TLS Security Score Simulator
Select your TLS configuration options and see your security score update in real time. Identify gaps and get specific recommendations.
TLS Configuration
Security Features
Score Breakdown
Protocol: TLS 1.2 only Disable TLS 1.0 and 1.1 — deprecated and vulnerable (POODLE, BEAST). Enable TLS 1.3 for best performance and security. | +15 pts | |
Cipher suites: Compatible Prefer AEAD ciphers (AES-GCM, ChaCha20-Poly1305). Disable RC4, 3DES, NULL, EXPORT, and DES ciphers. | +12 pts | |
Forward Secrecy (ECDHE/DHE) | +15 pts | |
Key size: 2048-bit RSA | +12 pts | |
HSTS Enabled Enable HSTS (Strict-Transport-Security) to prevent protocol downgrade attacks and SSL stripping. | +10 pts | |
HSTS Preload Listed Submit to hstspreload.org for maximum first-visit protection. Requires HSTS with includeSubDomains and min max-age=31536000. | +5 pts | |
OCSP Stapling Enable OCSP stapling for faster revocation checks without leaking visitor information to the CA. | +5 pts | |
Certificate Transparency (SCT) | +5 pts |
Simulations are useful — live checks catch what your server actually serves.
Check Live TLS ConfigWhat a TLS Grade Actually Measures
When a scanner like Qualys SSL Labs grades a server, it is not measuring one thing — it is auditing a negotiation. Every TLS connection begins with the client and server agreeing on a protocol version, a key-exchange method, and a cipher suite, and the server's job is to only agree to combinations that are still considered safe. A grade summarises how much dangerous ground your server is still willing to concede to an old or malicious client.
That is why grading is dominated by caps rather than points. Offering TLS 1.0 does not subtract a little from an otherwise perfect score — it caps the whole grade, because an active attacker can force a downgrade to the weakest option both sides support. The same logic applies to weak ciphers: it does not matter that AES-256-GCM is first in your list if RC4 is still last in it. This simulator mirrors that behaviour so you can see which single toggle moves your score the most.
The good news is that modern defaults do almost all the work. TLS 1.3 (RFC 8446) removed every legacy cipher, made forward secrecy mandatory, and cut the handshake to one round trip. A server running TLS 1.3 + a hardened TLS 1.2, an ECDHE-only cipher list, a 2048-bit or ECDSA certificate, and an HSTS header will score an A on essentially every grader in use today.
Raising Your Grade: The Config That Matters
nginx: ssl_protocols TLSv1.2 TLSv1.3; — Apache: SSLProtocol -all +TLSv1.2 +TLSv1.3. Both legacy versions were formally deprecated by RFC 8996 in 2021 and are blocked by all major browsers.
Use the Mozilla SSL Configuration Generator’s "intermediate" profile as a baseline. Any suite starting with ECDHE- provides forward secrecy; anything with RC4, 3DES, CBC-SHA, NULL, or EXPORT should not appear at all.
Strict-Transport-Security: max-age=31536000; includeSubDomains — start with a short max-age (e.g. 86400) during rollout, then raise it. Add the preload token and submit to hstspreload.org only when every subdomain serves HTTPS.
nginx: ssl_stapling on; ssl_stapling_verify on; with a resolver directive. This removes the browser’s round trip to the CA and keeps visitor IPs out of CA logs.
Config files describe intent; the network is truth. Test what is actually negotiated: openssl s_client -connect example.com:443 -tls1_1 should FAIL, and our TLS Checker should show only 1.2/1.3 accepted.
Frequently Asked Questions
How do TLS grading systems like SSL Labs work?
Graders inspect four areas of a live server: which protocol versions it accepts, the strength of its certificate and key exchange, which cipher suites it offers, and extra protections such as HSTS. The final grade is capped by the weakest area — a perfect certificate cannot compensate for TLS 1.0 being enabled, which is why single settings can drag an otherwise good server to a C.
What instantly caps or fails a TLS grade?
The classic grade-cappers are: TLS 1.0/1.1 enabled (capped around B/C), no forward secrecy (capped at B), SHA-1 or 1024-bit RSA certificates (fail), RC4/3DES/EXPORT ciphers offered (capped or failed), and support for insecure renegotiation. Fixing these usually matters far more than adding bonus features.
Should I disable TLS 1.2 and go TLS 1.3 only?
For most public sites, not yet. TLS 1.3 + 1.2 is the sweet spot: 1.3 serves modern clients with a faster one-round-trip handshake, while a hardened 1.2 configuration (AEAD ciphers, ECDHE only) covers older enterprise clients, embedded devices, and some corporate proxies. Go 1.3-only when you control all clients, such as internal APIs.
What are AEAD cipher suites and why do graders reward them?
AEAD (Authenticated Encryption with Associated Data) modes such as AES-GCM and ChaCha20-Poly1305 encrypt and authenticate in one operation, eliminating the padding-oracle attacks (Lucky13, POODLE variants) that plagued older CBC-mode ciphers. TLS 1.3 allows only AEAD suites — one of the main reasons it is considered structurally safer.
What is forward secrecy and how do I enable it?
Forward secrecy means each session negotiates a throwaway key via ECDHE or DHE, so a future compromise of your server’s private key cannot decrypt previously recorded traffic. Enable it by preferring ECDHE cipher suites — in nginx, an ssl_ciphers list that contains only ECDHE suites, or simply enabling TLS 1.3, which always uses ephemeral keys.
Is a 4096-bit RSA key worth it over 2048-bit?
2048-bit RSA remains the practical standard and is not the weak point of any real-world attack today; 4096-bit adds measurable CPU cost on every handshake for a marginal margin. A better upgrade is an ECDSA P-256 certificate, which offers security comparable to 3072-bit RSA with smaller, faster handshakes. Many servers deploy both and let clients pick.
What does OCSP stapling actually do?
Normally a browser would have to query the CA’s OCSP server to check whether your certificate was revoked — slow, unreliable, and it tells the CA who is visiting your site. With stapling, your server fetches the signed OCSP response itself and attaches ("staples") it to the TLS handshake. Enable it in nginx with ssl_stapling on; ssl_stapling_verify on;.
How do I test my real server instead of a simulation?
Point our free TLS Checker or SSL Checker at your domain to see the live protocol versions, certificate chain, and expiry your server actually presents. From a terminal you can also probe specific versions directly, e.g. openssl s_client -connect example.com:443 -tls1_2 to test whether TLS 1.2 is accepted.
Simulations Are Nice — Live Checks Are Better
CertNotify continuously checks your real TLS configuration and certificate expiry, and alerts you the moment something weakens or approaches its deadline.