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use crate::integer::ciphertext::IntegerRadixCiphertext;
use crate::integer::server_key::radix_parallel::OutputFlag;
use crate::integer::server_key::CheckError;
use crate::integer::{BooleanBlock, ServerKey, SignedRadixCiphertext};
use crate::shortint::ciphertext::{Degree, MaxDegree, NoiseLevel};
impl ServerKey {
/// Computes homomorphically an addition between two ciphertexts encrypting integer values.
///
/// 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 tfhe::integer::gen_keys_radix;
/// use tfhe::shortint::parameters::PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128;
///
/// // Generate the client key and the server key:
/// let num_blocks = 4;
/// let (cks, sks) = gen_keys_radix(PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128, num_blocks);
///
/// let msg1 = 10;
/// let msg2 = 127;
///
/// let ct1 = cks.encrypt(msg1);
/// let ct2 = cks.encrypt(msg2);
///
/// // Compute homomorphically an addition:
/// let ct_res = sks.unchecked_add(&ct1, &ct2);
///
/// // Decrypt:
/// let dec_result: u64 = cks.decrypt(&ct_res);
/// assert_eq!(dec_result, msg1 + msg2);
/// ```
pub fn unchecked_add<T>(&self, ct_left: &T, ct_right: &T) -> T
where
T: IntegerRadixCiphertext,
{
let mut result = ct_left.clone();
self.unchecked_add_assign(&mut result, ct_right);
result
}
/// Computes homomorphically an addition between two ciphertexts encrypting integer values.
///
/// This function computes the operation without checking if it exceeds the capacity of the
/// ciphertext.
///
/// The result is assigned to the `ct_left` ciphertext.
/// ```rust
/// use tfhe::integer::gen_keys_radix;
/// use tfhe::shortint::parameters::PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128;
///
/// let num_blocks = 4;
/// let (cks, sks) = gen_keys_radix(PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128, num_blocks);
///
/// let msg1 = 28;
/// let msg2 = 127;
///
/// let mut ct1 = cks.encrypt(msg1);
/// let ct2 = cks.encrypt(msg2);
///
/// // Compute homomorphically an addition:
/// sks.unchecked_add_assign(&mut ct1, &ct2);
///
/// // Decrypt:
/// let dec_ct1: u64 = cks.decrypt(&ct1);
/// assert_eq!(dec_ct1, msg1 + msg2);
/// ```
pub fn unchecked_add_assign<T>(&self, ct_left: &mut T, ct_right: &T)
where
T: IntegerRadixCiphertext,
{
for (ct_left_i, ct_right_i) in ct_left
.blocks_mut()
.iter_mut()
.zip(ct_right.blocks().iter())
{
self.key.unchecked_add_assign(ct_left_i, ct_right_i);
}
}
/// Verifies if ct1 and ct2 can be added together.
///
/// # Example
///
///```rust
/// use tfhe::integer::gen_keys_radix;
/// use tfhe::shortint::parameters::PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128;
///
/// // Generate the client key and the server key:
/// let num_blocks = 4;
/// let (cks, sks) = gen_keys_radix(PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128, num_blocks);
///
/// let msg1 = 46u64;
/// let msg2 = 87u64;
///
/// let ct1 = cks.encrypt(msg1);
/// let ct2 = cks.encrypt(msg2);
///
/// // Check if we can perform an addition
/// sks.is_add_possible(&ct1, &ct2).unwrap();
/// ```
pub fn is_add_possible<T>(&self, ct_left: &T, ct_right: &T) -> Result<(), CheckError>
where
T: IntegerRadixCiphertext,
{
// Assumes message_modulus and carry_modulus matches between pairs of block
let mut preceding_block_carry = Degree::new(0);
let mut extracted_carry_noise_level = NoiseLevel::ZERO;
for (left_block, right_block) in ct_left.blocks().iter().zip(ct_right.blocks().iter()) {
let degree_after_add = left_block.degree + right_block.degree;
// Also need to take into account preceding_carry
let max_degree = MaxDegree::from_msg_carry_modulus(
left_block.message_modulus,
left_block.carry_modulus,
);
max_degree.validate(degree_after_add + preceding_block_carry)?;
self.key.max_noise_level.validate(
left_block.noise_level() + right_block.noise_level() + extracted_carry_noise_level,
)?;
preceding_block_carry =
Degree::new(degree_after_add.get() / left_block.message_modulus.0);
extracted_carry_noise_level = NoiseLevel::NOMINAL;
}
Ok(())
}
/// Computes homomorphically an addition between two ciphertexts encrypting integer values.
///
/// If the operation can be performed, the result is returned in a new ciphertext.
/// Otherwise a [CheckError] is returned.
