import pytest
from cryptography.exceptions import InvalidTag

class TestEncryptionTDD:
    """TDD tests for encryption implementation."""

    def test_encrypt_decrypt_roundtrip(self):
        """Test that encryption followed by decryption returns original data."""
        from jarvis.security.encryption import SecureEncryption

        key = secrets.token_bytes(32)
        encryptor = SecureEncryption(key)

        plaintext = b"sensitive data for JARVIS"
        ciphertext = encryptor.encrypt(plaintext)
        decrypted = encryptor.decrypt(ciphertext)

        assert decrypted == plaintext
        assert ciphertext != plaintext  # Must be encrypted

    def test_tampered_ciphertext_raises_error(self):
        """Test that tampered ciphertext is rejected."""
        from jarvis.security.encryption import SecureEncryption

        key = secrets.token_bytes(32)
        encryptor = SecureEncryption(key)

        ciphertext = encryptor.encrypt(b"secret")
        tampered = ciphertext[:-1] + bytes([ciphertext[-1] ^ 0xFF])

        with pytest.raises(InvalidTag):
            encryptor.decrypt(tampered)

    def test_key_derivation_consistency(self):
        """Same password + salt = same key; different salt = different key."""
        from jarvis.security.encryption import SecureKeyDerivation
        password = "strong_password_123"
        salt = secrets.token_bytes(16)
        key1, _ = SecureKeyDerivation.derive_key(password, salt)
        key2, _ = SecureKeyDerivation.derive_key(password, salt)
        assert key1 == key2 and len(key1) == 32

        key3, salt3 = SecureKeyDerivation.derive_key(password)
        assert key1 != key3  # Different salt = different key

# Run encryption tests with coverage
pytest tests/security/test_encryption.py -v --cov=jarvis.security.encryption --cov-fail-under=90

# Run security-specific tests
pytest tests/security/ -k "encryption or crypto" -v

# Check for timing vulnerabilities
pytest tests/security/test_timing.py -v

# Verify no secrets in output
pytest --log-cli-level=DEBUG 2>&1 | grep -i "key\|secret\|password" && echo "WARNING: Secrets in logs!"

# SQLCipher secure configuration
SQLCIPHER_PRAGMAS = {
    'key': None,  # Set via secure key injection
    'cipher': 'aes-256-gcm',
    'kdf_iter': 256000,  # PBKDF2 iterations
    'cipher_page_size': 4096,
    'cipher_kdf_algorithm': 'PBKDF2_HMAC_SHA512',
    'cipher_hmac_algorithm': 'HMAC_SHA512',
    'cipher_plaintext_header_size': 0,
}

class CachedKeyManager:
    def __init__(self, cache_ttl: int = 300):
        self._cache: dict[str, tuple[bytes, float]] = {}
        self._ttl = cache_ttl

    def get_key(self, password: str, salt: bytes) -> bytes:
        cache_key = f"{hash(password)}:{salt.hex()}"
        if cache_key in self._cache:
            key, ts = self._cache[cache_key]
            if time.time() - ts < self._ttl:
                return key
        key, _ = SecureKeyDerivation.derive_key(password, salt)
        self._cache[cache_key] = (key, time.time())
        return key

nonce = secrets.token_bytes(12)
encryptor = Cipher(algorithms.AES(key), modes.GCM(nonce)).encryptor()
with open(input_path, 'rb') as fin, open(output_path, 'wb') as fout:
    fout.write(nonce)
    while chunk := fin.read(64 * 1024):
        fout.write(encryptor.update(chunk))
    fout.write(encryptor.finalize() + encryptor.tag)

results = []
for record in records:
    results.append(encryptor.encrypt(record))

encryptor = SecureEncryption(key)
results = [encryptor.encrypt(record) for record in records]

# For large batches, use ProcessPoolExecutor for parallelization

self.key = SecureKeyDerivation.derive_key(password)  # Never cleared

import ctypes

class SecureKeyHolder:
    def __init__(self, password: str):
        self._key, self.salt = SecureKeyDerivation.derive_key(password)

    def __exit__(self, *args):
        if self._key:
            key_buffer = (ctypes.c_char * len(self._key)).from_buffer_copy(self._key)
            ctypes.memset(key_buffer, 0, len(self._key))
            self._key = None

# Usage: with SecureKeyHolder(password) as kh: encrypt(kh._key, data)

from argon2 import PasswordHasher
from argon2.low_level import hash_secret_raw, Type
import secrets

class SecureKeyDerivation:
    """Derive encryption keys from passwords using Argon2id."""

