rsnark_provers_core/
backend.rs

1use rsnark_core::{
2    MetadataInfo,
3    types::{CircuitDefinition, PublicWitness, Witness},
4};
5
6/// Core trait defining the interface for zero-knowledge proof backends.
7///
8/// This trait abstracts over different ZK-SNARK implementations (such as Groth16, PLONK, Marlin, etc.)
9/// and provides a unified interface for circuit compilation, trusted setup, proof generation, and verification.
10///
11/// ## Type Parameters
12///
13/// The trait defines several associated types that must be implemented by concrete backends:
14/// - `CircuitConstraint`: The internal representation of compiled circuit constraints
15/// - `ProvingKey`: The proving key generated during the trusted setup phase
16/// - `VerifyingKey`: The verifying key generated during the trusted setup phase  
17/// - `Error`: The error type for backend-specific operations
18///
19/// ## Workflow
20///
21/// The typical workflow when using a backend implementation:
22/// 1. Create a new backend instance with [`Backend::new()`]
23/// 2. Compile the circuit definition with [`Backend::compile()`]
24/// 3. Perform trusted setup with [`Backend::setup()`] to generate keys
25/// 4. Generate proofs with [`Backend::prove()`]
26/// 5. Verify proofs with [`Backend::verify()`]
27///
28pub trait Backend {
29    type CircuitConstraint;
30    type ProvingKey;
31    type VerifyingKey;
32    type Proof;
33
34    /// Error type for backend operations that must implement standard error traits.
35    type Error: std::error::Error + Send + Sync + 'static;
36
37    /// Creates a new instance of the backend.
38    ///
39    /// This is typically used to initialize any backend-specific state or configuration.
40    fn new() -> Self;
41
42    fn metadata(&self) -> MetadataInfo;
43
44    /// Compiles a circuit definition into the backend's internal constraint representation.
45    ///
46    /// This method takes a high-level circuit definition and converts it into the specific
47    /// constraint system format required by the backend implementation.
48    ///
49    /// # Arguments
50    ///
51    /// * `circuit` - The circuit definition to compile
52    ///
53    /// # Returns
54    ///
55    /// Returns the compiled circuit constraints on success, or an error if compilation fails.
56    ///
57    /// # Errors
58    ///
59    /// This function may return an error if:
60    /// - The circuit definition is malformed or invalid
61    /// - The backend cannot represent the given circuit constraints
62    /// - Internal compilation errors occur
63    fn compile(&self, circuit: &CircuitDefinition) -> Result<Self::CircuitConstraint, Self::Error>;
64
65    /// Performs the trusted setup phase to generate proving and verifying keys.
66    ///
67    /// This is a critical phase in ZK-SNARK systems that generates the cryptographic keys
68    /// required for proof generation and verification. The setup is specific to the compiled
69    /// circuit constraints.
70    ///
71    /// # Arguments
72    ///
73    /// * `cs` - The compiled circuit constraints from [`Backend::compile()`]
74    ///
75    /// # Returns
76    ///
77    /// Returns a tuple containing the proving key and verifying key on success.
78    ///
79    /// # Security Note
80    ///
81    /// The security of the entire proving system depends on this setup phase being performed
82    /// correctly and the setup randomness being properly discarded ("toxic waste").
83    fn setup(
84        &self,
85        cs: &Self::CircuitConstraint,
86    ) -> Result<(Self::ProvingKey, Self::VerifyingKey), Self::Error>;
87
88    /// Generates a zero-knowledge proof for the given witness.
89    ///
90    /// Creates a cryptographic proof that demonstrates knowledge of a valid witness
91    /// satisfying the circuit constraints, without revealing the witness itself.
92    ///
93    /// # Arguments
94    ///
95    /// * `cs` - The compiled circuit constraints
96    /// * `pk` - The proving key from the trusted setup
97    /// * `witness` - The complete witness (both public and private inputs)
98    ///
99    /// # Returns
100    ///
101    /// Returns the generated proof on success.
102    ///
103    /// # Errors
104    ///
105    /// This function may return an error if:
106    /// - The witness does not satisfy the circuit constraints
107    /// - The proving key is incompatible with the circuit constraints
108    /// - Cryptographic operations fail during proof generation
109    fn prove(
110        &self,
111        cs: &Self::CircuitConstraint,
112        pk: &Self::ProvingKey,
113        witness: &Witness,
114    ) -> Result<Self::Proof, Self::Error>;
115
116    /// Verifies a zero-knowledge proof against public inputs.
117    ///
118    /// Checks whether a given proof is valid for the specified public witness,
119    /// without requiring knowledge of the private witness components.
120    ///
121    /// # Arguments
122    ///
123    /// * `vk` - The verifying key from the trusted setup
124    /// * `proof` - The proof to verify
125    /// * `public_witness` - The public inputs and outputs
126    ///
127    /// # Returns
128    ///
129    /// Returns `true` if the proof is valid, `false` otherwise.
130    ///
131    /// # Errors
132    ///
133    /// This function may return an error if:
134    /// - The verifying key is malformed or incompatible
135    /// * The proof format is invalid
136    /// - Cryptographic verification operations fail
137    fn verify(
138        &self,
139        vk: &Self::VerifyingKey,
140        proof: &Self::Proof,
141        public_witness: &PublicWitness,
142    ) -> Result<bool, Self::Error>;
143}
rsnark_provers_core/backend.rs

rsnark_provers_core/
backend.rs
