1  // Copyright (c) 2019-2025 Alpha-Delta Network Inc.
 2  // This file is part of the alphavm library.
 3  
 4  // Licensed under the Apache License, Version 2.0 (the "License");
 5  // you may not use this file except in compliance with the License.
 6  // You may obtain a copy of the License at:
 7  
 8  // http://www.apache.org/licenses/LICENSE-2.0
 9  
10  // Unless required by applicable law or agreed to in writing, software
11  // distributed under the License is distributed on an "AS IS" BASIS,
12  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  // See the License for the specific language governing permissions and
14  // limitations under the License.
15  
16  use super::*;
17  
18  impl<N: Network> Plaintext<N> {
19      /// Encrypts `self` to the given address under the given randomizer.
20      pub fn encrypt(&self, address: &Address<N>, randomizer: Scalar<N>) -> Result<Ciphertext<N>> {
21          // Compute the plaintext view key.
22          let plaintext_view_key = (**address * randomizer).to_x_coordinate();
23          // Encrypt the plaintext.
24          self.encrypt_symmetric(plaintext_view_key)
25      }
26  
27      /// Encrypts `self` under the given plaintext view key.
28      pub fn encrypt_symmetric(&self, plaintext_view_key: Field<N>) -> Result<Ciphertext<N>> {
29          // Determine the number of randomizers needed to encrypt the plaintext.
30          let num_randomizers = self.num_randomizers()?;
31          // Prepare a randomizer for each field element.
32          let randomizers = N::hash_many_psd8(&[N::encryption_domain(), plaintext_view_key], num_randomizers);
33          // Encrypt the plaintext.
34          self.encrypt_with_randomizers(&randomizers)
35      }
36  
37      /// Encrypts `self` under the given randomizers.
38      pub(crate) fn encrypt_with_randomizers(&self, randomizers: &[Field<N>]) -> Result<Ciphertext<N>> {
39          // Encrypt the plaintext.
40          Ciphertext::from_fields(
41              &self
42                  .to_fields()?
43                  .into_iter()
44                  .zip_eq(randomizers)
45                  .map(|(plaintext, randomizer)| plaintext + randomizer)
46                  .collect::<Vec<_>>(),
47          )
48      }
49  }