How can you implement a secure, encrypted, and scalable key-value store in Python using cryptography and redis that supports atomic operations, automatic encryption/decryption of data, concurrent access control, and seamless integration with distributed systems? Provide a concise yet comprehensive code example demonstrating advanced features such as AES-GCM encryption, transactional updates, rate limiting, and cluster-aware failover.

import redis
import asyncio
import json
from cryptography.fernet import Fernet
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.backends import default_backend
import os
import time
from typing import Dict, Any, Optional

# Configuration
REDIS_URL = "redis://localhost:6379/0"
SECRET_KEY = b"your-secure-secret-key-here-1234567890"  # Use environment variable in production
KEY_LENGTH = 32

class SecureKeyValueStore:
    def __init__(self, redis_url: str, secret_key: bytes):
        self.redis_client = redis.from_url(redis_url)
        self.fernet = Fernet(secret_key)
        self._lock = asyncio.Lock()
        self.rate_limit = {}
        
    async def _encrypt(self, data: Any) -> str:
        """Encrypt data using Fernet."""
        json_data = json.dumps(data).encode('utf-8')
        return self.fernet.encrypt(json_data).decode('utf-8')
    
    async def _decrypt(self, encrypted_data: str) -> Any:
        """Decrypt data using Fernet."""
        try:
            decrypted = self.fernet.decrypt(encrypted_data.encode('utf-8'))
            return json.loads(decrypted.decode('utf-8'))
        except Exception as e:
            logger.error(f"Decryption failed: {e}")
            return None
    
    async def set(self, key: str, value: Any, ttl: int = 300):
        """Set key-value pair with encryption and TTL."""
        encrypted_value = await self._encrypt(value)
        async with self._lock:
            await self.redis_client.setex(key, ttl, encrypted_value)
            
    async def get(self, key: str) -> Optional[Any]:
        """Get and decrypt value."""
        raw_value = await self.redis_client.get(key)
        if raw_value:
            return await self._decrypt(raw_value)
        return None
    
    async def atomic_transaction(self, operations: List[Dict]):
        """Execute atomic operations using Redis transactions."""
        pipe = self.redis_client.pipeline()
        for op in operations:
            if op['type'] == 'set':
                encrypted = await self._encrypt(op['value'])
                pipe.setex(op['key'], op.get('ttl', 300), encrypted)
            elif op['type'] == 'delete':
                pipe.delete(op['key'])
        await pipe.execute()
    
    async def rate_limited_set(self, key: str, value: Any, rate_limit: int = 10):
        """Rate-limited set operation."""
        now = time.time()
        if key not in self.rate_limit:
            self.rate_limit[key] = []
        self.rate_limit[key] = [t for t in self.rate_limit[key] if t > now - 60]
        
        if len(self.rate_limit[key]) >= rate_limit:
            raise Exception("Rate limit exceeded")
        
        self.rate_limit[key].append(now)
        await self.set(key, value)

# Example usage
async def main():
    store = SecureKeyValueStore(REDIS_URL, SECRET_KEY)
    await store.set("user:1", {"name": "John", "age": 30})
    data = await store.get("user:1")
    print(data)
    await store.atomic_transaction([
        {"type": "set", "key": "counter:1", "value": 1},
        {"type": "set", "key": "counter:2", "value": 2}
    ])
    await store.rate_limited_set("api_call", {"count": 1}, rate_limit=5)

# Run the example
asyncio.run(main())

#Python #Security #Encryption #Redis #KeyvalueStore #AtomicOperations #Concurrency #DistributedSystems #Scalability #Cryptography #AsyncIO

By: @DataScienceQ 🚀