What Is FHE?
Fully Homomorphic Encryption (FHE) is a cryptographic scheme that allows arbitrary computation on encrypted data without decrypting it first.TFHE: Fast Gate Bootstrapping
WAVIS uses TFHE (Torus Fully Homomorphic Encryption), which supports:- Boolean gates — NAND, AND, OR, XOR, NOT, MUX
- Programmable bootstrapping — arbitrary functions via LUT
- Gate bootstrapping — noise is reset after every gate (unlimited depth)
Bootstrap operation
Each gate evaluation performs:- External product (CMux) with the bootstrapping key
- Blind rotation of a test polynomial
- Sample extraction
- Key switching
fast_128 preset), or ~5.2 ms/gate
in GPU batch mode.
Security Model
WAVIS uses 128-bit security (all presets). The underlying hardness assumption is RLWE (Ring Learning With Errors).- Secret key: never leaves the client
- Evaluation key: safe to upload (cannot derive secret key)
- Ciphertexts: computationally indistinguishable from random
Parameters
| Preset | n | N | Security | Latency |
|---|---|---|---|---|
fast_128 | 630 | 1024 | 128-bit | 14 ms/gate |
standard_128 | 630 | 1024 | 128-bit | 32 ms/gate |
conservative_128 | 630 | 1024 | 128-bit | 48 ms/gate |
- n: TLWE dimension (affects key size and security)
- N: Polynomial degree for bootstrapping ring