cukks-cu118 0.1.2

CKKS Homomorphic Encryption backend with CUDA 11.8 GPU acceleration

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CuKKS

GPU-accelerated CKKS Homomorphic Encryption for PyTorch

Run trained PyTorch models on encrypted data — preserving privacy while maintaining accuracy.
Built on OpenFHE with CUDA acceleration.

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Quick Start

import torch.nn as nn
import cukks

# 1. Define and train your model (standard PyTorch)
model = nn.Sequential(nn.Linear(784, 128), nn.ReLU(), nn.Linear(128, 10))

# 2. Convert to encrypted model (polynomial ReLU approximation)
enc_model, ctx = cukks.convert(model)

# 3. Run encrypted inference
enc_input = ctx.encrypt(test_input)
enc_output = enc_model(enc_input)
output = ctx.decrypt(enc_output)

Installation

Automatic (Recommended)

pip install cukks        # Auto-detects PyTorch's CUDA and installs matching backend

pip install cukks detects the CUDA version your PyTorch was built with and automatically installs the matching cukks-cuXXX GPU backend. No manual version matching needed.

Manual

pip install cukks-cu121  # Explicitly install for CUDA 12.1

Package	CUDA	Supported GPUs
cukks-cu118	11.8	V100, T4, RTX 20/30/40xx, A100, H100
cukks-cu121	12.1	V100, T4, RTX 20/30/40xx, A100, H100
cukks-cu124	12.4	V100, T4, RTX 20/30/40xx, A100, H100
cukks-cu128	12.8	All above + RTX 50xx

Or use extras: pip install cukks[cu121]

Post-install CLI & environment variables

cukks-install-backend             # Auto-detect & install
cukks-install-backend cu128       # Install specific backend
cukks-install-backend --status    # Show CUDA compatibility status

Variable	Effect
CUKKS_BACKEND=cukks-cu128	Force a specific backend
CUKKS_NO_BACKEND=1	Skip backend (CPU-only)

Docker images

CUDA	Compatible Docker Images
11.8	pytorch/pytorch:2.1.0-cuda11.8-cudnn8-runtime
12.1	pytorch/pytorch:2.2.0-cuda12.1-cudnn8-runtime
12.4	pytorch/pytorch:2.4.0-cuda12.4-cudnn9-runtime
12.8	nvidia/cuda:12.8.0-cudnn9-runtime-ubuntu22.04

docker run --gpus all -it pytorch/pytorch:2.2.0-cuda12.1-cudnn8-runtime bash
pip install cukks  # auto-detects CUDA 12.1

Build from source

git clone https://github.com/devUuung/CuKKS.git && cd CuKKS
pip install -e .

# Build OpenFHE backend
cd openfhe-gpu-public && mkdir build && cd build
cmake .. -DWITH_CUDA=ON && make -j$(nproc)

cd ../../bindings/openfhe_backend
pip install -e .

Features

Feature	Description
PyTorch API	Familiar interface — just call cukks.convert(model)
GPU Acceleration	CUDA-accelerated HE operations via OpenFHE
Auto Optimization	BatchNorm folding, BSGS matrix multiplication
Wide Layer Support	Linear, Conv2d, ReLU/GELU/SiLU, Pool, LayerNorm, Attention

Supported Layers

Layer	Encrypted Version	Notes
nn.Linear	EncryptedLinear	BSGS optimization
nn.Conv2d	EncryptedConv2d	im2col method
nn.ReLU/GELU/SiLU	Polynomial approx	Configurable degree
nn.AvgPool2d	EncryptedAvgPool2d	Rotation-based
nn.BatchNorm	Folded	Merged into prev layer
nn.LayerNorm	EncryptedLayerNorm	Polynomial approx
nn.Attention	EncryptedApproxAttention	seq_len=1