    # OWASP recommended parameters for sensitive data
    TIME_COST = 3        # Iterations
    MEMORY_COST = 65536  # 64 MiB
    PARALLELISM = 4      # Threads
    HASH_LEN = 32        # 256 bits for AES-256
    SALT_LEN = 16        # 128 bits minimum

    @classmethod
    def derive_key(cls, password: str, salt: bytes = None) -> tuple[bytes, bytes]:
        """
        Derive a 256-bit key from password.

        Returns:
            tuple: (derived_key, salt) for storage
        """
        if salt is None:
            salt = secrets.token_bytes(cls.SALT_LEN)

        # Validate inputs
        if not password or len(password) < 12:
            raise ValueError("Password must be at least 12 characters")

        key = hash_secret_raw(
            secret=password.encode('utf-8'),
            salt=salt,
            time_cost=cls.TIME_COST,
            memory_cost=cls.MEMORY_COST,
            parallelism=cls.PARALLELISM,
            hash_len=cls.HASH_LEN,
            type=Type.ID  # Argon2id
        )

        return key, salt

from cryptography.hazmat.primitives.ciphers.aead import AESGCM
import secrets

class SecureEncryption:
    """AES-256-GCM authenticated encryption."""

    NONCE_SIZE = 12  # 96 bits recommended for GCM
    KEY_SIZE = 32    # 256 bits

    def __init__(self, key: bytes):
        if len(key) != self.KEY_SIZE:
            raise ValueError(f"Key must be {self.KEY_SIZE} bytes")
        self._aesgcm = AESGCM(key)

    def encrypt(self, plaintext: bytes, associated_data: bytes = None) -> bytes:
        """
        Encrypt with random nonce, prepended to ciphertext.

        Returns:
            bytes: nonce || ciphertext || tag
        """
        nonce = secrets.token_bytes(self.NONCE_SIZE)
        ciphertext = self._aesgcm.encrypt(nonce, plaintext, associated_data)
        return nonce + ciphertext

    def decrypt(self, ciphertext: bytes, associated_data: bytes = None) -> bytes:
        """
        Decrypt and verify authenticity.

        Raises:
            InvalidTag: If authentication fails
        """
        if len(ciphertext) < self.NONCE_SIZE + 16:  # nonce + tag minimum
            raise ValueError("Ciphertext too short")

        nonce = ciphertext[:self.NONCE_SIZE]
        actual_ciphertext = ciphertext[self.NONCE_SIZE:]

        return self._aesgcm.decrypt(nonce, actual_ciphertext, associated_data)

import sqlcipher3
from contextlib import contextmanager

class EncryptedDatabase:
    """Encrypted SQLite database using SQLCipher."""

    def __init__(self, db_path: str, key: bytes):
        self._db_path = db_path
        self._key = key
        self._conn = None

    @contextmanager
    def connect(self):
        """Context manager for database connections."""
        conn = sqlcipher3.connect(self._db_path)
        try:
            # Apply security pragmas
            conn.execute(f"PRAGMA key = \"x'{self._key.hex()}'\";")
            conn.execute("PRAGMA cipher = 'aes-256-gcm';")
            conn.execute("PRAGMA kdf_iter = 256000;")
            conn.execute("PRAGMA cipher_page_size = 4096;")

            # Verify encryption is active
            result = conn.execute("PRAGMA cipher_version;").fetchone()
            if not result:
                raise RuntimeError("SQLCipher encryption not active")

            yield conn
            conn.commit()
        except Exception:
            conn.rollback()
            raise
        finally:
            conn.close()

    def rekey(self, new_key: bytes):
        """Rotate database encryption key."""
        with self.connect() as conn:
            conn.execute(f"PRAGMA rekey = \"x'{new_key.hex()}'\";")
        self._key = new_key