Technical Documentation

Deep dive into Prism's privacy-preserving architecture, APIs, and implementation details.

System Architecture

Distributed architecture with privacy guarantees at every layer

iOS Client

Swift, iOS 26+

NEURLFilter extension with on-device ML

Responsibilities

✓Bloom filter checks (95% of requests)
✓CoreML classification (ambiguous cases)
✓PIR query encryption
✓Verdict enforcement

Apple OHTTP Relay

Apple Infrastructure

Privacy-preserving relay service

Responsibilities

✓Strips IP addresses
✓Routes encrypted PIR queries
✓Privacy Pass token validation
✓Cannot decrypt query contents

PIR Server

Rust, Homomorphic Encryption

Private Information Retrieval endpoint

Responsibilities

✓Processes encrypted queries
✓Database lookup without decryption
✓Returns encrypted results
✓Zero-knowledge architecture

Category Database

PostgreSQL, Redis

URL categorization and threat intelligence

Responsibilities

✓2M+ categorized URLs
✓Real-time threat feed integration
✓Daily updates from security sources
✓Encrypted at rest

Performance Targets

Benchmarks and optimization goals

Bloom Filter Check

<1ms

95%+ requests

CoreML Inference

5-10ms

Ambiguous URLs

PIR Query (P95)

100-500ms

~5% requests

Memory Usage

<50MB

Extension process

Battery Impact

<2%

Daily usage

Cache Hit Rate

>90%

Repeat requests

Additional Resources

GitHub Repository

View source code and contribute

API Documentation

Complete API reference

Implementation Guide

Step-by-step deployment

Best Practices

Optimization and security