tfhe/high_level_api/booleans/
compressed.rs

use crate::backward_compatibility::booleans::{
    CompressedFheBoolVersions, InnerCompressedFheBoolVersions,
};
use crate::conformance::ParameterSetConformant;
use crate::high_level_api::global_state::with_cpu_internal_keys;
use crate::high_level_api::traits::Tagged;
use crate::integer::BooleanBlock;
use crate::named::Named;
use crate::prelude::FheTryEncrypt;
use crate::shortint::ciphertext::{CompressedModulusSwitchedCiphertext, Degree};
use crate::shortint::CompressedCiphertext;
use crate::{ClientKey, FheBool, FheBoolConformanceParams, Tag};
use serde::{Deserialize, Serialize};
use tfhe_versionable::Versionize;

#[derive(Clone, Serialize, Deserialize, Versionize)]
#[versionize(InnerCompressedFheBoolVersions)]
pub enum InnerCompressedFheBool {
    Seeded(CompressedCiphertext),
    ModulusSwitched(CompressedModulusSwitchedCiphertext),
}

/// Compressed [FheBool]
///
/// Meant to save in storage space / transfer.
///
/// - A Compressed type must be decompressed before it can be used.
/// - It is not possible to compress an existing [FheBool], compression can only be achieved at
///   encryption time
///
/// # Example
///
/// ```rust
/// use tfhe::prelude::*;
/// use tfhe::{generate_keys, CompressedFheBool, ConfigBuilder};
///
/// let (client_key, _) = generate_keys(ConfigBuilder::default());
/// let compressed = CompressedFheBool::encrypt(true, &client_key);
///
/// let decompressed = compressed.decompress();
/// let decrypted: bool = decompressed.decrypt(&client_key);
/// assert!(decrypted);
/// ```
#[derive(Clone, Serialize, Deserialize, Versionize)]
#[versionize(CompressedFheBoolVersions)]
pub struct CompressedFheBool {
    pub(in crate::high_level_api) inner: InnerCompressedFheBool,
    pub(crate) tag: Tag,
}

impl Tagged for CompressedFheBool {
    fn tag(&self) -> &Tag {
        &self.tag
    }

    fn tag_mut(&mut self) -> &mut Tag {
        &mut self.tag
    }
}

impl CompressedFheBool {
    pub(in crate::high_level_api) fn new(ciphertext: CompressedCiphertext, tag: Tag) -> Self {
        Self {
            inner: InnerCompressedFheBool::Seeded(ciphertext),
            tag,
        }
    }

    /// Decompresses itself into a [FheBool]
    ///
    /// See [CompressedFheBool] example.
    pub fn decompress(&self) -> FheBool {
        let ciphertext = BooleanBlock::new_unchecked(match &self.inner {
            InnerCompressedFheBool::Seeded(seeded) => seeded.decompress(),
            InnerCompressedFheBool::ModulusSwitched(modulus_switched) => {
                with_cpu_internal_keys(|sk| sk.pbs_key().key.decompress(modulus_switched))
            }
        });
        let mut ciphertext = FheBool::new(ciphertext, self.tag.clone());

        ciphertext.ciphertext.move_to_device_of_server_key_if_set();

        ciphertext
    }
}

impl FheTryEncrypt<bool, ClientKey> for CompressedFheBool {
    type Error = crate::Error;

    /// Creates a compressed encryption of a boolean value
    fn try_encrypt(value: bool, key: &ClientKey) -> Result<Self, Self::Error> {
        let mut ciphertext = key.key.key.key.encrypt_compressed(u64::from(value));
        ciphertext.degree = Degree::new(1);
        Ok(Self::new(ciphertext, key.tag.clone()))
    }
}

impl ParameterSetConformant for CompressedFheBool {
    type ParameterSet = FheBoolConformanceParams;

    fn is_conformant(&self, params: &FheBoolConformanceParams) -> bool {
        match &self.inner {
            InnerCompressedFheBool::Seeded(seeded) => seeded.is_conformant(&params.0),
            InnerCompressedFheBool::ModulusSwitched(ct) => ct.is_conformant(&params.0),
        }
    }
}

impl Named for CompressedFheBool {
    const NAME: &'static str = "high_level_api::CompressedFheBool";
}

impl FheBool {
    pub fn compress(&self) -> CompressedFheBool {
        with_cpu_internal_keys(|sk| {
            let inner = InnerCompressedFheBool::ModulusSwitched(
                sk.pbs_key()
                    .key
                    .switch_modulus_and_compress(&self.ciphertext.on_cpu().0),
            );

            CompressedFheBool {
                inner,
                tag: sk.tag.clone(),
            }
        })
    }
}
tfhe/high_level_api/booleans/compressed.rs

tfhe/high_level_api/booleans/
compressed.rs
