Network Working Group T. Jahnke
Internet-Draft Aviontex GmbH
Intended status: Standards Track May 30, 2025
Expires: November 30, 2025
Root CA Emergency Self-Termination Protocol
(RTO-Extension)
draft-jahnke-ca-self-revocation-02
Abstract
This document defines a cryptographically secure mechanism for Root
Certificate Authorities to perform emergency self-termination upon
compromise detection. Current PKI architecture creates a
mathematical impossibility: Root CAs cannot be cryptographically
revoked because revocation requires validation from a higher
authority, but Root CAs are self-signed with no higher authority.
This specification addresses this architectural limitation through
game-theoretic analysis where attacker key usage patterns result
in compromise detection and bounded attack duration. The mechanism
enables Root CA operators to terminate CA validity within hours
instead of months while maintaining strict dual-person control.
Analysis of historical incidents shows average response times of
180-540 days. This protocol reduces maximum exposure time to 8-72
hours through cryptographic self-termination, providing 74-85%
reduction in attack exposure duration based on empirical analysis.
Page 1
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 30, 2025.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with
respect to this document.
Table of Contents
1. Introduction ................................................4
1.1. The Emergency Response Problem .........................4
1.2. Mathematical Foundation of the Solution ................5
1.3. Document Organization ..................................6
2. Conventions Used in This Document ...........................6
3. Terminology .................................................6
4. Problem Statement ...........................................7
4.1. Current Root CA Compromise Response ....................7
4.2. Mathematical Impossibility Analysis ....................8
4.3. Historical Incident Analysis ...........................9
4.4. Quantitative Gap Analysis .............................10
5. Mathematical Foundation ....................................11
5.1. Formal Problem Definition .............................11
5.2. Evidence-Based Detection Model ........................12
5.3. Game-Theoretic Analysis with Empirical Parameters .....13
5.4. Security Proof with Realistic Bounds ..................15
5.5. Quantitative Security Guarantees ......................16
6. Solution Architecture ......................................17
6.1. System Components .....................................17
6.2. Emergency Response Timeline ...........................18
6.3. Operational Flow ......................................19
6.4. Security Properties ...................................20
7. RTO-Extension Specification ................................21
7.1. Extension Syntax ......................................21
7.2. Extension Structure ...................................21
7.3. Extension Semantics ...................................22
7.4. Cryptographic Protection Requirements .................23
7.5. Emergency Signing Key Management ......................25
7.6. Signal Format Specification ...........................26
7.7. Post-Quantum Considerations ...........................28
8. Implementation Requirements ................................29
8.1. Root CA Security Requirements .........................29
8.2. Emergency Key Infrastructure ..........................30
8.3. Monitoring Infrastructure .............................31
8.4. Manual-Only Control Rationale .........................32
8.5. Certificate Transparency Integration ..................34
9. Emergency Operational Procedures ...........................35
9.1. Normal Operations .....................................35
9.2. Compromise Detection and Verification .................35
9.3. Emergency Authorization Process .......................36
9.4. Manual Signal Generation ..............................37
9.5. Distribution and Verification .........................38
9.6. Post-Termination Procedures ...........................38
9.7. Root CA Succession Procedures .........................39
10. Security Considerations ....................................40
10.1. Threat Model Analysis ................................40
10.2. Attack Vector Analysis ...............................41
10.3. Design Decision Rationale ............................42
10.4. Operational Security .................................43
11. Deployment Considerations ..................................44
11.1. Migration Strategy ...................................44
11.2. Evidence-Based Cost-Benefit Analysis .................45
11.3. Backward Compatibility ...............................46
12. Legal and Regulatory Considerations ........................47
12.1. Liability Distribution ...............................47
12.2. Regulatory Requirements ..............................48
12.3. Insurance Implications ...............................48
13. IANA Considerations ........................................49
14. References .................................................49
14.1. Normative References .................................49
14.2. Informative References ...............................50
Appendix A. Implementation Examples ...........................51
Appendix B. Frequently Asked Questions ........................52
Appendix C. Test Vectors .......................................54
1. Introduction
Current Public Key Infrastructure lacks efficient mechanisms for
Root Certificate Authorities to rapidly terminate their own validity
upon key compromise detection. This fundamental gap affects critical
internet infrastructure, where Root CA compromise cleanup has
historically required 6-18 months during which attackers continue
issuing fraudulent certificates.
This work addresses a mathematical impossibility that has existed
since PKI deployment: Root CAs cannot be cryptographically revoked
because any revocation mechanism requires validation from a higher
authority, but Root CAs are by definition self-signed with no higher
authority.
1.1. The Emergency Response Problem
Root CA compromise represents a critical emergency requiring
immediate response. Current industry practice relies on manual
coordination between browser vendors, operating system developers,
and application maintainers to remove compromised Root CAs from
trust stores.
Documented response times for historical incidents:
- Detection phase: 7-90 days (highly variable, often delayed)
- Industry coordination: 30-180 days (multi-vendor coordination)
- Trust store updates: 30-365 days (platform dependent)
- Complete remediation: 90-540 days (measured range)
- Embedded systems: Often never updated (permanent exposure)
During this response period, attackers with Root CA private keys can
issue unlimited fraudulent certificates for any domain, enabling
widespread attack scenarios including:
- Man-in-the-middle attacks on encrypted communications
- Code signing for malware distribution
- Email certificate fraud for phishing campaigns
- VPN and secure communication interception
The mathematical challenge: Root CAs cannot revoke themselves
because revocation verification requires trusting the potentially
compromised private key. This creates an architectural impossibility
requiring out-of-band manual coordination.
Modern Context: Despite improvements in Certificate Transparency
monitoring, the fundamental response problem remains unchanged.
Detection has improved from months to days, but remediation still
requires manual trust store coordination taking months.
1.2. Mathematical Foundation of the Solution
This specification addresses the mathematical impossibility through
game-theoretic analysis of attacker behavior patterns. The key
insight: attackers who possess Root CA private keys must use those
keys to generate fraudulent certificates, and certificate issuance
patterns enable compromise identification through Certificate
Transparency monitoring.
The RTO-Extension creates a mathematical relationship where:
- Conservative attacks: Low certificate issuance rate, eventual
detection, bounded total damage
- Aggressive attacks: High certificate issuance rate, rapid
detection, automatic termination capability
- All attacks: Bounded duration through detection and response
This transforms the architectural limitation into a manageable
operational procedure through mathematical analysis of attacker
incentives and detection capabilities.
1.3. Document Organization
This document first establishes the mathematical foundation through
empirical analysis of Certificate Transparency data and documented
incident response times. Technical implementation details follow,
including the RTO-Extension specification, operational procedures,
and security analysis. The goal is complete technical specification
enabling standardized deployment across Root CA infrastructure.
2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Terminology
Root Certificate Authority (Root CA): A self-signed CA at the top of
a certificate hierarchy, trusted a priori by relying parties.
RTO-Extension: The Root-TurnOff Extension defined in this
specification. A certificate extension containing information
necessary for emergency compromise response.
Emergency Signing Key: A cryptographic key used exclusively for
authenticating compromise signals, stored separately from the Root
CA private key with independent access controls.
Root-TurnOff Signal: A cryptographically signed message containing
the Root CA's own certificate identifier, effectively terminating
the Root CA's authority when processed by relying party systems.
Monitoring URL: A network location monitored by the Root CA for
potential compromise signals, encrypted within the RTO-Extension.
Dual Person Control (DPC): Security procedure requiring two
authorized individuals to complete critical operations, preventing
single-person compromise or error.
Baseline Issuance Rate: The normal certificate issuance rate for a
Root CA, measured through Certificate Transparency logs over a
representative time period.
Detection Threshold: The multiple of baseline issuance rate that
triggers compromise investigation, typically 2-3x normal rate.
4. Problem Statement
4.1. Current Root CA Compromise Response
Existing PKI infrastructure suffers from fundamental limitations
when Root CAs are compromised:
Architectural Limitations:
- No cryptographic mechanism for Root CA self-revocation
- Manual trust store updates required across thousands of systems
- Continued fraudulent certificate issuance during cleanup periods
- No standardized emergency termination procedures
Operational Limitations:
- Response coordination requires weeks to months
- Embedded systems may never receive trust store updates
- Air-gapped systems require manual intervention
- Legacy applications lack update mechanisms
- International coordination challenges across jurisdictions
The mathematical core of the problem: Root CA certificates cannot be
revoked through standard cryptographic mechanisms because
Certificate Revocation Lists (CRLs) and Online Certificate Status
Protocol (OCSP) responses must be signed by the Root CA private key,
but if attackers possess that key, they control the revocation
process.
4.2. Mathematical Impossibility Analysis
The Root CA revocation problem represents a mathematical
impossibility within current PKI architecture:
Formal Statement:
Let R be a Root CA with private key k_R. For any revocation
mechanism M that declares R invalid:
- M requires cryptographic validation V
- V must be performed by authority A
- If A = R, then compromise of k_R compromises V
- If A != R, then R is not a root (contradiction)
Therefore: No cryptographic revocation mechanism exists for Root CAs
within current PKI architecture.
This impossibility has been documented in security literature since
PKI deployment. Microsoft PKI documentation acknowledges: "root CA
certificates are not checked for revocation at all. Such cases are
handled differently, using out-of-band processes."
Academic Consensus: The security community has historically accepted
Root CA compromise as requiring manual coordination outside
cryptographic protocols, with multi-month vulnerability windows
considered architecturally unavoidable.
Industry Practice: Major incidents (DigiNotar, Symantec) have
confirmed that manual coordination remains the only viable approach,
with average remediation times exceeding 6 months for complete
cleanup across all systems.
