libq/zkp/

mod.rs

//! Zero-Knowledge Proofs (ZKPs) for lib-Q
//!
//! This module provides post-quantum secure zero-knowledge proof systems,
//! primarily focusing on zk-STARKs for their scalability and transparency.
//!
//! # Features
//!
//! - **zk-STARKs**: Scalable, transparent arguments of knowledge
//! - **Post-quantum secure**: Based on collision-resistant hash functions
//! - **WASM compatible**: Full browser and Node.js support
//! - **Privacy-preserving**: Hide sensitive data while proving statements
//!
//! # Example
//!
//! ```rust
//! use libq::zkp::{ZkpProver, ZkpVerifier, ZkpProof};
//!
//! fn main() -> Result<(), Box<dyn std::error::Error>> {
//!     // Create a proof that you know a secret value without revealing it
//!     let mut prover = ZkpProver::new();
//!     let secret_value = b"secret_value";
//!     let public_statement = b"public_statement";
//!     let proof = prover.prove_secret_value(secret_value, public_statement)?;
//!
//!     // Verify the proof without learning the secret
//!     let verifier = ZkpVerifier::new();
//!     let is_valid = verifier.verify(proof, public_statement)?;
//!     Ok(())
//! }
//! ```

use crate::error::Result;

/// A zero-knowledge proof
#[derive(Debug, Clone)]
pub struct ZkpProof {
    /// The proof data
    pub data: Vec<u8>,
    /// The proof type
    pub proof_type: ProofType,
    /// Security level
    pub security_level: u32,
}

/// Types of zero-knowledge proofs supported by lib-Q
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ProofType {
    /// zk-STARK proof
    Stark,
    /// Future: zk-SNARK proof
    Snark,
    /// Future: Bulletproofs
    Bulletproof,
}

/// Prover for creating zero-knowledge proofs
pub struct ZkpProver {
    // The underlying STARK prover (temporarily disabled)
    // stark_prover: Option<StarkProver>,
}

/// Verifier for verifying zero-knowledge proofs
pub struct ZkpVerifier {
    // The underlying STARK verifier (temporarily disabled)
    // stark_verifier: Option<StarkVerifier>,
}

/// STARK-specific prover implementation
#[cfg(feature = "zkp")]
#[allow(dead_code)]
struct StarkProver {
    // Implementation details will depend on the chosen STARK library
}

/// STARK-specific verifier implementation
#[cfg(feature = "zkp")]
#[allow(dead_code)]
struct StarkVerifier {
    // Implementation details will depend on the chosen STARK library
}

// Winterfell implementations temporarily disabled
// /// Winterfell-specific prover implementation
// #[cfg(feature = "winterfell")]
// struct WinterfellProver {
//     // Implementation details will depend on the chosen STARK library
// }
//
// /// Winterfell-specific verifier implementation
// #[cfg(feature = "winterfell")]
// struct WinterfellVerifier {
//     // Implementation details will depend on the chosen STARK library
// }

impl ZkpProver {
    /// Create a new ZKP prover
    pub fn new() -> Self {
        Self {
            // stark_prover: None, // Will be initialized when needed
        }
    }

    // Create a new ZKP prover with specific backend (temporarily disabled)
    // #[cfg(feature = "stark")]
    // pub fn new_stark() -> Self {
    //     Self {
    //         stark_prover: Some(StarkProver {}),
    //     }
    // }

    // Winterfell constructor temporarily disabled
    // /// Create a new ZKP prover with Winterfell backend
    // #[cfg(feature = "winterfell")]
    // pub fn new_winterfell() -> Self {
    //     Self {
    //         stark_prover: None, // Will be replaced with WinterfellProver when implemented
    //     }
    // }

    /// Prove knowledge of a secret value without revealing it
    pub fn prove_secret_value(
        &mut self,
        _secret: &[u8],
        _public_statement: &[u8],
    ) -> Result<ZkpProof> {
        // Implementation will depend on the chosen STARK library
        // For now, return a placeholder
        Ok(ZkpProof {
            data: vec![], // Placeholder
            proof_type: ProofType::Stark,
            security_level: 128,
        })
    }

