Backend

rsnark_provers_core

Trait Backend 

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pub trait Backend {
    type CircuitConstraint;
    type ProvingKey;
    type VerifyingKey;
    type Proof;
    type Error: Error + Send + Sync + 'static;

    // Required methods
    fn new() -> Self;
    fn metadata(&self) -> MetadataInfo;
    fn compile(
        &self,
        circuit: &CircuitDefinition,
    ) -> Result<Self::CircuitConstraint, Self::Error>;
    fn setup(
        &self,
        cs: &Self::CircuitConstraint,
    ) -> Result<(Self::ProvingKey, Self::VerifyingKey), Self::Error>;
    fn prove(
        &self,
        cs: &Self::CircuitConstraint,
        pk: &Self::ProvingKey,
        witness: &Witness,
    ) -> Result<Self::Proof, Self::Error>;
    fn verify(
        &self,
        vk: &Self::VerifyingKey,
        proof: &Self::Proof,
        public_witness: &PublicWitness,
    ) -> Result<bool, Self::Error>;
}
Expand description

Core trait defining the interface for zero-knowledge proof backends.

This trait abstracts over different ZK-SNARK implementations (such as Groth16, PLONK, Marlin, etc.) and provides a unified interface for circuit compilation, trusted setup, proof generation, and verification.

§Type Parameters

The trait defines several associated types that must be implemented by concrete backends:

  • CircuitConstraint: The internal representation of compiled circuit constraints
  • ProvingKey: The proving key generated during the trusted setup phase
  • VerifyingKey: The verifying key generated during the trusted setup phase
  • Error: The error type for backend-specific operations

§Workflow

The typical workflow when using a backend implementation:

  1. Create a new backend instance with Backend::new()
  2. Compile the circuit definition with Backend::compile()
  3. Perform trusted setup with Backend::setup() to generate keys
  4. Generate proofs with Backend::prove()
  5. Verify proofs with Backend::verify()

Required Associated Types§

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type CircuitConstraint

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type ProvingKey

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type VerifyingKey

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type Proof

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type Error: Error + Send + Sync + 'static

Error type for backend operations that must implement standard error traits.

Required Methods§

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fn new() -> Self

Creates a new instance of the backend.

This is typically used to initialize any backend-specific state or configuration.

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fn metadata(&self) -> MetadataInfo

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fn compile( &self, circuit: &CircuitDefinition, ) -> Result<Self::CircuitConstraint, Self::Error>

Compiles a circuit definition into the backend’s internal constraint representation.

This method takes a high-level circuit definition and converts it into the specific constraint system format required by the backend implementation.

§Arguments
  • circuit - The circuit definition to compile
§Returns

Returns the compiled circuit constraints on success, or an error if compilation fails.

§Errors

This function may return an error if:

  • The circuit definition is malformed or invalid
  • The backend cannot represent the given circuit constraints
  • Internal compilation errors occur
Source

fn setup( &self, cs: &Self::CircuitConstraint, ) -> Result<(Self::ProvingKey, Self::VerifyingKey), Self::Error>

Performs the trusted setup phase to generate proving and verifying keys.

This is a critical phase in ZK-SNARK systems that generates the cryptographic keys required for proof generation and verification. The setup is specific to the compiled circuit constraints.

§Arguments
§Returns

Returns a tuple containing the proving key and verifying key on success.

§Security Note

The security of the entire proving system depends on this setup phase being performed correctly and the setup randomness being properly discarded (“toxic waste”).

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fn prove( &self, cs: &Self::CircuitConstraint, pk: &Self::ProvingKey, witness: &Witness, ) -> Result<Self::Proof, Self::Error>

Generates a zero-knowledge proof for the given witness.

Creates a cryptographic proof that demonstrates knowledge of a valid witness satisfying the circuit constraints, without revealing the witness itself.

§Arguments
  • cs - The compiled circuit constraints
  • pk - The proving key from the trusted setup
  • witness - The complete witness (both public and private inputs)
§Returns

Returns the generated proof on success.

§Errors

This function may return an error if:

  • The witness does not satisfy the circuit constraints
  • The proving key is incompatible with the circuit constraints
  • Cryptographic operations fail during proof generation
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fn verify( &self, vk: &Self::VerifyingKey, proof: &Self::Proof, public_witness: &PublicWitness, ) -> Result<bool, Self::Error>

Verifies a zero-knowledge proof against public inputs.

Checks whether a given proof is valid for the specified public witness, without requiring knowledge of the private witness components.

§Arguments
  • vk - The verifying key from the trusted setup
  • proof - The proof to verify
  • public_witness - The public inputs and outputs
§Returns

Returns true if the proof is valid, false otherwise.

§Errors

This function may return an error if:

  • The verifying key is malformed or incompatible
  • The proof format is invalid
  • Cryptographic verification operations fail

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors§