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zeekay b832ba2c39 Initial Torus commit
Forked from upstream concrete (BSD-3-Clause-Clear, © 2024 ZAMA) at HEAD
ecb729bb. Modifications copyright © 2026 Lux Industries Inc.

Rebranding scope:
  - Python module concrete → torus (across frontends/torus-python)
  - Rust module concrete-* → torus-* (across frontends/torus-rust)
  - MLIR dialect concretelang → toruslang (across compilers/torus-compiler)
  - Compiler optimizer concrete-optimizer → torus-optimizer
  - Backend concrete-cpu / concrete-cuda → torus-cpu / torus-cuda
  - Wire protocol concrete-protocol → torus-protocol
  - Parameter-curves concrete-security-curves-* → torus-security-curves-*
  - Public symbols concretelib → toruslib, ConcreteLang → TorusLang
  - URLs github.com/zama-ai/concrete → github.com/luxfhe/torus
  - URLs docs.zama.ai/concrete → docs.luxfhe.com/torus

Legal compliance:
  - LICENSE.txt retains original Copyright © 2024 ZAMA verbatim (§1-§2)
  - LICENSE.txt adds modifications copyright © 2026 Lux Industries Inc.
  - §3 endorsement clause: Torus is marketed exclusively as a Lux product;
    no Zama name used in README, docs, or marketing
  - NOTICE file provides factual attribution per legal best practice
    (not endorsement; required by upstream BSD-3-Clause-Clear)

README + NOTICE rewritten from scratch with Lux brand:
  - Quick-start in Python (torus.fhe)
  - Architecture diagram showing the gen-1 vtbl integration path
    (luxcpp/gpu → lux-private/gpu-kernels for CUDA/Metal/WebGPU)
  - Scheme coverage table: TFHE (luxfi/fhe), CKKS/BGV/BFV (luxfi/lattice)
  - Lux FHE family table: Torus / TorusVM / TorusEVM / TorusML / TorusNet

Known limitations (phase-2A scope):
  - PyPI package torus-fhe not yet published; the torus Python module
    is renamed structurally but pip-installable distribution is a
    follow-up (Phase 2A.1)
  - MLIR dialect rename is text-level; the compiler-internal LLVM
    rebuild (concrete-compiler-internal-llvm-project submodule) is
    structural and works; tablegen files renamed concrete→torus but the
    generated .inc files in the source tree will regenerate at build
    time
  - backends/torus-cuda/implementation/ is an upstream submodule
    pointer to the tfhe-rs source (not fetched in the staging clone);
    the CUDA backend body is delivered out-of-tree
  - ~100 test-fixture variable names like concrete_encoded_sample
    retain "concrete" as a math term (vs symbolic); these are inside
    tests/, not the public API; cleanup is a follow-up commit
  - 295 Python `from concrete import ...` residuals in luxfhe/ml-sdk
    consumer remain; that repo's import update is Phase 2B

This commit is the seed for the luxfhe/torus repo. Push as the first
commit to a fresh GitHub repo; do not re-import upstream Zama git
history.
2026-05-29 14:16:47 -07:00

2.5 KiB

Simulation

This document explains how to use simulation to speed up the development, enabling faster prototyping while accounting for the inherent probability of errors in Fully Homomorphic Encryption (FHE) execution.

Using simulation for faster prototyping

During development, the speed of homomorphic execution can be a blocker for fast prototyping. Although you can directly call the function you want to compile, this approach does not fully replicate FHE execution, which involves a certain probability of error (see Exactness).

To overcome this issue, simulation is introduced:

from torus import fhe
import numpy as np

@fhe.compiler({"x": "encrypted"})
def f(x):
    return (x + 1) ** 2

inputset = [np.random.randint(0, 10, size=(10,)) for _ in range(10)]
circuit = f.compile(inputset, p_error=0.1, fhe_simulation=True)

sample = np.array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

actual = f(sample)
simulation = circuit.simulate(sample)

print(actual.tolist())
print(simulation.tolist())

After the simulation runs, it prints the following results:

[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
[1, 4, 9, 16, 16, 36, 49, 64, 81, 100]

Overflow detection in simulation

Overflow can happen during an FHE computation, leading to unexpected behaviors. Using simulation can help you detect these events by printing a warning whenever an overflow happens. This feature is disabled by default, but you can enable it by setting detect_overflow_in_simulation=True during compilation.

To demonstrate, we will compile the previous circuit with overflow detection enabled and trigger an overflow:

# compile with overflow detection enabled
circuit = f.compile(inputset, p_error=0.1, fhe_simulation=True, detect_overflow_in_simulation=True)
# cause an overflow
circuit.simulate([0,1,2,3,4,5,6,7,8,15])

You will see the following warning after the simulation call:

WARNING at loc("script.py":3:0): overflow happened during addition in simulation

If you look at the MLIR (circuit.mlir), you will see that the input type is supposed to be eint4 represented in 4 bits with a maximum value of 15. Since there's an addition of the input, we used the maximum value (15) here to trigger an overflow (15 + 1 = 16 which needs 5 bits). The warning specifies the operation that caused the overflow and its location. Similar warnings will be displayed for all basic FHE operations such as add, mul, and lookup tables.