DEF CON 33 - Cryptocurrency Weekend Keynote Chelsea Button, Alfonso Tinoco & Elaine Shi
Source: YouTube · DEFCONConference · published Oct 10, 2025 · 25:41
Elaine Shei: Oblivious RAM Evolution
ORAM evolved from theory to practical solution that hides memory access patterns, enabling real-world applications like Signal's contact discovery, reducing server requirements from 500 to just 6.
Key Takeaways:
• ORAM prevents access pattern leakage that encrypted databases can't stop, where observing memory accesses reveals sensitive info
• Signal's Path ORAM implementation achieved ~100x cost savings, reducing servers from 500 to 6
• ORAM works as a tree-based structure where blocks are constantly relocated to new random paths after access
• Practical implementations achieve 20-50 microsecond lookup times and throughput up to 200k queries/second
• ORAM applications include private blockchain reads, private AI/LLM queries, and MEV mitigation in crypto
ORAM has transformed from theoretical construct to essential privacy tool, with ongoing development creating oblivious versions of standard data structures and algorithms.
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First 800 characters of the transcript
Good morning everyone. Thank you for joining us today. I have the pleasure of adu introducing Elaine Shei. She is a professor in Carnegie Melon University. Her research interests include cryptography, security, mechanism design, algorithms, foundations of blockchains and programming languages. She is a co-founder of Oblivious Labs Inc. Her research on oblivious RAM and differentially private algorithms have been adopted by Signal, Meta, and Google. She is a Packard fellow, a Sloan fellow, an ACM fellow, and an IACR fellow. Without further ado, Elaine Shei presenting Oblivious RAM: From theory to Large Scale Development Deployment. >> Sorry. >> Thank you so much, Chelsea, for the introduction. I'm very excited to be here and I love my uh hacker badge. Uh okay, I'll talk about oblivious RAM …