trustformers_mobile/

advanced_security.rs

//! Advanced Security Features for Mobile AI
//!
//! This module provides next-generation security features for mobile AI applications,
//! including homomorphic encryption, secure multi-party computation, zero-knowledge
//! proofs, and quantum-resistant cryptography.

use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use trustformers_core::errors::{invalid_input, tensor_op_error, Result};
use trustformers_core::Tensor;

/// Advanced security configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AdvancedSecurityConfig {
    /// Enable homomorphic encryption for private inference
    pub homomorphic_encryption: HomomorphicConfig,
    /// Secure multi-party computation settings
    pub secure_multiparty: SecureMultipartyConfig,
    /// Zero-knowledge proof configuration
    pub zero_knowledge_proofs: ZKProofConfig,
    /// Quantum-resistant cryptography settings
    pub quantum_resistant: QuantumResistantConfig,
}

/// Homomorphic encryption configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct HomomorphicConfig {
    /// Enable homomorphic encryption
    pub enabled: bool,
    /// Encryption scheme to use
    pub scheme: HomomorphicScheme,
    /// Security level (key size)
    pub security_level: SecurityLevel,
    /// Optimization settings
    pub optimization: EncryptionOptimization,
}

/// Homomorphic encryption schemes
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum HomomorphicScheme {
    /// Brakerski-Gentry-Vaikuntanathan (BGV) scheme
    BGV,
    /// Brakerski/Fan-Vercauteren (BFV) scheme
    BFV,
    /// Cheon-Kim-Kim-Song (CKKS) scheme for approximate computation
    CKKS,
    /// Torus Fully Homomorphic Encryption
    TFHE,
}

/// Security levels for encryption
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum SecurityLevel {
    /// 128-bit security (fastest)
    Bit128,
    /// 192-bit security (balanced)
    Bit192,
    /// 256-bit security (most secure)
    Bit256,
}

/// Encryption optimization settings
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct EncryptionOptimization {
    /// Use batching for efficiency
    pub enable_batching: bool,
    /// Use bootstrapping for depth optimization
    pub enable_bootstrapping: bool,
    /// Relinearization threshold
    pub relinearization_threshold: usize,
    /// Memory vs computation tradeoff
    pub memory_optimization: bool,
}

/// Secure multi-party computation configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SecureMultipartyConfig {
    /// Enable secure multi-party computation
    pub enabled: bool,
    /// Number of parties
    pub num_parties: usize,
    /// Threshold for secret sharing
    pub threshold: usize,
    /// MPC protocol to use
    pub protocol: MPCProtocol,
    /// Communication settings
    pub communication: MPCCommunication,
}

/// Multi-party computation protocols
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum MPCProtocol {
    /// Shamir's Secret Sharing
    ShamirSecretSharing,
    /// Garbled Circuits
    GarbledCircuits,
    /// BGW Protocol
    BGW,
    /// GMW Protocol
    GMW,
}

/// MPC communication configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MPCCommunication {
    /// Use secure channels
    pub secure_channels: bool,
    /// Timeout for operations (seconds)
    pub timeout_seconds: u64,
    /// Maximum message size
    pub max_message_size: usize,
    /// Compression settings
    pub enable_compression: bool,
}

/// Zero-knowledge proof configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ZKProofConfig {
    /// Enable zero-knowledge proofs
    pub enabled: bool,
    /// Proof system to use
    pub proof_system: ZKProofSystem,
    /// Verification settings
    pub verification: ZKVerificationConfig,
}

/// Zero-knowledge proof systems
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum ZKProofSystem {
    /// zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge)
    ZkSNARKs,
    /// zk-STARKs (Zero-Knowledge Scalable Transparent Arguments of Knowledge)
    ZkSTARKs,
    /// Bulletproofs
    Bulletproofs,
    /// Plonk
    Plonk,
}

/// Zero-knowledge verification configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ZKVerificationConfig {
    /// Enable batch verification
    pub batch_verification: bool,
    /// Verification timeout (seconds)
    pub timeout_seconds: u64,
    /// Cache verification results
    pub cache_results: bool,
    /// Maximum proof size
    pub max_proof_size: usize,
}

/// Quantum-resistant cryptography configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QuantumResistantConfig {
    /// Enable quantum-resistant algorithms
    pub enabled: bool,
    /// Primary encryption algorithm
    pub encryption_algorithm: QuantumResistantAlgorithm,
    /// Digital signature algorithm
    pub signature_algorithm: QuantumResistantSignature,
    /// Key exchange mechanism
    pub key_exchange: QuantumResistantKeyExchange,
}

/// Quantum-resistant encryption algorithms
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum QuantumResistantAlgorithm {
    /// Lattice-based encryption (e.g., Kyber)
    Kyber,
    /// Code-based encryption (e.g., Classic McEliece)
    ClassicMcEliece,
    /// Multivariate encryption
    Multivariate,
    /// Hash-based encryption
    HashBased,
}

/// Quantum-resistant digital signatures
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum QuantumResistantSignature {
    /// CRYSTALS-Dilithium
    Dilithium,
    /// Falcon
    Falcon,
    /// SPHINCS+
    SPHINCS,
}

