Tamper-proof distributed nodes: SHA-256 source code integrity verification.

Day 03 of the wFabricSecurity Open-Source Engineering Series discusses how to ensure the integrity of worker nodes submitting transactions to a blockchain. wFabricSecurity addresses this by verifying SHA-256 code integrity before any transaction runs. The primary concerns this tool tackles are attackers injecting backdoors, silent configuration drift across decentralized node fleets, and ensuring that a smart contract worker executes the audited version of business logic.

The implementation involves importing the wFabricSecurity module and creating an instance called security. This instance is initialized with the node name and the path to the Membership Service Provider ( MSP ) directory. Next, critical application files such as worker_logic.py and contract_gateway.py are registered with their audited versions using the register_code method, specifying the release version (e.g., 1.0.0).

If an attacker modifies any of these files, the verification process will fail, preventing the code from executing.

The key to this architecture's effectiveness lies in SHA-256 code hashing, which generates a deterministic cryptographic hash of the critical source files. This hash allows for immediate tamper detection by halting execution if even a single byte of source code changes. Each registered file is bound to a specific release version, enabling on-chain audit trails.

The tool has been tested and verified in Hyperledger Fabric environments and is compatible with Python 3.10 and above, supporting cryptographic identity management, code integrity hashing, and token-bucket rate limiting. The source code and documentation can be found on GitHub and PyPI, with the author credited as William Steve Rodríguez Villamizar, also known as Wisrovi.