""" Security tests for AITBC Confidential Transactions """ import pytest import json from datetime import datetime, timedelta from unittest.mock import Mock, patch, AsyncMock from cryptography.hazmat.primitives.asymmetric import x25519 from cryptography.hazmat.primitives.ciphers.aead import AESGCM from cryptography.hazmat.primitives import hashes from cryptography.hazmat.primitives.kdf.hkdf import HKDF from apps.coordinator_api.src.app.services.confidential_service import ConfidentialTransactionService from apps.coordinator_api.src.app.models.confidential import ConfidentialTransaction, ViewingKey from packages.py.aitbc_crypto import encrypt_data, decrypt_data, generate_viewing_key @pytest.mark.security class TestConfidentialTransactionSecurity: """Security tests for confidential transaction functionality""" @pytest.fixture def confidential_service(self, db_session): """Create confidential transaction service""" return ConfidentialTransactionService(db_session) @pytest.fixture def sample_sender_keys(self): """Generate sender's key pair""" private_key = x25519.X25519PrivateKey.generate() public_key = private_key.public_key() return private_key, public_key @pytest.fixture def sample_receiver_keys(self): """Generate receiver's key pair""" private_key = x25519.X25519PrivateKey.generate() public_key = private_key.public_key() return private_key, public_key def test_encryption_confidentiality(self, sample_sender_keys, sample_receiver_keys): """Test that transaction data remains confidential""" sender_private, sender_public = sample_sender_keys receiver_private, receiver_public = sample_receiver_keys # Original transaction data transaction_data = { "sender": "0x1234567890abcdef", "receiver": "0xfedcba0987654321", "amount": 1000000, # 1 USDC "asset": "USDC", "nonce": 12345, } # Encrypt for receiver only ciphertext = encrypt_data( data=json.dumps(transaction_data), sender_key=sender_private, receiver_key=receiver_public ) # Verify ciphertext doesn't reveal plaintext assert transaction_data["sender"] not in ciphertext assert transaction_data["receiver"] not in ciphertext assert str(transaction_data["amount"]) not in ciphertext # Only receiver can decrypt decrypted = decrypt_data( ciphertext=ciphertext, receiver_key=receiver_private, sender_key=sender_public ) decrypted_data = json.loads(decrypted) assert decrypted_data == transaction_data def test_viewing_key_generation(self): """Test secure viewing key generation""" # Generate viewing key for auditor viewing_key = generate_viewing_key( purpose="audit", expires_at=datetime.utcnow() + timedelta(days=30), permissions=["view_amount", "view_parties"] ) # Verify key structure assert "key_id" in viewing_key assert "key_data" in viewing_key assert "expires_at" in viewing_key assert "permissions" in viewing_key # Verify key entropy assert len(viewing_key["key_data"]) >= 32 # At least 256 bits # Verify expiration assert viewing_key["expires_at"] > datetime.utcnow() def test_viewing_key_permissions(self, confidential_service): """Test that viewing keys respect permission constraints""" # Create confidential transaction tx = ConfidentialTransaction( id="confidential-tx-123", ciphertext="encrypted_data_here", sender_key="sender_pubkey", receiver_key="receiver_pubkey", created_at=datetime.utcnow(), ) # Create viewing key with limited permissions viewing_key = ViewingKey( id="view-key-123", transaction_id=tx.id, key_data="encrypted_viewing_key", permissions=["view_amount"], expires_at=datetime.utcnow() + timedelta(days=1), created_at=datetime.utcnow(), ) # Test permission enforcement with patch.object(confidential_service, 'decrypt_with_viewing_key') as mock_decrypt: mock_decrypt.return_value = {"amount": 1000} # Should succeed with valid permission result = confidential_service.view_transaction( tx.id, viewing_key.id, fields=["amount"] ) assert "amount" in result # Should fail with invalid permission with pytest.raises(PermissionError): confidential_service.view_transaction( tx.id, viewing_key.id, fields=["sender", "receiver"] # Not permitted ) def test_key_rotation_security(self, confidential_service): """Test secure key rotation""" # Create initial keys old_key = x25519.X25519PrivateKey.generate() new_key = x25519.X25519PrivateKey.generate() # Test key rotation process rotation_result = confidential_service.rotate_keys( transaction_id="tx-123", old_key=old_key, new_key=new_key ) assert rotation_result["success"] is True assert "new_ciphertext" in rotation_result assert "rotation_id" in rotation_result # Verify old key can't decrypt new ciphertext with pytest.raises(Exception): decrypt_data( ciphertext=rotation_result["new_ciphertext"], receiver_key=old_key, sender_key=old_key.public_key() ) # Verify new key can decrypt decrypted = decrypt_data( ciphertext=rotation_result["new_ciphertext"], receiver_key=new_key, sender_key=new_key.public_key() ) assert