SSL/TLS Certificate Expiry Risk Calculator

ANA›Life Services Authority›National Calculator Authority›SSL/TLS Certificate Expiry Risk Calculator

.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }

SSL/TLS Certificate Expiry Risk Calculator

Evaluate the risk score and estimated business impact of an expiring SSL/TLS certificate based on days remaining, site traffic, and system criticality.

Days Until Certificate Expiry

Enter 0 if already expired. Max standard validity is 825 days.

Average Daily Visitors / API Calls

Number of unique users or API requests per day served over HTTPS.

Average Revenue per Visitor / Request (USD)

Estimated revenue attributable per visitor or transaction. Use 0 for non-revenue systems.

System Criticality

Low – Internal tool, minimal user impact Medium – Internal service with moderate dependencies High – Customer-facing or revenue-generating Critical – Core infrastructure, payment, or healthcare

Higher criticality amplifies the risk score.

Auto-Renewal Configured?

Yes – Auto-renewal is active and tested Partial – Configured but not recently verified No – Manual renewal required

Auto-renewal reduces operational risk but does not eliminate monitoring needs.

Active Certificate Monitoring?

Yes – Alerts configured and tested Partial – Monitoring exists but not verified No – No monitoring in place

Active monitoring reduces the probability of surprise expiry.

Calculate Risk

function sslCalc() { // --- Gather inputs --- const daysRaw = document.getElementById('ssl-days-remaining').value.trim(); const visitorsRaw = document.getElementById('ssl-daily-visitors').value.trim(); const revenueRaw = document.getElementById('ssl-revenue-per-visitor').value.trim(); const criticality = parseFloat(document.getElementById('ssl-criticality').value); const autoRenewal = parseFloat(document.getElementById('ssl-auto-renewal').value); const monitoring = parseFloat(document.getElementById('ssl-monitoring').value);

// --- Validation --- const errors = []; if (daysRaw === '' || isNaN(Number(daysRaw)) || Number(daysRaw) 825) errors.push('Days until expiry cannot exceed 825 (maximum certificate validity per CA/Browser Forum).');

const resultDiv = document.getElementById('ssl-result'); if (errors.length > 0) { resultDiv.style.display = 'block'; resultDiv.innerHTML = 'Please fix the following:' + errors.map(e => '').join('') + ''; return; }

const days = parseFloat(daysRaw); const visitors = parseFloat(visitorsRaw); const revenue = parseFloat(revenueRaw);

// ───────────────────────────────────────────────────────────────── // FORMULA 1 — Urgency Score (U) // Based on exponential decay: U = 100 × e^(−λ × days) // λ = 0.05 (half-life ≈ 14 days, meaning urgency doubles every ~14 days closer to expiry) // U ∈ [0, 100]; already-expired cert (days=0) → U = 100 // ───────────────────────────────────────────────────────────────── const lambda = 0.05; const urgency = 100 * Math.exp(-lambda * days); // 0–100

// ───────────────────────────────────────────────────────────────── // FORMULA 2 — Exposure Mitigation Factor (M) // M = 1 − (0.5 × autoRenewal) − (0.5 × monitoring) // autoRenewal ∈ {0, 0.6, 1}, monitoring ∈ {0, 0.5, 1} // M ∈ [0, 1]; lower M = better mitigated risk // ───────────────────────────────────────────────────────────────── const mitigation = 1 - (0.5 * autoRenewal) - (0.5 * monitoring);

// ───────────────────────────────────────────────────────────────── // FORMULA 3 — Composite Risk Score (R) // R = U × criticality × M // criticality ∈ {1, 2, 3, 4} // R is then normalised to 0–100 by dividing by max possible (100 × 4 × 1 = 400) // R_norm = (R / 400) × 100 // ───────────────────────────────────────────────────────────────── const rawRisk = urgency * criticality * mitigation; const riskScore = Math.min((rawRisk / 400) * 100, 100);

// ───────────────────────────────────────────────────────────────── // FORMULA 4 — Estimated Daily Revenue at Risk (DRR) // DRR = visitors × revenue × P_impact // P_impact = probability that an expired cert causes full service disruption // = min(1, (100 − days) / 100) for days = 75) { band = 'Critical'; bandClass = 'risk-critical'; recommendation = 'Immediate action required. Renew or replace the certificate now. Escalate to security and DevOps teams. Verify all dependent services.'; } else if (riskScore >= 50) { band = 'High'; bandClass = 'risk-high'; recommendation = 'Urgent renewal needed within 24–48 hours. Enable auto-renewal and configure monitoring alerts immediately.'; } else if (riskScore >= 25) { band = 'Medium'; bandClass = 'risk-medium'; recommendation = 'Schedule renewal within the next 7–14 days. Verify auto-renewal pipeline and confirm monitoring is active.'; } else { band = 'Low'; bandClass = 'risk-low'; recommendation = 'Certificate is within a safe validity window. Maintain monitoring and confirm auto-renewal is tested quarterly.'; }