/// Quantum-resistant key exchange
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum QuantumResistantKeyExchange {
    /// Kyber KEM
    KyberKEM,
    /// SIKE (Supersingular Isogeny Key Encapsulation)
    SIKE,
    /// NTRU
    NTRU,
}

/// Homomorphic encryption engine
pub struct HomomorphicEncryptionEngine {
    config: HomomorphicConfig,
    public_key: Vec<u8>,     // Placeholder for actual key
    private_key: Vec<u8>,    // Placeholder for actual key
    evaluation_key: Vec<u8>, // Placeholder for actual key
}

impl HomomorphicEncryptionEngine {
    /// Create a new homomorphic encryption engine
    pub fn new(config: HomomorphicConfig) -> Result<Self> {
        // Generate keys based on the scheme and security level
        let (public_key, private_key, evaluation_key) = Self::generate_keys(&config)?;

        Ok(Self {
            config,
            public_key,
            private_key,
            evaluation_key,
        })
    }

    /// Generate encryption keys
    fn generate_keys(config: &HomomorphicConfig) -> Result<(Vec<u8>, Vec<u8>, Vec<u8>)> {
        // Placeholder key generation - in a real implementation, this would use
        // libraries like Microsoft SEAL, HEAAN, or similar
        let key_size = match config.security_level {
            SecurityLevel::Bit128 => 128,
            SecurityLevel::Bit192 => 192,
            SecurityLevel::Bit256 => 256,
        };

        // Simplified key generation (in reality, this would be much more complex)
        let public_key = vec![0u8; key_size];
        let private_key = vec![1u8; key_size];
        let evaluation_key = vec![2u8; key_size * 2];

        Ok((public_key, private_key, evaluation_key))
    }

    /// Encrypt a tensor using homomorphic encryption
    pub fn encrypt(&self, tensor: &Tensor) -> Result<EncryptedTensor> {
        match &self.config.scheme {
            HomomorphicScheme::CKKS => self.encrypt_ckks(tensor),
            HomomorphicScheme::BFV => self.encrypt_bfv(tensor),
            HomomorphicScheme::BGV => self.encrypt_bgv(tensor),
            HomomorphicScheme::TFHE => self.encrypt_tfhe(tensor),
        }
    }

    /// Decrypt an encrypted tensor
    pub fn decrypt(&self, encrypted: &EncryptedTensor) -> Result<Tensor> {
        match encrypted.scheme {
            HomomorphicScheme::CKKS => self.decrypt_ckks(encrypted),
            HomomorphicScheme::BFV => self.decrypt_bfv(encrypted),
            HomomorphicScheme::BGV => self.decrypt_bgv(encrypted),
            HomomorphicScheme::TFHE => self.decrypt_tfhe(encrypted),
        }
    }

    /// Perform homomorphic addition
    pub fn add_encrypted(
        &self,
        a: &EncryptedTensor,
        b: &EncryptedTensor,
    ) -> Result<EncryptedTensor> {
        // Verify compatibility
        if a.scheme != b.scheme || a.shape != b.shape {
            return Err(invalid_input("Incompatible encrypted tensors for addition"));
        }

        // Perform homomorphic addition (placeholder implementation)
        let mut result_data = a.data.clone();
        for (i, val) in b.data.iter().enumerate() {
            if i < result_data.len() {
                result_data[i] ^= val; // Simplified XOR operation
            }
        }

        Ok(EncryptedTensor {
            data: result_data,
            shape: a.shape.clone(),
            scheme: a.scheme.clone(),
            noise_budget: (a.noise_budget + b.noise_budget) / 2,
        })
    }

    /// Perform homomorphic multiplication
    pub fn multiply_encrypted(
        &self,
        a: &EncryptedTensor,
        b: &EncryptedTensor,
    ) -> Result<EncryptedTensor> {
        // Verify compatibility
        if a.scheme != b.scheme || a.shape != b.shape {
            return Err(invalid_input(
                "Incompatible encrypted tensors for multiplication",
            ));
        }

        // Perform homomorphic multiplication (placeholder implementation)
        let mut result_data = Vec::new();
        for (i, val_a) in a.data.iter().enumerate() {
            if i < b.data.len() {
                result_data.push(val_a.wrapping_add(b.data[i])); // Simplified operation
            }
        }

        Ok(EncryptedTensor {
            data: result_data,
            shape: a.shape.clone(),
            scheme: a.scheme.clone(),
            noise_budget: (a.noise_budget * b.noise_budget) / 100, // Noise grows with multiplication
        })
    }

    /// Perform private inference on encrypted data
    pub fn private_inference<F>(
        &self,
        encrypted_input: &EncryptedTensor,
        model_fn: F,
    ) -> Result<EncryptedTensor>
    where
        F: Fn(&EncryptedTensor) -> Result<EncryptedTensor>,
    {
        // Verify noise budget
        if encrypted_input.noise_budget < 10 {
            return Err(tensor_op_error(
                "Insufficient noise budget for secure computation",
                "homomorphic_inference",
            ));
        }

        // Apply the model function to encrypted data
        let result = model_fn(encrypted_input)?;

        // Verify result integrity
        if result.noise_budget < 5 {
            return Err(tensor_op_error(
                "Computation exceeded noise budget",
                "homomorphic_inference",
            ));
        }