decrypted is not None def test_transaction_replay_protection(self, confidential_service): """Test protection against transaction replay""" # Create transaction with nonce transaction = { "sender": "0x123", "receiver": "0x456", "amount": 1000, "nonce": 12345, "timestamp": datetime.utcnow().isoformat(), } # Store nonce confidential_service.store_nonce(12345, "tx-123") # Try to replay with same nonce with pytest.raises(ValueError, match="nonce already used"): confidential_service.validate_transaction_nonce( transaction["nonce"], transaction["sender"] ) def test_side_channel_resistance(self, confidential_service): """Test resistance to timing attacks""" import time # Create transactions with different amounts small_amount = {"amount": 1} large_amount = {"amount": 1000000} # Encrypt both small_cipher = encrypt_data( json.dumps(small_amount), x25519.X25519PrivateKey.generate(), x25519.X25519PrivateKey.generate().public_key() ) large_cipher = encrypt_data( json.dumps(large_amount), x25519.X25519PrivateKey.generate(), x25519.X25519PrivateKey.generate().public_key() ) # Measure decryption times times = [] for ciphertext in [small_cipher, large_cipher]: start = time.perf_counter() try: decrypt_data( ciphertext, x25519.X25519PrivateKey.generate(), x25519.X25519PrivateKey.generate().public_key() ) except: pass # Expected to fail with wrong keys end = time.perf_counter() times.append(end - start) # Times should be similar (within 10%) time_diff = abs(times[0] - times[1]) / max(times) assert time_diff < 0.1, f"Timing difference too large: {time_diff}" def test_zero_knowledge_proof_integration(self): """Test ZK proof integration for privacy""" from apps.zk_circuits import generate_proof, verify_proof # Create confidential transaction transaction = { "input_commitment": "commitment123", "output_commitment": "commitment456", "amount": 1000, } # Generate ZK proof with patch('apps.zk_circuits.generate_proof') as mock_generate: mock_generate.return_value = { "proof": "zk_proof_here", "inputs": ["hash1", "hash2"], } proof_data = mock_generate(transaction) # Verify proof structure assert "proof" in proof_data assert "inputs" in proof_data assert len(proof_data["inputs"]) == 2 # Verify proof with patch('apps.zk_circuits.verify_proof') as mock_verify: mock_verify.return_value = True is_valid = mock_verify( proof=proof_data["proof"], inputs=proof_data["inputs"] ) assert is_valid is True def test_audit_log_integrity(self, confidential_service): """Test that audit logs maintain integrity""" # Create confidential transaction tx = ConfidentialTransaction( id="audit-tx-123", ciphertext="encrypted_data", sender_key="sender_key", receiver_key="receiver_key", created_at=datetime.utcnow(), ) # Log access access_log = confidential_service.log_access( transaction_id=tx.id, user_id="auditor-123", action="view_with_viewing_key", timestamp=datetime.utcnow() ) # Verify log integrity assert "log_id" in access_log assert "hash" in access_log assert "signature" in access_log # Verify log can't be tampered original_hash = access_log["hash"] access_log["user_id"] = "malicious-user" # Recalculate hash should differ new_hash = confidential_service.calculate_log_hash(access_log) assert new_hash != original_hash def test_hsm_integration_security(self): """Test HSM integration for key management""" from apps.coordinator_api.src.app.services.hsm_service import HSMService # Mock HSM client mock_hsm = Mock() mock_hsm.generate_key.return_value = {"key_id": "hsm-key-123"} mock_hsm.sign_data.return_value = {"signature": "hsm-signature"} mock_hsm.encrypt.return_value = {"ciphertext": "hsm-encrypted"} with patch('apps.coordinator_api.src.app.services.hsm_service.HSMClient') as mock_client: mock_client.return_value = mock_hsm hsm_service = HSMService() # Test key generation key_result = hsm_service.generate_key( key_type="encryption", purpose="confidential_tx" ) assert key_result["key_id"] == "hsm-key-123" # Test signing sign_result = hsm_service.sign_data( key_id="hsm-key-123", data="transaction_data" ) assert "signature" in sign_result # Verify HSM was called mock_hsm.generate_key.assert_called_once() mock_hsm.sign_data.assert_called_once() def test_multi_party_computation(self): """Test MPC for transaction validation""" from apps.coordinator_api.src.app.services.mpc_service import MPCService mpc_service = MPCService() # Create transaction shares transaction = { "amount": 1000, "sender": "0x123", "receiver": "0x456", } # Generate shares shares = mpc_service.create_shares(transaction, threshold=3, total=5) assert len(shares) == 5 assert all("share_id" in share for share in shares) assert all("encrypted_data" in share for share in shares) # Test reconstruction with sufficient shares selected_shares = shares[:3] reconstructed = mpc_service.reconstruct_transaction(selected_shares) assert