rsnark_provers_core/
backend.rs

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

rsnark_provers_core/
backend.rs
