Web & Client Encryption Guide

G5 Cyber Security

1 week ago

TL;DR

This guide covers how to securely encrypt data between your website and specific clients. We’ll focus on using TLS (Transport Layer Security) with strong ciphers, certificate management, and client-specific configurations for enhanced cyber security.

1. Understand TLS/SSL

TLS (and its older version SSL) is the standard protocol for encrypting communication over the internet. It ensures data privacy and integrity. Your website needs an SSL/TLS certificate to enable HTTPS, which is essential for secure connections.

2. Choose a Strong Certificate

Certificate Authority (CA): Use a reputable CA like Let’s Encrypt, DigiCert, or Sectigo.
Certificate Type: For most websites, a Domain Validated (DV) certificate is sufficient. For higher security needs (e.g., e-commerce), consider Organization Validation (OV) or Extended Validation (EV).
Key Size: Use at least a 2048-bit RSA key or an equivalent ECC key size. Avoid weaker keys like 1024-bit.

3. Configure Your Web Server

The configuration varies depending on your web server (Apache, Nginx, IIS). Here’s a general outline:

Install the Certificate: Follow your CA’s instructions to install the certificate and private key on your server.
Enable HTTPS: Configure your server to listen on port 443 (the standard HTTPS port).
Redirect HTTP to HTTPS: Automatically redirect all HTTP requests to their HTTPS equivalents. This ensures users always connect securely.
```
# Example Nginx configuration snippet
```
```
server {
```
```
    listen 80;
```
```
    return 301 https://$host$request_uri;
```
```
}
```
Cipher Suite Configuration: Select strong cipher suites. Disable weak or outdated ciphers like SSLv3, TLS 1.0 and RC4. Prioritize modern ciphers that support Forward Secrecy (e.g., ECDHE).

# Example Apache configuration snippet

SSLProtocol all -SSLv3 -TLSv1 -TLSv1.1

SSLCipherSuite HIGH:!aNULL:!MD5

4. Client-Specific Configurations (Advanced)

For specific clients requiring extra security, consider these options:

Mutual TLS (mTLS): Require clients to present a certificate in addition to the server’s. This adds an extra layer of authentication.

Generate client certificates using your CA.
Configure your web server to verify these client certificates.
Clients must be configured to send their certificate during connection.

HTTP Strict Transport Security (HSTS): Tell browsers to *always* connect to your site via HTTPS, even if a user types http://. This prevents man-in-the-middle attacks.

# Example HSTS header in your web server configuration

Strict-Transport-Security: max-age=31536000; includeSubDomains; preload

Certificate Pinning (Client-Side): Embed the expected certificate or public key within the client application. This prevents attackers from using rogue certificates, even if a CA is compromised. Use with caution as it can cause connectivity issues if your certificate changes.

5. Keep Software Updated

Regularly update your web server software, operating system, and any related libraries to patch security vulnerabilities.

6. Monitor Your Certificates

Use tools like OpenSSL or online certificate checkers to monitor the expiration dates of your certificates and ensure they are valid. Set up alerts for upcoming expirations.

7. Test Your Configuration

Use online SSL testing tools (e.g., SSL Labs Server Test) to verify your configuration and identify any weaknesses. Regularly test after making changes.