///
/// # Example
///
/// ```rust
/// use tfhe::integer::gen_keys_radix;
/// use tfhe::shortint::parameters::PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128;
///
/// // Generate the client key and the server key:
/// let num_blocks = 4;
/// let (cks, sks) = gen_keys_radix(PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128, num_blocks);
///
/// let msg1 = 41;
/// let msg2 = 101;
///
/// let ct1 = cks.encrypt(msg1);
/// let ct2 = cks.encrypt(msg2);
///
/// // Compute homomorphically an addition:
/// let ct_res = sks.checked_add(&ct1, &ct2);
///
/// match ct_res {
/// Err(x) => panic!("{x:?}"),
/// Ok(y) => {
/// let clear: u64 = cks.decrypt(&y);
/// assert_eq!(msg1 + msg2, clear);
/// }
/// }
/// ```
pub fn checked_add<T>(&self, ct_left: &T, ct_right: &T) -> Result<T, CheckError>
where
T: IntegerRadixCiphertext,
{
self.is_add_possible(ct_left, ct_right)?;
Ok(self.unchecked_add(ct_left, ct_right))
}
/// Computes homomorphically an addition between two ciphertexts encrypting integer values.
///
/// If the operation can be performed, the result is stored in the `ct_left` ciphertext.
/// Otherwise a [CheckError] is returned, and `ct_left` is not modified.
///
/// # Example
///
/// ```rust
/// use tfhe::integer::gen_keys_radix;
/// use tfhe::shortint::parameters::PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128;
///
/// // Generate the client key and the server key:
/// let num_blocks = 4;
/// let (cks, sks) = gen_keys_radix(PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128, num_blocks);
///
/// let msg1 = 41;
/// let msg2 = 101;
///
/// let mut ct1 = cks.encrypt(msg1);
/// let ct2 = cks.encrypt(msg2);
///
/// // Compute homomorphically an addition:
/// sks.checked_add_assign(&mut ct1, &ct2).unwrap();
///
/// let clear: u64 = cks.decrypt(&ct1);
/// assert_eq!(msg1 + msg2, clear);
/// ```
pub fn checked_add_assign<T>(&self, ct_left: &mut T, ct_right: &T) -> Result<(), CheckError>
where
T: IntegerRadixCiphertext,
{
self.is_add_possible(ct_left, ct_right)?;
self.unchecked_add_assign(ct_left, ct_right);
Ok(())
}
/// Computes homomorphically an addition between two ciphertexts encrypting integer values.
///
/// # Example
///
/// ```rust
/// use tfhe::integer::gen_keys_radix;
/// use tfhe::shortint::parameters::PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128;
///
/// // Generate the client key and the server key:
/// let num_blocks = 4;
/// let (cks, sks) = gen_keys_radix(PARAM_MESSAGE_2_CARRY_2_KS_PBS_GAUSSIAN_2M128, num_blocks);
///
/// let msg1 = 14;
/// let msg2 = 97;
///
/// let mut ct1 = cks.encrypt(msg1);
/// let mut ct2 = cks.encrypt(msg2);
///
/// // Compute homomorphically an addition:
/// let ct_res = sks.smart_add(&mut ct1, &mut ct2);
///
/// // Decrypt:
/// let dec_result: u64 = cks.decrypt(&ct_res);
/// assert_eq!(dec_result, msg1 + msg2);
/// ```
pub fn smart_add<T>(&self, ct_left: &mut T, ct_right: &mut T) -> T
where
T: IntegerRadixCiphertext,
{
if self.is_add_possible(ct_left, ct_right).is_err() {
self.full_propagate(ct_left);
self.full_propagate(ct_right);
}
self.is_add_possible(ct_left, ct_right).unwrap();
self.unchecked_add(ct_left, ct_right)
}
pub fn smart_add_assign<T>(&self, ct_left: &mut T, ct_right: &mut T)
where
T: IntegerRadixCiphertext,
{
//If the ciphertext cannot be added together without exceeding the capacity of a ciphertext
if self.is_add_possible(ct_left, ct_right).is_err() {
self.full_propagate(ct_left);
self.full_propagate(ct_right);
}
self.is_add_possible(ct_left, ct_right).unwrap();
self.unchecked_add_assign(ct_left, ct_right);
}
pub fn unchecked_signed_overflowing_add(
&self,
lhs: &SignedRadixCiphertext,
rhs: &SignedRadixCiphertext,
) -> (SignedRadixCiphertext, BooleanBlock) {
let mut result = lhs.clone();
let overflowed = self
.advanced_add_assign_with_carry_sequential_parallelized(
&mut result.blocks,
&rhs.blocks,
None,
OutputFlag::from_signedness(true),
)
.expect("overflow flag was requested");
(result, overflowed)
}
}