tfhe 1.5.5

TFHE-rs is a fully homomorphic encryption (FHE) library that implements Zama's variant of TFHE.
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use rand::Rng;

use crate::core_crypto::gpu::get_number_of_gpus;
use crate::high_level_api::global_state::CustomMultiGpuIndexes;
use crate::prelude::*;
use crate::{
    set_server_key, unset_server_key, ClientKey, CompressedServerKey, ConfigBuilder, Device,
    FheUint32, GpuIndex,
};

#[test]
fn test_gpu_selection() {
    let config = ConfigBuilder::default().build();
    let keys = ClientKey::generate(config);
    let compressed_server_keys = CompressedServerKey::new(&keys);

    let mut rng = rand::thread_rng();

    let last_gpu = GpuIndex::new(get_number_of_gpus() - 1);

    let clear_a: u32 = rng.gen();
    let clear_b: u32 = rng.gen();

    let mut a = FheUint32::try_encrypt(clear_a, &keys).unwrap();
    let mut b = FheUint32::try_encrypt(clear_b, &keys).unwrap();

    assert_eq!(a.current_device(), Device::Cpu);
    assert_eq!(b.current_device(), Device::Cpu);
    assert_eq!(a.gpu_indexes(), &[]);
    assert_eq!(b.gpu_indexes(), &[]);

    let cuda_key = compressed_server_keys.decompress_to_specific_gpu(last_gpu);

    set_server_key(cuda_key);
    let c = &a + &b;
    let decrypted: u32 = c.decrypt(&keys);
    assert_eq!(c.current_device(), Device::CudaGpu);
    assert_eq!(c.gpu_indexes(), &[last_gpu]);
    assert_eq!(decrypted, clear_a.wrapping_add(clear_b));

    // Check explicit move, but first make sure input are on Cpu still
    assert_eq!(a.current_device(), Device::Cpu);
    assert_eq!(b.current_device(), Device::Cpu);
    assert_eq!(a.gpu_indexes(), &[]);
    assert_eq!(b.gpu_indexes(), &[]);

    a.move_to_current_device();
    b.move_to_current_device();

    assert_eq!(a.current_device(), Device::CudaGpu);
    assert_eq!(b.current_device(), Device::CudaGpu);
    assert_eq!(a.gpu_indexes(), &[last_gpu]);
    assert_eq!(b.gpu_indexes(), &[last_gpu]);

    let c = &a + &b;
    let decrypted: u32 = c.decrypt(&keys);
    assert_eq!(c.current_device(), Device::CudaGpu);
    assert_eq!(c.gpu_indexes(), &[last_gpu]);
    assert_eq!(decrypted, clear_a.wrapping_add(clear_b));
}

#[test]
fn test_gpu_selection_2() {
    // The purpose of if this is to test that we can set_server_key using a cuda key that is on GpuY
    // do some computations, then set_server_key using a cuda key that is on GpuX, and try to copy
    // from GpuY to CPU data resulting from the first set of computations (meaning we have
    // access to a stream on GpuY)
    if get_number_of_gpus() < 2 {
        // This test is only really useful if there are 2 GPUs
        return;
    }
    let config = ConfigBuilder::default().build();
    let keys = ClientKey::generate(config);
    let compressed_server_keys = CompressedServerKey::new(&keys);

    let mut rng = rand::thread_rng();

    let first_gpu = GpuIndex::new(0);
    let last_gpu = GpuIndex::new(get_number_of_gpus() - 1);

    let clear_a: u32 = rng.gen();
    let clear_b: u32 = rng.gen();

    let mut a = FheUint32::try_encrypt(clear_a, &keys).unwrap();
    let mut b = FheUint32::try_encrypt(clear_b, &keys).unwrap();

    assert_eq!(a.current_device(), Device::Cpu);
    assert_eq!(b.current_device(), Device::Cpu);
    assert_eq!(a.gpu_indexes(), &[]);
    assert_eq!(b.gpu_indexes(), &[]);

    let cuda_key = compressed_server_keys.decompress_to_specific_gpu(last_gpu);
    set_server_key(cuda_key);

    a.move_to_current_device();
    b.move_to_current_device();

    assert_eq!(a.current_device(), Device::CudaGpu);
    assert_eq!(b.current_device(), Device::CudaGpu);
    assert_eq!(a.gpu_indexes(), &[last_gpu]);
    assert_eq!(b.gpu_indexes(), &[last_gpu]);

    let c = &a + &b;

    let cuda_key = compressed_server_keys.decompress_to_specific_gpu(first_gpu);
    set_server_key(cuda_key);