        Ok(result)
    }

    // Scheme-specific encryption methods (placeholders)
    fn encrypt_ckks(&self, tensor: &Tensor) -> Result<EncryptedTensor> {
        let data = self.serialize_tensor_for_encryption(tensor)?;
        Ok(EncryptedTensor {
            data,
            shape: tensor.shape().to_vec(),
            scheme: HomomorphicScheme::CKKS,
            noise_budget: 100, // Initial noise budget
        })
    }

    fn encrypt_bfv(&self, tensor: &Tensor) -> Result<EncryptedTensor> {
        let data = self.serialize_tensor_for_encryption(tensor)?;
        Ok(EncryptedTensor {
            data,
            shape: tensor.shape().to_vec(),
            scheme: HomomorphicScheme::BFV,
            noise_budget: 100,
        })
    }

    fn encrypt_bgv(&self, tensor: &Tensor) -> Result<EncryptedTensor> {
        let data = self.serialize_tensor_for_encryption(tensor)?;
        Ok(EncryptedTensor {
            data,
            shape: tensor.shape().to_vec(),
            scheme: HomomorphicScheme::BGV,
            noise_budget: 100,
        })
    }

    fn encrypt_tfhe(&self, tensor: &Tensor) -> Result<EncryptedTensor> {
        let data = self.serialize_tensor_for_encryption(tensor)?;
        Ok(EncryptedTensor {
            data,
            shape: tensor.shape().to_vec(),
            scheme: HomomorphicScheme::TFHE,
            noise_budget: 100,
        })
    }

    // Scheme-specific decryption methods (placeholders)
    fn decrypt_ckks(&self, encrypted: &EncryptedTensor) -> Result<Tensor> {
        self.deserialize_tensor_from_encryption(&encrypted.data, &encrypted.shape)
    }

    fn decrypt_bfv(&self, encrypted: &EncryptedTensor) -> Result<Tensor> {
        self.deserialize_tensor_from_encryption(&encrypted.data, &encrypted.shape)
    }

    fn decrypt_bgv(&self, encrypted: &EncryptedTensor) -> Result<Tensor> {
        self.deserialize_tensor_from_encryption(&encrypted.data, &encrypted.shape)
    }

    fn decrypt_tfhe(&self, encrypted: &EncryptedTensor) -> Result<Tensor> {
        self.deserialize_tensor_from_encryption(&encrypted.data, &encrypted.shape)
    }

    // Helper methods
    fn serialize_tensor_for_encryption(&self, tensor: &Tensor) -> Result<Vec<u8>> {
        // Simplified serialization - in practice, this would depend on the scheme
        let data = tensor.to_vec_f32()?;
        let mut bytes = Vec::new();
        for value in data {
            bytes.extend_from_slice(&value.to_ne_bytes());
        }
        Ok(bytes)
    }

    fn deserialize_tensor_from_encryption(&self, data: &[u8], shape: &[usize]) -> Result<Tensor> {
        // Simplified deserialization
        let mut values = Vec::new();
        for chunk in data.chunks(4) {
            if chunk.len() == 4 {
                let bytes: [u8; 4] = chunk
                    .try_into()
                    .map_err(|_| tensor_op_error("Invalid byte chunk", "homomorphic_decrypt"))?;
                values.push(f32::from_ne_bytes(bytes));
            }
        }

        Tensor::from_vec(values, shape)
    }
}

/// Encrypted tensor representation
#[derive(Debug, Clone)]
pub struct EncryptedTensor {
    /// Encrypted data
    pub data: Vec<u8>,
    /// Original tensor shape
    pub shape: Vec<usize>,
    /// Encryption scheme used
    pub scheme: HomomorphicScheme,
    /// Remaining noise budget
    pub noise_budget: u32,
}

/// Secure multi-party computation engine
pub struct SecureMultipartyEngine {
    config: SecureMultipartyConfig,
    party_id: usize,
    shares: HashMap<String, Vec<u8>>,
}

impl SecureMultipartyEngine {
    /// Create a new secure multi-party computation engine
    pub fn new(config: SecureMultipartyConfig, party_id: usize) -> Result<Self> {
        if party_id >= config.num_parties {
            return Err(invalid_input("Party ID exceeds number of parties"));
        }

        Ok(Self {
            config,
            party_id,
            shares: HashMap::new(),
        })
    }

    /// Create secret shares of a tensor
    pub fn create_shares(&mut self, tensor: &Tensor, secret_id: String) -> Result<Vec<Vec<u8>>> {
        match self.config.protocol {
            MPCProtocol::ShamirSecretSharing => self.shamir_share(tensor, secret_id),
            MPCProtocol::GarbledCircuits => self.garbled_circuits_share(tensor, secret_id),
            MPCProtocol::BGW => self.bgw_share(tensor, secret_id),
            MPCProtocol::GMW => self.gmw_share(tensor, secret_id),
        }
    }

    /// Reconstruct a tensor from shares
    pub fn reconstruct_secret(&self, shares: &[Vec<u8>], secret_id: &str) -> Result<Tensor> {
        match self.config.protocol {
            MPCProtocol::ShamirSecretSharing => self.shamir_reconstruct(shares, secret_id),
            MPCProtocol::GarbledCircuits => self.garbled_circuits_reconstruct(shares, secret_id),
            MPCProtocol::BGW => self.bgw_reconstruct(shares, secret_id),
            MPCProtocol::GMW => self.gmw_reconstruct(shares, secret_id),
        }
    }

