snarkvm_console_program/data/record/
is_owner.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<N: Network> Record<N, Ciphertext<N>> {
19    /// Returns `true` if the given view key corresponds to the owner of the record.
20    /// Decrypts `self` into plaintext using the given view key.
21    pub fn is_owner(&self, view_key: &ViewKey<N>) -> bool {
22        // Compute the address.
23        let address = view_key.to_address();
24        // Check if the address is the owner.
25        self.is_owner_with_address_x_coordinate(view_key, &address.to_x_coordinate())
26    }
27
28    /// Returns `true` if the given view key and address x-coordinate corresponds to the owner of the record.
29    /// Decrypts `self` into plaintext using the x-coordinate of the address corresponding to the given view key.
30    pub fn is_owner_with_address_x_coordinate(&self, view_key: &ViewKey<N>, address_x_coordinate: &Field<N>) -> bool {
31        // In debug mode, check that the address corresponds to the given view key.
32        debug_assert_eq!(
33            &view_key.to_address().to_x_coordinate(),
34            address_x_coordinate,
35            "Failed to check record - view key and address do not match"
36        );
37
38        match &self.owner {
39            // If the owner is public, check if the address is the owner.
40            Owner::Public(owner) => &owner.to_x_coordinate() == address_x_coordinate,
41            // If the owner is private, decrypt the owner to check if it matches the address.
42            Owner::Private(ciphertext) => {
43                // Compute the record view key.
44                let record_view_key = (self.nonce * **view_key).to_x_coordinate();
45                // Compute the 0th randomizer.
46                let randomizer = N::hash_many_psd8(&[N::encryption_domain(), record_view_key], 1);
47                // Decrypt the owner.
48                let owner_x = ciphertext[0] - randomizer[0];
49                // Compare the x coordinates of computed and supplied addresses.
50                // We can skip recomputing the address from `owner_x` due to the following reasoning.
51                // First, the transaction SNARK that generated the ciphertext would have checked that the ciphertext encrypts a valid address.
52                // Now, since a valid address is an element of the prime-order subgroup of the curve, we know that the encrypted x-coordinate corresponds to a prime-order element.
53                // Finally, since the SNARK + hybrid encryption
54                // together are an authenticated encryption scheme, we know that the ciphertext has not been malleated.
55                // Thus overall we know that if the x-coordinate matches that of `address`, then the underlying `address`es must also match.
56                // Therefore we can skip recomputing the address from `owner_x` and instead compare the x-coordinates directly.
57                &owner_x == address_x_coordinate
58            }
59        }
60    }
61}
62
63#[cfg(test)]
64mod tests {
65    use super::*;
66    use crate::Literal;
67    use snarkvm_console_account::PrivateKey;
68    use snarkvm_console_network::MainnetV0;
69    use snarkvm_console_types::Field;
70
71    type CurrentNetwork = MainnetV0;
72
73    const ITERATIONS: u64 = 1_000;
74
75    fn check_is_owner<N: Network>(
76        view_key: ViewKey<N>,
77        owner: Owner<N, Plaintext<N>>,
78        rng: &mut TestRng,
79    ) -> Result<()> {
80        // Prepare the record.
81        let randomizer = Scalar::rand(rng);
82        let record = Record {
83            owner,
84            data: IndexMap::from_iter(vec![
85                (Identifier::from_str("a")?, Entry::Private(Plaintext::from(Literal::Field(Field::rand(rng))))),
86                (Identifier::from_str("b")?, Entry::Private(Plaintext::from(Literal::Scalar(Scalar::rand(rng))))),
87            ]),
88            nonce: N::g_scalar_multiply(&randomizer),
89            version: U8::rand(rng),
90        };
91
92        // Encrypt the record.
93        let ciphertext = record.encrypt(randomizer)?;
94
95        // Ensure the record belongs to the owner.
96        assert!(ciphertext.is_owner(&view_key));
97
98        // Sample a random view key and address.
99        let private_key = PrivateKey::<N>::new(rng)?;
100        let view_key = ViewKey::try_from(&private_key)?;
101
102        // Ensure the random address is not the owner.
103        assert!(!ciphertext.is_owner(&view_key));
104
105        Ok(())
106    }
107
108    #[test]
109    fn test_is_owner() -> Result<()> {
110        let mut rng = TestRng::default();
111
112        for _ in 0..ITERATIONS {
113            // Sample a view key and address.
114            let private_key = PrivateKey::<CurrentNetwork>::new(&mut rng)?;
115            let view_key = ViewKey::try_from(&private_key)?;
116            let address = Address::try_from(&private_key)?;
117
118            // Public owner.
119            let owner = Owner::Public(address);
120            check_is_owner::<CurrentNetwork>(view_key, owner, &mut rng)?;
121
122            // Private owner.
123            let owner = Owner::Private(Plaintext::from(Literal::Address(address)));
124            check_is_owner::<CurrentNetwork>(view_key, owner, &mut rng)?;
125        }
126        Ok(())
127    }
128}
snarkvm_console_program/data/record/is_owner.rs

snarkvm_console_program/data/record/
is_owner.rs
