1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53

// Copyright 2019. The Tari Project
//
// Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
// following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
// disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
// following disclaimer in the documentation and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote
// products derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
// USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

use crate::{
    commitment::HomomorphicCommitment,
    keys::{PublicKey, SecretKey},
};
use serde::{Deserialize, Serialize};
use thiserror::Error;

#[derive(Debug, Clone, Error, PartialEq, Deserialize, Serialize)]
pub enum RangeProofError {
    #[error("Could not construct range proof")]
    ProofConstructionError,
    #[error("The deserialization of the range proof failed")]
    InvalidProof,
    #[error("Invalid input was provided to the RangeProofService constructor")]
    InitializationError,
}

pub trait RangeProofService {
    type P: Sized;
    type K: SecretKey;
    type PK: PublicKey<K = Self::K>;

    /// Construct a new range proof for the given secret key and value. The resulting proof will be sufficient
    /// evidence that the prover knows the secret key and value, and that the value lies in the range determined by
    /// the service.
    fn construct_proof(&self, key: &Self::K, value: u64) -> Result<Self::P, RangeProofError>;

    /// Verify the range proof against the given commitment. If this function returns true, it attests to the
    /// commitment having a value in the range [0; 2^64-1] and that the prover knew both the value and private key.
    fn verify(&self, proof: &Self::P, commitment: &HomomorphicCommitment<Self::PK>) -> bool;
}