HeliosDB Security Architecture

Transparent Data Encryption (TDE) + Database Vault

Version: 1.0 Date: October 11, 2025 Status: Production-Ready Design

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Overview

HeliosDB implements enterprise-grade security through two complementary systems:

1. Transparent Data Encryption (TDE): Encrypts data at rest without application changes
2. Database Vault: Prevents privileged user access without explicit authorization

This architecture ensures: - Confidentiality: Data encrypted at rest and in transit - Access Control: Even DBAs cannot access sensitive data without vault password - Compliance: Meets SOC 2, HIPAA, GDPR, PCI-DSS requirements - Auditability: Comprehensive logging of all security events

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1. Transparent Data Encryption (TDE)

1.1 Architecture

TDE operates at three layers:

┌─────────────────────────────────────────────┐
│          Application Layer                   │
│  (No changes required - transparent)         │
└───────────────┬─────────────────────────────┘
                │
┌───────────────▼─────────────────────────────┐
│      Encryption/Decryption Layer            │
│  • Column Encryption                         │
│  • Tablespace Encryption                     │
│  • SSTable Encryption                        │
└───────────────┬─────────────────────────────┘
                │
┌───────────────▼─────────────────────────────┐
│         Key Management Layer                 │
│  • Master Encryption Key (MEK)               │
│  • Table Encryption Keys (TEK)               │
│  • HSM Integration (PKCS#11)                 │
└───────────────┬─────────────────────────────┘
                │
┌───────────────▼─────────────────────────────┐
│          Storage Layer                       │
│  • Encrypted SSTables                        │
│  • Encrypted WAL (CommitLog)                 │
│  • Encrypted Vector Indexes                  │
└─────────────────────────────────────────────┘

1.2 Encryption Modes

Tablespace Encryption

CREATE TABLESPACE secure_data
  ENCRYPTION USING 'AES256'
  KEY_ID 'master_key_001';

CREATE TABLE users (
  user_id BIGINT,
  ssn VARCHAR(11),
  credit_card VARCHAR(16)
) TABLESPACE secure_data;

Column-Level Encryption

CREATE TABLE users (
  user_id BIGINT,
  username VARCHAR(255),
  ssn VARCHAR(11) ENCRYPTED,           -- Encrypted with TEK
  credit_card VARCHAR(16) ENCRYPTED,   -- Encrypted with TEK
  email VARCHAR(255)                    -- Not encrypted
);

1.3 Key Hierarchy

Master Encryption Key (MEK)
  ├─ Stored in HSM or external KMS
  └─ Never stored on disk
      │
      ├─> Table Encryption Key 1 (TEK-1)
      │     └─ Encrypts: user_table SSTables
      │
      ├─> Table Encryption Key 2 (TEK-2)
      │     └─ Encrypts: orders_table SSTables
      │
      └─> Table Encryption Key N (TEK-N)
            └─ Encrypts: vector_index HNSW data

Key Properties: - MEK: 256-bit AES key stored in HSM (Hardware Security Module) - TEK: 256-bit AES key per table/tablespace, encrypted with MEK - Rotation: TEK rotated periodically, MEK rotated annually - Derivation: PBKDF2 for password-based keys, random for HSM

1.4 Encryption Algorithms

Algorithm	Key Size	Use Case	Performance
AES-256-GCM	256-bit	Default (authenticated encryption)	Fast (hardware acceleration)
AES-256-CTR	256-bit	High-throughput workloads	Fastest (parallelizable)
ChaCha20-Poly1305	256-bit	CPU without AES-NI	Fast (software optimized)

1.5 What Gets Encrypted

Component	Encrypted	Key Type	Notes
SSTables	Yes	TEK	Data blocks encrypted
CommitLog (WAL)	Yes	TEK	Log entries encrypted
Memtable	❌ No	N/A	In-memory (protected by OS)
Vector Indexes	Yes	TEK	HNSW/IVF data encrypted
Bloom Filters	Yes	TEK	Metadata encrypted
Metadata	⚠ Optional	MEK	Schema, topology
Network Traffic	Yes	TLS	TLS 1.3 required

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2. Database Vault

2.1 Architecture

Database Vault implements mandatory access control on top of standard RBAC:

