Lightweight Blockchain Client Privacy via TEE and ORAM
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Solution Overview
Problem
Lightweight blockchain clients face privacy and efficiency issues due to their reliance on full nodes for transaction verification, with Bloom filters providing limited privacy and increased network overhead, and existing solutions like SPV mode compromising usability and privacy.
Innovation Solution
Implementing a trusted execution environment (TEE) using SGX enclaves with an oblivious RAM (ORAM) protocol to securely access unspent transaction output information, allowing lightweight clients to outsource verification and maintain privacy without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If lightweight clients use Bloom filters to filter transactional data from full nodes, then some level of anonymity and privacy is provided to end users, but the false positives rate increases network overhead and computational load
Solution Approach 1:
The patent introduces a trusted execution environment (TEE) as an intermediary component within the full node that acts as a secure mediator between the lightweight client and the blockchain data. The TEE performs private set intersection (PSI) computations to filter transactions without revealing client addresses to the full node, thereby reducing false positives in Bloom filters while maintaining privacy. This intermediary secure computation layer resolves the contradiction by enabling more accurate filtering without increasing network overhead.
2Device complexity
If lightweight clients rely on full nodes for transaction verification, then computational and storage requirements are reduced for clients, but privacy is compromised as full nodes can see all client addresses
Solution Approach 1:
The TEE serves as a privacy-preserving intermediary that enables lightweight clients to outsource verification while maintaining confidentiality. The TEE implements PSI protocols that allow the full node to verify transactions without learning client addresses, and allows clients to verify transactions without exposing their full transaction history. This resolves the contradiction by maintaining the computational simplicity of lightweight clients while adding a privacy-protecting layer.
Solution Approach 2:
The patent applies local quality by creating a specialized secure computation environment (TEE) with specific privacy-preserving properties within the full node infrastructure. This localized secure zone handles only the privacy-critical address matching operations using PSI protocols, while the rest of the full node continues its normal verification functions. This targeted approach maintains client simplicity while adding privacy protection where needed.
3Reliability
If full nodes verify all transactions broadcasted to the P2P network, then transaction correctness is ensured, but computational and storage intensive operations increase with the size of the blockchain system
Solution Approach 1:
The patent segments the transaction verification process into two distinct parts: (1) full nodes perform comprehensive verification of all received transactions to ensure blockchain integrity, and (2) lightweight clients perform selective verification of only their relevant transactions through the TEE-mediated PSI process. This segmentation allows full nodes to maintain verification reliability while reducing the computational burden on the overall system by offloading selective filtering to the TEE.
Data Source
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AI summary
A method of preserving privacy for usage of a lightweight blockchain client in a blockchain network, the method comprises using, in a full blockchain node (11) of the blockchain network (10), a secure trusted execution environment, TEE (16); establishing a secure communication between the lightweight blockchain client (15) and the TEE(16); receiving, by the TEE (16), a request from the lightweight blockchain client (15) for at least one transaction or address of the lightweight blockchain client (15); and by the TEE(16), obtaining unspent transaction output, UTXO, information in respect to the lightweight blockchain client's (15) request from a UTXO database (13b) by means of oblivious database access using an oblivious RAM, ORAM, protocol. Furthermore, a suitably adapted full blockchain node is disclosed.