Most modern blockchain systems face trade-offs between transaction efficiency and smart contract functionality. Ethereum's account-based model enables robust smart contracts but limits parallel execution, while Bitcoin's UTXO model supports concurrent transactions but lacks advanced smart contract capabilities. This paper introduces an innovative solution: a hierarchical multi-blockchain system that harmonizes both approaches through sharded sidechains and account-chain technology.
Core Architecture
1. Multi-Tiered Sidechain Design
- Sharded Sidechains: Each pair of sidechains forms an independent "shard" for parallel processing.
- Bilateral Sidechains: Enable secure cross-shard communication while maintaining isolation for concurrent operations.
2. Account-Chain Integration
- State Change Recording: An accountchain tracks smart contract outcomes per shard as compact, modifiable blockchain entries.
- Trustless Verification: Nodes validate results without re-executing contracts via cryptographic proofs.
Advantages Over Existing Models
| Feature | Proposed System | Ethereum (Account-Based) | Bitcoin (UTXO) |
|-----------------------|----------------|------------------------|----------------|
| Parallel Execution | ✅ Multi-shard | ❌ Single-threaded | ✅ Transactions only |
| Smart Contract Support| ✅ Full | ✅ Full | ❌ Limited |
| Concurrency Safety | ✅ Accountchain | ❌ Race conditions | ✅ Native |
👉 Discover how sharding boosts blockchain scalability
Threat Analysis: Key Findings
- Double-Spend Attacks: Mitigated via shard-bound UTXO tracking.
- Cross-Shard Conflicts: Resolved through atomic accountchain commits.
- 51% Attacks: Localized to individual shards, reducing systemic risk.
FAQ
Q1: How does this system improve smart contract throughput?
A: By distributing contracts across shards, it processes thousands of transactions per second (TPS) vs. Ethereum's ~30 TPS.
Q2: Is the accountchain a single point of failure?
A: No—it’s replicated across nodes and secured via the same consensus rules as the main chain.
Q3: Can existing dApps migrate to this model?
A: Yes, with modifications to support shard-aware state management.
👉 Explore blockchain interoperability solutions
Conclusion
This system unlocks secure parallel execution for both payments and smart contracts—a critical step toward mass blockchain adoption. Future work includes optimizing cross-shard latency and developer tooling.
Keywords: hierarchical blockchain, sharding, smart contracts, UTXO, accountchain, parallel computation, cryptocurrency transfers
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