    /// Prove that a computation was performed correctly
    pub fn prove_computation(
        &mut self,
        _computation: &Computation,
        _inputs: &[u8],
        _outputs: &[u8],
    ) -> Result<ZkpProof> {
        // Implementation will depend on the chosen STARK library
        Ok(ZkpProof {
            data: vec![], // Placeholder
            proof_type: ProofType::Stark,
            security_level: 128,
        })
    }
}

impl ZkpVerifier {
    /// Create a new ZKP verifier
    pub fn new() -> Self {
        Self {
            // stark_verifier: None, // Will be initialized when needed
        }
    }

    // Create a new ZKP verifier with specific backend (temporarily disabled)
    // #[cfg(feature = "stark")]
    // pub fn new_stark() -> Self {
    //     Self {
    //         stark_verifier: Some(StarkVerifier {}),
    //     }
    // }

    // Winterfell constructor temporarily disabled
    // /// Create a new ZKP verifier with Winterfell backend
    // #[cfg(feature = "winterfell")]
    // pub fn new_winterfell() -> Self {
    //     Self {
    //         stark_verifier: None, // Will be replaced with WinterfellVerifier when implemented
    //     }
    // }

    /// Verify a zero-knowledge proof
    pub fn verify(&self, proof: ZkpProof, public_statement: &[u8]) -> Result<bool> {
        match proof.proof_type {
            ProofType::Stark => self.verify_stark(proof, public_statement),
            ProofType::Snark => Err(crate::error::Error::NotImplemented {
                feature: "zk-SNARK".to_string(),
            }),
            ProofType::Bulletproof => Err(crate::error::Error::NotImplemented {
                feature: "Bulletproofs".to_string(),
            }),
        }
    }

    /// Verify a STARK proof
    fn verify_stark(&self, _proof: ZkpProof, _public_statement: &[u8]) -> Result<bool> {
        // Implementation will depend on the chosen STARK library
        // For now, return a placeholder
        Ok(true) // Placeholder
    }
}

/// Represents a computation that can be proven with ZKPs
#[derive(Debug, Clone)]
pub struct Computation {
    /// The computation type
    pub comp_type: ComputationType,
    /// Parameters for the computation
    pub parameters: Vec<u8>,
}

/// Types of computations that can be proven
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ComputationType {
    /// Arithmetic circuit
    Arithmetic,
    /// Boolean circuit
    Boolean,
    /// Custom computation
    Custom,
}

impl Default for ZkpProver {
    fn default() -> Self {
        Self::new()
    }
}

impl Default for ZkpVerifier {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_zkp_prover_creation() {
        let _prover = ZkpProver::new();
        // assert!(prover.stark_prover.is_none()); // Temporarily disabled
    }

    #[test]
    fn test_zkp_verifier_creation() {
        let _verifier = ZkpVerifier::new();
        // assert!(verifier.stark_verifier.is_none()); // Temporarily disabled
    }

    #[test]
    fn test_proof_creation() {
        let mut prover = ZkpProver::new();
        let _secret = b"secret_value";
        let _statement = b"public_statement";

        let proof = prover
            .prove_secret_value(_secret, _statement)
            .expect("Proof creation should succeed");
        assert_eq!(proof.proof_type, ProofType::Stark);
        assert_eq!(proof.security_level, 128);
    }

    #[test]
    fn test_proof_verification() {
        let _verifier = ZkpVerifier::new();
        let proof = ZkpProof {
            data: vec![],
            proof_type: ProofType::Stark,
            security_level: 128,
        };
        let _statement = b"public_statement";

        let is_valid = _verifier
            .verify(proof, _statement)
            .expect("Proof verification should succeed");
        assert!(is_valid); // Placeholder implementation returns true
    }
}