Aegis

This project is a cryptographic shielded pool framework leveraging @protokit Zero-Knowledge Proofs (ZKPs) to facilitate secure and private transactions. It implements a JoinSplit transaction model, where users can privately deposit, transfer, and withdraw funds while maintaining verifiable integrity and privacy.

The system uses a Merkle tree structure to track commitments and nullifiers, ensuring spent assets cannot be reused. It supports input-output balance verification, cryptographic nullifier tracking, and efficient note management. Integration with a runtime module provides seamless blockchain operation, including setting roots and processing transactions with enforced privacy guarantees.

The project is built using the Protokit Framework from Mina.

1. Technologies:

   • o1js: For cryptographic primitives like Poseidon hash, Merkle trees, and key handling (private and public keys).
   • Merkle Tree: Manages transaction commitments and nullifiers with tree-based proofs of inclusion.
   • Proto-kit Module SDK: Provides runtime hooks and blockchain state handling for integrating the shielded pool.

2. Components:

   • JoinSplitTransaction:
     • Encodes the ZKPs logic for verifying inputs, outputs, and nullifiers.
     • Proves input-output balance while maintaining confidentiality of amounts and participants.
   • ShieldedPool Runtime:
     • Processes transactions by verifying proofs, validating roots, and recording nullifiers to prevent double-spending.
     • Emits events for nullifiers to track changes in state.
   • NoteStore:
     • Manages notes (spendable assets) and integrates with Merkle tree for inclusion proofs.
     • Handles note creation, addition, and nullifier management.

3. Hacky Details:

   • A custom IndexedMerkleTree was created for precise leaf handling and proof generation, streamlining root updates and witness creation.
   • The Note abstraction simplifies cryptographic encoding of user-specific transactions, making it easy to work with commitments and nullifiers programmatically.

4. Integration:

   • Combined with a blockchain testing environment (TestingAppChain) to simulate transaction workflows, enabling end-to-end validation.
   • Utilized Proto-kit for seamless runtime deployment and proof-of-concept testing.