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 system and a method for providing user related data, such as reputational information, on users of a blockchain involved in transactions is detailed. The method includes an approach for evaluating fulfilment of transactions, particularly in the context of contracts, and then providing a record of that on the blockchain through reputational information. As a result, at a late time, this reputational information can be retrieved. Similar reputational information for other transactions can be retrieved and linked to the same user, for instance based on the use of a hash of the master public key for a user. Aggregate reputational information can be computed from the pieces of reputational information retrieved.

Abstract: The present disclosure provides methods and systems for ensuring the security of a blockchain and associated network, and for enabling the establishment of consensus regarding the state of the blockchain. A method of the disclosure may be implemented by one or more nodes on a blockchain network, using a non-parallelisable algorithm to calculate an output based on a computational difficulty parameter, a hash of at least one blockchain transaction; and/or a hash of at least one blockchain block header. The non-parallelisable, inherently sequential algorithm comprises at least one of the following operations or a combination thereof: a recursive operation, a modular exponentiation and/or a repeated squaring operation.

Abstract: A computer-implemented method of using a blockchain to form connections between P2P nodes of a P2P network, wherein each P2P node is associated with a respective public key, and wherein the method comprises: obtaining a respective public key associated with a second one of the P2P nodes; generating a first blockchain transaction comprising a first input signed with a signature corresponding to the respective public key of the first P2P node, a first output locked to the respective public key of the second P2P node, and wherein the first blockchain transaction comprises the network address of the P2P network; and causing the first blockchain transaction to be submitted to a blockchain network to be recorded on the blockchain, wherein the second P2P node is configured to connect with the first P2P node on the P2P network in response to the first blockchain transaction being recorded on the blockchain.

Abstract: Provided herein is an invention with a computer-implemented method, a computer-implement system, and a non-transitory computer-readable storage medium for unlocking an output (UTXO) in a blockchain transaction. The invention may be used in conjunction with the Bitcoin blockchain, for example, or another blockchain implementation, with functionality for arranging a locking script in the blockchain transaction such that it takes as input a value and uses that input in a calculation to produce a time-related result which is used to determine a time lock mechanism, wherein the output of the blockchain transaction is unlocked at a pre-determined time.

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 computer-implemented exchange method is provided. The method may be performed on one or more blockchains. The method comprises communicating a first veiled secret value (H(A0)) from a first user to a second user and a second veiled secret value (H(B0) from the second user to the first user; and constructing first and second blockchain transactions (tx1, tx2) each comprising the first veiled secret value and the second veiled secret value, the transactions arranged to be unlockable to transfer control of a respective first or second resource upon provision of both the first secret value (A0) and the second secret value (B0) to the respective blockchain transaction, wherein unlocking of the first blockchain transaction causes a first secret value to be revealed to the second user, and unlocking of the second blockchain transaction causes a second secret value to be revealed to the first user.

Abstract: The invention provides a secure method for exchanging entities via a blockchain. The invention incorporates tokenisation techniques, and also techniques for embedding metadata in a redeem script of a blockchain transaction.

Abstract: Distributing first shares of a first secret value, known to a first participant, to second participants. The first shares encrypted using a private key and a public key that is elliptic curve generator point multiplied by the private key. A first threshold number of first shares being required to enable a second participant to determine the first secret value. A second share of a second secret value is received from each of the second participants. The second shares encrypted using a private key and a public key that is an elliptic curve generator point multiplied by the private key. A second threshold number of second shares being required to enable a participant other than the second participant to determine the second secret value. A third share of a third secret value formed from the second shares. A third threshold number of third shares being required to enable the third secret value to be determined.

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 performed in a system comprising a first user with a first public key and a second user, the method comprising: generating, by the first user, a second public key based on: the first public key; a first message; and a signature for the first message generated by the second user; providing, by the first user, the second public key to the second user; determining, by the second user, a third public key based on: the first public key; a second message; and the signature for the second message generated by the second user; verifying, by the second user, whether the third public key is equal to the second public key; and when the third public key is equal to the second public key, determining that the first message is equal to the second message and submitting a transaction comprising the second public key to a blockchain network.

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 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: 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 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 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 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 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 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 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.