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use crate::{CrtCiphertext, ServerKey};
impl ServerKey {
/// Computes homomorphically an addition between two ciphertexts encrypting integer values.
///
/// # Example
///
///```rust
/// use concrete_integer::gen_keys;
/// use concrete_shortint::parameters::PARAM_MESSAGE_2_CARRY_2;
///
/// // Generate the client key and the server key:
/// let (cks, sks) = gen_keys(&PARAM_MESSAGE_2_CARRY_2);
///
/// let clear_1 = 14;
/// let clear_2 = 14;
/// let basis = vec![2, 3, 5];
/// // Encrypt two messages
/// let mut ctxt_1 = cks.encrypt_crt(clear_1, basis.clone());
/// let mut ctxt_2 = cks.encrypt_crt(clear_2, basis);
///
/// sks.smart_crt_add_assign(&mut ctxt_1, &mut ctxt_2);
///
/// // Decrypt
/// let res = cks.decrypt_crt(&ctxt_1);
/// assert_eq!((clear_1 + clear_2) % 30, res);
/// ```
pub fn smart_crt_add(
&self,
ct_left: &mut CrtCiphertext,
ct_right: &mut CrtCiphertext,
) -> CrtCiphertext {
if !self.is_crt_add_possible(ct_left, ct_right) {
self.full_extract(ct_left);
self.full_extract(ct_right);
}
self.unchecked_crt_add(ct_left, ct_right)
}
pub fn smart_crt_add_assign(&self, ct_left: &mut CrtCiphertext, ct_right: &mut CrtCiphertext) {
//If the ciphertext cannot be added together without exceeding the capacity of a ciphertext
if !self.is_crt_add_possible(ct_left, ct_right) {
self.full_extract(ct_left);
self.full_extract(ct_right);
}
self.unchecked_crt_add_assign(ct_left, ct_right);
}
pub fn is_crt_add_possible(&self, ct_left: &CrtCiphertext, ct_right: &CrtCiphertext) -> bool {
for (ct_left_i, ct_right_i) in ct_left.blocks.iter().zip(ct_right.blocks.iter()) {
if !self.key.is_add_possible(ct_left_i, ct_right_i) {
return false;
}
}
true
}
pub fn unchecked_crt_add_assign(&self, ct_left: &mut CrtCiphertext, ct_right: &CrtCiphertext) {
for (ct_left_i, ct_right_i) in ct_left.blocks.iter_mut().zip(ct_right.blocks.iter()) {
self.key.unchecked_add_assign(ct_left_i, ct_right_i);
}
}
pub fn unchecked_crt_add(
&self,
ct_left: &CrtCiphertext,
ct_right: &CrtCiphertext,
) -> CrtCiphertext {
let mut ct_res = ct_left.clone();
self.unchecked_crt_add_assign(&mut ct_res, ct_right);
ct_res
}
}