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TLS Versions and Cipher Suites

Transport Layer Security (TLS) protocol versions and cipher suites determine the cryptographic algorithms used to secure Cassandra communications. Selecting appropriate versions and ciphers is critical for both security and interoperability.

TLS Protocol Versions

Version Comparison

Version Status Java Requirement Cassandra Support
SSL 3.0 Deprecated - Disabled by default
TLS 1.0 Deprecated Java 6+ Supported, not recommended
TLS 1.1 Deprecated Java 7+ Supported, not recommended
TLS 1.2 Current Java 7+ Recommended minimum
TLS 1.3 Current Java 11+ Recommended (Cassandra 4.0+)

Protocol Security Status

TLS 1.3 (Recommended) - Removed obsolete cryptographic algorithms - Faster handshake (1-RTT, 0-RTT resumption) - Forward secrecy mandatory - Simplified cipher suite configuration

TLS 1.2 (Acceptable) - Widely supported - Secure when configured with strong cipher suites - Requires careful cipher suite selection

TLS 1.0/1.1 (Deprecated) - Vulnerable to BEAST, POODLE attacks - PCI-DSS compliance prohibits use - Disable in production environments

Cipher Suites

A cipher suite defines the combination of algorithms used for: - Key exchange (how keys are established) - Authentication (how identity is verified) - Encryption (how data is protected) - Message authentication (how integrity is verified)

TLS 1.3 Cipher Suites

TLS 1.3 simplified cipher suite naming. All TLS 1.3 suites use AEAD encryption and are considered secure.

Cipher Suite Encryption Notes
TLS_AES_256_GCM_SHA384 AES-256-GCM Recommended
TLS_AES_128_GCM_SHA256 AES-128-GCM Good performance
TLS_CHACHA20_POLY1305_SHA256 ChaCha20-Poly1305 Good for non-AES-NI CPUs

TLS 1.2 Cipher Suites

TLS 1.2 cipher suites require careful selection. Use only AEAD ciphers with forward secrecy.

Recommended:

Cipher Suite Key Exchange Encryption
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 ECDHE AES-256-GCM
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 ECDHE AES-128-GCM
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 ECDHE AES-256-GCM
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 ECDHE AES-128-GCM
TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 DHE AES-256-GCM
TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 DHE AES-128-GCM

Avoid:

Pattern Reason
*_CBC_* Vulnerable to padding oracle attacks
*_RC4_* RC4 is broken
*_DES_* DES is weak
*_NULL_* No encryption
*_EXPORT_* Weak export-grade cryptography
TLS_RSA_* No forward secrecy

Forward Secrecy

Forward secrecy (also called perfect forward secrecy) ensures that session keys cannot be compromised even if the server's private key is later exposed.

How It Works

Without forward secrecy (RSA key exchange): - Session keys are encrypted with the server's RSA public key - If the private key is compromised, all past sessions can be decrypted

With forward secrecy (ECDHE/DHE key exchange): - Session keys are generated using ephemeral Diffie-Hellman - Each session uses unique keys - Compromised private key cannot decrypt past sessions

Configuration

Enable forward secrecy by prioritizing ECDHE and DHE cipher suites:

# cassandra.yaml
server_encryption_options:
    cipher_suites:
        - TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
        - TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256

Configuration Examples

Cassandra 4.0+ with TLS 1.3

# cassandra.yaml
server_encryption_options:
    internode_encryption: all
    protocol: TLS
    accepted_protocols:
        - TLSv1.3
        - TLSv1.2
    cipher_suites:
        - TLS_AES_256_GCM_SHA384
        - TLS_AES_128_GCM_SHA256
        - TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
        - TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256

TLS 1.2 Only (Java 8)

# cassandra.yaml
server_encryption_options:
    internode_encryption: all
    protocol: TLS
    accepted_protocols:
        - TLSv1.2
    cipher_suites:
        - TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
        - TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
        - TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
        - TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256

Explicitly Disable Weak Protocols

# cassandra.yaml
server_encryption_options:
    # Only allow TLS 1.2+
    accepted_protocols:
        - TLSv1.2
        - TLSv1.3
    # Explicitly exclude weak protocols (redundant but explicit)
    # SSLv3, TLSv1, TLSv1.1 are not listed

Verifying TLS Configuration

Check Supported Protocols

# Test TLS 1.3
openssl s_client -connect cassandra-node:9042 -tls1_3

# Test TLS 1.2
openssl s_client -connect cassandra-node:9042 -tls1_2

# Test TLS 1.1 (should fail if properly configured)
openssl s_client -connect cassandra-node:9042 -tls1_1

Check Cipher Suites

# Show negotiated cipher suite
openssl s_client -connect cassandra-node:9042 -tls1_2 2>/dev/null | grep "Cipher is"

# Test specific cipher suite
openssl s_client -connect cassandra-node:9042 -cipher ECDHE-RSA-AES256-GCM-SHA384

Using nmap for TLS Analysis

# Scan TLS configuration
nmap --script ssl-enum-ciphers -p 9042 cassandra-node

Java Version Considerations

Java 8

  • TLS 1.2 supported
  • TLS 1.3 not available
  • Some GCM cipher suites may have performance issues

Java 11+

  • TLS 1.3 supported
  • Improved TLS performance
  • Recommended for production deployments

JVM Options

# Disable weak protocols at JVM level
-Djdk.tls.disabledAlgorithms=SSLv3,TLSv1,TLSv1.1,RC4,DES,MD5withRSA,DH keySize < 1024,EC keySize < 224

# Enable TLS 1.3 (Java 11+)
-Djdk.tls.client.protocols=TLSv1.3,TLSv1.2

Compliance Requirements

Standard Minimum TLS Version Notes
PCI-DSS 3.2+ TLS 1.2 TLS 1.0/1.1 prohibited since 2018
HIPAA TLS 1.2 Strong encryption required
NIST SP 800-52 TLS 1.2 TLS 1.3 recommended
FedRAMP TLS 1.2 Federal systems requirement