    // Check that, even though the current key is on Gpu 0, and c on Gpu 1, we can copy it to cpu
    // to decrypt
    let decrypted: u32 = c.decrypt(&keys);
    assert_eq!(c.current_device(), Device::CudaGpu);
    assert_eq!(c.gpu_indexes(), &[last_gpu]);
    assert_eq!(decrypted, clear_a.wrapping_add(clear_b));

    // This will effectively require internally to copy from last gpu to first gpu
    let c = &a + &b;
    let decrypted: u32 = c.decrypt(&keys);
    assert_eq!(c.current_device(), Device::CudaGpu);
    assert_eq!(c.gpu_indexes(), &[first_gpu]);
    assert_eq!(decrypted, clear_a.wrapping_add(clear_b));
}

#[test]
fn test_specific_gpu_selection() {
    let config = ConfigBuilder::default().build();
    let keys = ClientKey::generate(config);
    let compressed_server_keys = CompressedServerKey::new(&keys);

    let mut rng = rand::thread_rng();

    let total_gpus = get_number_of_gpus() as usize;
    // There are 2^total_gpus possible subsets, excluding the empty one
    for num_gpus_to_use in 1..(1 << total_gpus) {
        let mut selected_indices = Vec::new();
        for j in 0..total_gpus {
            if (num_gpus_to_use & (1 << j)) != 0 {
                selected_indices.push(j);
            }
        }

        // Convert the selected indices to GpuIndex objects
        let gpus_to_be_used = CustomMultiGpuIndexes::new(
            selected_indices
                .iter()
                .map(|idx| GpuIndex::new(*idx as u32))
                .collect(),
        );

        let cuda_key = compressed_server_keys.decompress_to_specific_gpu(gpus_to_be_used);

        let first_gpu = GpuIndex::new(selected_indices[0] as u32);

        let clear_a: u32 = rng.gen();
        let clear_b: u32 = rng.gen();

        let mut a = FheUint32::try_encrypt(clear_a, &keys).unwrap();
        let mut b = FheUint32::try_encrypt(clear_b, &keys).unwrap();

        assert_eq!(a.current_device(), Device::Cpu);
        assert_eq!(b.current_device(), Device::Cpu);
        assert_eq!(a.gpu_indexes(), &[]);
        assert_eq!(b.gpu_indexes(), &[]);

        set_server_key(cuda_key);
        let c = &a + &b;
        let decrypted: u32 = c.decrypt(&keys);
        assert_eq!(c.current_device(), Device::CudaGpu);
        assert_eq!(c.gpu_indexes(), &[first_gpu]);
        assert_eq!(decrypted, clear_a.wrapping_add(clear_b));

        // Check explicit move, but first make sure input are on Cpu still
        assert_eq!(a.current_device(), Device::Cpu);
        assert_eq!(b.current_device(), Device::Cpu);
        assert_eq!(a.gpu_indexes(), &[]);
        assert_eq!(b.gpu_indexes(), &[]);

        a.move_to_current_device();
        b.move_to_current_device();

        assert_eq!(a.current_device(), Device::CudaGpu);
        assert_eq!(b.current_device(), Device::CudaGpu);
        assert_eq!(a.gpu_indexes(), &[first_gpu]);
        assert_eq!(b.gpu_indexes(), &[first_gpu]);

        let c = &a + &b;
        let decrypted: u32 = c.decrypt(&keys);
        assert_eq!(c.current_device(), Device::CudaGpu);
        assert_eq!(c.gpu_indexes(), &[first_gpu]);
        assert_eq!(decrypted, clear_a.wrapping_add(clear_b));
        unset_server_key();
    }
}