trustformers-mobile 0.1.1

//! Cryptographic Protocols for Secure Federated Learning
//!
//! This module implements advanced cryptographic protocols including homomorphic
//! encryption, secure multi-party computation, zero-knowledge proofs, and
//! post-quantum cryptographic schemes for secure federated learning.

use serde::{Deserialize, Serialize};

/// Cryptographic configuration for secure protocols
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CryptographicConfig {
    /// Secure aggregation protocol
    pub aggregation_protocol: SecureAggregationProtocol,
    /// Homomorphic encryption settings
    pub homomorphic_encryption: HomomorphicEncryptionConfig,
    /// Secure multi-party computation
    pub secure_mpc: SecureMPCConfig,
    /// Digital signature scheme
    pub signature_scheme: DigitalSignatureScheme,
    /// Key exchange protocol
    pub key_exchange: KeyExchangeProtocol,
    /// Zero-knowledge proofs
    pub zero_knowledge_proofs: ZKProofConfig,
}

/// Secure aggregation protocols
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum SecureAggregationProtocol {
    /// Basic secure aggregation
    BasicSecureAggregation,
    /// Federated secure aggregation
    FederatedSecureAggregation,
    /// Private federated learning
    PrivateFederatedLearning,
    /// SecAgg+ protocol
    SecAggPlus,
    /// Flamingo protocol
    Flamingo,
    /// FATE protocol
    FATE,
}

/// Homomorphic encryption configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct HomomorphicEncryptionConfig {
    /// Encryption scheme
    pub scheme: HomomorphicScheme,
    /// Security level (bits)
    pub security_level: u16,
    /// Polynomial modulus degree
    pub poly_modulus_degree: u32,
    /// Coefficient modulus
    pub coeff_modulus: Vec<u64>,
    /// Plaintext modulus
    pub plaintext_modulus: u64,
    /// Optimization level
    pub optimization_level: OptimizationLevel,
}

/// Homomorphic encryption schemes
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum HomomorphicScheme {
    /// BFV scheme
    BFV,
    /// CKKS scheme
    CKKS,
    /// BGV scheme
    BGV,
    /// TFHE scheme
    TFHE,
}

/// Optimization levels for homomorphic encryption
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum OptimizationLevel {
    /// No optimization
    None,
    /// Basic optimization
    Basic,
    /// Advanced optimization
    Advanced,
    /// Maximum optimization
    Maximum,
}

/// Secure multi-party computation configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SecureMPCConfig {
    /// MPC protocol
    pub protocol: MPCProtocol,
    /// Number of parties
    pub num_parties: u32,
    /// Threshold for secret sharing
    pub threshold: u32,
    /// Security parameter
    pub security_parameter: u16,
    /// Communication rounds
    pub communication_rounds: u32,
}

/// MPC protocols
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum MPCProtocol {
    /// Shamir's secret sharing
    ShamirSecretSharing,
    /// BGW protocol
    BGW,
    /// GMW protocol
    GMW,
    /// SPDZ protocol
    SPDZ,
    /// ABY protocol
    ABY,
    /// CrypTFlow protocol
    CrypTFlow,
}

/// Digital signature schemes
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum DigitalSignatureScheme {
    /// ECDSA
    ECDSA,
    /// EdDSA
    EdDSA,
    /// RSA-PSS
    RSAPSS,
    /// BLS signatures
    BLS,
    /// Ring signatures
    RingSignature,
}

/// Key exchange protocols
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum KeyExchangeProtocol {
    /// ECDH
    ECDH,
    /// X25519
    X25519,
    /// CRYSTALS-Kyber (post-quantum)
    Kyber,
    /// NTRU (post-quantum)
    NTRU,
}

/// Zero-knowledge proof configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ZKProofConfig {
    /// Proof system
    pub proof_system: ZKProofSystem,
    /// Circuit complexity
    pub circuit_complexity: u32,
    /// Proof size optimization
    pub proof_size_optimization: bool,
    /// Verification key caching
    pub verification_key_caching: bool,
}