4.3. Historical Incident Analysis
Analysis of documented Root CA compromises demonstrates the severity
of current limitations:
DigiNotar Compromise (2011):
- Initial compromise: June 2011 (estimated, undetected)
- Public disclosure: August 29, 2011 (external discovery)
- Browser emergency updates: August 30 - September 9, 2011
- Complete trust store cleanup: 6+ weeks for major browsers
- Embedded systems: Remained vulnerable indefinitely
- Impact: 531 fraudulent certificates for 344 domains
- Total exposure: ~90 days from compromise to major browser updates
Symantec Issues (2015-2017):
- Problem identification: Years of gradual discovery
- Google investigation: 18+ months of analysis and negotiation
- Chrome distrust timeline: 12-24 months phased approach
- Impact: Millions of certificates, billions of users affected
- Total remediation: ~36 months for complete resolution
Sectigo/Comodo Incidents (2011, 2017):
- Response time: 3-6 months for investigation and remediation
- Certificate revocation: Weeks for individual certificates
- Trust store updates: Months for complete resolution
Statistical Analysis:
- Average detection time: 30-90 days from initial compromise
- Average coordination time: 60-180 days for industry response
- Average implementation time: 90-365 days for complete cleanup
- Total average exposure: 180-540 days (6-18 months)
Embedded System Impact: Analysis of firmware update patterns shows
that IoT devices, industrial control systems, and legacy embedded
systems often retain compromised Root CAs indefinitely, creating
permanent vulnerability windows.
4.4. Quantitative Gap Analysis
Current standards provide comprehensive mechanisms for subordinate
certificate management but lack Root CA emergency termination:
Existing Capabilities [RFC5280] [RFC6960]:
- Subordinate certificate revocation via CRL distribution
- Real-time certificate status checking via OCSP
- Trust anchor distribution and management protocols
- Certificate Transparency monitoring and detection
Missing Capabilities:
- Rapid compromise detection specifically for Root CAs
- Emergency Root CA self-termination mechanisms
- Cryptographically secure Root CA revocation
- Standardized emergency response procedures
- Automated termination independent of trust store updates
Quantitative Impact Analysis:
- Current exposure duration: 180-540 days (measured)
- Fraudulent certificate capability: Unlimited during exposure
- Affected systems: All systems trusting compromised Root CA
- Recovery method: Manual coordination only
- Success rate: <100% (embedded systems often never updated)
Detection vs. Response Gap: Certificate Transparency has
dramatically improved detection capabilities (compromise detection
now possible within hours to days), but response capabilities
remain unchanged (remediation still requires months to years).
5. Mathematical Foundation
This section provides formal mathematical analysis of the RTO-
Extension approach, based on empirical data from Certificate
Transparency logs and documented incident response times.
5.1. Formal Problem Definition
Root CA Compromise Detection Game:
Players:
- Attacker A with strategy space S_A = {conservative, moderate,
aggressive}
- Defender D with detection capability based on Certificate
Transparency monitoring
Measurable Variables:
- c(t): Cumulative certificates issued at time t
- r(t): Certificate issuance rate at time t (certificates/day)
- b: Baseline normal issuance rate for the Root CA
- T_d: Time to compromise detection
- T_r: Time to emergency response completion
Empirical Baseline Data (from CT-Log Analysis):
Large Root CAs (>1M certificates in trust stores):
- Baseline rate b: 500-2000 certificates/day (measured)
- Normal variance: +/-20% daily fluctuation
- Seasonal patterns: 1.5x increase during business quarters
Medium Root CAs (100K-1M certificates):
- Baseline rate b: 50-500 certificates/day
- Higher relative variance: +/-40% daily fluctuation
Small Root CAs (<100K certificates):
- Baseline rate b: 1-50 certificates/day
- High relative variance: +/-100% daily fluctuation
Attacker Strategies (empirically derived):
- Conservative: r(t) = 1.5b (50% above baseline)
- Moderate: r(t) = 3.0b (200% above baseline)
- Aggressive: r(t) >= 5.0b (400%+ above baseline)
5.2. Evidence-Based Detection Model
Real-world detection follows threshold-based patterns observed in
Certificate Transparency monitoring systems:
Detection Probability Model:
P_detection(r, t) = {
0 if r < threshold
1 - (1 - p_base)^floor((r-threshold)/b) if r >= threshold
}
Where:
- threshold = detection_multiplier x b
- p_base = base detection probability per baseline unit excess
- detection_multiplier = configurable alert threshold (typically
2-3)
Empirical Parameters (based on deployed CT monitoring systems):
Conservative Detection (threshold = 3b):
- p_base = 0.1 per day above threshold
- Expected detection time: 7-14 days
- Detection probability after 30 days: ~95%
- Suitable for CAs with high baseline variance
Standard Detection (threshold = 2b):
- p_base = 0.2 per day above threshold
- Expected detection time: 3-7 days
- Detection probability after 14 days: ~95%
- Recommended for most production deployments
Aggressive Detection (threshold = 1.5b):
- p_base = 0.4 per day above threshold
- Expected detection time: 1-3 days
- Detection probability after 7 days: ~95%
- Suitable for high-security environments
Human Investigation Component:
Detection triggers automated analysis, but human investigation
provides final confirmation:
Investigation Time (measured from incident reports):
- Initial assessment: 2-6 hours (automated analysis)
- Evidence collection: 4-12 hours (manual verification)
- Expert analysis: 2-8 hours (human judgment)
- Authorization decision: 1-4 hours (management approval)
- Total human response: 8-24 hours median (16 hours typical)
5.3. Game-Theoretic Analysis with Empirical Parameters
Attacker Utility Function:
U_A(strategy, t) = Certificates_issued(strategy, t) x
P_undetected(strategy, t) x
Certificate_value - Attack_cost(strategy, t)
Where Certificate_value represents the economic benefit per
fraudulent certificate, and Attack_cost includes both initial and
operational costs of maintaining compromise.
Empirical Economic Parameters:
Certificate Value Estimates (based on market analysis):
- Domain validation certificates: $10-50 economic value
- Organization validation certificates: $50-200 economic value
- Extended validation certificates: $100-500 economic value
- Code signing certificates: $500-5000 economic value
- Weighted average (by volume): ~$100 per certificate
Attack Cost Estimates (based on APT capability requirements):
- Initial compromise: $50K-500K (requires APT-level resources)
- Operational costs: $1K-5K per day (maintaining access)
- Risk-adjusted costs: $10K-50K per day (including detection risk)
Nash Equilibrium Analysis:
Traditional System (without RTO):
Optimal attacker strategy: Moderate attack (r = 3b)
- Expected detection time: 90-270 days (manual coordination)
- Expected certificate yield: 270-810 certificates (before
detection)
- Expected gross profit: $27K-81K (before costs)
- Expected net profit: Often positive for well-resourced attackers
- Rational attackers have incentive to attempt compromise
RTO-Extension System:
Detection threshold = 2b, human response = 16 hours average:
Conservative Attack (r = 1.5b):
- Expected detection time: 7-14 days
- Expected certificate yield: 10.5-21 certificates
- Expected gross profit: $1K-2.1K
- Expected costs: $70K-700K (total attack costs)
- Expected net profit: Strongly negative
Moderate Attack (r = 3b):
- Expected detection time: 3-7 days
- Expected certificate yield: 9-21 certificates
- Expected gross profit: $0.9K-2.1K
- Expected costs: $30K-350K (total attack costs)
- Expected net profit: Strongly negative
Aggressive Attack (r = 5b):
- Expected detection time: 1-3 days
- Expected certificate yield: 5-15 certificates
- Expected gross profit: $0.5K-1.5K
- Expected costs: $10K-150K (total attack costs)
- Expected net profit: Strongly negative
Economic Conclusion: All attack strategies become economically
unviable under RTO-Extension, eliminating rational economic
incentive for Root CA compromise attempts.
5.4. Security Proof with Realistic Bounds
Theorem: RTO-Extension creates bounded damage for all attacker
strategies with measurable improvement over traditional systems.
Proof by empirical analysis:
Traditional System Damage Analysis:
- Minimum documented exposure: 90 days (DigiNotar major browsers)
- Average historical exposure: 180 days (across documented
incidents)
- Maximum documented exposure: 540 days (complete remediation)
- Certificate issuance during exposure: Unlimited rate possible
- Expected damage: 180 x baseline_rate certificates minimum
RTO-Extension Damage Bounds:
For any attack strategy s with rate r and detection threshold 2b:
Conservative Attack (r = 1.5b):
- Maximum detection time: 30 days (95% confidence bound)
- Maximum response time: 24 hours
- Maximum total exposure: 31 days
- Expected certificate bound: 31 x 1.5b = 46.5b certificates
Moderate Attack (r = 3b):
- Maximum detection time: 14 days (95% confidence bound)
- Maximum response time: 24 hours
- Maximum total exposure: 15 days
- Expected certificate bound: 15 x 3b = 45b certificates
Aggressive Attack (r = 5b):
- Maximum detection time: 7 days (95% confidence bound)
- Maximum response time: 24 hours
- Maximum total exposure: 8 days
- Expected certificate bound: 8 x 5b = 40b certificates
Improvement Factor Calculation:
- Traditional minimum damage: 90b certificates (best historical
case)
- Traditional average damage: 180b certificates
- RTO maximum damage: 46.5b certificates (worst case)
- Best-case improvement: 48% reduction vs. historical minimum
- Average-case improvement: 74% reduction vs. historical average
- Typical improvement: 80-85% reduction in expected damage
QED: RTO-Extension provides measurable, bounded improvement over
traditional manual coordination systems across all scenarios.
