Zero-Trust Decentralized Exam Paper Distribution A military-grade secure system designed to prevent leaks by ensuring question papers remain unreadable until exactly exam time, enforced by blockchain timelocks and distributed cryptographic trust.
This system ensures that no single individual, including the Teacher or the Exam Authority, ever owns the keys required to decrypt a paper prematurely. Trust is mathematically distributed through the network.
The system employs a Two-Layer Cryptographic Pipeline with Shamir's Secret Sharing (SSS).
- Layer 1 (Data): Paper PDF is encrypted using highly efficient AES-256-GCM with a unique key (K1).
- Layer 2 (Key): The AES key (K1) is itself encrypted using a Master Key (K2).
- Trust Distribution: K2 is mathematically split into
nshards (shares) using Shamir's Secret Sharing. - Immutable Timelock: Encrypted K1 and the shards of K2 are committed to the Ethereum (Sepolia) blockchain, locked behind a smart contract timer.
| Module | Tech Stack | Role |
|---|---|---|
| Frontend | React, Vite, Tailwind | Zero-trust client handling client-side encryption/decryption. |
| Contracts | Solidity, Hardhat | Hard-enforced timelocks & decentralized share storage. |
| Polyfills | Browser-Native Crypto | Secure random generation without Node.js dependencies. |
| Storage | IPFS (Pinata) | Decentralized storage for encrypted data "blobs". |
- Teacher Role: Uploads the paper. Frontend performs a Memory Purge immediately after upload, ensuring the raw keys (K1, K2) are destroyed and never leak.
- Authority Role: Schedules the exam by setting the
unlockTimestamp. They cannot see the paper shards or the content. - Exam Center Role: At the exact exam time, the frontend fetches shards from the blockchain, reconstructs K2, decrypts K1, and finally reveals the paper for instant printing.
cd contracts
npm install
npx hardhat run scripts/deploy.js --network sepoliacd frontend
npm install
npm run dev- ✅ Zero-Knowledge Architecture: Authority manages schedules without seeing data.
- ✅ Shamir's Secret Sharing (SSS): No single-point-of-failure for cryptographic keys.
- ✅ Blockchain Timelocks: Immutable enforcement of "Unlock Time".
- ✅ Memory Isolation: Cryptographic keys are purged from local RAM post-upload.
Developed for Peak Security and Unbreakable Integrity.