/// Zero-knowledge proof systems
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum ZKProofSystem {
    /// zk-SNARKs
    ZkSNARKs,
    /// zk-STARKs
    ZkSTARKs,
    /// Bulletproofs
    Bulletproofs,
    /// Plonk
    Plonk,
    /// Marlin
    Marlin,
}

/// Post-quantum cryptographic configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PostQuantumConfig {
    /// Key encapsulation mechanism
    pub kem: PostQuantumKEM,
    /// Digital signature scheme
    pub signature: PostQuantumSignature,
    /// Security level (NIST level 1-5)
    pub security_level: u8,
    /// Quantum-safe aggregation
    pub quantum_safe_aggregation: bool,
}

/// Post-quantum key encapsulation mechanisms
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum PostQuantumKEM {
    /// CRYSTALS-Kyber
    Kyber,
    /// NTRU
    NTRU,
    /// SABER
    SABER,
    /// FrodoKEM
    FrodoKEM,
}

/// Post-quantum digital signatures
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum PostQuantumSignature {
    /// CRYSTALS-Dilithium
    Dilithium,
    /// Falcon
    Falcon,
    /// SPHINCS+
    SPHINCSPlus,
    /// Rainbow
    Rainbow,
}

impl Default for CryptographicConfig {
    fn default() -> Self {
        Self {
            aggregation_protocol: SecureAggregationProtocol::SecAggPlus,
            homomorphic_encryption: HomomorphicEncryptionConfig::default(),
            secure_mpc: SecureMPCConfig::default(),
            signature_scheme: DigitalSignatureScheme::EdDSA,
            key_exchange: KeyExchangeProtocol::X25519,
            zero_knowledge_proofs: ZKProofConfig::default(),
        }
    }
}

impl Default for HomomorphicEncryptionConfig {
    fn default() -> Self {
        Self {
            scheme: HomomorphicScheme::CKKS,
            security_level: 128,
            poly_modulus_degree: 8192,
            coeff_modulus: vec![60, 40, 40, 60],
            plaintext_modulus: 40961,
            optimization_level: OptimizationLevel::Advanced,
        }
    }
}

impl Default for SecureMPCConfig {
    fn default() -> Self {
        Self {
            protocol: MPCProtocol::SPDZ,
            num_parties: 3,
            threshold: 2,
            security_parameter: 128,
            communication_rounds: 3,
        }
    }
}

impl Default for ZKProofConfig {
    fn default() -> Self {
        Self {
            proof_system: ZKProofSystem::Plonk,
            circuit_complexity: 1000000,
            proof_size_optimization: true,
            verification_key_caching: true,
        }
    }
}

impl Default for PostQuantumConfig {
    fn default() -> Self {
        Self {
            kem: PostQuantumKEM::Kyber,
            signature: PostQuantumSignature::Dilithium,
            security_level: 3, // NIST level 3
            quantum_safe_aggregation: true,
        }
    }
}

/// Cryptographic key manager for federated learning
#[derive(Debug, Clone)]
pub struct CryptographicKeyManager {
    /// Master public key
    pub master_public_key: Vec<u8>,
    /// Participant public keys
    pub participant_keys: std::collections::HashMap<String, Vec<u8>>,
    /// Symmetric encryption keys
    pub symmetric_keys: std::collections::HashMap<String, Vec<u8>>,
    /// Key rotation schedule
    pub key_rotation_interval: std::time::Duration,
    /// Last key rotation time
    pub last_rotation: std::time::SystemTime,
}

impl CryptographicKeyManager {
    /// Create new key manager
    pub fn new() -> Self {
        Self {
            master_public_key: Vec::new(),
            participant_keys: std::collections::HashMap::new(),
            symmetric_keys: std::collections::HashMap::new(),
            key_rotation_interval: std::time::Duration::from_secs(86400), // 24 hours
            last_rotation: std::time::SystemTime::now(),
        }
    }

    /// Add participant key
    pub fn add_participant_key(&mut self, participant_id: String, public_key: Vec<u8>) {
        self.participant_keys.insert(participant_id, public_key);
    }

    /// Remove participant key
    pub fn remove_participant_key(&mut self, participant_id: &str) {
        self.participant_keys.remove(participant_id);
    }