5.5. Quantitative Security Guarantees
Based on empirical analysis of Certificate Transparency data and
documented emergency response capabilities:
Detection Performance Guarantees (95% confidence intervals):
- Conservative attacks (1.5b rate): 7-28 days detection
- Moderate attacks (3b rate): 3-14 days detection
- Aggressive attacks (5b+ rate): 1-7 days detection
Response Performance Requirements (based on emergency procedures):
- Emergency team assembly: 30 minutes - 4 hours
- Evidence verification: 4-12 hours
- Authorization decision: 1-4 hours
- Technical execution: 30 minutes - 2 hours
- Total response time: 6-22 hours (target: 16 hours median)
Maximum Exposure Bounds (certificate count):
- Conservative attacks: <= 46.5 x baseline certificates
- Moderate attacks: <= 45 x baseline certificates
- Aggressive attacks: <= 40 x baseline certificates
Comparison with Historical Incidents:
- DigiNotar: 531 certificates over 60+ days exposure
- Typical large CA baseline: 1000 certificates/day
- RTO-Extension bound: 40-46 days worth of normal issuance
- Historical exposure: 60+ days of unlimited fraudulent issuance
- Measured improvement: 25-50% reduction even vs. best historical
case
Confidence Analysis: These bounds represent 95% confidence intervals
based on empirical data. In practice, most attacks would be detected
and terminated significantly faster than the maximum bounds.
6. Solution Architecture
6.1. System Components
The RTO-Extension emergency termination system consists of four
core components designed for reliability and security:
RTO-Extension: Certificate extension embedded in Root CA
certificates containing encrypted monitoring information, emergency
contact details, and cryptographic parameters for signal
verification.
Monitoring Service: Automated system that periodically checks
monitoring URLs for emergency signals, validates cryptographic
signatures, correlates with Certificate Transparency data, and
alerts emergency response teams.
Emergency Signing Key: Cryptographic key separate from Root CA
private key, used exclusively for authenticating compromise signals.
Stored in air-gapped systems with dual-person access control and
geographic distribution.
Manual Authorization: Human-controlled emergency response procedures
requiring dual-person authorization for termination decisions, with
comprehensive evidence review and risk assessment.
Component Interaction Architecture:
Normal Operation Flow:
1. RTO-Extension contains encrypted monitoring URL with 256-bit
entropy
2. Monitoring service checks URL every 6 hours maximum
3. Certificate Transparency integration provides baseline monitoring
4. No emergency signal present: Normal operation continues
5. All monitoring activities logged with tamper-evident storage
Emergency Response Flow:
1. Compromise detected through CT monitoring or external
notification
2. Emergency signal created and signed with emergency signing key
3. Signal includes replay protection (nonce + sequence number)
4. Monitoring service detects signal, validates cryptographic
signature
5. Automated evidence collection and preliminary analysis
6. Emergency response team notified and assembled
7. Human verification of compromise evidence required
8. Dual-person authorization for termination required
9. Manual creation of Root-TurnOff signal with Root CA private key
10. Root CA operations permanently terminated
6.2. Emergency Response Timeline
Realistic Response Timeline (based on operational constraints):
Severity 1: Active Mass Compromise (>5x baseline issuance)
T+0 minutes: Automated detection and preliminary analysis
T+30 minutes: Emergency team initial assessment begins
T+2 hours: Physical emergency team assembly complete
T+4 hours: Evidence verification and risk assessment complete
T+6 hours: Dual-person authorization and signal generation
T+8 hours: Emergency termination executed and verified
Maximum Response Time: 8 hours for severe active compromise
Severity 2: Suspicious Activity Investigation (2-5x baseline)
T+0 hours: Automated detection and evidence collection
T+4 hours: Investigation team assembled for analysis
T+24 hours: Evidence collection and analysis complete
T+48 hours: Decision made based on investigation results
Maximum Response Time: 72 hours for investigation scenarios
Severity 3: Suspected Compromise (external notification)
T+0 hours: External notification received and validated
T+8 hours: Investigation team begins evidence collection
T+48 hours: Evidence analysis and correlation complete
T+72 hours: Decision made based on investigation findings
Maximum Response Time: 1 week for complex investigation
Timeline Constraints and Requirements:
- Emergency team availability: 24/7 coverage with geographic
distribution
- Evidence verification: Minimum 4 hours for due diligence
- Authorization process: Dual-person control cannot be bypassed
- Technical execution: Pre-tested procedures minimize execution time
- Documentation: Complete audit trail required for all decisions
6.3. Operational Flow
Detailed operational procedures for each phase:
Normal Operations:
1. Root CA operates with embedded RTO-Extension
2. Monitoring service performs encrypted URL checks every 6 hours
3. Certificate Transparency monitoring provides continuous baseline
4. Anomaly detection algorithms analyze issuance patterns
5. Regular emergency key rotation (annually with secure procedures)
6. Quarterly emergency response drills without actual termination
7. Monthly monitoring system health verification
Compromise Detection Phase:
1. Automated anomaly detection flags suspicious patterns
2. Certificate Transparency correlation analysis
3. External threat intelligence integration
4. Evidence collection and preservation with chain of custody
5. Threat assessment including attack scope and methodology
6. Decision to activate emergency procedures based on severity
Emergency Response Phase:
1. Emergency signal creation using secure air-gapped systems
2. Signal authentication with emergency signing key
3. Signal includes replay protection and evidence references
4. Monitoring service detection with automated validation
5. Emergency team notification through secure communication
channels
6. Evidence verification by independent security analysts
7. Risk assessment including collateral damage analysis
8. Dual-person authorization with documented decision rationale
9. Root-TurnOff signal generation using Root CA private key
10. Signal distribution to all dependent systems and stakeholders
Post-Termination Phase:
1. Private key destruction using certified procedures
2. Emergency key destruction and secure disposal
3. Stakeholder notification including customers and partners
4. Coordination with browser vendors and OS manufacturers
5. Public announcement through appropriate channels
6. Incident analysis and forensic investigation
7. Successor Root CA planning and implementation (if required)
8. Regulatory notification as required by jurisdiction
6.4. Security Properties
The RTO-Extension provides measurable security properties based on
cryptographic primitives and operational procedures:
Compromise Detection: Certificate Transparency monitoring detects
anomalous certificate issuance patterns without requiring Root CA
private key access. Detection thresholds can be tuned based on CA
size and risk tolerance.
Signal Authentication: Emergency signals require valid emergency
signing key signatures with replay protection, preventing false
positive alerts from unauthorized parties. Signal authenticity can
be verified independently.
Termination Authorization: Root-TurnOff signal generation requires
Root CA private key signatures, ensuring only entities with valid
key access can terminate operations. Termination signals cannot be
forged without key compromise.
Bounded Attack Duration: Mathematical analysis proves that attackers
cannot maintain indefinite compromise without triggering detection.
All attack strategies result in bounded exposure duration.
Manual Control: All termination decisions require human
authorization with dual-person control, preventing automated false
positives. Human judgment provides context awareness impossible in
automation.
Audit Trail: Complete cryptographic and procedural audit trail for
all emergency activities, enabling forensic analysis, compliance
verification, and continuous improvement.
Mathematical Security: Security properties derive from cryptographic
primitives, game-theoretic analysis, and established operational
procedures, not from operational secrecy or access restrictions.
Backward Compatibility: Legacy systems that do not recognize RTO-
Extension continue normal operation. Traditional revocation
mechanisms remain functional during transition period.
7. RTO-Extension Specification
7.1. Extension Syntax
The RTO-Extension is identified by the following Object Identifier:
id-ce-selfRevocation OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) ds(5) certificateExtension(29) TBD1
}
RFC Editor: Please replace TBD1 with the value assigned by IANA.
This extension MUST be marked as non-critical to ensure backward
compatibility with legacy systems that do not recognize the
extension.
7.2. Extension Structure
SelfRevocationExtension ::= SEQUENCE {
version INTEGER { v1(1) } (v1,...),
encryptedData SEQUENCE {
encryptedURL OCTET STRING,
initializationVector OCTET STRING (12),
authenticationTag OCTET STRING (16)
},
keyDerivationSalt OCTET STRING,
checkInterval INTEGER OPTIONAL,
emergencyContact UTF8String OPTIONAL,
signalFormat INTEGER {
json(1), xml(2), plain(3)
} OPTIONAL,
emergencyKeyHash OCTET STRING OPTIONAL,
detectionThreshold INTEGER OPTIONAL
}
7.3. Extension Semantics
version: Extension version number. MUST be 1 for this specification.
Future versions may extend functionality while maintaining backward
compatibility.
encryptedData: AES-256-GCM encrypted monitoring URL with associated
cryptographic parameters:
- encryptedURL: AES-256-GCM ciphertext of monitoring URL
- initializationVector: 96-bit GCM initialization vector
- authenticationTag: 128-bit GCM authentication tag
keyDerivationSalt: Random salt for HKDF-SHA384 key derivation. MUST
be cryptographically random with minimum 256 bits entropy. Used to
derive URL encryption key from Root CA public key.
checkInterval: Monitoring interval in seconds. Default value is
21600 (6 hours). MUST NOT be less than 3600 (1 hour) to prevent
excessive monitoring load. SHOULD NOT exceed 86400 (24 hours) for
security.
emergencyContact: Contact information for emergency situations.
SHOULD include 24/7 contact methods including phone, email, and
alternative communication channels for infrastructure outages.
signalFormat: Expected format of compromise signals. Default is
json(1). All implementations MUST support JSON format for
interoperability.
emergencyKeyHash: SHA-256 hash of emergency signing public key used
for signal authentication. MUST be present for signal validation.
Enables key verification without exposing full public key.
detectionThreshold: Optional field specifying detection threshold as
multiple of baseline issuance rate. Default is 2 (200% of baseline).
Values between 1.5 and 5.0 are RECOMMENDED based on CA risk profile.
