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: According to a first aspect of the disclosure, there is provided a request-response protocol for requesting access to data from a destination transaction. According to a second aspect of the disclosure, there is provided a method of accessing data from one or more destination transactions stored on a blockchain, wherein the method comprises selecting one or more hyperlinks linking to the destination transaction(s).

Abstract: Techniques are presented for securely transmitting a output script or information associated with a payroll and a user between a first node and a second node. The method comprises: determining a symmetric-key based on a common secret, based on a first node second private key and a second node second private key, wherein the second node has the same common secret based on a first node second public key and a second node second private key; encrypting at least part of the output script or information associated with the payroll and the second node with the symmetric-key, to an encrypted output script or encrypted information associated with the payroll and the second node; and sending the encrypted output script or encrypted information associated from the first node to the second node.

Abstract: A computer-implemented method of creating different versions of a tree structure overlaid on a blockchain, wherein the method is performed by a tree creator and comprises: creating one or more target child nodes of a target parent node, each target child node comprising a respective data payload; and forming a respective edge between each target child node and the target parent node by associating each of the target child nodes with a respective link identifier, wherein the respective link identifier is based on at least one off-chain parameter.

Abstract: An implementation of the present application provides a computer-implemented method to increase the security of a blockchain-implemented transaction, the transaction including participation from a plurality of participating nodes, each participating node participating as a message originator, selector, and propagator. The method, implemented at a participating node, includes: receiving ciphertext from a prior node and determining whether the participating node is a selector node for said ciphertext received from the prior node. When the participating node is the selector node for said ciphertext, the method includes selecting a subset of said ciphertext, decrypting the selected subset of said ciphertext to provide opted ciphertext and transmitting said opted ciphertext to the next node. When the participating node is other than the selector node for said ciphertext, the method includes decrypting said ciphertext received from the prior node and transmitting the decrypted ciphertext to the next node.

Abstract: The invention provides methods and systems which enable additional functionality to be inserted into blockchain scripts with ease and in an effective and manner. According to one embodiment, the invention provides a blockchain-implemented method comprising the steps of arranging a plurality or selection of scripting language primitives to provide, upon execution, the functionality of a high-level scripting language primitive, wherein the scripting language is associated with a blockchain protocol; inserting the plurality of scripting language primitives at least once into a script; and inserting the script into blockchain transaction (Tx). The high-level scripting language primitive may perform, for example, an arithmetic operation such as multiplication or division. The scripting language primitives may be called op-codes, words or commands, and are native to the scripting language. The scripting language may be Script, and the blockchain protocol may be a version of the Bitcoin protocol.

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: A system is provided for performing transaction mixing between a plurality of users on a blockchain. The system is configured to carry out the steps of: selecting an initiator node to calculate a deterministic hash function using a chosen random number; distribute the deterministic hash function to a plurality of users on the blockchain; choose an amount of time each user is given to construct a payment channel, retrieve the random number, and submit an execution transaction to a blockchain network; choose a second time for when a payment to a user is submitted to the blockchain network; and establish a one-way payment channel between every pair of users in an ordered set of the plurality of users to establish a transaction chain linking all users.

Abstract: A method and system for generating a transaction for a blockchain protocol are disclosed. The method comprises using a software resource to receive, generate, or derive at least one data item, insert, at least once, a portion of code into a script associated with the transaction, where the script is written in a language that is functionally restricted. Upon execution of the script, the portion of code provides functionality of a control flow mechanism controlled or influenced by the at least one data item. The method further comprises using the software resource to generate the blockchain transaction comprising the script and submit the blockchain transaction to a blockchain network.

Abstract: Techniques are presented for controlling or influencing use of and/or access to a resource. This resource may be a device, such as an IoT (Internet of Things) device or a process. Techniques include a method comprising generating a blockchain transaction (TxA) indicative of a condition on use of, or access to, the resource for a specified period of time, 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 (TxA) to generate a partially signed signature script to partially complete the blockchain transaction (SI 14); and responsive to the condition on the use of, or access to, the resource being satisfied, providing a second subset of the plurality of signatures (S204) to the blockchain transaction to fully complete the blockchain transaction.

Abstract: A computer-implemented access method is provided. The method comprises the steps of: (i) providing a verification data item of a one-way function chain of data items; (ii) submitting, to a blockchain (such as the Bitcoin blockchain), an access blockchain transaction comprising a data item of the chain; (iii) applying the one-way function to the data item to provide an output; (iv) comparing the output of step (iii) to the verification item to provide an outcome; and (v) based on the outcome of step (iv): (a) allocating the output as a further verification data item for verifying a further data item of the chain; and (b) granting access to a resource associated with the data item.

