Certificate Validation Using Blockchain

Abstract

Conventional certificate verification, whether paper-based or backed by a centralized digital registry, remains exposed to forgery, single points of failure, and slow manual cross-checking between issuers, holders, and verifiers. This paper presents a decentralized, blockchain-based framework for issuing, storing, and verifying academic and professional certificates that addresses these weaknesses without placing the full document on-chain. Each certificate is reduced to a SHA-256 hash, signed with the issuing institution's RSA private key, and recorded through an Ethereum smart contract, while the original file is retained off-chain on IPFS and referenced by its Content Identifier. Only institutions that pass a unanimous, vote-based onboarding process administered by a validator consortium are permitted to issue certificates, which constrains the system to a trusted-issuer model while preserving decentralization across the validator set. A hash-mapped Bloom Filter sits in front of the blockchain query path and performs a fast probabilistic existence check, allowing forged or non-existent certificates to be rejected before an on-chain lookup is triggered. A prototype was implemented with Solidity smart contracts on the Ethereum Sepolia testnet, a Node.js/Web3.js application layer, and a React.js frontend with MetaMask-based authentication. Evaluation on the testnet shows that the Bloom Filter pre-check lowers the average lookup time for invalid certificates by roughly 87%, keeps verification of valid certificates under two seconds end-to-end, holds the false-positive rate below 0.5% for up to 50,000 stored certificate hashes, and reduces the gas cost of issuing a certificate to approximately 4.57 USD. These results indicate that combining consortium governance, cryptographic hashing, and probabilistic filtering yields a certificate validation pipeline that is simultaneously tamper-resistant, low-cost, and fast enough for real-time institutional use.