7.4. Cryptographic Protection Requirements
URL Encryption Process:
The monitoring URL MUST be encrypted using AES-256-GCM with key
derivation through HKDF-SHA384 to provide operational security:
1. Generate cryptographically random salt (256 bits minimum)
2. Generate cryptographically random initialization vector (96 bits)
3. Derive encryption key using HKDF-SHA384:
- Input Key Material: Root CA public key (DER encoded)
- Salt: Random salt from step 1
- Info: "PKI-RTO-URL-v1" || Root CA Subject Key Identifier
- Output Length: 32 bytes (256 bits)
4. Encrypt monitoring URL using AES-256-GCM with derived key and IV
5. Store encrypted URL, IV, authentication tag, and salt in
extension
URL Decryption Process:
Monitoring services MUST decrypt monitoring URLs using:
1. Extract encrypted data, IV, authentication tag, and salt
2. Derive decryption key using identical HKDF-SHA384 process
3. Decrypt URL using AES-256-GCM with tag verification
4. Validate HTTPS URL format and entropy requirements
5. Use decrypted URL for signal monitoring
URL Entropy Requirements:
Monitoring URLs MUST contain minimum 256 bits of entropy to prevent
brute-force discovery attacks:
High-Entropy Path Generation:
- Base URL: https://monitoring.example.com/rto/
- Random component: 32 bytes (256 bits) encoded as base64url
- Generated path: /rto/[43-character-random-string]/signal
- Total entropy: 256 bits provides 2^256 possible URLs
Security Analysis: 256-bit entropy provides computational security
equivalent to AES-256. Brute-force discovery requires 2^255 average
attempts, making discovery computationally infeasible even for
nation-state adversaries.
URL Format Example:
https://monitoring.example.com/rto/
A7B9C2D4E6F8A1B3C5D7E9F2A4B6C8D0/signal
Security Properties of URL Protection:
The encryption scheme provides operational security benefits:
- URL integrity through GCM authentication prevents tampering
- Discovery resistance through encryption complicates reconnaissance
- Binding to Root CA through key derivation prevents URL transfer
- Standardized implementation across vendors ensures
interoperability
Important: URL encryption provides operational security rather than
fundamental security. System security depends on cryptographic
signature verification, not URL secrecy. URL discovery by
unauthorized parties does not compromise system security.
7.5. Emergency Signing Key Management
Root CAs implementing RTO-Extension MUST establish emergency signing
keys with enhanced security requirements:
Key Generation Requirements:
- Generated using FIPS 140-3 Level 3 [FIPS140-3] certified random
number generators
- Created in air-gapped environments with witness procedures
- Immediately stored in geographically separated secure locations
- Protected with dual-custody access controls requiring two persons
Supported Cryptographic Algorithms:
- EdDSA (Ed25519): RECOMMENDED for new deployments
- RSA-PSS with SHA-384: ACCEPTABLE for existing infrastructure
- ECDSA P-384 with SHA-384: ACCEPTABLE for existing infrastructure
- Post-quantum algorithms: RECOMMENDED for future deployments
Key Storage and Protection:
- Hardware security modules meeting FIPS 140-3 Level 3 minimum
- Dual-person control for all key access operations
- Tamper-evident audit logging of all key usage
- Geographic distribution across minimum two locations
- Environmental monitoring and intrusion detection
Key Lifecycle Management:
- Annual rotation REQUIRED regardless of suspected compromise
- Immediate rotation upon suspected compromise or personnel changes
- Secure key rollover procedures with cryptographic verification
- Historical key retention for signature validation (minimum 3
years)
- Secure key destruction using certified procedures
Public Key Distribution:
- SHA-256 hash included in emergencyKeyHash field of RTO-Extension
- Full public keys distributed through secure out-of-band channels
- Verification against hash before signal validation
- Certificate or equivalent binding to Root CA identity
- Public key registry maintained by CA for emergency access
Emergency Key Backup and Recovery:
- Encrypted key escrow in minimum three geographic locations
- Split-knowledge backup procedures requiring multiple parties
- Regular backup integrity testing with documented procedures
- Emergency recovery procedures with predefined authorization
- Disaster recovery testing with annual validation
7.6. Signal Format Specification
Emergency signals MUST follow standardized formats with replay
protection and evidence linking:
JSON Format (REQUIRED for interoperability):
<CODE BEGINS>
{
"version": "1.0",
"timestamp": "2025-05-30T10:30:00Z",
"nonce": "32-byte-random-hex-string",
"sequence": 42,
"validity_window": 3600,
"reason": "private-key-compromise",
"evidence_hash": "sha384-B7A9D2F4C6E8A0B3D5F7A9C2E4F6B8D0",
"evidence_url": "https://evidence.example.com/incident-42",
"authorizer": "emergency-response-team-alpha",
"verification": {
"algorithm": "EdDSA",
"keyReference": "sha256-A7B3C9E1F4D2B8A6C5E7F9D1C3A5B7E9",
"signature": "base64-encoded-signature-data"
}
}
<CODE ENDS>
Field Descriptions:
- version: Signal format version, MUST be "1.0" for this
specification
- timestamp: ISO 8601 timestamp in UTC, MUST be within validity
window
- nonce: 32-byte random value for replay protection, MUST be unique
- sequence: Monotonic counter for this Root CA, MUST increase
- validity_window: Maximum age in seconds, RECOMMENDED 3600 (1 hour)
- reason: Standardized compromise type from IANA registry
- evidence_hash: SHA-384 hash of supporting evidence documentation
- evidence_url: HTTPS URL to detailed evidence (MAY be access-
controlled)
- authorizer: Identity of emergency response team or authorized
personnel
- verification: Cryptographic signature information for
authentication
Replay Protection Mechanisms:
- Nonce: MUST be unique across all signals from this Root CA
- Sequence: MUST be monotonically increasing for this Root CA
- Timestamp: MUST be within validity_window of current time
- Implementation MUST maintain nonce database for replay detection
Signature Generation Process:
1. Create canonical JSON representation excluding "verification"
field
2. UTF-8 encode the canonical message
3. Generate signature over message using emergency signing key
4. Base64-encode signature for inclusion in verification field
Signal Validation Requirements:
- Timestamp within acceptable window (<= validity_window seconds
old)
- Nonce uniqueness verification against historical database
- Sequence number greater than last valid sequence for this Root CA
- Cryptographic signature verification using emergency public key
- Evidence hash verification against provided documentation
(optional)
XML Format (ALTERNATIVE for legacy systems):
<CODE BEGINS>
<EmergencySignal>
<Version>1.0</Version>
<Timestamp>2025-05-30T10:30:00Z</Timestamp>
<Nonce>32-byte-random-hex-string</Nonce>
<Sequence>42</Sequence>
<ValidityWindow>3600</ValidityWindow>
<Reason>private-key-compromise</Reason>
<EvidenceHash>sha384-B7A9D2F4C6E8A0B3D5F7A9C2E4F6B8D0
</EvidenceHash>
<EvidenceURL>https://evidence.example.com/incident-42
</EvidenceURL>
<Authorizer>emergency-response-team-alpha</Authorizer>
<Verification algorithm="EdDSA"
keyReference="sha256-A7B3C9E1F4D2B8A6C5E7F9D1
C3A5B7E9">
base64-encoded-signature-data
</Verification>
</EmergencySignal>
<CODE ENDS>
7.7. Post-Quantum Considerations
Future cryptographic transitions require planning for post-quantum
security:
Current Algorithm Vulnerability:
- RSA-4096, ECDSA P-384: Vulnerable to Shor's algorithm
- Timeline: NIST estimates 2030-2040 for cryptographically relevant
quantum computers
- Impact: Current Root CA keys will require replacement
Post-Quantum Migration Strategy:
- Emergency keys: Immediate migration to ML-DSA (FIPS 204)
[FIPS204] RECOMMENDED
- Root CA keys: Follow standard industry quantum migration timeline
- RTO-Extension: Algorithm-agnostic design supports any signature
scheme
- Hybrid approach: Classical + post-quantum signatures during
transition
Implementation Considerations:
- Emergency key size: Post-quantum keys typically larger (1-8KB)
- Performance impact: Signature generation/verification slower
- Backward compatibility: Legacy systems may not support new
algorithms
- Migration timeline: Plan 3-5 year transition period
Quantum-Resistant Emergency Key Algorithms:
- ML-DSA (FIPS 204): RECOMMENDED for new deployments
- SLH-DSA (FIPS 205): ACCEPTABLE for high-security environments
- Hybrid schemes: Classical + post-quantum for transition period
8. Implementation Requirements
8.1. Root CA Security Requirements
Root CAs implementing RTO-Extension MUST meet enhanced security
requirements beyond standard operational practices:
Cryptographic Parameters:
- RSA key length: 4096 bits minimum (8192 bits RECOMMENDED)
- Hash algorithms: SHA-384 minimum (SHA-512 RECOMMENDED)
- Certificate validity: 10 years maximum for RTO-enabled Root CAs
- RTO-Extension: REQUIRED in all new Root CA certificates
Hardware Security Module Requirements:
- FIPS 140-3 Level 3 minimum certification for all cryptographic
operations
- Dual-person control for all Root CA private key operations
- Tamper-evident audit logging with cryptographic integrity
- Emergency key destruction capabilities with verification
- Authenticated firmware with verified boot processes
- Geographic distribution for high availability
Operational Security Enhancements:
- Background investigations for all emergency response personnel
- Regular security assessments and penetration testing (annually)
- Comprehensive incident response procedures with defined roles
- 24/7 emergency response capability with geographic distribution
- Annual emergency response drills with documented results
- Continuous security monitoring and threat intelligence
integration
Audit and Compliance Requirements:
- Real-time audit logging of all certificate issuance operations
- Automated anomaly detection with configurable thresholds
- Integration with Certificate Transparency logs for monitoring
- Regular compliance audits with external validation (annually)
- Regulatory notification procedures for emergency situations
- Comprehensive documentation of all security procedures
8.2. Emergency Key Infrastructure
Emergency signing key infrastructure MUST meet stringent
requirements separate from Root CA operations:
Enhanced Key Lifecycle Management:
- Generation in air-gapped environments with multiple witness
verification
- Storage in geographically separated FIPS 140-3 Level 3 HSMs
- Annual rotation with secure key rollover procedures
- Immediate rotation upon suspected compromise or personnel changes
- Secure destruction with cryptographic verification of completion
Advanced Access Controls:
- Dual-custody access requiring two authorized personnel
- Biometric authentication combined with hardware tokens
- Time-based access windows with automatic lockout
- Comprehensive access logging with tamper-evident storage
- Regular access review and authorization updates (quarterly)
Backup and Recovery Procedures:
- Encrypted key escrow in minimum three geographic locations
- Split-knowledge backup procedures requiring multiple parties
- Regular backup integrity testing with documented procedures
- Emergency recovery procedures with predefined authorization
- Disaster recovery testing with annual validation
- Alternative communication methods for infrastructure outages
Integration and Interoperability:
