Module psi 

Private Set Intersection (PSI) for privacy-preserving P2P content discovery.

This module provides protocols for finding common elements between two sets without revealing elements that are not in the intersection.

Use Cases in CHIE Protocol

• Content Discovery: Peers can find common content without revealing their full catalogs
• Privacy-Preserving Matching: Match chunks/files without exposing complete inventories
• Efficient Peer Selection: Find peers with desired content while maintaining privacy

Protocol

1. Hash-based PSI: Uses keyed hashing for exact intersection
2. Bloom Filter PSI: Uses Bloom filters for approximate intersection with better efficiency

Example

use chie_crypto::psi::{BloomPsiClient, BloomPsiServer};

// Server has a set of content hashes
let server_set = vec![
    b"content_1".to_vec(),
    b"content_2".to_vec(),
    b"content_3".to_vec(),
];

// Client has their own set
let client_set = vec![
    b"content_2".to_vec(),
    b"content_4".to_vec(),
];

// Server generates Bloom filter PSI
let server = BloomPsiServer::new(10, 0.01);
let bloom_msg = server.encode_set(&server_set);

// Client computes approximate intersection
let client = BloomPsiClient::new();
let intersection = client.compute_intersection(&client_set, &bloom_msg).unwrap();

// Intersection should contain common elements
assert!(intersection.contains(&b"content_2".to_vec()));

Structs

BloomPsiClient

Bloom filter PSI client

BloomPsiMessage

Bloom filter-based PSI for approximate intersection with better efficiency

BloomPsiServer

Bloom filter PSI server

PsiClient

PSI client for computing intersections

PsiServer

PSI server for encoding sets

PsiServerMessage

PSI server message containing encoded set elements

Enums

PsiError

Type Aliases

PsiResult