Accessing Data Privately, from Theory to Practice with Elaine Shi | a16z crypto Research Series
Source: YouTube · a16z crypto · published Nov 3, 2025 · 59:00
This A16Z crypto research seminar explores private data access while protecting access patterns, covering applications like Signal's contact discovery, blockchain order flow privacy, and LLM retrieval. The main technical approaches are Oblivious RAM (ORAM), which performs well in outsourcing scenarios, and Private Information Retrieval (PIR), better for global shared databases.
Key Takeaways:
• Access pattern leakage reveals sensitive information even with encrypted data, as in Signal where contact discovery reveals connections
• Private blockchain order flow could address MEV and centralization issues (85% of blocks produced by two builders)
• ORAM with trusted execution achieves 20-50 microsecond lookups at 200k queries/second
• Tree-based ORAM schemes like Path ORAM relocate blocks after access with eviction algorithms
• Practical PIR with client pre-processing achieves efficient performance for large databases
The talk concludes that cryptographic approaches to private data access are becoming practically deployable for production systems today.
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First 800 characters of the transcript
All right, welcome everyone to today's A16Z crypto research seminar. Very pleased to introduce Ela Shei, full professor at Carnegie Melon. Uh Elaine's worked extensively in almost every area relevant to blockchain technology, whether it's cryptography or consensus or mechanism design. Uh she's won lots of stuff, Sloan fellow, Packard fellow, etc. very happy she's here to talk to us today about accessing data privately. So >> yeah, thank you so much. Uh I'm very excited to uh be here today. I'll talk about how to access uh your data privately. So I'll start with some motivating examples like why real life applications really need this and and I'll start with Signals application. So Signal is running private contact discovery and what happens is like let's say Tim wants to join Signal and he…