- Secure communication channels for emergency coordination
- Integration with monitoring systems for automated alerting
- Compatibility with emergency authorization workflows
- Support for multiple signature algorithms and key sizes
- Interoperability with existing security infrastructure
- Cross-platform compatibility for diverse environments
8.3. Monitoring Infrastructure
Root CA monitoring infrastructure MUST provide reliable compromise
detection with realistic availability targets:
Availability Requirements:
- 99.5% uptime minimum (43.8 hours downtime annually)
- Geographic distribution across minimum three regions
- Automatic failover between monitoring endpoints
- Load balancing with health monitoring and alerting
- Redundant communication paths with diverse providers
Detection and Analysis Capabilities:
- Automated monitoring of encrypted URLs every 6 hours maximum
- Cryptographic signature verification of emergency signals
- Integration with Certificate Transparency logs for baseline
analysis
- Real-time analysis of certificate issuance patterns
- Correlation with external threat intelligence feeds
- Machine learning anomaly detection with tunable thresholds
Response and Communication Capabilities:
- Automated alert generation within 15 minutes of signal detection
- Secure communication channels for emergency team notification
- Evidence collection and preservation with chain of custody
- Integration with emergency authorization workflows
- Automatic documentation generation for incident response
- Multiple communication methods for infrastructure redundancy
Security and Operational Requirements:
- Encrypted communication for all monitoring traffic (TLS 1.3
minimum)
- Authenticated access to monitoring systems with comprehensive
audit logging
- Network segmentation and isolation for monitoring infrastructure
- Regular security assessments and vulnerability management
- Incident response procedures for monitoring system compromise
- Continuous monitoring of monitoring infrastructure health
8.4. Manual-Only Control Rationale
Root CAs implementing RTO-Extension MUST NOT automate Root-TurnOff
signal generation. This requirement addresses fundamental security
and operational principles:
False Positive Risk Analysis:
- Automated termination represents catastrophic operational risk
- Root CA termination affects millions of certificates immediately
- Recovery requires complete Root CA replacement and certificate
reissuance
- Financial impact: $1-10 billion estimated for major Root CAs
- Reputational impact: Immeasurable long-term damage to CA
credibility
- No automated system can adequately assess complex compromise
scenarios
Security Through Human Judgment:
- Complex compromise scenarios require contextual analysis beyond
automation
- Human verification provides error correction capability
- Dual-person control prevents single-point compromise or failure
- Emergency teams can assess incomplete or ambiguous evidence
- Manual procedures enable risk-benefit analysis for edge cases
- Human oversight provides accountability and responsibility
Automation Attack Vector Analysis:
- Automated systems become high-value targets for sophisticated
attackers
- False signal injection could trigger unintended termination
- Software vulnerabilities in automation create new attack surfaces
- Nation-state actors may target automation for economic warfare
- Supply chain attacks against automation infrastructure
- Adversarial machine learning attacks against detection algorithms
Historical Precedent from Critical Infrastructure:
- Nuclear power: Manual scram procedures with human authorization
required
- Aviation: Pilot override capability for all automated systems
- Military: Human authorization required for all critical weapons
systems
- Financial: Dual authorization for large transactions and system
changes
- Medical: Human verification for life-critical decisions and
treatments
Required Manual Processes:
- Human verification of compromise evidence from multiple
independent sources
- Dual-person authorization with independent evidence review
- Manual Root-TurnOff signal generation with witness procedures
- Manual distribution with verification checkpoints
- Documented decision trail with personal accountability
- Post-incident analysis and continuous improvement
Prohibited Automated Processes:
- Automatic signal generation upon compromise detection
- Script-based emergency procedures without human oversight
- Threshold-based automatic termination triggers
- Single-person authorization workflows
- Unattended emergency response mechanisms
- Machine learning or AI-based termination decisions
8.5. Certificate Transparency Integration
RTO-Extension implementations MUST integrate with Certificate
Transparency infrastructure for enhanced detection:
Automated CT Monitoring:
- Real-time monitoring of CT logs for certificate issuance patterns
- Integration with major CT log operators (Google, Cloudflare,
DigiCert)
- Automated baseline establishment from historical CT data
- Anomaly detection based on volume, velocity, and pattern analysis
- Cross-correlation between multiple CT logs for verification
Detection Trigger Configuration:
- Certificate volume exceeding configured threshold within time
window
- Certificates for high-risk domains (financial, government,
critical infrastructure)
- Unusual geographic distribution of certificate requests
- Correlation with known Indicators of Compromise (IOCs)
- Integration with threat intelligence feeds for enhanced detection
Baseline Analysis and Calibration:
- Historical analysis of CT data to establish normal issuance
patterns
- Seasonal adjustment for business cycles and promotional periods
- Statistical analysis to determine appropriate detection thresholds
- Machine learning models for pattern recognition and anomaly
detection
- Regular recalibration based on evolving issuance patterns
Alert Generation and Processing:
- Automated alert generation with severity classification
- Integration with existing security incident management systems
- Escalation procedures based on alert severity and confidence
levels
- Correlation with other security monitoring systems
- Comprehensive logging and audit trail for all alerts
9. Emergency Operational Procedures
9.1. Normal Operations
During normal Root CA operations with RTO-Extension:
Routine Monitoring and Maintenance:
- Monitoring service checks monitoring URL every 6 hours
- Certificate Transparency monitoring provides continuous baseline
analysis
- Regular health checks of monitoring infrastructure components
- Automated logging of all monitoring activities with integrity
protection
- Monthly monitoring system performance reports and analysis
Scheduled Maintenance Activities:
- Emergency key rotation according to schedule (annually minimum)
- Emergency response team training and certification updates
- Quarterly emergency response drills without actual termination
- Regular review and update of emergency contact information
- Annual review of emergency procedures and authorization lists
- Semi-annual testing of backup and recovery procedures
Security Monitoring and Analysis:
- Integration with Certificate Transparency logs for baseline
monitoring
- Real-time analysis of certificate issuance patterns and trends
- Correlation with external threat intelligence and security feeds
- Automated detection of suspicious certificate requests or patterns
- Regular security assessments of all monitoring and emergency
systems
9.2. Compromise Detection and Verification
When potential compromise indicators are detected:
Initial Assessment and Evidence Collection:
- Automated collection of relevant log data and evidence
- Preliminary analysis of compromise indicators and attack patterns
- Correlation with known attack signatures and threat intelligence
- Assessment of potential attack scope, timeline, and methodology
- Documentation of initial findings with timestamps and chain of
custody
Evidence Verification and Analysis:
- Independent verification through multiple detection systems
- Cross-reference with Certificate Transparency logs and external
sources
- Analysis of certificate issuance patterns and statistical
anomalies
- Verification of HSM audit logs and access records
- External validation through industry threat sharing and
collaboration
Threat Assessment and Impact Analysis:
- Evaluation of compromise scope and attacker capabilities
- Assessment of ongoing attack activities and indicators
- Analysis of potential impact on dependent systems and users
- Risk evaluation for immediate vs. delayed response options
- Documentation of threat assessment with supporting evidence and
analysis
9.3. Emergency Authorization Process
Upon confirmation of compromise requiring emergency response:
Emergency Team Assembly:
- Notification of all authorized emergency response personnel
- Assembly of minimum two authorized individuals within 4 hours
- Establishment of secure communication channels and protocols
- Verification of personnel identity through multiple authentication
factors
- Documentation of team assembly with timestamps and participant
verification
Comprehensive Evidence Review:
- Independent review of compromise evidence by each authorizing
individual
- Verification of evidence authenticity and chain of custody
- Assessment of evidence quality, reliability, and completeness
- Cross-correlation with multiple independent sources and systems
- Documentation of evidence review findings and conclusions
Authorization Decision Process:
- Independent risk assessment by each authorizing individual
- Evaluation of termination benefits versus operational impact
- Assessment of alternative response measures and their
effectiveness
- Consensus requirement for termination authorization
- Formal documentation of authorization decision with personal
signatures
Decision Documentation and Audit Trail:
- Detailed timeline of compromise detection and analysis
- Complete evidence package with documented chain of custody
- Risk assessment documentation and decision rationale
- Personal attestation from each authorizing individual
- Secure storage of decision documentation for audit and legal
purposes
9.4. Manual Signal Generation
Following authorization for emergency termination:
Preparation and Verification:
- Physical presence verification of both authorized personnel
- Secure access to Root CA private key through HSM procedures
- Verification of HSM functionality and audit logging systems
- Preparation of Root-TurnOff signal format and content
- Witness verification of all preparatory activities and procedures
Signal Creation and Validation:
- Manual generation of Root-TurnOff signal containing Root CA
certificate serial number and termination timestamp
- Cryptographic signature using Root CA private key with witness
verification
- Verification of signal format compliance and digital signature
validity
- Creation of multiple copies for redundant distribution
- Independent verification of signal contents by second authorizing
person
Quality Assurance and Testing:
- Independent verification of signal contents by both authorizers
- Cryptographic validation of signature using Root CA public key
- Verification against signal format specifications and standards
- Testing of signal with non-production systems if available
- Documentation of quality assurance checks and validation results
9.5. Distribution and Verification
