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use crate::integer::{CrtCiphertext, ServerKey};
impl ServerKey {
/// Computes homomorphically a multiplication between two ciphertexts encrypting integer
/// values in the CRT decomposition.
///
/// # Example
///
/// ```rust
/// use tfhe::integer::gen_keys_crt;
/// use tfhe::shortint::parameters::PARAM_MESSAGE_3_CARRY_3_KS_PBS_GAUSSIAN_2M128;
///
/// // Generate the client key and the server key:
/// let basis = vec![2, 3, 5];
/// let modulus: u64 = basis.iter().product();
/// let (cks, sks) = gen_keys_crt(PARAM_MESSAGE_3_CARRY_3_KS_PBS_GAUSSIAN_2M128, basis);
///
/// let clear_1 = 29;
/// let clear_2 = 23;
/// // Encrypt two messages
/// let mut ctxt_1 = cks.encrypt(clear_1);
/// let ctxt_2 = cks.encrypt(clear_2);
///
/// // Compute homomorphically a multiplication
/// sks.unchecked_crt_mul_assign(&mut ctxt_1, &ctxt_2);
/// // Decrypt
/// let res = cks.decrypt(&ctxt_1);
/// assert_eq!((clear_1 * clear_2) % modulus, res);
/// ```
pub fn unchecked_crt_mul_assign(&self, ct_left: &mut CrtCiphertext, ct_right: &CrtCiphertext) {
for (ct_left, ct_right) in ct_left.blocks.iter_mut().zip(ct_right.blocks.iter()) {
if self
.key
.is_functional_bivariate_pbs_possible(
ct_left.noise_degree(),
ct_right.noise_degree(),
None,
)
.is_ok()
{
self.key.unchecked_mul_lsb_assign(ct_left, ct_right);
} else {
self.key
.unchecked_mul_lsb_small_carry_assign(ct_left, ct_right);
}
}
}
pub fn unchecked_crt_mul(
&self,
ct_left: &CrtCiphertext,
ct_right: &CrtCiphertext,
) -> CrtCiphertext {
let mut ct_res = ct_left.clone();
self.unchecked_crt_mul_assign(&mut ct_res, ct_right);
ct_res
}
/// Computes homomorphically a multiplication between two ciphertexts encrypting integer
/// values in the CRT decomposition.
///
/// This checks that the addition is possible. In the case where the carry buffers are full,
/// then it is automatically cleared to allow the operation.
///
/// # Example
///
/// ```rust
/// use tfhe::integer::gen_keys_crt;
/// use tfhe::shortint::parameters::PARAM_MESSAGE_3_CARRY_3_KS_PBS_GAUSSIAN_2M128;
///
/// let basis = vec![2, 3, 5];
/// let modulus: u64 = basis.iter().product();
/// let (cks, sks) = gen_keys_crt(PARAM_MESSAGE_3_CARRY_3_KS_PBS_GAUSSIAN_2M128, basis);
///
/// let clear_1 = 29;
/// let clear_2 = 29;
/// // Encrypt two messages
/// let mut ctxt_1 = cks.encrypt(clear_1);
/// let mut ctxt_2 = cks.encrypt(clear_2);
///
/// // Compute homomorphically a multiplication
/// sks.smart_crt_mul_assign(&mut ctxt_1, &mut ctxt_2);
///
/// // Decrypt
/// let res = cks.decrypt(&ctxt_1);
/// assert_eq!((clear_1 * clear_2) % modulus, res);
/// ```
pub fn smart_crt_mul_assign(&self, ct_left: &mut CrtCiphertext, ct_right: &mut CrtCiphertext) {
for (block_left, block_right) in ct_left.blocks.iter_mut().zip(ct_right.blocks.iter_mut()) {
self.key.smart_mul_lsb_assign(block_left, block_right);
}
}
// by convention smart operations take mut refs to their inputs, even if they do not modify them
#[allow(clippy::needless_pass_by_ref_mut)]
pub fn smart_crt_mul(
&self,
ct_left: &mut CrtCiphertext,
ct_right: &mut CrtCiphertext,
) -> CrtCiphertext {
let mut ct_res = ct_left.clone();
self.smart_crt_mul_assign(&mut ct_res, ct_right);
ct_res
}
}