    /// Perform secure computation on shared data
    pub fn secure_computation<F>(&self, operation: F) -> Result<Vec<u8>>
    where
        F: Fn(&[Vec<u8>]) -> Result<Vec<u8>>,
    {
        // Collect shares from all parties (placeholder)
        let shares: Vec<Vec<u8>> = self.shares.values().cloned().collect();

        // Perform computation
        operation(&shares)
    }

    // Protocol-specific implementations (placeholders)
    fn shamir_share(&mut self, tensor: &Tensor, secret_id: String) -> Result<Vec<Vec<u8>>> {
        let data = tensor.to_vec_f32()?;
        let mut shares = Vec::new();

        // Simplified Shamir's secret sharing
        for i in 0..self.config.num_parties {
            let mut share = Vec::new();
            for value in &data {
                // Simple polynomial evaluation (placeholder)
                let share_value = value + (i as f32 * 0.1);
                share.extend_from_slice(&share_value.to_ne_bytes());
            }
            shares.push(share);
        }

        // Store our share
        if let Some(our_share) = shares.get(self.party_id) {
            self.shares.insert(secret_id, our_share.clone());
        }

        Ok(shares)
    }

    fn shamir_reconstruct(&self, shares: &[Vec<u8>], _secret_id: &str) -> Result<Tensor> {
        if shares.len() < self.config.threshold {
            return Err(tensor_op_error(
                "Insufficient shares for reconstruction",
                "shamir_reconstruct",
            ));
        }

        // Simplified reconstruction (placeholder)
        let first_share = &shares[0];
        let mut values = Vec::new();

        for chunk in first_share.chunks(4) {
            if chunk.len() == 4 {
                let bytes: [u8; 4] = chunk
                    .try_into()
                    .map_err(|_| tensor_op_error("Invalid share chunk", "shamir_reconstruct"))?;
                values.push(f32::from_ne_bytes(bytes));
            }
        }

        // For now, return a simple tensor (placeholder)
        let values_len = values.len();
        Tensor::from_vec(values, &[values_len])
    }

    fn garbled_circuits_share(
        &mut self,
        _tensor: &Tensor,
        _secret_id: String,
    ) -> Result<Vec<Vec<u8>>> {
        // Placeholder implementation
        Ok(vec![vec![0u8; 32]; self.config.num_parties])
    }

    fn garbled_circuits_reconstruct(
        &self,
        _shares: &[Vec<u8>],
        _secret_id: &str,
    ) -> Result<Tensor> {
        // Placeholder implementation
        Tensor::zeros(&[1])
    }

    fn bgw_share(&mut self, _tensor: &Tensor, _secret_id: String) -> Result<Vec<Vec<u8>>> {
        // Placeholder implementation
        Ok(vec![vec![0u8; 32]; self.config.num_parties])
    }

    fn bgw_reconstruct(&self, _shares: &[Vec<u8>], _secret_id: &str) -> Result<Tensor> {
        // Placeholder implementation
        Tensor::zeros(&[1])
    }

    fn gmw_share(&mut self, _tensor: &Tensor, _secret_id: String) -> Result<Vec<Vec<u8>>> {
        // Placeholder implementation
        Ok(vec![vec![0u8; 32]; self.config.num_parties])
    }

    fn gmw_reconstruct(&self, _shares: &[Vec<u8>], _secret_id: &str) -> Result<Tensor> {
        // Placeholder implementation
        Tensor::zeros(&[1])
    }
}

/// Zero-knowledge proof engine
pub struct ZeroKnowledgeProofEngine {
    config: ZKProofConfig,
    proving_key: Vec<u8>,
    verification_key: Vec<u8>,
}

impl ZeroKnowledgeProofEngine {
    /// Create a new zero-knowledge proof engine
    pub fn new(config: ZKProofConfig) -> Result<Self> {
        let (proving_key, verification_key) = Self::generate_keys(&config)?;

        Ok(Self {
            config,
            proving_key,
            verification_key,
        })
    }

    /// Generate proving and verification keys
    fn generate_keys(config: &ZKProofConfig) -> Result<(Vec<u8>, Vec<u8>)> {
        // Placeholder key generation
        let key_size = match config.proof_system {
            ZKProofSystem::ZkSNARKs => 256,
            ZKProofSystem::ZkSTARKs => 512,
            ZKProofSystem::Bulletproofs => 128,
            ZKProofSystem::Plonk => 256,
        };

        Ok((vec![1u8; key_size], vec![2u8; key_size / 2]))
    }

    /// Generate a zero-knowledge proof for model verification
    pub fn prove_model_integrity(&self, model_hash: &[u8], witness: &[u8]) -> Result<ZKProof> {
        match self.config.proof_system {
            ZKProofSystem::ZkSNARKs => self.generate_snark_proof(model_hash, witness),
            ZKProofSystem::ZkSTARKs => self.generate_stark_proof(model_hash, witness),
            ZKProofSystem::Bulletproofs => self.generate_bulletproof(model_hash, witness),
            ZKProofSystem::Plonk => self.generate_plonk_proof(model_hash, witness),
        }
    }

