1//! This module defines a collection of traits that define the behavior of a commitment engine
 2//! We require the commitment engine to provide a commitment to vectors with a single group element
 3use crate::{
 4  errors::NovaError,
 5  traits::{AbsorbInROTrait, Group, TranscriptReprTrait},
 6};
 7use core::{
 8  fmt::Debug,
 9  ops::{Add, AddAssign},
10};
11use serde::{Deserialize, Serialize};
12
13use super::ScalarMul;
14
15/// Defines basic operations on commitments
16pub trait CommitmentOps<Rhs = Self, Output = Self>:
17  Add<Rhs, Output = Output> + AddAssign<Rhs>
18{
19}
20
21impl<T, Rhs, Output> CommitmentOps<Rhs, Output> for T where
22  T: Add<Rhs, Output = Output> + AddAssign<Rhs>
23{
24}
25
26/// A helper trait for references with a commitment operation
27pub trait CommitmentOpsOwned<Rhs = Self, Output = Self>:
28  for<'r> CommitmentOps<&'r Rhs, Output>
29{
30}
31impl<T, Rhs, Output> CommitmentOpsOwned<Rhs, Output> for T where
32  T: for<'r> CommitmentOps<&'r Rhs, Output>
33{
34}
35
36/// This trait defines the behavior of the commitment
37pub trait CommitmentTrait<G: Group>:
38  Clone
39  + Copy
40  + Debug
41  + Default
42  + PartialEq
43  + Eq
44  + Send
45  + Sync
46  + TranscriptReprTrait<G>
47  + Serialize
48  + for<'de> Deserialize<'de>
49  + AbsorbInROTrait<G>
50  + CommitmentOps
51  + CommitmentOpsOwned
52  + ScalarMul<G::Scalar>
53{
54  /// Holds the type of the compressed commitment
55  type CompressedCommitment: Clone
56    + Debug
57    + PartialEq
58    + Eq
59    + Send
60    + Sync
61    + TranscriptReprTrait<G>
62    + Serialize
63    + for<'de> Deserialize<'de>;
64
65  /// Compresses self into a compressed commitment
66  fn compress(&self) -> Self::CompressedCommitment;
67
68  /// Returns the coordinate representation of the commitment
69  fn to_coordinates(&self) -> (G::Base, G::Base, bool);
70
71  /// Decompresses a compressed commitment into a commitment
72  fn decompress(c: &Self::CompressedCommitment) -> Result<Self, NovaError>;
73}
74
75/// A trait that ties different pieces of the commitment generation together
76pub trait CommitmentEngineTrait<G: Group>:
77  Clone + Send + Sync + Serialize + for<'de> Deserialize<'de>
78{
79  /// Holds the type of the commitment key
80  type CommitmentKey: Clone + Debug + Send + Sync + Serialize + for<'de> Deserialize<'de>;
81
82  /// Holds the type of the commitment
83  type Commitment: CommitmentTrait<G>;
84
85  /// Samples a new commitment key of a specified size
86  fn setup(label: &'static [u8], n: usize) -> Self::CommitmentKey;
87
88  /// Commits to the provided vector using the provided generators
89  fn commit(ck: &Self::CommitmentKey, v: &[G::Scalar]) -> Self::Commitment;
90}