Privy secures over 120 million wallets for more than 2,000 developer teams, processing a monthly volume exceeding $9 billion. The architecture behind them relies on two complementary technologies: AWS Nitro Enclaves, a form of trusted execution environment (TEE), and Shamir’s Secret Sharing (SSS), a cryptographic method for splitting a private key into fragments held by separate parties.
How the system actually works
Privy uses Shamir’s Secret Sharing to ensure no single entity ever holds a complete private key during normal operations. The fragments are distributed, and only when a user needs to sign a transaction do those shards come together, briefly, inside a secure enclave.
That enclave is the AWS Nitro system: an isolated computing environment designed to be completely sealed off from the rest of the cloud infrastructure, including Amazon itself.
The problem is that the reconstitution step, where the key shards are briefly assembled for signing, creates a window. A technique called Prime+Probe allows an attacker sharing the same physical machine to infer what computations are happening inside a supposedly isolated environment by monitoring patterns in the processor cache. AWS Nitro is specifically engineered to prevent this class of attack through strict isolation, but recent academic research has probed the limits of that isolation in cloud environments broadly. No confirmed end-to-end attack against Privy’s specific implementation has been publicly documented.
