Lab-04: PQC Revocation

Incident Response: When Keys Are Compromised

Key Message: Revoking a PQC certificate works exactly like revoking a classical one. Same workflow, same commands.

The Scenario

It’s 3 AM. You receive an alert:

🚨 SECURITY ALERT
   The private key for server.example.com
   was detected on GitHub.

What do you do?

“We had a security incident. A private key was compromised. How do we revoke a post-quantum certificate?”

The same way you revoke any certificate. PKI operations are algorithm-agnostic.

┌──────────────────────────────────────────────────────────────────┐
│                                                                  │
│  COMPROMISED KEY: The attacker can impersonate your server      │
│                                                                  │
│    Attacker                                                      │
│        │                                                         │
│        │  server.key (stolen)                                    │
│        ▼                                                         │
│    ┌──────────┐                                                  │
│    │ Fake     │  The attacker can now:                          │
│    │ Server   │  - Impersonate server.example.com               │
│    │          │  - Intercept client traffic                     │
│    │          │  - Sign malicious content                       │
│    └──────────┘                                                  │
│                                                                  │
│    The certificate is still technically "valid".                │
│    Solution: REVOKE IT IMMEDIATELY                              │
│                                                                  │
└──────────────────────────────────────────────────────────────────┘

What We’ll Do

Create a CA (ML-DSA-65) 1b. Issue a TLS certificate
Revoke the certificate (after key compromise) 2b. Generate a CRL (Certificate Revocation List)
Verify the revoked certificate is rejected

Run the Demo

./journey/04-revocation/demo.sh

The Commands

Step 1: Create CA

# Create PQC CA
qpki ca init --profile profiles/pqc-ca.yaml \
    --var cn="PQC CA" \
    --ca-dir output/pqc-ca

qpki ca export --ca-dir output/pqc-ca --out output/pqc-ca/ca.crt

Step 1b: Issue Certificate

# Generate ML-DSA-65 key, CSR, and issue certificate
qpki csr gen --algorithm ml-dsa-65 \
    --keyout output/server.key \
    --cn server.example.com \
    --out output/server.csr

qpki cert issue --ca-dir output/pqc-ca \
    --profile profiles/pqc-tls-server.yaml \
    --csr output/server.csr \
    --out output/server.crt

# Extract serial number - needed for revocation command
openssl x509 -in output/server.crt -noout -serial

Step 2: Revoke Certificate

# Revoke certificate with reason
qpki cert revoke <serial> --ca-dir output/pqc-ca --reason keyCompromise

The certificate is now marked as revoked in the CA database. But clients don’t know yet — we need to publish a CRL.

Step 2b: Generate CRL

# Generate the Certificate Revocation List
qpki crl gen --ca-dir output/pqc-ca

qpki inspect output/pqc-ca/crl/ca.crl

The CRL is now published. Clients can check if certificates are revoked.

Step 3: Verify CRL

# Verify certificate against CRL (should fail - certificate is revoked)
qpki cert verify output/server.crt \
    --ca output/pqc-ca/ca.crt \
    --crl output/pqc-ca/crl/ca.crl

Revocation Reasons (RFC 5280)

Code	Reason	When to Use
0	unspecified	Default, no specific reason
1	keyCompromise	Private key exposed
2	cACompromise	CA’s key was compromised
3	affiliationChanged	Subject’s organization changed
4	superseded	Replaced by new certificate
5	cessationOfOperation	Service no longer needed

Incident Response Workflow

1. DETECT
   └─► Key compromise discovered (leak, breach, etc.)

2. ASSESS
   └─► Identify affected certificates (serial numbers)

3. REVOKE
   └─► qpki cert revoke <serial> --ca-dir <ca> --reason keyCompromise

4. PUBLISH
   └─► qpki crl gen --ca-dir <ca>

5. NOTIFY
   └─► Inform relying parties, update distribution points

6. REMEDIATE
   └─► Issue replacement certificates with new keys

Note: Revocation prevents future trust. It does not remove already-installed malware or undo past compromise.

Size Comparison

Component	Classical (ECDSA)	Post-Quantum (ML-DSA)	Ratio
CRL signature	~96 bytes	~3,309 bytes	~34x
CRL total size	~500 bytes	~3,800 bytes	~7.6x

CRLs are larger due to PQC signatures, but the protocol is unchanged.

CRL size usually remains negligible compared to network traffic.

When Revocation Matters Most

Industry	Scenario	Impact
Financial services	Stolen code signing key	Malicious transactions signed
Healthcare	Compromised device cert	Patient data exposed
Government	Employee termination	Unauthorized access continues
E-commerce	TLS key leaked on GitHub	Man-in-the-middle attacks
IoT/Industrial	Factory device breach	Supply chain compromise

Compliance requirements:

PCI-DSS: Revoke compromised keys within 24 hours
HIPAA: Immediate revocation for terminated employees
SOC 2: Document revocation procedures and response times

What You Learned

Algorithm-agnostic: Revocation workflow is identical for classical and PQC
CRLs are signed: PQC CRLs have larger signatures
Same commands: No new tools or procedures needed
Ops teams: No retraining required for basic PKI operations

References

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