The Noise Ceiling
Watch an FHE ciphertext's noise climb toward the decryption ceiling as you evaluate a circuit — and see why CKKS bootstraps rarely-but-slowly while TFHE bootstraps constantly-but-cheaply.
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The Bootstrapping Tax: FHE's Fundamental Limit on Private AI Inference
BERT-base under FHE takes 149 seconds, needs 112 GB, and sustains 0.007 samples/sec. Best-case MPC takes 2.3 seconds and 4 GB. The gap traces to one operation: bootstrapping — the noise-refresh that makes FHE theoretically unlimited but practically expensive.
8 min read ⬢ interactive