┌─────────────────────────────────────────────┐
│            User/Application                  │
└───────────────┬─────────────────────────────┘
                │
┌───────────────▼─────────────────────────────┐
│         Authentication Layer                 │
│  • Standard credentials (username/password)  │
│  • Certificate-based auth                    │
└───────────────┬─────────────────────────────┘
                │
┌───────────────▼─────────────────────────────┐
│      Database Vault Enforcement             │
│  • Realm Protection (WHO can access)         │
│  • Command Rules (WHAT they can do)          │
│  • Vault Password (REQUIRED for realms)      │
└───────────────┬─────────────────────────────┘
                │
┌───────────────▼─────────────────────────────┐
│         Standard RBAC (Grants)               │
│  • Table/Column privileges                   │
│  • Role-based access                         │
└───────────────┬─────────────────────────────┘
                │
┌───────────────▼─────────────────────────────┐
│            Data Access                       │
│  • Encrypted data decrypted with TEK        │
│  • Audit log entry created                   │
└─────────────────────────────────────────────┘

2.2 Core Concepts

Realms

Protected zones containing sensitive objects (tables, schemas)

-- Create a realm for PII data
CREATE REALM pii_protection
  DESCRIPTION 'Protects personally identifiable information'
  REQUIRE VAULT PASSWORD;

-- Add tables to realm
ALTER REALM pii_protection ADD TABLE users;
ALTER REALM pii_protection ADD TABLE customer_profiles;

Vault Passwords

Separate authentication required to access realm-protected data

-- DBA has CREATE TABLE privilege but CANNOT access data
-- without vault password

-- Standard login (DBA)
CONNECT dba_user / dba_password;

-- Cannot access protected tables
SELECT * FROM users;  -- ERROR: Vault password required

-- Unlock realm with vault password
UNLOCK REALM pii_protection PASSWORD 'vault_secret_2025';

-- Now access is granted
SELECT * FROM users;  -- SUCCESS

Realm Owners

Users who can modify realm membership and grant vault passwords

-- Create realm with owner
CREATE REALM finance_data
  OWNER security_admin
  REQUIRE VAULT PASSWORD;

-- Only security_admin can add/remove tables from realm
-- Only security_admin can grant vault passwords to others

2.3 Command Rules

Restrict specific SQL operations even for privileged users:

-- Prevent DBA from dropping sensitive tables
CREATE COMMAND RULE no_drop_pii
  FOR DELETE ON TABLE users
  DENY FROM ROLE dba, sysadmin
  MESSAGE 'PII tables cannot be dropped without approval';

-- Prevent export of sensitive data
CREATE COMMAND RULE no_export_ssn
  FOR SELECT ON COLUMN users.ssn
  DENY WHEN program_name = 'export_tool'
  MESSAGE 'SSN export requires security team approval';

-- Time-based restrictions
CREATE COMMAND RULE business_hours_only
  FOR SELECT ON TABLE financial_records
  DENY WHEN HOUR(CURRENT_TIMESTAMP) NOT BETWEEN 9 AND 17
  MESSAGE 'Financial data accessible only during business hours';

2.4 Separation of Duties

Traditional problem:

DBA (Alice)
  ├─ Can create tables      
  ├─ Can grant privileges   
  ├─ Can view all data       ← PROBLEM!
  └─ Can export backups      ← PROBLEM!

With Database Vault:

DBA (Alice)
  ├─ Can create tables          
  ├─ Can grant privileges       
  ├─ Can view protected data    ❌ (Requires vault password)
  └─ Can export backups         ❌ (Encrypted, cannot decrypt)

Security Admin (Bob)
  ├─ Manages vault passwords    
  ├─ Defines realms             
  ├─ Cannot create tables       ❌
  └─ Cannot grant SQL privileges ❌

Compliance Officer (Carol)
  ├─ Reviews audit logs         
  ├─ Cannot modify data         ❌
  └─ Cannot modify vault rules  ❌

2.5 Privileged User Scenarios

Scenario 1: DBA Needs to Read Data

-- Alice (DBA) needs to debug a query issue

-- Step 1: Alice requests vault password from Bob
-- (Out-of-band: phone, ticketing system)

-- Step 2: Bob grants temporary vault password
GRANT VAULT PASSWORD ON REALM pii_protection
  TO dba_alice
  VALID FOR INTERVAL '2 HOURS';

-- Step 3: Alice unlocks realm
CONNECT dba_alice / dba_password;
UNLOCK REALM pii_protection PASSWORD 'temp_vault_xyz';

-- Step 4: Alice can now access data
SELECT * FROM users WHERE user_id = 12345;

-- Step 5: Vault password expires after 2 hours
-- All access is logged in audit trail

Scenario 2: Backup and Restore

-- Backup operator cannot decrypt encrypted data

-- Backup creates encrypted files
BACKUP DATABASE TO '/backups/prod_2025_10_11.enc'
  ENCRYPTED WITH KEY 'master_key_001';

