tls_setup

TLS/SSL Setup Guide for ThemisDB

Overview

ThemisDB supports both HTTP and HTTPS modes with optional mutual TLS (mTLS) for enhanced security. This guide covers certificate generation, configuration, and testing.

Security Features

Transport Layer Security (TLS)

• TLS 1.3 Support: Modern, secure protocol with perfect forward secrecy
• TLS 1.2 Fallback: Configurable for compatibility with legacy clients
• Strong Cipher Suites: ECDHE-RSA-AES256-GCM-SHA384, ECDHE-RSA-AES128-GCM-SHA256, ChaCha20-Poly1305
• Disabled Weak Protocols: SSLv2, SSLv3, TLSv1.0, TLSv1.1 explicitly disabled

Mutual TLS (mTLS)

• Client Certificate Verification: Enforce client authentication with X.509 certificates
• Certificate Chain Validation: Verify certificates against trusted CA bundle
• Client Identity Logging: Extract and log client certificate DN for audit trails

HTTP Security Headers

• HSTS (Strict-Transport-Security): Forces HTTPS for 1 year with subdomain inclusion
• X-Frame-Options: Prevents clickjacking attacks (DENY)
• X-Content-Type-Options: Prevents MIME type sniffing (nosniff)
• Content-Security-Policy: Restricts content sources (default-src 'self')

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Certificate Generation

Using the Test Certificate Script

For development and testing only, use the provided script to generate self-signed certificates:

# Generate certificates in default location (config/certs)
./scripts/generate_test_certs.sh

# Generate certificates in custom location
./scripts/generate_test_certs.sh /path/to/certs

This script generates:

• CA certificate and key (ca.crt, ca.key) - Root authority for signing
• Server certificate and key (server.crt, server.key) - For HTTPS endpoint
• Client certificate and key (client.crt, client.key) - For mTLS authentication
• Full chain files (server-fullchain.pem, client-bundle.pem) - Combined PEM formats

Production Certificates

For production environments, obtain certificates from a trusted Certificate Authority (CA):

1. Internal CA (e.g., Active Directory Certificate Services, HashiCorp Vault)
2. Public CA (e.g., Let's Encrypt, DigiCert, GlobalSign)
3. Enterprise PKI (integrate with existing organizational PKI infrastructure)

Let's Encrypt Example

# Install certbot
sudo apt-get install certbot

# Obtain certificate (HTTP-01 challenge)
sudo certbot certonly --standalone -d themisdb.example.com

# Certificates will be in /etc/letsencrypt/live/themisdb.example.com/
# - fullchain.pem (server certificate + intermediate CA)
# - privkey.pem (private key)

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Configuration

Environment Variables

ThemisDB TLS configuration is controlled via environment variables:

Basic TLS (One-Way Authentication)

# Enable HTTPS
export THEMIS_TLS_ENABLED=1

# Server certificate (PEM format)
export THEMIS_TLS_CERT=/path/to/server.crt

# Server private key (PEM format)
export THEMIS_TLS_KEY=/path/to/server.key

# Minimum TLS version (TLSv1.2 or TLSv1.3, default: TLSv1.3)
export THEMIS_TLS_MIN_VERSION=TLSv1.3

# Optional: Custom cipher list (OpenSSL format)
# export THEMIS_TLS_CIPHER_LIST="ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256"

Mutual TLS (Two-Way Authentication)

# Enable HTTPS with mTLS
export THEMIS_TLS_ENABLED=1
export THEMIS_TLS_CERT=/path/to/server.crt
export THEMIS_TLS_KEY=/path/to/server.key

# CA certificate for client verification
export THEMIS_TLS_CA_CERT=/path/to/ca.crt

# Require client certificate (enforce mTLS)
export THEMIS_TLS_REQUIRE_CLIENT_CERT=1

Code Configuration (C++ API)

#include "server/http_server.h"

themis::server::HttpServer::Config config;
config.host = "0.0.0.0";
config.port = 8443; // Standard HTTPS port

// Enable TLS
config.enable_tls = true;
config.tls_cert_path = "/path/to/server.crt";
config.tls_key_path = "/path/to/server.key";
config.tls_min_version = "TLSv1.3";

// Enable mTLS
config.tls_ca_cert_path = "/path/to/ca.crt";
config.tls_require_client_cert = true;

auto server = std::make_unique<themis::server::HttpServer>(
    config, storage, secondary_index, graph_index, vector_index, tx_manager
);

---

Testing

Test HTTPS Connection (One-Way TLS)

# Health check with CA verification
curl --cacert config/certs/ca.crt https://localhost:8443/health

# Skip verification (development only)
curl -k https://localhost:8443/health

# Test with verbose output
curl -v --cacert config/certs/ca.crt https://localhost:8443/metrics

Test mTLS Connection (Mutual TLS)

