snarkvm_circuit_program/data/record/
decrypt.rs

1// Copyright (c) 2019-2025 Provable Inc.
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<A: Aleo> Record<A, Ciphertext<A>> {
19    /// Decrypts `self` into a plaintext record using the given view key & nonce.
20    pub fn decrypt(&self, view_key: &ViewKey<A>) -> Record<A, Plaintext<A>> {
21        // Compute the record view key.
22        let record_view_key = (&**view_key * &self.nonce).to_x_coordinate();
23        // Decrypt the record.
24        let record = self.decrypt_symmetric_unchecked(record_view_key);
25        // Ensure the view key corresponds to the record owner.
26        A::assert_eq(view_key.to_address(), record.owner().deref());
27        // Return the decrypted record.
28        record
29    }
30
31    /// Decrypts `self` into a plaintext record using the given record view key.
32    /// Note: This method does not check that the record view key corresponds to the record owner.
33    /// Use `Self::decrypt` for the checked variant.
34    pub fn decrypt_symmetric_unchecked(&self, record_view_key: Field<A>) -> Record<A, Plaintext<A>> {
35        // Determine the number of randomizers needed to encrypt the record.
36        let num_randomizers = self.num_randomizers();
37        // Prepare a randomizer for each field element.
38        let randomizers = A::hash_many_psd8(&[A::encryption_domain(), record_view_key], num_randomizers);
39        // Decrypt the record.
40        self.decrypt_with_randomizers(&randomizers)
41    }
42
43    /// Decrypts `self` into a plaintext record using the given randomizers.
44    fn decrypt_with_randomizers(&self, randomizers: &[Field<A>]) -> Record<A, Plaintext<A>> {
45        // Initialize an index to keep track of the randomizer index.
46        let mut index: usize = 0;
47
48        // Decrypt the owner.
49        let owner = match self.owner.is_public().eject_value() {
50            true => self.owner.decrypt(&[]),
51            false => self.owner.decrypt(&[randomizers[index].clone()]),
52        };
53
54        // Increment the index if the owner is private.
55        if owner.is_private().eject_value() {
56            index += 1;
57        }
58
59        // Decrypt the program data.
60        let mut decrypted_data = IndexMap::with_capacity(self.data.len());
61        for (id, entry, num_randomizers) in self.data.iter().map(|(id, entry)| (id, entry, entry.num_randomizers())) {
62            // Retrieve the randomizers for this entry.
63            let randomizers = &randomizers[index..index + num_randomizers as usize];
64            // Decrypt the entry.
65            let entry = match entry {
66                // Constant entries do not need to be decrypted.
67                Entry::Constant(plaintext) => Entry::Constant(plaintext.clone()),
68                // Public entries do not need to be decrypted.
69                Entry::Public(plaintext) => Entry::Public(plaintext.clone()),
70                // Private entries are decrypted with the given randomizers.
71                Entry::Private(private) => Entry::Private(private.decrypt_with_randomizers(randomizers)),
72            };
73            // Insert the decrypted entry.
74            if decrypted_data.insert(id.clone(), entry).is_some() {
75                A::halt(format!("Duplicate identifier in record: {id}"))
76            }
77            // Increment the index.
78            index += num_randomizers as usize;
79        }
80
81        // Return the decrypted record.
82        Record { owner, data: decrypted_data, nonce: self.nonce.clone(), version: self.version.clone() }
83    }
84}
85
86#[cfg(test)]
87mod tests {
88    use super::*;
89    use crate::{Circuit, Literal};
90    use snarkvm_circuit_types::{Address, Field};
91    use snarkvm_utilities::{TestRng, Uniform};
92
93    use anyhow::Result;
94
95    const ITERATIONS: u64 = 100;
96
97    fn check_encrypt_and_decrypt<A: Aleo>(
98        view_key: &ViewKey<A>,
99        owner: Owner<A, Plaintext<A>>,
100        rng: &mut TestRng,
101    ) -> Result<()> {
102        // Prepare the record.
103        let randomizer = Scalar::new(Mode::Private, Uniform::rand(rng));
104        let record = Record {
105            owner,
106            data: IndexMap::from_iter(vec![
107                (
108                    Identifier::from_str("a")?,
109                    Entry::Private(Plaintext::from(Literal::Field(Field::new(Mode::Private, Uniform::rand(rng))))),
110                ),
111                (
112                    Identifier::from_str("b")?,
113                    Entry::Private(Plaintext::from(Literal::Scalar(Scalar::new(Mode::Private, Uniform::rand(rng))))),
114                ),
115            ]),
116            nonce: A::g_scalar_multiply(&randomizer),
117            version: U8::new(Mode::Private, Uniform::rand(rng)),
118        };
119
120        // Encrypt the record.
121        let ciphertext = record.encrypt(&randomizer);
122        // Decrypt the record.
123        assert_eq!(record.eject(), ciphertext.decrypt(view_key).eject());
124        Ok(())
125    }
126
127    #[test]
128    fn test_encrypt_and_decrypt() -> Result<()> {
129        let mut rng = TestRng::default();
130
131        for _ in 0..ITERATIONS {
132            // Generate a private key, view key, and address.
133            let private_key = snarkvm_console_account::PrivateKey::<<Circuit as Environment>::Network>::new(&mut rng)?;
134            let view_key = snarkvm_console_account::ViewKey::try_from(private_key)?;
135            let address = snarkvm_console_account::Address::try_from(private_key)?;
136
137            // Initialize a view key and address.
138            let view_key = ViewKey::<Circuit>::new(Mode::Private, view_key);
139            let owner = address;
140
141            // Public owner.
142            {
143                let owner = Owner::Public(Address::<Circuit>::new(Mode::Public, owner));
144                check_encrypt_and_decrypt::<Circuit>(&view_key, owner, &mut rng)?;
145            }
146
147            // Private owner.
148            {
149                let owner =
150                    Owner::Private(Plaintext::from(Literal::Address(Address::<Circuit>::new(Mode::Private, owner))));
151                check_encrypt_and_decrypt::<Circuit>(&view_key, owner, &mut rng)?;
152            }
153        }
154        Ok(())
155    }
156}
snarkvm_circuit_program/data/record/decrypt.rs

snarkvm_circuit_program/data/record/
decrypt.rs