    /// Verify a zero-knowledge proof
    pub fn verify_proof(&self, proof: &ZKProof, public_inputs: &[u8]) -> Result<bool> {
        // Check proof size
        if proof.data.len() > self.config.verification.max_proof_size {
            return Ok(false);
        }

        match proof.system {
            ZKProofSystem::ZkSNARKs => self.verify_snark_proof(proof, public_inputs),
            ZKProofSystem::ZkSTARKs => self.verify_stark_proof(proof, public_inputs),
            ZKProofSystem::Bulletproofs => self.verify_bulletproof(proof, public_inputs),
            ZKProofSystem::Plonk => self.verify_plonk_proof(proof, public_inputs),
        }
    }

    // Proof generation methods (placeholders)
    fn generate_snark_proof(&self, model_hash: &[u8], witness: &[u8]) -> Result<ZKProof> {
        let mut proof_data = Vec::new();
        proof_data.extend_from_slice(model_hash);
        proof_data.extend_from_slice(witness);
        proof_data.extend_from_slice(&self.proving_key[..32]);

        Ok(ZKProof {
            data: proof_data,
            system: ZKProofSystem::ZkSNARKs,
            timestamp: std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("SystemTime before UNIX_EPOCH")
                .as_secs(),
        })
    }

    fn generate_stark_proof(&self, model_hash: &[u8], witness: &[u8]) -> Result<ZKProof> {
        let mut proof_data = Vec::new();
        proof_data.extend_from_slice(model_hash);
        proof_data.extend_from_slice(witness);

        Ok(ZKProof {
            data: proof_data,
            system: ZKProofSystem::ZkSTARKs,
            timestamp: std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("SystemTime before UNIX_EPOCH")
                .as_secs(),
        })
    }

    fn generate_bulletproof(&self, model_hash: &[u8], witness: &[u8]) -> Result<ZKProof> {
        let mut proof_data = Vec::new();
        proof_data.extend_from_slice(model_hash);
        proof_data.extend_from_slice(witness);

        Ok(ZKProof {
            data: proof_data,
            system: ZKProofSystem::Bulletproofs,
            timestamp: std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("SystemTime before UNIX_EPOCH")
                .as_secs(),
        })
    }

    fn generate_plonk_proof(&self, model_hash: &[u8], witness: &[u8]) -> Result<ZKProof> {
        let mut proof_data = Vec::new();
        proof_data.extend_from_slice(model_hash);
        proof_data.extend_from_slice(witness);

        Ok(ZKProof {
            data: proof_data,
            system: ZKProofSystem::Plonk,
            timestamp: std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("SystemTime before UNIX_EPOCH")
                .as_secs(),
        })
    }

    // Proof verification methods (placeholders)
    fn verify_snark_proof(&self, proof: &ZKProof, _public_inputs: &[u8]) -> Result<bool> {
        // Simplified verification
        Ok(proof.data.len() > 32 && proof.system == ZKProofSystem::ZkSNARKs)
    }

    fn verify_stark_proof(&self, proof: &ZKProof, _public_inputs: &[u8]) -> Result<bool> {
        Ok(proof.data.len() > 32 && proof.system == ZKProofSystem::ZkSTARKs)
    }

    fn verify_bulletproof(&self, proof: &ZKProof, _public_inputs: &[u8]) -> Result<bool> {
        Ok(proof.data.len() > 32 && proof.system == ZKProofSystem::Bulletproofs)
    }

    fn verify_plonk_proof(&self, proof: &ZKProof, _public_inputs: &[u8]) -> Result<bool> {
        Ok(proof.data.len() > 32 && proof.system == ZKProofSystem::Plonk)
    }
}

/// Zero-knowledge proof representation
#[derive(Debug, Clone)]
pub struct ZKProof {
    /// Proof data
    pub data: Vec<u8>,
    /// Proof system used
    pub system: ZKProofSystem,
    /// Timestamp when proof was generated
    pub timestamp: u64,
}

/// Quantum-resistant cryptography engine
pub struct QuantumResistantEngine {
    config: QuantumResistantConfig,
    encryption_keys: (Vec<u8>, Vec<u8>), // (public, private)
    signature_keys: (Vec<u8>, Vec<u8>),  // (public, private)
}

impl QuantumResistantEngine {
    /// Create a new quantum-resistant cryptography engine
    pub fn new(config: QuantumResistantConfig) -> Result<Self> {
        let encryption_keys = Self::generate_encryption_keys(&config.encryption_algorithm)?;
        let signature_keys = Self::generate_signature_keys(&config.signature_algorithm)?;

        Ok(Self {
            config,
            encryption_keys,
            signature_keys,
        })
    }

    /// Generate quantum-resistant encryption keys
    fn generate_encryption_keys(
        algorithm: &QuantumResistantAlgorithm,
    ) -> Result<(Vec<u8>, Vec<u8>)> {
        let key_size = match algorithm {
            QuantumResistantAlgorithm::Kyber => (1568, 3168), // Kyber-1024 approximate sizes
            QuantumResistantAlgorithm::ClassicMcEliece => (261120, 13892), // McEliece348864
            QuantumResistantAlgorithm::Multivariate => (1024, 2048),
            QuantumResistantAlgorithm::HashBased => (64, 128),
        };

