Catalog
technology#Security#Architecture#Integration

Secure Sockets Layer (SSL)

SSL is a historical cryptographic protocol for encrypting and authenticating network connections. It defines handshake procedures, certificate use and cipher negotiation and serves as the precursor to modern TLS deployments.

Secure Sockets Layer (SSL) is a cryptographic protocol historically used to provide confidentiality, integrity and authentication for networked communications.
Established
Medium

Classification

  • Medium
  • Technical
  • Architectural
  • Advanced

Technical context

Web servers (Apache, Nginx, IIS)Load balancers and TLS termination proxiesPKI and certificate management systems

Principles & goals

Use current protocol versions and secure cipher suites.Verify certificate chains against trusted CAs or internal PKI.Minimize attack surface via HSTS, secure redirects and protocol hardening.
Build
Enterprise, Domain, Team

Use cases & scenarios

Compromises

  • Insecure configurations can enable MITM attacks.
  • Expired or misissued certificates cause service disruptions.
  • Use of deprecated protocols leaves systems vulnerable.
  • Use TLS 1.2+ or TLS 1.3 and disable SSLv2/SSLv3.
  • Implement automated certificate rotation (e.g., ACME).
  • Perform regular scans and checks using TLS scanners.

I/O & resources

  • Certificates (CA, intermediate and server certificates)
  • Configuration parameters for protocol version and ciphers
  • End-of-support and client compatibility requirements
  • Encrypted transport connections (TLS/SSL)
  • Certificate proofs and validation logs
  • Metrics for handshake successes and latencies

Description

Secure Sockets Layer (SSL) is a cryptographic protocol historically used to provide confidentiality, integrity and authentication for networked communications. It establishes encrypted channels between clients and servers and defines handshakes, certificates and cipher negotiation. Modern deployments use TLS, the successor standard, while SSL itself is deprecated.

✔

  • Protects confidentiality and integrity of data in transit.
  • Enables server authentication to clients.
  • Foundation for additional security mechanisms like mTLS.

✖

  • Older SSL versions are insecure and must not be used.
  • Complexity in certificate management and rotation in large environments.
  • Performance overhead with strong encryption without hardware support.

  • TLS connection error rate

    Proportion of failed TLS handshakes among all connection attempts.

  • TLS latency (handshake)

    Average time to complete a TLS handshake.

  • Certificate expiry incidents

    Number of incidents due to expired or invalid certificates per period.

HTTPS on Apache/Nginx

Common web servers configured for TLS termination using CA certificates and modern cipher suites.

Mail servers with STARTTLS

Mail servers enable STARTTLS for encrypted SMTP connections and validate certificate chain.

OpenSSL as implementation example

OpenSSL library serves as a reference implementation for SSL/TLS operations and tools.

1

Analyze existing TLS/SSL configurations and deployed versions.

2

Create plan for certificate management and rotation.

3

Configure server and client software, enable secure cipher suites.

4

Run tests, set up monitoring and roll out to production incrementally.

⚠️ Technical debt & bottlenecks

  • Legacy configurations that still allow insecure protocols.
  • Lack of automation for certificate issuance and rotation.
  • Insufficient documentation of TLS configurations and policies.
Certificate managementCPU load during TLS handshakeLegacy client compatibility
  • Continuing to operate SSLv3 for legacy clients despite known vulnerabilities.
  • Using self-signed certificates on public services without validation.
  • Deploying weak cipher suites to support legacy clients.
  • Omitting intermediate certificates in the chain leads to trust errors.
  • Lack of testing with real client implementations causes compatibility issues.
  • Ignoring vendor recommendations for secure cipher suites.
Basic knowledge of cryptographic concepts and PKIOperational experience with server configuration and security updatesMonitoring and incident handling skills
Confidentiality and integrity of data in transitCertificate and key managementCompatibility with client ecosystems
  • • Requirement for trusted CA chains or internal PKI
  • • Hardware acceleration may be required for high load
  • • Legal/regulatory constraints on cryptography in some regions