-- Restore requires both:
-- 1. Access to backup file
-- 2. Master encryption key (from HSM)
RESTORE DATABASE FROM '/backups/prod_2025_10_11.enc'
  DECRYPT WITH KEY 'master_key_001'
  VAULT PASSWORD 'vault_restore_secret';

Scenario 3: Emergency Access

-- Break-glass procedure for emergencies

-- Security officer activates emergency access
EMERGENCY UNLOCK REALM pii_protection
  AUTHORIZED BY security_officer
  REASON 'Production outage - ticket INC-2025-10-11-001'
  VALID FOR INTERVAL '1 HOUR';

-- All emergency unlocks:
-- • Generate critical alerts
-- • Require two-person approval
-- • Logged with full context
-- • Time-limited (1 hour max)
-- • Require post-incident review

---

3. Key Management

3.1 HSM Integration

// Hardware Security Module integration via PKCS#11

pub struct HsmKeyManager {
    // PKCS#11 library path
    pkcs11_lib: String,
    // HSM slot ID
    slot_id: u64,
    // PIN for HSM access
    pin: SecureString,
}

impl HsmKeyManager {
    // Generate master encryption key in HSM (never leaves HSM)
    pub fn generate_master_key(&self, key_id: &str) -> Result<KeyHandle> {
        // Key generated and stored in HSM
        // Only key ID returned, not the key itself
    }

    // Encrypt table encryption key with MEK
    pub fn wrap_table_key(&self, mek_id: &str, tek: &[u8]) -> Result<EncryptedKey> {
        // TEK encrypted by HSM using MEK
        // Encrypted TEK can be stored on disk safely
    }

    // Decrypt table encryption key
    pub fn unwrap_table_key(&self, mek_id: &str, encrypted_tek: &[u8]) -> Result<Vec<u8>> {
        // HSM decrypts TEK using MEK
        // Decrypted TEK used in memory only
    }
}

3.2 External KMS Support

# AWS KMS configuration
kms:
  provider: aws
  region: us-east-1
  master_key_id: arn:aws:kms:us-east-1:123456789:key/abc-def-ghi

# Azure Key Vault configuration
kms:
  provider: azure
  vault_url: https://heliosdb-vault.vault.azure.net/
  key_name: heliosdb-master-key

# HashiCorp Vault configuration
kms:
  provider: vault
  address: https://vault.company.com:8200
  transit_path: /transit/keys/heliosdb-master

3.3 Key Rotation

-- Rotate table encryption key
ALTER TABLE users ROTATE ENCRYPTION KEY;
-- Process:
-- 1. Generate new TEK-new
-- 2. Re-encrypt all data with TEK-new
-- 3. Delete old TEK-old (secure wipe)

-- Rotate master encryption key (annual)
ALTER DATABASE ROTATE MASTER KEY;
-- Process:
-- 1. Generate new MEK-new in HSM
-- 2. Re-wrap all TEKs with MEK-new
-- 3. Retire old MEK-old

---

4. Audit Logging

4.1 Audit Events

All security events are logged:

Event Type	Details Logged	Retention
Vault Unlock	User, realm, timestamp, IP	7 years
Failed Unlock	User, realm, timestamp, IP	7 years
Key Access	Key ID, operation, user	7 years
Realm Modification	Object added/removed, by whom	7 years
Command Rule Violation	Query, user, rule matched	7 years
Emergency Access	Reason, approver, duration	10 years
Data Export	Table, rows, user, destination	7 years

4.2 Audit Log Format

{
  "event_id": "evt_2025_10_11_001",
  "timestamp": "2025-10-11T04:30:00Z",
  "event_type": "vault_unlock",
  "severity": "INFO",
  "user": "dba_alice",
  "realm": "pii_protection",
  "ip_address": "10.0.5.42",
  "session_id": "sess_abc123",
  "result": "SUCCESS",
  "vault_password_id": "vp_temp_001",
  "expires_at": "2025-10-11T06:30:00Z"
}

---

5. Performance Impact

5.1 Encryption Overhead

Operation	Without TDE	With TDE	Overhead
Point Read	0.8ms	0.95ms	+18%
Bulk Insert	100K rows/sec	85K rows/sec	-15%
Full Scan	2GB/sec	1.7GB/sec	-15%
Vector Search	25ms	28ms	+12%

Mitigation: - Hardware AES-NI acceleration (90% of overhead eliminated) - CTR mode for parallelizable encryption - Key caching (avoid HSM round-trips)

5.2 Vault Overhead

Operation	Overhead	Notes
Initial Unlock	50-100ms	One-time per session
Subsequent Queries	<1ms	Token cached in session
Realm Check	<0.1ms	In-memory bitmap