// ───────────────────────────────────────────────────────────────── // Urgency label // ───────────────────────────────────────────────────────────────── let urgencyLabel; if (days === 0) urgencyLabel = 'EXPIRED'; else if (days 90 days';

// ───────────────────────────────────────────────────────────────── // Format helpers // ───────────────────────────────────────────────────────────────── const fmt = (n, d=2) => n.toLocaleString('en-US', {minimumFractionDigits: d, maximumFractionDigits: d}); const fmtC = (n) => '$' + fmt(n, 2);

// ───────────────────────────────────────────────────────────────── // Render // ───────────────────────────────────────────────────────────────── resultDiv.style.display = 'block'; resultDiv.innerHTML = `

.ssl-band { display:inline-block; padding:4px 14px; border-radius:4px; font-weight:700; font-size:1.1em; } .risk-critical { background:#ff4d4d; color:#fff; } .risk-high { background:#ff944d; color:#fff; } .risk-medium { background:#ffd24d; color:#333; } .risk-low { background:#5cb85c; color:#fff; } .ssl-grid { display:grid; grid-template-columns:1fr 1fr; gap:10px; margin:14px 0; } .ssl-card { background:#f8f9fa; border:1px solid #dee2e6; border-radius:6px; padding:12px; } .ssl-card .label { font-size:0.82em; color:#666; margin-bottom:4px; } .ssl-card .value { font-size:1.25em; font-weight:700; color:#212529; } .ssl-rec { background:#e8f4fd; border-left:4px solid #2196F3; padding:12px; border-radius:4px; margin-top:12px; } @media(max-width:500px){ .ssl-grid{ grid-template-columns:1fr; } }

### Risk Assessment Results

Certificate Status: ${urgencyLabel} Risk Band: ${band}

Composite Risk Score ${fmt(riskScore, 1)} / 100

Urgency Score (U) ${fmt(urgency, 1)} / 100

Exposure Mitigation Factor (M) ${fmt(mitigation, 2)} (lower = better)

Probability of Impact ${fmt(pImpact * 100, 1)}%

Daily Revenue at Risk ${fmtC(dailyRevenueAtRisk)}

Est. Remediation Window Cost ${fmtC(remediationCost)}

Recommendation: ${recommendation}

Show Calculation Breakdown

ParameterValue Days until expiry${days} λ (decay constant)0.05 Urgency U = 100 × e^(−0.05 × ${days})${fmt(urgency,4)} Criticality multiplier${criticality} Auto-renewal factor${autoRenewal} Monitoring factor${monitoring} Mitigation M = 1 − 0.5×${autoRenewal} − 0.5×${monitoring}${fmt(mitigation,4)} Raw Risk = U × criticality × M${fmt(rawRisk,4)} Normalised Risk Score = (Raw / 400) × 100${fmt(riskScore,2)} P_impact = U / 100${fmt(pImpact,4)} Daily Revenue at Risk = ${visitors} × ${revenue} × ${fmt(pImpact,4)}${fmtC(dailyRevenueAtRisk)} Expected downtime (days)${downtimeDays} Remediation Window Cost = DRR × ${downtimeDays}${fmtC(remediationCost)}

`; }

#### Formulas Used

1. Urgency Score (U) U = 100 × e−λ × days, where λ = 0.05 Exponential decay model: urgency approaches 100 as days → 0 (expired), and decays toward 0 for distant expiry dates. Half-life ≈ 14 days.

2. Exposure Mitigation Factor (M) M = 1 − (0.5 × autoRenewal) − (0.5 × monitoring) M ∈ [0, 1]. Auto-renewal and monitoring each contribute up to 50% risk reduction. M = 0 means fully mitigated; M = 1 means no controls.

3. Composite Risk Score (R) R = min([(U × criticality × M) / 400] × 100, 100) Normalised to 0–100. Maximum raw risk = 100 × 4 × 1 = 400 (expired, critical, no controls).

4. Daily Revenue at Risk (DRR) DRR = visitors × revenue_per_visitor × P_impact, where P_impact = U / 100 P_impact is the probability that the expiry event causes a full service disruption, proxied by the urgency score.

5. Remediation Window Cost (RWC) RWC = DRR × expected_downtime_days Expected downtime: 0.5 days (auto-renewal active), 1 day (partial), 3 days (manual renewal).

#### Assumptions & References

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