# Authenticate with client certificate
curl --cacert config/certs/ca.crt \
     --cert config/certs/client.crt \
     --key config/certs/client.key \
     https://localhost:8443/health

# Test authenticated API endpoint
curl --cacert config/certs/ca.crt \
     --cert config/certs/client.crt \
     --key config/certs/client.key \
     -H "Authorization: Bearer YOUR_TOKEN" \
     https://localhost:8443/api/entities/test-key

Verify Certificate Details

# Inspect server certificate
openssl x509 -in config/certs/server.crt -text -noout

# Check certificate chain
openssl verify -CAfile config/certs/ca.crt config/certs/server.crt

# Test TLS handshake
openssl s_client -connect localhost:8443 -CAfile config/certs/ca.crt

# Test mTLS handshake with client cert
openssl s_client -connect localhost:8443 \
    -CAfile config/certs/ca.crt \
    -cert config/certs/client.crt \
    -key config/certs/client.key

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Security Best Practices

Certificate Management

1. Private Key Protection: Store private keys with restricted permissions (chmod 600)
2. Certificate Rotation: Implement automated certificate renewal (e.g., Let's Encrypt auto-renewal)
3. Certificate Revocation: Monitor CRL/OCSP for revoked certificates (future enhancement)
4. Key Separation: Never reuse private keys across environments (dev/staging/prod)

Cipher Suite Selection

Default strong ciphers (automatically configured):

• ECDHE-RSA-AES256-GCM-SHA384 - Perfect Forward Secrecy (PFS) with AES-256
• ECDHE-RSA-AES128-GCM-SHA256 - PFS with AES-128 (performance/security balance)
• ECDHE-RSA-CHACHA20-POLY1305 - PFS with ChaCha20 (mobile/IoT devices)

Avoid weak ciphers (automatically disabled):

• RC4, MD5, 3DES, DES, EXPORT ciphers
• Anonymous DH (aDH), NULL encryption

TLS Version Policy

• Recommended: TLS 1.3 only (modern clients, highest security)
• Compatible: TLS 1.2+ (legacy client support, still secure)
• Prohibited: TLS 1.1, TLS 1.0, SSLv3, SSLv2 (deprecated, known vulnerabilities)

mTLS Use Cases

Enable mutual TLS for:

• Service-to-Service Communication (microservices authentication)
• High-Security APIs (financial, healthcare, government sectors)
• Zero-Trust Networks (verify every client connection)
• Compliance Requirements (PCI-DSS, HIPAA, GDPR)

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Troubleshooting

Common Errors

1. TLS initialization failed: No such file or directory

Cause: Certificate or key file path is incorrect.
Solution: Verify paths with ls -l $THEMIS_TLS_CERT and ensure files are readable.

2. TLS handshake error: certificate verify failed

Cause: Client cannot verify server certificate (CA not trusted).
Solution: Add --cacert with CA certificate or install CA in system trust store.

3. mTLS: no client certificate presented despite requirement

Cause: Client did not provide certificate in mTLS mode.
Solution: Ensure client uses --cert and --key flags, or disable mTLS requirement.

4. SSL shutdown error: stream truncated

Cause: Client closed connection abruptly (normal during testing).
Solution: Non-critical, can be ignored in development.

Debug TLS Issues

# Enable OpenSSL debug logging
export SSLKEYLOGFILE=/tmp/sslkeys.log
curl --cacert config/certs/ca.crt https://localhost:8443/health

# Analyze TLS handshake with tcpdump
sudo tcpdump -i lo -w /tmp/tls.pcap port 8443
# Open /tmp/tls.pcap in Wireshark with SSLKEYLOGFILE for decryption

# Check server logs for TLS details
tail -f data/logs/themis.log | grep -i "tls\|ssl\|handshake"

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Future Enhancements

Planned TLS/PKI features:

• OCSP Stapling (RFC 6066) for certificate revocation checking
• Certificate Pinning for HSM/TSA outbound connections
• Automated Let's Encrypt integration with ACME protocol
• Hardware Security Module (HSM) integration for private key storage
• Certificate Transparency (CT) log monitoring
• TLS session resumption (session IDs, session tickets)

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References

• RFC 8446: TLS 1.3
• Mozilla SSL Configuration Generator
• OWASP TLS Cheat Sheet
• Qualys SSL Labs Server Test
• NIST SP 800-52 Rev. 2: TLS Guidelines

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Support

For issues or questions:

• Security Issues: Report to [email protected] (do not open public issues)
• General Help: GitHub Issues or Discussions
• Documentation: https://docs.themisdb.io/security/tls