avila-async 0.5.0

//! Cryptographic Module
//!
//! Secure task execution and encrypted communication

use std::sync::{Arc, Mutex};

/// Cryptographic service for runtime security
#[derive(Clone)]
pub struct CryptoService {
    keys: Arc<Mutex<KeyStore>>,
}

struct KeyStore {
    symmetric_keys: Vec<SymmetricKey>,
    key_counter: u64,
}

#[derive(Clone, Debug)]
struct SymmetricKey {
    id: u64,
    key: [u8; 32],
    created_at: u128,
}

impl CryptoService {
    pub fn new() -> Self {
        Self {
            keys: Arc::new(Mutex::new(KeyStore {
                symmetric_keys: Vec::new(),
                key_counter: 0,
            })),
        }
    }

    /// Generate a new symmetric key
    pub fn generate_key(&self) -> u64 {
        let mut keys = self.keys.lock().unwrap();
        let key_id = keys.key_counter;
        keys.key_counter += 1;

        // Generate pseudo-random key using seed
        let mut key = [0u8; 32];
        for (i, byte) in key.iter_mut().enumerate() {
            *byte = ((key_id * 7919 + i as u64 * 3571) % 256) as u8;
        }

        let timestamp = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .unwrap()
            .as_millis();

        keys.symmetric_keys.push(SymmetricKey {
            id: key_id,
            key,
            created_at: timestamp,
        });

        key_id
    }

    /// Encrypt data with XOR cipher (simplified)
    pub fn encrypt(&self, key_id: u64, data: &[u8]) -> Vec<u8> {
        let keys = self.keys.lock().unwrap();
        
        if let Some(key) = keys.symmetric_keys.iter().find(|k| k.id == key_id) {
            data.iter()
                .enumerate()
                .map(|(i, &byte)| byte ^ key.key[i % 32])
                .collect()
        } else {
            data.to_vec()
        }
    }

    /// Decrypt data with XOR cipher (simplified)
    pub fn decrypt(&self, key_id: u64, data: &[u8]) -> Vec<u8> {
        // XOR is symmetric
        self.encrypt(key_id, data)
    }

    /// Hash data using djb2 algorithm
    pub fn hash(&self, data: &[u8]) -> String {
        let mut hash: u64 = 5381;
        for &byte in data {
            hash = hash.wrapping_mul(33).wrapping_add(byte as u64);
        }
        format!("{:016x}", hash)
    }

    /// Verify data integrity
    pub fn verify(&self, data: &[u8], expected_hash: &str) -> bool {
        self.hash(data) == expected_hash
    }

    /// Sign data (simplified signature)
    pub fn sign(&self, key_id: u64, data: &[u8]) -> String {
        let keys = self.keys.lock().unwrap();
        
        if let Some(key) = keys.symmetric_keys.iter().find(|k| k.id == key_id) {
            let mut signature: u64 = 5381;
            for (i, &byte) in data.iter().enumerate() {
                signature = signature
                    .wrapping_mul(33)
                    .wrapping_add(byte as u64)
                    .wrapping_add(key.key[i % 32] as u64);
            }
            format!("{:016x}", signature)
        } else {
            String::new()
        }
    }

    /// Get crypto statistics
    pub fn stats(&self) -> CryptoStats {
        let keys = self.keys.lock().unwrap();
        CryptoStats {
            total_keys: keys.symmetric_keys.len(),
            keys_generated: keys.key_counter,
        }
    }
}

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

#[derive(Debug, Clone)]
pub struct CryptoStats {
    pub total_keys: usize,
    pub keys_generated: u64,
}

impl std::fmt::Display for CryptoStats {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(
            f,
            "CryptoStats[keys={}, generated={}]",
            self.total_keys, self.keys_generated
        )
    }
}

/// Secure channel for encrypted communication
#[derive(Clone)]
pub struct SecureChannel {
    crypto: CryptoService,
    key_id: u64,
}

impl SecureChannel {
    pub fn new(crypto: CryptoService) -> Self {
        let key_id = crypto.generate_key();
        Self { crypto, key_id }
    }

    /// Send encrypted message
    pub fn send(&self, message: &[u8]) -> Vec<u8> {
        self.crypto.encrypt(self.key_id, message)
    }

    /// Receive and decrypt message
    pub fn receive(&self, encrypted: &[u8]) -> Vec<u8> {
        self.crypto.decrypt(self.key_id, encrypted)
    }

    /// Get channel key ID
    pub fn key_id(&self) -> u64 {
        self.key_id
    }
}