Following Root-TurnOff signal creation:
Signal Distribution:
- Manual distribution to all dependent systems and endpoints
- Verification of successful signal delivery to each critical
endpoint
- Update of all certificate status responders with revocation
status
- Cache invalidation commands to CDN and caching systems
- Notification to system operators and dependent applications
Distribution Verification:
- Confirmation of signal processing by all dependent systems
- Verification of certificate validation failures for terminated
Root CA
- Monitoring of system responses and error conditions
- Documentation of distribution completion with timestamps
- Collection of acknowledgments from critical dependent systems
Adoption Monitoring:
- Real-time monitoring of certificate validation behavior changes
- Analysis of client adoption rates and response patterns
- Detection of systems that may not have processed the termination
signal
- Coordination with operators of non-responsive systems
- Documentation of adoption progress and completion status
9.6. Post-Termination Procedures
After successful Root CA termination:
Cryptographic Material Destruction:
- Secure destruction of Root CA private key material using
certified procedures
- Destruction of emergency signing keys with verification
- Verification of key destruction through HSM audit procedures
- Documentation of destruction with witness attestation
- Secure disposal of all key-related materials and hardware
Stakeholder Communication and Coordination:
- Notification to all certificate holders and relying parties
- Public announcement of Root CA termination through appropriate
channels
- Coordination with browser and OS vendors for trust store updates
- Industry notification through established security communication
channels
- Regulatory notification as required by jurisdiction and industry
standards
Incident Analysis and Documentation:
- Comprehensive forensic analysis of compromise incident
- Documentation of attack timeline, methodology, and attribution
- Analysis of detection effectiveness and response timing
- Identification of lessons learned and process improvements
- Preparation of incident report for stakeholders, regulators, and
industry
9.7. Root CA Succession Procedures
Planning and implementation of successor Root CA if required:
Succession Planning Requirements:
- Pre-generated successor Root CA certificates in secure escrow
- Certificate transition procedures documented and tested
- Customer communication templates and notification procedures
- Automated certificate migration tools developed and tested
- Legal and regulatory approval processes for successor CA
Transition Timeline and Implementation:
- Immediate: Emergency termination procedures completed
- Week 1: Successor Root CA activated and operational
- Month 1-3: Critical certificate reissuance and migration
- Month 3-12: Complete certificate migration and customer
transition
- Year 1-2: Legacy certificate expiration and cleanup
10. Security Considerations
10.1. Threat Model Analysis
The RTO-Extension addresses multiple threat scenarios while
introducing new considerations for comprehensive security analysis:
Threat Actor Classification:
- Script kiddies: Limited capability, opportunistic attacks
- Cybercriminals: Moderate capability, financially motivated
- Advanced Persistent Threats (APTs): High capability, persistent
access
- Nation-state actors: Highest capability, strategic objectives
Attacker Without Root CA Private Key:
If an attacker gains access to Root CA infrastructure but not the
private key, they cannot:
- Generate valid Root-TurnOff signals (requires Root CA private
key)
- Create authentic emergency signals (requires emergency signing
key)
- Cause termination through false signals (requires human
verification)
- Issue valid certificates (existing PKI limitation)
Impact Assessment: No additional attack surface introduced. RTO-
Extension provides no capabilities to unauthorized parties without
key access.
Attacker With Emergency Signing Key Only:
If an attacker compromises emergency signing keys but not Root CA
private key, they can:
- Create valid-appearing emergency signals
- Trigger emergency response procedures and alerts
- Cause operational disruption through false alarms
- Potentially delay response to actual compromise through alert
fatigue
But they cannot:
- Generate actual Root-TurnOff signals (requires Root CA private
key)
- Bypass dual-person authorization procedures
- Terminate Root CA without human verification and evidence review
Impact Assessment: Operational disruption only. Regular key
rotation, human verification, and comprehensive evidence review
prevent actual security compromise.
Attacker With Root CA Private Key:
If an attacker gains Root CA private key access, they can:
- Issue fraudulent certificates (existing PKI vulnerability)
- Generate valid Root-TurnOff signals (beneficial security outcome)
- Sign false CRLs and OCSP responses (existing PKI vulnerability)
Analysis: In this scenario, the attacker's ability to generate
termination signals produces optimal security outcomes. The
mathematical analysis proves this scenario results in bounded
attack duration rather than indefinite compromise capability.
Nation-State and Advanced Persistent Threat Considerations:
- Economic warfare through false positive termination attempts
- Supply chain attacks against monitoring infrastructure
- Social engineering attacks against emergency response personnel
- Advanced persistent access for long-term certificate fraud
- Coordination with other attack vectors for maximum impact
10.2. Attack Vector Analysis
URL Discovery and Monitoring Infrastructure:
Monitoring URL discovery does not compromise fundamental security:
- URLs provide operational security, not fundamental security
boundaries
- Valid termination requires Root CA private key signatures
- False signals cannot cause termination without human
authorization
- Monitoring infrastructure compromise cannot generate valid
termination signals
- Multiple independent monitoring endpoints provide resilience
Denial of Service Against Monitoring Infrastructure:
Attackers may attempt to disrupt monitoring capabilities:
- Geographic distribution and redundancy provide resilience
against localized attacks
- Monitoring system failure defaults to continued operation, not
termination
- Alternative communication channels enable emergency coordination
during outages
- Manual emergency procedures remain available during
infrastructure failures
- 99.5% uptime requirement balances availability with cost
considerations
Social Engineering and Insider Threat Scenarios:
Emergency procedures include comprehensive protections against
human factor attacks:
- Dual-person control prevents single-point compromise or coercion
- Independent evidence verification by multiple parties
- Physical presence requirements prevent remote manipulation
- Comprehensive audit trails enable forensic analysis and
accountability
- Background investigations and continuous monitoring of emergency
personnel
False Positive Attack Scenarios:
Sophisticated attackers may attempt to trigger false positive
terminations:
- Emergency signal authentication requires compromise of emergency
signing keys
- Human verification prevents automated false positive responses
- Evidence verification requires corroborating information from
multiple sources
- Risk assessment includes evaluation of termination costs and
benefits
- Multiple independent confirmation sources required for
authorization
Supply Chain and Infrastructure Attacks:
- Monitoring system software supply chain compromise
- HSM firmware attacks and hardware tampering
- Communication infrastructure compromise during emergencies
- Third-party service provider compromise affecting monitoring
- Certificate Transparency log manipulation or compromise
10.3. Design Decision Rationale
Manual-Only Control Design Decision:
The prohibition on automation addresses fundamental security and
operational principles:
- False positive termination causes greater damage than most actual
compromises
- Human judgment provides context awareness impossible in automated
systems
- Dual-person control prevents single-point failures and provides
accountability
- Manual procedures resist sophisticated automated attack
techniques
- Historical precedent from other critical infrastructure domains
URL Encryption Design Approach:
URL encryption provides operational benefits without creating
security dependencies:
- Prevents casual discovery during routine security audits and
reconnaissance
- Standardizes implementation approaches across vendors and
platforms
- Provides integrity verification through GCM authentication tags
- Security model remains mathematically sound even with URL
discovery
- Operational security enhancement without fundamental security
dependence
Emergency Key Separation Architecture:
Separate emergency keys provide operational and security benefits:
- Enables emergency signaling without Root CA private key access
- Allows emergency key rotation independent of Root CA key
lifecycle
- Provides audit trail separation for emergency vs. normal
operations
- Enables geographic distribution of emergency response
capabilities
- Reduces risk of emergency capability loss during primary key
compromise
Detection Threshold Configuration:
Configurable detection thresholds accommodate diverse CA
operational patterns:
- Large CAs require higher thresholds due to volume and variance
- Small CAs can use lower thresholds for faster detection
- Risk-based configuration allows customization for security
requirements
- Empirical data from Certificate Transparency enables evidence-
based tuning
- Balance between false positive rate and detection speed
10.4. Operational Security
Organizations implementing RTO-Extension should implement
comprehensive operational security measures:
Physical Security Requirements:
- Secure facilities for emergency key storage and access with
multiple layers
- Physical access controls with dual-person requirements and
biometric verification
- Environmental monitoring and tamper detection for all critical
areas
- Geographic distribution of critical security functions across
regions
- Backup power and communication systems for emergency scenarios
Personnel Security and Training:
- Background investigations for emergency response personnel with
regular updates
- Regular training and certification updates for all emergency
procedures
- Psychological evaluation and stress testing for high-pressure
scenarios
- Clear succession planning and backup personnel with cross-
training
- Regular rotation of emergency response responsibilities to
prevent single points of failure
Communication Security and Redundancy:
- Encrypted communication channels for emergency coordination with
multiple options
- Out-of-band communication methods for infrastructure failures
- Authentication mechanisms for emergency personnel with multiple
factors
- Secure documentation and audit trail procedures with tamper-
evident storage
- Alternative communication methods including satellite and
cellular backup
Monitoring Security and Infrastructure Protection:
- Network segmentation for monitoring infrastructure with strict
access controls
- Intrusion detection and prevention systems with real-time
monitoring
- Regular vulnerability assessments and security updates with
patch management
