snarkvm_console_program/data/record/
decrypt.rs

1// Copyright 2024 Aleo Network Foundation
2// This file is part of the snarkVM 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
16use super::*;
17
18impl<N: Network> Record<N, Ciphertext<N>> {
19    /// Decrypts `self` into plaintext using the given view key and checks that the owner matches the view key.
20    pub fn decrypt(&self, view_key: &ViewKey<N>) -> Result<Record<N, Plaintext<N>>> {
21        // Compute the record view key.
22        let record_view_key = (self.nonce * **view_key).to_x_coordinate();
23        // Decrypt the record.
24        let record = self.decrypt_symmetric_unchecked(&record_view_key)?;
25        // Ensure the record owner matches the view key.
26        match view_key.to_address() == **record.owner() {
27            true => Ok(record),
28            false => bail!("Illegal operation: Record::decrypt() view key does not correspond to the record owner."),
29        }
30    }
31
32    /// Decrypts `self` into plaintext using the given record view key.
33    /// Note: This method does not check that the record view key corresponds to the record owner.
34    /// Use `Self::decrypt` for the checked variant.
35    pub fn decrypt_symmetric_unchecked(&self, record_view_key: &Field<N>) -> Result<Record<N, Plaintext<N>>> {
36        // Determine the number of randomizers needed to encrypt the record.
37        let num_randomizers = self.num_randomizers()?;
38        // Prepare a randomizer for each field element.
39        let randomizers = N::hash_many_psd8(&[N::encryption_domain(), *record_view_key], num_randomizers);
40        // Decrypt the record.
41        self.decrypt_with_randomizers(&randomizers)
42    }
43
44    /// Decrypts `self` into plaintext using the given randomizers.
45    fn decrypt_with_randomizers(&self, randomizers: &[Field<N>]) -> Result<Record<N, Plaintext<N>>> {
46        // Initialize an index to keep track of the randomizer index.
47        let mut index: usize = 0;
48
49        // Decrypt the owner.
50        let owner = match self.owner.is_public() {
51            true => self.owner.decrypt_with_randomizer(&[])?,
52            false => self.owner.decrypt_with_randomizer(&[randomizers[index]])?,
53        };
54
55        // Increment the index if the owner is private.
56        if owner.is_private() {
57            index += 1;
58        }
59
60        // Decrypt the program data.
61        let mut decrypted_data = IndexMap::with_capacity(self.data.len());
62        for (id, entry, num_randomizers) in self.data.iter().map(|(id, entry)| (id, entry, entry.num_randomizers())) {
63            // Retrieve the result for `num_randomizers`.
64            let num_randomizers = num_randomizers? as usize;
65            // Retrieve the randomizers for this entry.
66            let randomizers = &randomizers[index..index + num_randomizers];
67            // Decrypt the entry.
68            let entry = match entry {
69                // Constant entries do not need to be decrypted.
70                Entry::Constant(plaintext) => Entry::Constant(plaintext.clone()),
71                // Public entries do not need to be decrypted.
72                Entry::Public(plaintext) => Entry::Public(plaintext.clone()),
73                // Private entries are decrypted with the given randomizers.
74                Entry::Private(private) => Entry::Private(Plaintext::from_fields(
75                    &private
76                        .iter()
77                        .zip_eq(randomizers)
78                        .map(|(ciphertext, randomizer)| *ciphertext - randomizer)
79                        .collect::<Vec<_>>(),
80                )?),
81            };
82            // Insert the decrypted entry.
83            if decrypted_data.insert(*id, entry).is_some() {
84                bail!("Duplicate identifier in record: {}", id);
85            }
86            // Increment the index.
87            index += num_randomizers;
88        }
89
90        // Return the decrypted record.
91        Self::from_plaintext(owner, decrypted_data, self.nonce)
92    }
93}
94
95#[cfg(test)]
96mod tests {
97    use super::*;
98    use crate::Literal;
99    use snarkvm_console_account::PrivateKey;
100    use snarkvm_console_network::MainnetV0;
101    use snarkvm_console_types::Field;
102
103    type CurrentNetwork = MainnetV0;
104
105    const ITERATIONS: u64 = 1000;
106
107    fn check_encrypt_and_decrypt<N: Network>(
108        view_key: ViewKey<N>,
109        owner: Owner<N, Plaintext<N>>,
110        rng: &mut TestRng,
111    ) -> Result<()> {
112        // Prepare the record.
113        let randomizer = Scalar::rand(rng);
114        let record = Record {
115            owner,
116            data: IndexMap::from_iter(vec![
117                (Identifier::from_str("a")?, Entry::Private(Plaintext::from(Literal::Field(Field::rand(rng))))),
118                (Identifier::from_str("b")?, Entry::Private(Plaintext::from(Literal::Scalar(Scalar::rand(rng))))),
119            ]),
120            nonce: N::g_scalar_multiply(&randomizer),
121        };
122        // Encrypt the record.
123        let ciphertext = record.encrypt(randomizer)?;
124        // Decrypt the record.
125        assert_eq!(record, ciphertext.decrypt(&view_key)?);
126
127        // Generate a new random private key.
128        let incorrect_private_key = PrivateKey::<N>::new(rng)?;
129        // Generate a new view key.
130        let incorrect_view_key = ViewKey::try_from(&incorrect_private_key)?;
131        // Ensure that decrypting with the incorrect view key fails.
132        assert!(ciphertext.decrypt(&incorrect_view_key).is_err());
133
134        Ok(())
135    }
136
137    #[test]
138    fn test_encrypt_and_decrypt() -> Result<()> {
139        let mut rng = TestRng::default();
140
141        for _ in 0..ITERATIONS {
142            // Sample a view key and address.
143            let private_key = PrivateKey::<CurrentNetwork>::new(&mut rng)?;
144            let view_key = ViewKey::try_from(&private_key)?;
145            let address = Address::try_from(&private_key)?;
146
147            // Public owner.
148            let owner = Owner::Public(address);
149            check_encrypt_and_decrypt::<CurrentNetwork>(view_key, owner, &mut rng)?;
150
151            // Private owner.
152            let owner = Owner::Private(Plaintext::from(Literal::Address(address)));
153            check_encrypt_and_decrypt::<CurrentNetwork>(view_key, owner, &mut rng)?;
154        }
155        Ok(())
156    }
157}
snarkvm_console_program/data/record/decrypt.rs

snarkvm_console_program/data/record/
decrypt.rs