reconstructed["amount"] == transaction["amount"] assert reconstructed["sender"] == transaction["sender"] # Test insufficient shares fail with pytest.raises(ValueError): mpc_service.reconstruct_transaction(shares[:2]) def test_forward_secrecy(self): """Test forward secrecy of confidential transactions""" # Generate ephemeral keys ephemeral_private = x25519.X25519PrivateKey.generate() ephemeral_public = ephemeral_private.public_key() receiver_private = x25519.X25519PrivateKey.generate() receiver_public = receiver_private.public_key() # Create shared secret shared_secret = ephemeral_private.exchange(receiver_public) # Derive encryption key derived_key = HKDF( algorithm=hashes.SHA256(), length=32, salt=None, info=b"aitbc-confidential-tx", ).derive(shared_secret) # Encrypt transaction aesgcm = AESGCM(derived_key) nonce = AESGCM.generate_nonce(12) transaction_data = json.dumps({"amount": 1000}) ciphertext = aesgcm.encrypt(nonce, transaction_data.encode(), None) # Even if ephemeral key is compromised later, past transactions remain secure # because the shared secret is not stored # Verify decryption works with current keys aesgcm_decrypt = AESGCM(derived_key) decrypted = aesgcm_decrypt.decrypt(nonce, ciphertext, None) assert json.loads(decrypted) == {"amount": 1000} def test_deniable_encryption(self): """Test deniable encryption for plausible deniability""" from apps.coordinator_api.src.app.services.deniable_service import DeniableEncryption deniable = DeniableEncryption() # Create two plausible messages real_message = {"amount": 1000000, "asset": "USDC"} fake_message = {"amount": 100, "asset": "USDC"} # Generate deniable ciphertext result = deniable.encrypt( real_message=real_message, fake_message=fake_message, receiver_key=x25519.X25519PrivateKey.generate() ) assert "ciphertext" in result assert "real_key" in result assert "fake_key" in result # Can reveal either message depending on key provided real_decrypted = deniable.decrypt( ciphertext=result["ciphertext"], key=result["real_key"] ) assert json.loads(real_decrypted) == real_message fake_decrypted = deniable.decrypt( ciphertext=result["ciphertext"], key=result["fake_key"] ) assert json.loads(fake_decrypted) == fake_message @pytest.mark.security class TestConfidentialTransactionVulnerabilities: """Test for potential vulnerabilities in confidential transactions""" def test_timing_attack_prevention(self): """Test prevention of timing attacks on amount comparison""" import time import statistics # Create various transaction amounts amounts = [1, 100, 1000, 10000, 100000, 1000000] encryption_times = [] for amount in amounts: transaction = {"amount": amount} # Measure encryption time start = time.perf_counter_ns() ciphertext = encrypt_data( json.dumps(transaction), x25519.X25519PrivateKey.generate(), x25519.X25519PrivateKey.generate().public_key() ) end = time.perf_counter_ns() encryption_times.append(end - start) # Check if encryption time correlates with amount correlation = statistics.correlation(amounts, encryption_times) assert abs(correlation) < 0.1, f"Timing correlation detected: {correlation}" def test_memory_sanitization(self): """Test that sensitive memory is properly sanitized""" import gc import sys # Create confidential transaction sensitive_data = "secret_transaction_data_12345" # Encrypt data ciphertext = encrypt_data( sensitive_data, x25519.X25519PrivateKey.generate(), x25519.X25519PrivateKey.generate().public_key() ) # Force garbage collection del sensitive_data gc.collect() # Check if sensitive data still exists in memory memory_dump = str(sys.getsizeof(ciphertext)) assert "secret_transaction_data_12345" not in memory_dump def test_key_derivation_security(self): """Test security of key derivation functions""" from cryptography.hazmat.primitives.kdf.hkdf import HKDF from cryptography.hazmat.primitives import hashes # Test with different salts base_key = b"base_key_material" salt1 = b"salt_1" salt2 = b"salt_2" kdf1 = HKDF( algorithm=hashes.SHA256(), length=32, salt=salt1, info=b"aitbc-key-derivation", ) kdf2 = HKDF( algorithm=hashes.SHA256(), length=32, salt=salt2, info=b"aitbc-key-derivation", ) key1 = kdf1.derive(base_key) key2 = kdf2.derive(base_key) # Different salts should produce different keys assert key1 != key2 # Keys should be sufficiently random # Test by checking bit distribution bit_count = sum(bin(byte).count('1') for byte in key1) bit_ratio = bit_count / (len(key1) * 8) assert 0.45 < bit_ratio < 0.55, "Key bits not evenly distributed" def test_side_channel_leakage_prevention(self): """Test prevention of various side channel attacks""" import psutil import os # Monitor resource usage during encryption process = psutil.Process(os.getpid()) # Baseline measurements baseline_cpu = process.cpu_percent() baseline_memory = process.memory_info().rss # Perform encryption operations for i in range(100): data = f"transaction_data_{i}" encrypt_data( data, x25519.X25519PrivateKey.generate(), x25519.X25519PrivateKey.generate().public_key() ) # Check for unusual resource usage patterns final_cpu = process.cpu_percent() final_memory = process.memory_info().rss cpu_increase = final_cpu - baseline_cpu memory_increase = final_memory - baseline_memory # Resource usage should be consistent assert cpu_increase < 50, f"Excessive CPU usage: {cpu_increase}%" assert memory_increase < 100 * 1024 * 1024, f"Excessive memory usage: {memory_increase} bytes" def test_quantum_resistance_preparation(self): """Test preparation for quantum-resistant cryptography""" # Test post-quantum key exchange simulation from apps.coordinator_api.src.app.services.pqc_service import PostQuantumCrypto pqc = PostQuantumCrypto() # Generate quantum-resistant key pair key_pair = pqc.generate_keypair(algorithm="kyber768") assert "private_key" in key_pair assert "public_key" in key_pair assert "algorithm" in key_pair assert key_pair["algorithm"] == "kyber768" # Test quantum-resistant signature message = "confidential_transaction_hash" signature = pqc.sign( message=message, private_key=key_pair["private_key"], algorithm="dilithium3" ) assert "signature" in signature assert "algorithm" in signature # Verify signature is_valid = pqc.verify( message=message, signature=signature["signature"], public_key=key_pair["public_key"], algorithm="dilithium3" ) assert is_valid is True @pytest.mark.security class TestConfidentialTransactionCompliance: """Test compliance features for confidential transactions""" def test_regulatory_reporting(self, confidential_service): """Test regulatory reporting while maintaining privacy""" # Create confidential transaction tx = ConfidentialTransaction( id="regulatory-tx-123", ciphertext="encrypted_data", sender_key="sender_key", receiver_key="receiver_key", created_at=datetime.utcnow(), ) # Generate regulatory report report = confidential_service.generate_regulatory_report( transaction_id=tx.id, reporting_fields=["timestamp", "asset_type", "jurisdiction"], viewing_authority="financial_authority_123" ) # Report should contain required fields but not private data assert "transaction_id" in report assert "timestamp" in report assert "asset_type" in report assert "jurisdiction" in report assert "amount" not in report # Should remain confidential assert "sender" not in report # Should remain confidential assert "receiver" not in report # Should remain confidential def test_kyc_aml_integration(self, confidential_service): """Test KYC/AML checks without compromising privacy""" # Create transaction with encrypted parties encrypted_parties = { "sender": "encrypted_sender_data", "receiver": "encrypted_receiver_data", } # Perform KYC/AML check with patch('apps.coordinator_api.src.app.services.aml_service.check_parties') as mock_aml: mock_aml.return_value = { "sender_status": "cleared", "receiver_status": "cleared", "risk_score": 0.2, } aml_result = confidential_service.perform_aml_check( encrypted_parties=encrypted_parties, viewing_permission="regulatory_only" ) assert aml_result["sender_status"] == "cleared" assert aml_result["risk_score"] < 0.5 # Verify parties remain encrypted assert "sender_address" not in aml_result assert "receiver_address" not in aml_result def test_audit_trail_privacy(self, confidential_service): """Test audit trail that preserves privacy""" # Create series of confidential transactions transactions = [ {"id": f"tx-{i}", "amount": 1000 * i} for i in range(10) ] # Generate privacy-preserving audit trail audit_trail = confidential_service.generate_audit_trail( transactions=transactions, privacy_level="high", auditor_id="auditor_123" ) # Audit trail should have: assert "transaction_count" in audit_trail assert "total_volume" in audit_trail assert "time_range" in audit_trail assert "compliance_hash" in audit_trail # But should not have: assert "transaction_ids" not in audit_trail assert "individual_amounts" not in audit_trail assert "party_addresses" not in audit_trail def test_data_retention_policy(self, confidential_service): """Test data retention and automatic deletion""" # Create old confidential transaction old_tx = ConfidentialTransaction( id="old-tx-123", ciphertext="old_encrypted_data", created_at=datetime.utcnow() - timedelta(days=400), # Over 1 year ) # Test retention policy enforcement with patch('apps.coordinator_api.src.app.services.retention_service.check_retention') as mock_check: mock_check.return_value = {"should_delete": True, "reason": "expired"} deletion_result = confidential_service.enforce_retention_policy( transaction_id=old_tx.id, policy_duration_days=365 ) assert deletion_result["deleted"] is True assert "deletion_timestamp" in deletion_result assert "compliance_log" in deletion_result