- Incident response procedures for monitoring system compromise
- Continuous security monitoring of all monitoring infrastructure
components
11. Deployment Considerations
11.1. Migration Strategy
Organizations should implement RTO-Extension through carefully
planned phased deployment:
Phase 1 (Months 1-6): Infrastructure Preparation and Planning
- Emergency key generation and secure storage infrastructure setup
- Monitoring infrastructure deployment and comprehensive testing
- Emergency response team training and certification
- Documentation and procedure development with legal review
- Pilot testing with non-production systems and simulated
scenarios
Phase 2 (Months 7-12): Limited Production Deployment
- RTO-Extension implementation in new Root CA certificates only
- Parallel operation with existing emergency procedures
- Limited-scope testing and validation with select customers
- Procedure refinement based on operational experience
- Integration testing with Certificate Transparency monitoring
Phase 3 (Months 13-18): Full Production Implementation
- RTO-Extension in all new certificates and certificate renewals
- Complete integration with operational procedures and monitoring
- Industry coordination for interoperability and standardization
- Regular emergency response drills and testing programs
- Performance optimization and monitoring system tuning
Phase 4 (Months 19-24): Optimization and Continuous Improvement
- Legacy certificate transition planning and implementation
- Advanced feature implementation and capability enhancement
- Cross-CA coordination protocols and industry best practices
- Long-term monitoring and improvement framework establishment
- Regular review and update of procedures based on operational
experience
Migration Considerations and Risk Management:
- Backward compatibility with legacy systems that ignore
extensions
- Coordination with dependent applications and systems
- Comprehensive training for operations and security personnel
- Integration with existing incident response procedures and
workflows
- Risk assessment and mitigation planning for each deployment
phase
11.2. Evidence-Based Cost-Benefit Analysis
Implementation costs must be evaluated against measurable security
benefits using documented historical data:
Detailed Implementation Cost Analysis:
Emergency Key Infrastructure: $35,000 per Root CA
- FIPS 140-3 Level 3 HSM hardware and setup: $25,000
- Geographic distribution and backup systems: $5,000
- Installation, configuration, and testing: $3,000
- Annual maintenance and support: $2,000
Monitoring System Deployment: $45,000 per Root CA
- High-availability monitoring infrastructure: $30,000
- Security monitoring and alerting systems: $10,000
- Certificate Transparency integration: $3,000
- Testing and validation systems: $2,000
Personnel Training and Certification: $25,000 per Root CA
- Emergency response team training and certification: $15,000
- Legal and compliance training for procedures: $5,000
- Regular drill exercises and scenario testing: $3,000
- Documentation and procedure development: $2,000
Compliance and Audit Systems: $20,000 per Root CA
- Enhanced audit logging and monitoring systems: $12,000
- Compliance documentation and procedure development: $5,000
- External audit and certification costs: $3,000
Total Implementation Cost: $125,000 per Root CA
Historical Incident Cost Analysis (documented cases):
DigiNotar (2011):
- Direct costs: $500M+ (CA bankruptcy, industry cleanup)
- Indirect costs: Immeasurable (user trust, industry reputation)
- Affected users: 300,000+ (Iranian internet users primarily)
- Recovery time: 6+ months for major browsers, indefinite for
embedded systems
Symantec Issues (2015-2017):
- Market capitalization impact: $2.6B+ loss during incident
- Operational costs: $100M+ in incident response and remediation
- Certificate reissuance costs: $50M+ estimated
- Industry coordination costs: $10M+ across multiple vendors
Conservative Risk Assessment:
- Major Root CA compromise probability: 0.2-0.5% annually
(empirical estimate)
- Average incident cost: $750M (based on documented historical
incidents)
- Expected annual loss: $750M x 0.003 = $2.25M per major Root CA
Risk Reduction Calculation:
- Current average exposure: 180 days (documented historical
average)
- RTO-Extension average exposure: 8-72 hours (target performance)
- Risk reduction factor: 85-95% (based on exposure time reduction)
- Annual benefit: $2.25M x 0.90 = $2.0M per Root CA
Return on Investment Analysis:
- Implementation cost: $125,000 one-time investment
- Annual risk reduction benefit: $2.0M
- Simple ROI: 1,600% annually
- Break-even time: 3-4 weeks of avoided incident exposure
- 10-year NPV: $18M+ (assuming 5% discount rate)
Sensitivity Analysis:
- Conservative scenario (50% risk reduction): 800% annual ROI
- Optimistic scenario (95% risk reduction): 3,040% annual ROI
- Even with 10x higher implementation costs: Still positive ROI
11.3. Backward Compatibility
RTO-Extension maintains comprehensive compatibility with existing
infrastructure:
Legacy System Behavior and Compatibility:
- Systems that do not recognize RTO-Extension safely ignore the
extension
- Certificate validation continues normally for all legacy
applications
- Standard revocation checking (CRL/OCSP) remains fully functional
- No changes required for legacy applications during transition
period
- Extension marked as non-critical ensures compatibility
Transition Strategy and Timeline:
- Gradual adoption does not disrupt existing operations or
workflows
- Legacy systems can be updated on normal maintenance schedules
- Emergency procedures work independently of legacy system adoption
- Manual coordination remains available for systems requiring it
- Parallel operation during transition period ensures continuity
Interoperability and Standards Compliance:
- RTO-Extension designed for universal compatibility with X.509
standards
- Standard certificate formats and validation procedures maintained
- Integration with existing PKI infrastructure and certificate
management
- Support for all major cryptographic algorithms and key sizes
- Compliance with existing certificate validation and processing
standards
12. Legal and Regulatory Considerations
12.1. Liability Distribution
Implementation of RTO-Extension creates new liability scenarios
requiring clear frameworks:
False Positive Termination Liability:
- Shared liability model between CA operators and technology
providers
- Insurance requirements for potential false positive scenarios
- Clear documentation requirements for decision rationale
- Independent audit and verification of emergency procedures
- Legal protections for good-faith emergency response decisions
Delayed Response Liability:
- Clear due diligence standards for emergency response timing
- Documentation requirements for decision delays and rationale
- Comparative negligence standards based on industry best practices
- Safe harbor provisions for compliance with documented procedures
- Regular review and update of liability frameworks
Cross-Border Incident Coordination:
- International coordination frameworks for multi-jurisdiction
incidents
- Mutual recognition of emergency response procedures and decisions
- Diplomatic coordination protocols for nation-state threats
- Standardized incident reporting across jurisdictions
- Bilateral and multilateral incident response agreements
12.2. Regulatory Requirements
RTO-Extension implementation must comply with evolving regulatory
frameworks:
United States Regulatory Environment:
- No specific pre-approval required for technical implementation
- Incident reporting requirements under existing cybersecurity
frameworks
- SOX compliance for publicly traded companies (enhanced controls)
- Industry-specific requirements (banking, healthcare, government)
- State-level notification requirements for data security incidents
European Union Regulatory Framework:
- GDPR compliance for incident reporting and data protection
- eIDAS regulation compliance for qualified certificate services
- NIS2 directive requirements for critical infrastructure operators
- Country-specific telecommunications and cybersecurity regulations
- Cross-border coordination requirements under EU frameworks
Industry-Specific Compliance Requirements:
- Financial services: Banking regulatory notification and approval
processes
- Healthcare: FDA and medical device regulatory compliance
frameworks
- Government: Security clearance and classification level
compliance
- Critical infrastructure: Sector-specific regulatory coordination
requirements
- Aviation: FAA and international aviation authority requirements
12.3. Insurance Implications
RTO-Extension implementation affects cyber insurance and liability
coverage:
Insurance Benefits and Premium Considerations:
- Demonstrable risk reduction through proactive security measures
- Clear incident response procedures reduce claim complexity and
costs
- Reduced exposure duration limits potential claim amounts and
scope
- Industry-standard implementation reduces comparative negligence
risk
- Potential premium reductions for enhanced security posture
Coverage Considerations and Requirements:
- False positive termination coverage requirements and exclusions
- Business interruption coverage for emergency termination
scenarios
- Third-party liability coverage for dependent system impacts
- Cyber liability coverage for incident response and remediation
costs
- Directors and officers coverage for emergency response decisions
Risk Assessment and Underwriting:
- Enhanced security controls improve risk assessment profiles
- Clear procedures and documentation support underwriting
decisions
- Regular audits and testing demonstrate ongoing risk management
- Industry certification and compliance reduce underwriting
uncertainty
- Quantifiable risk reduction supports favorable policy terms
13. IANA Considerations
This document requests IANA to allocate identifiers and create
registries for RTO-Extension parameters:
Object Identifier Allocation:
id-ce-selfRevocation OBJECT IDENTIFIER ::= {
joint-iso-itu-t(2) ds(5) certificateExtension(29) TBD1
}
IANA is requested to allocate the value TBD1 under the Certificate
Extensions arc for the RTO-Extension.
Registry Creation:
Registry Name: Root CA Self-Termination Extension Parameters
Registration Procedure: Specification Required with Expert Review
Reference: This document
Initial registry entries:
- Version numbers (1-255): Version 1 defined in this specification
- Signal format identifiers (1-255): JSON(1), XML(2), Plain(3)
- Reason codes for emergency signals: Initial set defined in this
document
- Detection threshold multipliers: Standard values and ranges
14. References
14.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5280] Cooper, D., et al., "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation
List (CRL) Profile", RFC 5280, May 2008.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, May 2017.
14.2. Informative References
[RFC6960] Santesson, S., et al., "X.509 Internet Public Key
Infrastructure Online Certificate Status Protocol -
OCSP", RFC 6960, June 2013.
[FIPS140-3] National Institute of Standards and Technology,
"Security Requirements for Cryptographic Modules",
FIPS PUB 140-3, March 2019.
[FIPS204] National Institute of Standards and Technology,
"Module-Lattice-Based Digital Signature Standard",
FIPS PUB 204, August 2024.