        Ok((vec![1u8; key_size.0], vec![2u8; key_size.1]))
    }

    /// Generate quantum-resistant signature keys
    fn generate_signature_keys(
        algorithm: &QuantumResistantSignature,
    ) -> Result<(Vec<u8>, Vec<u8>)> {
        let key_size = match algorithm {
            QuantumResistantSignature::Dilithium => (1952, 4864), // Dilithium5
            QuantumResistantSignature::Falcon => (1793, 2305),    // Falcon-1024
            QuantumResistantSignature::SPHINCS => (64, 128),      // SPHINCS+-256
        };

        Ok((vec![3u8; key_size.0], vec![4u8; key_size.1]))
    }

    /// Encrypt data using quantum-resistant algorithms
    pub fn encrypt(&self, data: &[u8]) -> Result<Vec<u8>> {
        match self.config.encryption_algorithm {
            QuantumResistantAlgorithm::Kyber => self.kyber_encrypt(data),
            QuantumResistantAlgorithm::ClassicMcEliece => self.mceliece_encrypt(data),
            QuantumResistantAlgorithm::Multivariate => self.multivariate_encrypt(data),
            QuantumResistantAlgorithm::HashBased => self.hash_based_encrypt(data),
        }
    }

    /// Decrypt data using quantum-resistant algorithms
    pub fn decrypt(&self, encrypted_data: &[u8]) -> Result<Vec<u8>> {
        match self.config.encryption_algorithm {
            QuantumResistantAlgorithm::Kyber => self.kyber_decrypt(encrypted_data),
            QuantumResistantAlgorithm::ClassicMcEliece => self.mceliece_decrypt(encrypted_data),
            QuantumResistantAlgorithm::Multivariate => self.multivariate_decrypt(encrypted_data),
            QuantumResistantAlgorithm::HashBased => self.hash_based_decrypt(encrypted_data),
        }
    }

    /// Sign data using quantum-resistant digital signatures
    pub fn sign(&self, data: &[u8]) -> Result<Vec<u8>> {
        match self.config.signature_algorithm {
            QuantumResistantSignature::Dilithium => self.dilithium_sign(data),
            QuantumResistantSignature::Falcon => self.falcon_sign(data),
            QuantumResistantSignature::SPHINCS => self.sphincs_sign(data),
        }
    }

    /// Verify a quantum-resistant digital signature
    pub fn verify(&self, data: &[u8], signature: &[u8]) -> Result<bool> {
        match self.config.signature_algorithm {
            QuantumResistantSignature::Dilithium => self.dilithium_verify(data, signature),
            QuantumResistantSignature::Falcon => self.falcon_verify(data, signature),
            QuantumResistantSignature::SPHINCS => self.sphincs_verify(data, signature),
        }
    }

    // Encryption algorithm implementations (placeholders)
    fn kyber_encrypt(&self, data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder Kyber encryption
        let mut encrypted = self.encryption_keys.0.clone();
        encrypted.extend_from_slice(data);
        Ok(encrypted)
    }

    fn kyber_decrypt(&self, encrypted_data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder Kyber decryption
        if encrypted_data.len() > self.encryption_keys.0.len() {
            Ok(encrypted_data[self.encryption_keys.0.len()..].to_vec())
        } else {
            Err(tensor_op_error("Invalid encrypted data", "quantum_decrypt"))
        }
    }

    fn mceliece_encrypt(&self, data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder McEliece encryption
        let mut encrypted = vec![0u8; data.len() * 2];
        for (i, &byte) in data.iter().enumerate() {
            encrypted[i * 2] = byte;
            encrypted[i * 2 + 1] = byte ^ 0xFF;
        }
        Ok(encrypted)
    }

    fn mceliece_decrypt(&self, encrypted_data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder McEliece decryption
        let mut decrypted = Vec::new();
        for chunk in encrypted_data.chunks(2) {
            if chunk.len() == 2 {
                decrypted.push(chunk[0]);
            }
        }
        Ok(decrypted)
    }

    fn multivariate_encrypt(&self, data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder multivariate encryption
        let mut encrypted = data.to_vec();
        for byte in &mut encrypted {
            *byte = byte.wrapping_add(42);
        }
        Ok(encrypted)
    }

    fn multivariate_decrypt(&self, encrypted_data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder multivariate decryption
        let mut decrypted = encrypted_data.to_vec();
        for byte in &mut decrypted {
            *byte = byte.wrapping_sub(42);
        }
        Ok(decrypted)
    }

    fn hash_based_encrypt(&self, data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder hash-based encryption
        let mut encrypted = Vec::new();
        for &byte in data {
            encrypted.push(byte);
            encrypted.push(byte.wrapping_mul(3));
        }
        Ok(encrypted)
    }

    fn hash_based_decrypt(&self, encrypted_data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder hash-based decryption
        let mut decrypted = Vec::new();
        for chunk in encrypted_data.chunks(2) {
            if chunk.len() == 2 {
                decrypted.push(chunk[0]);
            }
        }
        Ok(decrypted)
    }

