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use crate::server_key::CheckError;
use crate::server_key::CheckError::CarryFull;
use crate::{CrtCiphertext, ServerKey};
use rayon::prelude::*;
impl ServerKey {
/// Computes homomorphically a subtraction between a ciphertext and a scalar.
///
/// This function computes the operation without checking if it exceeds the capacity of the
/// ciphertext.
///
/// The result is returned as a new ciphertext.
///
/// # 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 = 7;
/// let basis = vec![2, 3, 5];
/// // Encrypt two messages
/// let mut ctxt_1 = cks.encrypt_crt(clear_1, basis.clone());
///
/// sks.unchecked_crt_scalar_sub_assign_parallelized(&mut ctxt_1, clear_2);
///
/// // Decrypt
/// let res = cks.decrypt_crt(&ctxt_1);
/// assert_eq!((clear_1 - clear_2) % 30, res);
/// ```
pub fn unchecked_crt_scalar_sub_parallelized(
&self,
ct: &CrtCiphertext,
scalar: u64,
) -> CrtCiphertext {
let mut result = ct.clone();
self.unchecked_crt_scalar_sub_assign_parallelized(&mut result, scalar);
result
}
pub fn unchecked_crt_scalar_sub_assign_parallelized(
&self,
ct: &mut CrtCiphertext,
scalar: u64,
) {
//Put each decomposition into a new ciphertext
ct.blocks
.par_iter_mut()
.zip(ct.moduli.par_iter())
.for_each(|(ct_i, mod_i)| {
let neg_scalar = (mod_i - scalar % mod_i) % mod_i;
self.key
.unchecked_scalar_add_assign_crt(ct_i, neg_scalar as u8);
});
}
/// Computes homomorphically a subtraction of a ciphertext by a scalar.
///
/// If the operation can be performed, the result is returned in a new ciphertext.
/// Otherwise [CheckError::CarryFull] is returned.
///
/// # Example
///
/// ```rust
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// 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 = 8;
/// let basis = vec![2, 3, 5];
///
/// let mut ctxt_1 = cks.encrypt_crt(clear_1, basis.clone());
///
/// let ct_res = sks.checked_crt_scalar_sub_parallelized(&mut ctxt_1, clear_2)?;
///
/// // Decrypt:
/// let dec = cks.decrypt_crt(&ct_res);
/// assert_eq!((clear_1 - clear_2) % 30, dec);
/// # Ok(())
/// # }
/// ```
pub fn checked_crt_scalar_sub_parallelized(
&self,
ct: &CrtCiphertext,
scalar: u64,
) -> Result<CrtCiphertext, CheckError> {
if self.is_crt_scalar_sub_possible(ct, scalar) {
Ok(self.unchecked_crt_scalar_sub_parallelized(ct, scalar))
} else {
Err(CarryFull)
}
}
/// Computes homomorphically a subtraction of a ciphertext by a scalar.
///
/// If the operation can be performed, the result is returned in a new ciphertext.
/// Otherwise [CheckError::CarryFull] is returned.
///
/// # Example
///
/// ```rust
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// 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 = 7;
/// let basis = vec![2, 3, 5];
///
/// let mut ctxt_1 = cks.encrypt_crt(clear_1, basis.clone());
///
/// sks.checked_crt_scalar_sub_assign_parallelized(&mut ctxt_1, clear_2)?;
///
/// // Decrypt:
/// let dec = cks.decrypt_crt(&ctxt_1);
/// assert_eq!((clear_1 - clear_2) % 30, dec);
/// # Ok(())
/// # }
/// ```
pub fn checked_crt_scalar_sub_assign_parallelized(
&self,
ct: &mut CrtCiphertext,
scalar: u64,
) -> Result<(), CheckError> {
if self.is_crt_scalar_sub_possible(ct, scalar) {
self.unchecked_crt_scalar_sub_assign_parallelized(ct, scalar);
Ok(())
} else {
Err(CarryFull)
}
}
/// Computes homomorphically a subtraction of a ciphertext by a scalar.
///
/// # 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 = 7;
/// let basis = vec![2, 3, 5];
/// // Encrypt two messages
/// let mut ctxt_1 = cks.encrypt_crt(clear_1, basis.clone());
///
/// sks.smart_crt_scalar_sub_assign_parallelized(&mut ctxt_1, clear_2);
///
/// // Decrypt
/// let res = cks.decrypt_crt(&ctxt_1);
/// assert_eq!((clear_1 - clear_2) % 30, res);
/// ```
pub fn smart_crt_scalar_sub_parallelized(
&self,
ct: &mut CrtCiphertext,
scalar: u64,
) -> CrtCiphertext {
if !self.is_crt_scalar_sub_possible(ct, scalar) {
self.full_extract_parallelized(ct);
}
self.unchecked_crt_scalar_sub_parallelized(ct, scalar)
}
pub fn smart_crt_scalar_sub_assign_parallelized(&self, ct: &mut CrtCiphertext, scalar: u64) {
if !self.is_crt_scalar_sub_possible(ct, scalar) {
self.full_extract_parallelized(ct);
}
self.unchecked_crt_scalar_sub_assign_parallelized(ct, scalar);
}
}