Abstract: A computer-implemented method of transferring control of a digital asset on a blockchain network. The method described in one of the embodiments provides an advantage of enabling easy increase of the number of participants in the signature scheme. The method comprises the steps of distributing a version of cryptographic key, encrypted by means of cryptography system, to a plurality of second participants, wherein a homomorphic property enables derivation of a second public key from a first public key and said version of said cryptographic key. The shares communicated to each a first and/or second participant may be inaccessible to each other said first and/or second participants.

Abstract: A method, system and program enabling a third party to determine whether a first party and a second party agree on membership of a set of blockchain transactions transacting between the first and second party.

Abstract: The invention presents a solution in which blockchain Transactions are created to implement the functionality of a logic gate. The invention may be implemented on the Bitcoin platform or an alternative blockchain platform. The transaction includes a locking script which comprises instructions selected so as to implement the functionality of a logic gate such as OR, AND, XOR, NOT and so on. In some examples, the instructions may be provided in a hashed form. When the script is executed (because a second transaction is attempting to spend the output associated with the locking script) the inputs will be processed by the conditional instructions to provide an output of TRUE or FALSE. The second transaction is transmitted to the blockchain network for validation and, if determined to be valid, it will be written to the blockchain. Validation of the second transaction can be interpreted as a TRUE output. Thus, the locking script of the first transaction provides the functionality of the desired logic gate.

Abstract: Techniques are presented relating to security of blockchain transactions that transfer digital assets or entities from one resource to another. Techniques provide a computer-implemented method for improving the security, anonymity and/or control of a value-mixing blockchain transaction having a plurality of participating nodes, each node having a respective output address to which the transaction is to allocate value. The method includes encrypting by a node its output address using that node's public key, adding the encrypted output address to a set of output addresses for the transaction, shuffling the order of the encrypted output addresses in the set. Each participating node identifies its encrypted output address in the set, and replaces its encrypted output address with its unencrypted output address. The result is a shuffled set of output addresses that cannot be linked to a particular input. with its unencrypted output address.

Abstract: A computer-implemented method to validate a block at a node within a network of nodes implementing a blockchain conforming to a blockchain protocol. This may be the Bitcoin protocol or an alternative. The method includes determining, serially, that each unspent transaction output referenced as an input in each of the plurality of transactions is unique and, based on that determination allocating each transaction in the plurality of transactions to one of two or more parallel processors, and verifying, in parallel, by the two or more parallel processors, that the transactions in the plurality of transactions comply with transaction-level validation criteria. The node also determines that the block meets block-level validation criteria. If the transactions comply with transaction-level validation criteria and the block complies with block-level validation criteria, the block is deemed valid and the node forwards the block to one or more peer nodes in the network.

Abstract: A specialized network (“merchant”) node to facilitate fast distribution of blockchain transactions over a network of interconnected nodes, as subset of which are merchant nodes interconnected by an overlay network. The merchant node includes a memory storing an assigned portion of a distributed mempool structured as a distributed hash table, the distributed mempool containing pending transactions awaiting confirmation. The merchant node operates by receiving a transaction, including a transaction identifier; hashing the new transaction identifier to obtain a key; determining, using the key, whether the transaction is stored in the distributed mempool or not and, if not, then storing the transaction in the distributed mempool as a pending transaction; and sending the transaction to a set of nodes other than merchant nodes using peer-to-peer connections. The invention may be used in conjunction with the Bitcoin blockchain or an alternative.

Abstract: Systems and methods are disclosed for establishing information on a state of a machine-executable contract in the context of unspent transactions (UTXOs), blockchain and deterministic finite automaton implementation of contracts, and determination of states within those. Stages of a method include determining information of interest and codes or tags identifying that information, constructing metadata associated with those codes or tags, and combining the metadata with a public key for an agent associated with the information. ScriptPubKey values of each script are used to provide keys for constructing a database and mapping the keys from the scriptPubKey values, linked to the information. A derivation of script hash addresses from the scriptPubKey values is used to populate a digital wallet. A search and match algorithm is used to find UTXOs with matching script hash addresses on a blockchain. The database is populated with UTXOs that match the script hash addresses and keys to complete the combinations.

Abstract: According to a first aspect of the disclosure, there is provided a method of accessing data from one or more destination transactions stored on a blockchain, wherein the method comprises selecting one or more hyperlinks linking to the destination transaction(s). According to a second aspect of the disclosure, there is provided a request-response protocol for requesting access to data from a destination transaction.