    /// Check if key rotation is needed
    pub fn needs_key_rotation(&self) -> bool {
        std::time::SystemTime::now()
            .duration_since(self.last_rotation)
            .unwrap_or_default() > self.key_rotation_interval
    }

    /// Rotate keys
    pub fn rotate_keys(&mut self) -> Result<(), String> {
        // In practice, this would generate new keys and distribute them
        self.last_rotation = std::time::SystemTime::now();
        Ok(())
    }

    /// Get participant count
    pub fn participant_count(&self) -> usize {
        self.participant_keys.len()
    }
}

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

    #[test]
    fn test_cryptographic_config_default() {
        let config = CryptographicConfig::default();
        assert_eq!(config.aggregation_protocol, SecureAggregationProtocol::SecAggPlus);
        assert_eq!(config.signature_scheme, DigitalSignatureScheme::EdDSA);
        assert_eq!(config.key_exchange, KeyExchangeProtocol::X25519);
    }

    #[test]
    fn test_homomorphic_encryption_config() {
        let config = HomomorphicEncryptionConfig::default();
        assert_eq!(config.scheme, HomomorphicScheme::CKKS);
        assert_eq!(config.security_level, 128);
        assert_eq!(config.poly_modulus_degree, 8192);
        assert_eq!(config.optimization_level, OptimizationLevel::Advanced);
    }

    #[test]
    fn test_mpc_config() {
        let config = SecureMPCConfig::default();
        assert_eq!(config.protocol, MPCProtocol::SPDZ);
        assert_eq!(config.num_parties, 3);
        assert_eq!(config.threshold, 2);
        assert_eq!(config.security_parameter, 128);
    }

    #[test]
    fn test_post_quantum_config() {
        let config = PostQuantumConfig::default();
        assert_eq!(config.kem, PostQuantumKEM::Kyber);
        assert_eq!(config.signature, PostQuantumSignature::Dilithium);
        assert_eq!(config.security_level, 3);
        assert!(config.quantum_safe_aggregation);
    }

    #[test]
    fn test_key_manager() {
        let mut manager = CryptographicKeyManager::new();
        assert_eq!(manager.participant_count(), 0);

        manager.add_participant_key("participant1".to_string(), vec![1, 2, 3, 4]);
        manager.add_participant_key("participant2".to_string(), vec![5, 6, 7, 8]);
        assert_eq!(manager.participant_count(), 2);

        manager.remove_participant_key("participant1");
        assert_eq!(manager.participant_count(), 1);

        assert!(manager.rotate_keys().is_ok());
    }

    #[test]
    fn test_zk_proof_systems() {
        let systems = [
            ZKProofSystem::ZkSNARKs,
            ZKProofSystem::ZkSTARKs,
            ZKProofSystem::Bulletproofs,
            ZKProofSystem::Plonk,
            ZKProofSystem::Marlin,
        ];

        for system in &systems {
            let serialized = serde_json::to_string(system).expect("Operation failed");
            let deserialized: ZKProofSystem = serde_json::from_str(&serialized).expect("Operation failed");
            assert_eq!(*system, deserialized);
        }
    }

    #[test]
    fn test_homomorphic_schemes() {
        let schemes = [
            HomomorphicScheme::BFV,
            HomomorphicScheme::CKKS,
            HomomorphicScheme::BGV,
            HomomorphicScheme::TFHE,
        ];

        for scheme in &schemes {
            let serialized = serde_json::to_string(scheme).expect("Operation failed");
            let deserialized: HomomorphicScheme = serde_json::from_str(&serialized).expect("Operation failed");
            assert_eq!(*scheme, deserialized);
        }
    }

    #[test]
    fn test_mpc_protocols() {
        let protocols = [
            MPCProtocol::ShamirSecretSharing,
            MPCProtocol::BGW,
            MPCProtocol::GMW,
            MPCProtocol::SPDZ,
            MPCProtocol::ABY,
            MPCProtocol::CrypTFlow,
        ];

        for protocol in &protocols {
            let serialized = serde_json::to_string(protocol).expect("Operation failed");
            let deserialized: MPCProtocol = serde_json::from_str(&serialized).expect("Operation failed");
            assert_eq!(*protocol, deserialized);
        }
    }
}