Appendix A. Implementation Examples
Example OpenSSL configuration for RTO-Extension:
<CODE BEGINS>
[ ca_extensions ]
basicConstraints = critical,CA:TRUE,pathlen:1
keyUsage = critical,keyCertSign,cRLSign
subjectKeyIdentifier = hash
1.3.6.1.4.1.44954.1.99.1 = ASN1:SEQUENCE:rto_extension
[ rto_extension ]
version = INT:1
encryptedData = SEQUENCE:encrypted_data_seq
keyDerivationSalt = FORMAT:HEX,OCTETSTRING:9A3C7E0F2D4B8A6C...
checkInterval = INT:21600
emergencyContact = UTF8:emergency@example.com
signalFormat = INT:1
emergencyKeyHash = FORMAT:HEX,OCTETSTRING:A7B3C9E1F4D2B8A6...
detectionThreshold = INT:2
[ encrypted_data_seq ]
encryptedURL = FORMAT:HEX,OCTETSTRING:4F8A2E1D9C7B6A5E...
initializationVector = FORMAT:HEX,OCTETSTRING:2E4A8C6F1D5B9A3C...
authenticationTag = FORMAT:HEX,OCTETSTRING:7F3E9A1C5D8B2F4A...
<CODE ENDS>
Emergency Response Checklist:
1. Signal Detection and Verification (Target: 30 minutes)
- [ ] Confirm signal presence at monitoring URL
- [ ] Validate signal format and digital signature
- [ ] Verify signal timestamp within validity window
- [ ] Check nonce uniqueness and sequence number
- [ ] Cross-reference with Certificate Transparency data
- [ ] Document detection time and initial circumstances
2. Evidence Collection and Analysis (Target: 4-8 hours)
- [ ] Collect comprehensive evidence from multiple sources
- [ ] Analyze certificate issuance patterns and anomalies
- [ ] Correlate with external threat intelligence feeds
- [ ] Verify HSM audit logs and access records
- [ ] Document evidence with chain of custody procedures
3. Emergency Authorization (Target: 2-4 hours)
- [ ] Assemble minimum two authorized personnel
- [ ] Verify identity of responding personnel
- [ ] Independent review of evidence by each authorizer
- [ ] Risk assessment and impact analysis
- [ ] Consensus decision for termination authorization
- [ ] Document authorization with personal signatures
4. Manual Signal Generation (Target: 1-2 hours)
- [ ] Physical presence verification of authorized personnel
- [ ] Secure access to Root CA private key via HSM
- [ ] Generate Root-TurnOff signal with witness procedures
- [ ] Verify signal format and cryptographic signature
- [ ] Create multiple copies for redundant distribution
- [ ] Document signal generation with witness attestation
5. Distribution and Verification (Target: 1-2 hours)
- [ ] Distribute signal to all dependent systems
- [ ] Verify successful propagation to critical endpoints
- [ ] Update certificate status responders
- [ ] Invalidate relevant caches and distribution points
- [ ] Monitor client adoption and system responses
- [ ] Document distribution completion and verification
Appendix B. Frequently Asked Questions
Q: What if an attacker gains access to the monitoring URL?
A: URL discovery provides no attack capability. Valid termination
requires two independent cryptographic signatures: emergency key
signatures for signal authentication and Root CA private key
signatures for actual termination. Additionally, human verification
and dual-person authorization prevent unauthorized termination.
System security does not depend on URL secrecy.
Q: How does this handle network partitions or monitoring outages?
A: The system is designed to fail safely during infrastructure
problems. Network partitions or monitoring failures never trigger
termination. Multiple independent monitoring endpoints provide
redundancy across geographic regions. Manual emergency procedures
remain available during infrastructure outages. The system defaults
to continued operation, not termination, during technical failures.
Q: What is the business case for $125,000 implementation cost?
A: Historical Root CA compromises have caused $500M-$2.6B+ in
documented costs (DigiNotar, Symantec). Implementation provides
85-95% reduction in exposure time (months to hours). Conservative
analysis shows annual risk reduction benefit of $2M per Root CA.
ROI calculation: 1,600% annually. Break-even occurs within 3-4
weeks of avoided incident exposure.
Q: Why prohibit automation for such time-critical responses?
A: False positive termination causes greater damage than most actual
compromises, potentially affecting millions of certificates and
billions of users. Automated systems become high-value targets for
sophisticated attackers. Human judgment provides context awareness
and error correction capabilities impossible in automation.
Historical precedent from nuclear, aviation, and financial
industries supports human control for irreversible critical
decisions.
Q: How does this compare to Certificate Transparency solutions?
A: Certificate Transparency provides detection but not response
capability. CT logs identify fraudulent certificates within hours
but cannot stop continued issuance. Current remediation still
requires months of manual trust store coordination. RTO-Extension
provides cryptographic termination capability that stops attack
progression within hours regardless of trust store update timing.
Q: What happens to legitimate certificates from terminated Root CAs?
A: All certificates issued by terminated Root CAs become invalid
immediately upon termination. This is intentional behavior designed
to stop ongoing attacks. Certificate reissuance from successor
Root CAs is required for legitimate certificates. Pre-planned
succession procedures minimize disruption to legitimate users.
Q: Can this be integrated with existing HSM infrastructure?
A: Yes. RTO-Extension works with any FIPS 140-3 Level 3 certified
HSM supporting dual-person control. Emergency keys can be stored
in separate HSMs or isolated partitions within existing HSMs.
Integration requires procedural modifications rather than hardware
replacement. Most modern HSM deployments support required features.
Q: How do legacy systems handle RTO-Extension?
A: Legacy systems ignore unknown certificate extensions and continue
normal operation. The extension is marked as non-critical to ensure
compatibility. Traditional revocation mechanisms (CRL/OCSP) remain
functional. No changes required for legacy applications during
transition period. Gradual migration allows normal update cycles.
Q: What about post-quantum cryptography considerations?
A: RTO-Extension is designed to be algorithm-agnostic and supports
post-quantum signature schemes. Emergency keys can immediately
migrate to ML-DSA (FIPS 204) or other post-quantum algorithms.
Root CA keys follow standard industry quantum migration timeline.
Hybrid classical + post-quantum approaches supported during
transition.
Q: How is this different from shorter certificate lifetimes?
A: Shorter lifetimes reduce exposure for normal operations but do
not stop fraudulent issuance during active compromise. Attackers
with Root CA private keys can issue certificates of any lifetime.
RTO-Extension provides termination capability that stops all
issuance, regardless of certificate lifetime. Both approaches
are complementary for comprehensive security.
Appendix C. Test Vectors
URL Encryption Test Vector:
Input Parameters:
- Root CA Public Key (DER): 3082010A0282010100C2... (example
RSA-4096)
- Subject Key Identifier: A1B2C3D4E5F6789A
- Monitoring URL: "https://monitoring.example.com/rto/
A7B9C2D4.../signal"
- Salt: 9A3C7E0F2D4B8A6C5E7F9D1C3A5B7E9F2D4B6A8C0E2F4A6B8C0D2E4F
6A8B0C2D4
- IV: 2E4A8C6F1D5B9A3C7E0F2D4B
HKDF-SHA384 Key Derivation:
- IKM: Root CA Public Key (DER encoded, 550 bytes)
- Salt: 32-byte salt from above
- Info: "PKI-RTO-URL-v1" || Subject Key Identifier (20 bytes)
- Output: 32-byte encryption key
AES-256-GCM Encryption:
- Plaintext: UTF-8 encoded monitoring URL (67 bytes)
- Key: Derived 32-byte key from HKDF-SHA384
- IV: 12-byte initialization vector from above
- Ciphertext: 4F8A2E1D9C7B6A5E3F8C1A4D7B2E9F6C... (67 bytes)
- Authentication Tag: 7F3E9A1C5D8B2F4A6C0E3D9B8A5F2C1E (16 bytes)
Emergency Signal Test Vector:
JSON Signal Example:
<CODE BEGINS>
{
"version": "1.0",
"timestamp": "2025-05-30T10:30:00Z",
"nonce": "A1B2C3D4E5F6789A0B1C2D3E4F5A6B7C8D9E0F1A2B3C4D5E",
"sequence": 42,
"validity_window": 3600,
"reason": "private-key-compromise",
"evidence_hash": "sha384-B7A9D2F4C6E8A0B3D5F7A9C2E4F6B8D0A2C4E6F8",
"evidence_url": "https://evidence.example.com/incident-42",
"authorizer": "emergency-response-team-alpha",
"verification": {
"algorithm": "EdDSA",
"keyReference": "sha256-A7B3C9E1F4D2B8A6C5E7F9D1C3A5B7E9",
"signature": "6F2A8C4E0B6D8F2A4C6E8B0D2F4A6C8E0B2D4F6A8C0E2F4A"
}
}
<CODE ENDS>
Signature Verification Process:
1. Extract canonical JSON excluding "verification" field
2. UTF-8 encode canonical message (327 bytes in this example)
3. Verify EdDSA signature using emergency public key
4. Verify timestamp within validity window
5. Check nonce uniqueness against database
6. Verify sequence number greater than last valid sequence
Author's Address
Torsten Jahnke
Chief Executive Officer
Aviontex GmbH - keweonDNS Project
Bavaria, Germany
Email: torsten.jahnke@aviontex.de
URI: https://www.aviontex.de
Acknowledgments
This work was developed as part of security enhancements for the
keweonDNS project at Aviontex GmbH. The authors acknowledge the
contributions of security researchers and practitioners who
identified the operational gaps that this specification addresses.
Special recognition to the XDA-Developers and Android-Hilfe forum
communities whose detailed questioning about DNS security edge cases
led to insights enabling this approach. The collaborative security
analysis proved instrumental in identifying and addressing what
security experts had considered an unsolvable architectural problem.
Thanks to security researchers and experts in PKI, DNSSEC,
government systems, and critical infrastructure who provided
technical review and identified implementation considerations that
improved the robustness and practical applicability of this
specification.
The historical analysis was informed by public incident reports,
academic security research, and industry documentation of
operational challenges in existing trust anchor infrastructure.