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use super::engine_error;
use crate::prelude::LweSize;
use crate::specification::engines::AbstractEngine;
use crate::specification::entities::{LweCiphertextEntity, PlaintextEntity};
engine_error! {
LweCiphertextTrivialEncryptionError for LweCiphertextTrivialEncryptionEngine @
}
/// A trait for engines trivially encrypting LWE ciphertext.
///
/// # Semantics
///
/// This [pure](super#operation-semantics) operation generates anLWE ciphertext containing the
/// trivial encryption of the `input` plaintext with the requested `lwe_size`.
///
/// # Formal Definition
///
/// A trivial encryption uses a zero mask and no noise.
/// It is absolutely not secure, as the body contains a direct copy of the plaintext.
/// However, it is useful for some FHE algorithms taking public information as input. For
/// example, a trivial GLWE encryption of a public lookup table is used in the bootstrap.
pub trait LweCiphertextTrivialEncryptionEngine<Plaintext, Ciphertext>: AbstractEngine
where
Plaintext: PlaintextEntity,
Ciphertext: LweCiphertextEntity,
{
/// Trivially encrypts an LWE ciphertext.
fn trivially_encrypt_lwe_ciphertext(
&mut self,
lwe_size: LweSize,
input: &Plaintext,
) -> Result<Ciphertext, LweCiphertextTrivialEncryptionError<Self::EngineError>>;
/// Unsafely creates the trivial LWE encryption of the plaintext.
///
/// # Safety
/// For the _general_ safety concerns regarding this operation, refer to the different variants
/// of [`LweCiphertextTrivialEncryptionError ]. For safety concerns _specific_ to an engine,
/// refer to the implementer safety section.
unsafe fn trivially_encrypt_lwe_ciphertext_unchecked(
&mut self,
lwe_size: LweSize,
input: &Plaintext,
) -> Ciphertext;
}