Anthropic-Cybersecurity-Skills/skills/configuring-tls-1-3-for-secure-communications/assets/template.md

TLS 1.3 Configuration Template

Pre-Configuration Checklist

• Verify OpenSSL version >= 1.1.1 (openssl version)
• Obtain valid TLS certificate from trusted CA
• Identify all server endpoints requiring TLS
• Determine minimum TLS version (1.2 or 1.3 only)
• Plan certificate renewal automation (Let's Encrypt / ACME)
• Review compliance requirements (PCI-DSS, HIPAA)

nginx Configuration Template

ssl_protocols TLSv1.2 TLSv1.3;
ssl_ciphers 'ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256';
ssl_prefer_server_ciphers off;
ssl_ecdh_curve X25519:secp256r1:secp384r1;
ssl_session_timeout 1d;
ssl_session_cache shared:SSL:10m;
ssl_session_tickets off;
ssl_stapling on;
ssl_stapling_verify on;
add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload" always;

Python TLS 1.3 Client Template

import ssl
import socket

context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
context.minimum_version = ssl.TLSVersion.TLSv1_3
context.load_default_certs()

with socket.create_connection(("example.com", 443)) as sock:
    with context.wrap_socket(sock, server_hostname="example.com") as tls:
        print(f"Protocol: {tls.version()}")
        print(f"Cipher: {tls.cipher()}")

Validation Commands

# Test TLS 1.3 support
openssl s_client -connect example.com:443 -tls1_3

# Show full certificate chain
openssl s_client -connect example.com:443 -showcerts

# List supported cipher suites
openssl s_client -connect example.com:443 -cipher 'ALL' -tls1_3

# Test with testssl.sh
./testssl.sh --protocols --ciphers --headers example.com

Security Headers Checklist

Header	Value	Purpose
Strict-Transport-Security	max-age=63072000; includeSubDomains; preload	Force HTTPS
X-Content-Type-Options	nosniff	Prevent MIME sniffing
X-Frame-Options	DENY	Prevent clickjacking
Content-Security-Policy	default-src 'self'	Prevent XSS
Referrer-Policy	strict-origin-when-cross-origin	Limit referrer leakage