Blockchain Security

Bitcoins and the underlying blockchain technology are one of the main innovations in building decentralized applications. The effects of quantum computing on this technology are analyzed in general. Provided herein are effective solutions to address security vulnerabilities in a blockchain-based system that can be exploited by a quantum attacker.

Bitcoins and the underlying blockchain technology are one of the main innovations in building decentralized applications. The effects of quantum computing on this technology are analyzed in general. Provided herein are effective solutions to address security vulnerabilities in a blockchain-based system that can be exploited by a quantum attacker.

A distributed ledger system configured to create, update and maintain at least one blockchain indicative of transactions performed by a network of users of the system, the system comprising a network of computing devices including a network of user nodes in communication with one another to participate in transactions and subsequently write the transactions to an associated blockchain, each node being associated with at least one processor and at least one computer-readable medium having recorded thereon instructions to be executed by the processor(s) to carry out one or more blockchain-related tasks for creating, updating and/or maintaining at least one associated blockchain of the system based on the transactions; and wherein the network of computing devices is operable to enable at least one ephemeral user node to join the network of computing devices to carry out the blockchain-related tasks in association with at least one blockchain during an active session of the ephemeral user node.

A data processing method performed by a first consensus node in a first network of a multi-blockchain, includes: obtaining a clearing transaction request submitted by a service object; performing verification on an identity authority of a service clearing node to obtain an identity authority verification result; invoking a first authority clearing contract associated with a first authority contract to obtain first service data and first ledger data; obtaining first contract data corresponding to the first ledger data from a contract database corresponding to a first main chain; using the first service data, the first ledger data, and the first contract data as first clearing response information corresponding to the clearing transaction request; and returning the first clearing response information to a first-type clearing node having authority to obtain the first service data, to cause the first-type clearing node to recover a sub-ledger corresponding to the first ledger data.

Disclosed are various embodiments for authenticating a user using non-fungible tokens (NFTs). A trusted token issuer verifies a user's identity according to identifying credentials (e.g., government issued identification, passport, driver's license, etc.) presented by the user and creates a non-fungible token in response to verifying the credentials. The non-fungible token is associated with a user identifier and can be used by an access provider to authenticate a user requesting access to restricted content provided by the access provider. For example, when a client device associated with the user requests access from an access provider to an access-restricted website or other type of access-restricted area (e.g., building, concert venue, network, etc.), the access provider (e.g., website server, building computing device, venue system, etc.) uses the properties of the non-fungible token to verify one's identity and permit access upon verification.