Design a secure and efficient peer-to-peer (P2P) network for a file-sharing system. The system should meet the following requirements:

1. Security: Ensure data integrity, confidentiality, and authentication between peers.
2. Efficiency: Optimize for low latency and high throughput in data transfer.
3. Scalability: The system should handle a growing number of peers and files without significant performance degradation.
4. Redundancy and Fault Tolerance: Implement mechanisms to handle node failures and ensure availability of files.
5. Privacy: Ensure that users' identities and file-sharing activities are kept confidential.