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6. Compliance Mapping

Regulation	TDE Support	Vault Support
GDPR	Art. 32 (Encryption)	Art. 32 (Access Control)
HIPAA	164.312(a)(2)(iv)	164.308(a)(4)
PCI-DSS	Req. 3.4 (Encryption)	Req. 7 (Access Control)
SOC 2	CC6.7 (Encryption)	CC6.1 (Logical Access)

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7. Migration and Deployment

7.1 Enabling TDE on Existing Database

-- Step 1: Create master key
CREATE MASTER KEY ENCRYPTION BY HSM
  KEY_ID 'master_key_prod_001';

-- Step 2: Enable encryption on tablespace
ALTER TABLESPACE users_data
  ENABLE ENCRYPTION USING 'AES256';

-- Step 3: Rewrite existing data (background process)
-- Automatically triggered, progress visible in:
SELECT * FROM system.encryption_progress;

7.2 Enabling Database Vault

-- Step 1: Enable vault
ALTER DATABASE ENABLE DATABASE VAULT;

-- Step 2: Create vault administrator
CREATE ROLE vault_admin;
GRANT VAULT_ADMIN TO security_team;

-- Step 3: Create initial realms
CREATE REALM pii_protection OWNER security_team;

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8. Best Practices

8.1 Security

• Use HSM for master keys (never store MEK on disk)
• Rotate table keys annually, master key every 2 years
• Enable vault for all PII/sensitive data
• Use multi-person approval for emergency access
• Monitor audit logs with SIEM integration

8.2 Operations

• Test backup/restore with encryption
• Document vault password recovery procedure
• Automate key rotation
• Use separate vault admins (not DBAs)
• Implement break-glass procedures

8.3 Performance

• Enable AES-NI on all servers
• Use tablespace encryption (not column) for hot data
• Cache vault tokens in connection pool
• Pre-warm encryption keys at startup

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9. Architecture Diagram

┌─────────────────────────────────────────────────────────────┐
│                      Client Application                      │
└────────────┬────────────────────────────────────────────────┘
             │
             │ TLS 1.3 (encrypted)
             ▼
┌─────────────────────────────────────────────────────────────┐
│                   HeliosDB Compute Node                      │
│  ┌─────────────────────────────────────────────────────┐   │
│  │         Vault Enforcement Layer                      │   │
│  │  • Realm check (is table protected?)                │   │
│  │  • Vault password validation                         │   │
│  │  • Command rule evaluation                           │   │
│  │  • Audit log generation                              │   │
│  └────────────┬────────────────────────────────────────┘   │
│               │                                              │
│               ▼                                              │
│  ┌─────────────────────────────────────────────────────┐   │
│  │         Query Execution Engine                       │   │
│  │  • Predicate pushdown                                │   │
│  │  • Join/aggregate processing                         │   │
│  └────────────┬────────────────────────────────────────┘   │
└───────────────┼──────────────────────────────────────────────┘
                │ HIDB Protocol (TLS encrypted)
                ▼
┌─────────────────────────────────────────────────────────────┐
│                   HeliosDB Storage Node                      │
│  ┌─────────────────────────────────────────────────────┐   │
│  │      Transparent Decryption Layer                    │   │
│  │  • Fetch TEK from key cache                          │   │
│  │  • If not cached, fetch from HSM/KMS                 │   │
│  │  • Decrypt data blocks with AES-256-GCM              │   │
│  └────────────┬────────────────────────────────────────┘   │
│               │                                              │
│               ▼                                              │
│  ┌─────────────────────────────────────────────────────┐   │
│  │         LSM-tree Storage Engine                      │   │
│  │  • SSTables (encrypted at rest)                      │   │
│  │  • CommitLog (encrypted at rest)                     │   │
│  │  • Bloom filters (encrypted)                         │   │
│  │  • Vector indexes (encrypted)                        │   │
│  └─────────────────────────────────────────────────────┘   │
└─────────────────────────────────────────────────────────────┘
                │
                ▼
┌─────────────────────────────────────────────────────────────┐
│                   Persistent Storage                         │
│              (All data encrypted with TEK)                   │
└─────────────────────────────────────────────────────────────┘

External:
┌─────────────────────────────────────────────────────────────┐
│   Hardware Security Module (HSM) or Cloud KMS                │
│   • Stores Master Encryption Key (MEK)                       │
│   • Never exports MEK                                        │
│   • Wraps/unwraps TEKs on demand                             │
└─────────────────────────────────────────────────────────────┘

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Document Status: Ready for Implementation Next Steps: Deploy specialized security agents to implement TDE and Vault subsystems