concatenated with a respective intermediate result and that respective intermediate result has been hashed to obtain the transaction representation; and constructing the candidate block, wherein the candidate block comprises the transaction representation.

Abstract: A computer-implemented method of constructing a candidate block of a blockchain, wherein the method comprises: obtaining a set of blockchain transactions; and constructing the candidate block, wherein the candidate block comprises a current block header used to link the candidate block to a previous block of the blockchain, and wherein the current block header comprises i) a hash of the respective block header of the previous block, ii) a nonce value, such that when the current block header is hashed, the resulting hash of the current block header satisfies a predetermined difficulty target, and iii) the set of blockchain transactions.

Abstract: A computer-implemented method of generating a secondary transaction identifier of a target transaction which enables a querying user to determine whether the target transaction comprises a candidate data field. The method comprises identifying a set of data fields of the target transaction, each data field comprising respective data of the transaction; and generating a transaction hash tree. Each data field is hashed to generate a respective one of a plurality of leaf hashes of the transaction hash tree. The root hash of the transaction hash tree comprises the secondary transaction identifier.

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: A method and corresponding system is presented for controlling a blockchain transaction output and/or specifying the recipient of the output. It also provides a method of controlling and/or generating an electronic communication. The unlocking script is provided in order to spend an output from a further transaction (Tx2) on the blockchain. The input of the transaction (Tx1) and/or the output of the further transaction (Tx2) may be associated with a tokenised asset represented on, or referenced via, the blockchain. The notification address may be associated with an asset or resource represented on the blockchain, or a controller of an asset or resource represented on the blockchain. The notification address may be a network address, a cryptographic key, a uniform resource locator (URI), email address or any other address or identifier which can be represented in the metadata of a transaction script and used as a destination for an electronic communication.

Abstract: A computer-implemented method of using a multi-level (ML) data chain protocol to embed a data chain on a core blockchain, comprising: obtaining one or more ML transactions, wherein each ML transaction comprises one or more carrier pairs, each carrier pair comprising an input and an output, wherein each output comprises data associated with the data chain, and wherein each input comprises a signature that signs the carrier pair; generating a first ML block of the ML data chain, wherein the first ML block is a core blockchain transaction and comprises the respective carrier pairs of the obtained one or more ML transactions, wherein for each carrier pair, a respective position index of the respective input corresponds to a respective position index of the respective output, and b) a first chain output, wherein the first chain output is for being spent by a respective chain input of a subsequent ML block.

Abstract: A method of generating a blockchain transaction, wherein each second party is associated with a public key and each public key is associated with an index, and wherein the method comprises: generating a transaction comprising a locking script comprising a shared hash value, the shared hash value comprising a sequence of hash values, each being a hash of one of the public keys and placed at a position corresponding to the respective index, and wherein the locking script is configured to require an unlocking script to comprise a target index, a target public key, and a target signature, extract the hash value from the shared hash value at a position corresponding to the target index, generate a hash of the target public key and require the generated hash value to match the extracted hash value, and verify that the target signature is a valid signature.

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: 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 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: 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: 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 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.