    // Digital signature implementations (placeholders)
    fn dilithium_sign(&self, data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder Dilithium signature
        let mut signature = self.signature_keys.1[..64].to_vec();
        signature.extend_from_slice(&data[..std::cmp::min(32, data.len())]);
        Ok(signature)
    }

    fn dilithium_verify(&self, data: &[u8], signature: &[u8]) -> Result<bool> {
        // Placeholder Dilithium verification
        Ok(signature.len() >= 64 && signature[64..] == data[..std::cmp::min(32, data.len())])
    }

    fn falcon_sign(&self, data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder Falcon signature
        let mut signature = self.signature_keys.1[..48].to_vec();
        signature.extend_from_slice(&data[..std::cmp::min(16, data.len())]);
        Ok(signature)
    }

    fn falcon_verify(&self, data: &[u8], signature: &[u8]) -> Result<bool> {
        // Placeholder Falcon verification
        Ok(signature.len() >= 48 && signature[48..] == data[..std::cmp::min(16, data.len())])
    }

    fn sphincs_sign(&self, data: &[u8]) -> Result<Vec<u8>> {
        // Placeholder SPHINCS+ signature
        let mut signature = self.signature_keys.1[..96].to_vec();
        signature.extend_from_slice(&data[..std::cmp::min(32, data.len())]);
        Ok(signature)
    }

    fn sphincs_verify(&self, data: &[u8], signature: &[u8]) -> Result<bool> {
        // Placeholder SPHINCS+ verification
        Ok(signature.len() >= 96 && signature[96..] == data[..std::cmp::min(32, data.len())])
    }
}

/// Advanced security manager that combines all security features
pub struct AdvancedSecurityManager {
    config: AdvancedSecurityConfig,
    homomorphic_engine: Option<HomomorphicEncryptionEngine>,
    mpc_engine: Option<SecureMultipartyEngine>,
    zk_engine: Option<ZeroKnowledgeProofEngine>,
    quantum_engine: Option<QuantumResistantEngine>,
}

impl AdvancedSecurityManager {
    /// Create a new advanced security manager
    pub fn new(config: AdvancedSecurityConfig) -> Result<Self> {
        let homomorphic_engine = if config.homomorphic_encryption.enabled {
            Some(HomomorphicEncryptionEngine::new(
                config.homomorphic_encryption.clone(),
            )?)
        } else {
            None
        };

        let mpc_engine = if config.secure_multiparty.enabled {
            Some(SecureMultipartyEngine::new(
                config.secure_multiparty.clone(),
                0,
            )?)
        } else {
            None
        };

        let zk_engine = if config.zero_knowledge_proofs.enabled {
            Some(ZeroKnowledgeProofEngine::new(
                config.zero_knowledge_proofs.clone(),
            )?)
        } else {
            None
        };

        let quantum_engine = if config.quantum_resistant.enabled {
            Some(QuantumResistantEngine::new(
                config.quantum_resistant.clone(),
            )?)
        } else {
            None
        };

        Ok(Self {
            config,
            homomorphic_engine,
            mpc_engine,
            zk_engine,
            quantum_engine,
        })
    }

    /// Perform secure inference with all enabled security features
    pub fn secure_inference<F>(&self, input: &Tensor, model_fn: F) -> Result<SecureInferenceResult>
    where
        F: Fn(&Tensor) -> Result<Tensor>,
    {
        let start_time = std::time::Instant::now();

        let result = if let Some(he_engine) = &self.homomorphic_engine {
            // Use homomorphic encryption for private inference
            let encrypted_input = he_engine.encrypt(input)?;
            let encrypted_result = he_engine.private_inference(&encrypted_input, |encrypted| {
                // For demonstration, we decrypt, apply the model, then re-encrypt
                // In a real implementation, the model would work directly on encrypted data
                let decrypted = he_engine.decrypt(encrypted)?;
                let result = model_fn(&decrypted)?;
                he_engine.encrypt(&result)
            })?;
            he_engine.decrypt(&encrypted_result)?
        } else {
            // Regular inference
            model_fn(input)?
        };

        let computation_time = start_time.elapsed();

        // Generate proof of computation if ZK proofs are enabled
        let proof = if let Some(zk_engine) = &self.zk_engine {
            let model_hash = b"model_hash_placeholder";
            let witness = b"computation_witness";
            Some(zk_engine.prove_model_integrity(model_hash, witness)?)
        } else {
            None
        };

        Ok(SecureInferenceResult {
            result,
            computation_time,
            security_level: self.estimate_security_level(),
            proof,
            homomorphic_used: self.homomorphic_engine.is_some(),
            mpc_used: self.mpc_engine.is_some(),
            quantum_resistant_used: self.quantum_engine.is_some(),
        })
    }

    /// Estimate the overall security level
    fn estimate_security_level(&self) -> f32 {
        let mut score = 0.0;

        if self.homomorphic_engine.is_some() {
            score += 0.3;
        }
        if self.mpc_engine.is_some() {
            score += 0.2;
        }
        if self.zk_engine.is_some() {
            score += 0.2;
        }
        if self.quantum_engine.is_some() {
            score += 0.3;
        }

        score
    }
}

/// Result of secure inference
#[derive(Debug)]
pub struct SecureInferenceResult {
    /// The inference result
    pub result: Tensor,
    /// Time taken for computation
    pub computation_time: std::time::Duration,
    /// Security level (0.0 to 1.0)
    pub security_level: f32,
    /// Zero-knowledge proof (if generated)
    pub proof: Option<ZKProof>,
    /// Whether homomorphic encryption was used
    pub homomorphic_used: bool,
    /// Whether multi-party computation was used
    pub mpc_used: bool,
    /// Whether quantum-resistant cryptography was used
    pub quantum_resistant_used: bool,
}