Full layer support table

PyTorch Layer	Encrypted Version	Notes
nn.Linear	EncryptedLinear	Full support with BSGS optimization
nn.Conv2d	EncryptedConv2d	Via im2col method
nn.ReLU	EncryptedReLU	Polynomial approximation
nn.GELU	EncryptedGELU	Polynomial approximation
nn.SiLU	EncryptedSiLU	Polynomial approximation
nn.Sigmoid	EncryptedSigmoid	Polynomial approximation
nn.Tanh	EncryptedTanh	Polynomial approximation
nn.AvgPool2d	EncryptedAvgPool2d	Full support
nn.MaxPool2d	EncryptedMaxPool2d	Approximate via polynomial
nn.Flatten	EncryptedFlatten	Logical reshape
nn.BatchNorm1d/2d	Folded	Merged into preceding layer
nn.Sequential	EncryptedSequential	Full support
nn.Dropout	EncryptedDropout	No-op during inference
nn.LayerNorm	EncryptedLayerNorm	Pure HE polynomial approximation
nn.MultiheadAttention	EncryptedApproxAttention	Polynomial softmax (seq_len=1)

Activation Functions

CKKS only supports polynomial operations. CuKKS approximates activations (ReLU, GELU, SiLU, etc.) using polynomial fitting:

# Default: degree-4 polynomial approximation (recommended)
enc_model, ctx = cukks.convert(model)

# Higher degree for better accuracy (costs more multiplicative depth)
enc_model, ctx = cukks.convert(model, activation_degree=8)

The default activation_degree=4 provides a good balance between accuracy and depth consumption. Higher degrees approximate the original activation more closely but require deeper circuits.

GPU Acceleration

Operation	Accelerated
Add/Sub/Mul/Square	✅ GPU
Rotate/Rescale	✅ GPU
Bootstrap	✅ GPU
Encrypt/Decrypt	CPU

from ckks.torch_api import CKKSContext, CKKSConfig

config = CKKSConfig(poly_mod_degree=8192, scale_bits=40)
ctx = CKKSContext(config, enable_gpu=True)  # GPU enabled by default

Examples

# Quick demo (no GPU required)
python -m cukks.examples.encrypted_inference --demo conversion

# MNIST encrypted inference
python examples/mnist_encrypted.py --hidden 64 --samples 5

CNN example

import torch.nn as nn
import cukks

class MNISTCNN(nn.Module):
    def __init__(self):
        super().__init__()
        self.conv1 = nn.Conv2d(1, 8, kernel_size=3, padding=1)
        self.act1 = nn.ReLU()
        self.pool1 = nn.AvgPool2d(2)
        self.flatten = nn.Flatten()
        self.fc = nn.Linear(8 * 14 * 14, 10)
    
    def forward(self, x):
        return self.fc(self.flatten(self.pool1(self.act1(self.conv1(x)))))

model = MNISTCNN()
enc_model, ctx = cukks.convert(model)

enc_input = ctx.encrypt(image)
prediction = ctx.decrypt(enc_model(enc_input)).argmax()

Note: All operations in forward() must be layer attributes (e.g., self.act1), not inline operations like x ** 2.

Batch processing

# Pack multiple samples into a single ciphertext (SIMD)
samples = [torch.randn(784) for _ in range(8)]
enc_batch = ctx.encrypt_batch(samples)
enc_output = enc_model(enc_batch)
outputs = ctx.decrypt_batch(enc_output, num_samples=8)

Troubleshooting

Issue	Solution
Out of Memory	Reduce poly_mod_degree (8192 instead of 16384)
Low Accuracy	Increase activation_degree (e.g., 8 or 16) for better approximation
Slow Performance	Enable batch processing, reduce network depth

Documentation

• API Reference
• GPU Acceleration Guide
• CKKS Concepts

License

Apache License 2.0

Citation

@software{cukks,
  title = {CuKKS: PyTorch-compatible Encrypted Deep Learning},
  year = {2024},
  url = {https://github.com/devUuung/CuKKS}
}

Related

Libraries

• OpenFHE — Underlying HE library
• Microsoft SEAL — Alternative HE library

Papers

• Homomorphic Encryption for Arithmetic of Approximate Numbers — Cheon et al. (CKKS)
• Bootstrapping for Approximate Homomorphic Encryption — Cheon et al.
• Faster Homomorphic Linear Transformations in HElib — Halevi & Shoup (BSGS)