impl Default for AdvancedSecurityConfig {
    fn default() -> Self {
        Self {
            homomorphic_encryption: HomomorphicConfig {
                enabled: false,
                scheme: HomomorphicScheme::CKKS,
                security_level: SecurityLevel::Bit128,
                optimization: EncryptionOptimization {
                    enable_batching: true,
                    enable_bootstrapping: false,
                    relinearization_threshold: 2,
                    memory_optimization: true,
                },
            },
            secure_multiparty: SecureMultipartyConfig {
                enabled: false,
                num_parties: 3,
                threshold: 2,
                protocol: MPCProtocol::ShamirSecretSharing,
                communication: MPCCommunication {
                    secure_channels: true,
                    timeout_seconds: 30,
                    max_message_size: 1024 * 1024, // 1MB
                    enable_compression: true,
                },
            },
            zero_knowledge_proofs: ZKProofConfig {
                enabled: false,
                proof_system: ZKProofSystem::ZkSNARKs,
                verification: ZKVerificationConfig {
                    batch_verification: true,
                    timeout_seconds: 10,
                    cache_results: true,
                    max_proof_size: 1024 * 1024, // 1MB
                },
            },
            quantum_resistant: QuantumResistantConfig {
                enabled: false,
                encryption_algorithm: QuantumResistantAlgorithm::Kyber,
                signature_algorithm: QuantumResistantSignature::Dilithium,
                key_exchange: QuantumResistantKeyExchange::KyberKEM,
            },
        }
    }
}

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

    #[test]
    fn test_homomorphic_encryption_basic() {
        let config = HomomorphicConfig {
            enabled: true,
            scheme: HomomorphicScheme::CKKS,
            security_level: SecurityLevel::Bit128,
            optimization: EncryptionOptimization {
                enable_batching: true,
                enable_bootstrapping: false,
                relinearization_threshold: 2,
                memory_optimization: true,
            },
        };

        let engine = HomomorphicEncryptionEngine::new(config).expect("Operation failed");
        let input = Tensor::randn(&[2, 2]).expect("Operation failed");

        let encrypted = engine.encrypt(&input).expect("Operation failed");
        let decrypted = engine.decrypt(&encrypted).expect("Operation failed");

        assert_eq!(input.shape(), decrypted.shape());
    }

    #[test]
    fn test_secure_multiparty_computation() {
        let config = SecureMultipartyConfig {
            enabled: true,
            num_parties: 3,
            threshold: 2,
            protocol: MPCProtocol::ShamirSecretSharing,
            communication: MPCCommunication {
                secure_channels: true,
                timeout_seconds: 30,
                max_message_size: 1024,
                enable_compression: false,
            },
        };

        let mut engine = SecureMultipartyEngine::new(config, 0).expect("Operation failed");
        let input = Tensor::ones(&[2]).expect("Operation failed");

        let shares = engine
            .create_shares(&input, "test_secret".to_string())
            .expect("Operation failed");
        assert_eq!(shares.len(), 3);

        let reconstructed =
            engine.reconstruct_secret(&shares, "test_secret").expect("Operation failed");
        assert_eq!(reconstructed.shape(), &[2]);
    }

    #[test]
    fn test_zero_knowledge_proofs() {
        let config = ZKProofConfig {
            enabled: true,
            proof_system: ZKProofSystem::ZkSNARKs,
            verification: ZKVerificationConfig {
                batch_verification: false,
                timeout_seconds: 10,
                cache_results: false,
                max_proof_size: 1024,
            },
        };

        let engine = ZeroKnowledgeProofEngine::new(config).expect("Operation failed");
        let model_hash = b"test_model_hash";
        let witness = b"test_witness";

        let proof = engine.prove_model_integrity(model_hash, witness).expect("Operation failed");
        let verification = engine.verify_proof(&proof, model_hash).expect("Operation failed");

        assert!(verification);
    }

    #[test]
    fn test_quantum_resistant_cryptography() {
        let config = QuantumResistantConfig {
            enabled: true,
            encryption_algorithm: QuantumResistantAlgorithm::Kyber,
            signature_algorithm: QuantumResistantSignature::Dilithium,
            key_exchange: QuantumResistantKeyExchange::KyberKEM,
        };

        let engine = QuantumResistantEngine::new(config).expect("Operation failed");
        let data = b"test_data";

        let encrypted = engine.encrypt(data).expect("Operation failed");
        let decrypted = engine.decrypt(&encrypted).expect("Operation failed");
        assert_eq!(data, &decrypted[..]);

        let signature = engine.sign(data).expect("Operation failed");
        let verification = engine.verify(data, &signature).expect("Operation failed");
        assert!(verification);
    }

    #[test]
    fn test_advanced_security_manager() {
        let config = AdvancedSecurityConfig::default();
        let manager = AdvancedSecurityManager::new(config).expect("Operation failed");

        let input = Tensor::randn(&[1, 10]).expect("Operation failed");
        let model_fn = |x: &Tensor| -> Result<Tensor> { x.scalar_mul(0.5) };

        let result = manager.secure_inference(&input, model_fn).expect("Operation failed");
        assert_eq!(result.result.shape(), input.shape());
        assert!(result.security_level >= 0.0);
    }
}