Cryptographic Implementation Audit¶

Document Version: 1.0 Last Updated: 2025-12-17 Scope: Bindy DNS Operator for Kubernetes Audit Type: Internal cryptographic review for compliance purposes

Executive Summary¶

This document provides a comprehensive audit of all cryptographic operations in the Bindy DNS Operator. This audit is required for SOX, NIST 800-53 (SC-13), and FIPS compliance in regulated banking environments.

Audit Findings: - ✅ All cryptographic operations use industry-standard, audited libraries - ✅ No custom cryptographic implementations (high-risk) - ✅ TLS/mTLS used for all network communication - ✅ Secrets properly managed via Kubernetes Secrets API - ⚠️ FIPS mode requires explicit deployment configuration (see fips.md)

Cryptographic Inventory¶

1. TLS/mTLS (Transport Layer Security)¶

Purpose: Secure communication between operator and Kubernetes API server

Library: - Name: rustls or native-tls (via kube-rs) - Version: See Cargo.lock - Audit Status: ✅ Widely audited open-source library - FIPS Support: Yes (when using OpenSSL or BoringSSL backend)

Implementation:

// In Cargo.toml (via kube dependency)
kube = { version = "0.x", features = ["client", "rustls-tls"] }

// TLS automatically configured by kube::Client
let client = Client::try_default().await?;

Algorithms Used: - Cipher Suites: TLS 1.2+ with AES-GCM (configured by Kubernetes API server) - Key Exchange: ECDHE (Elliptic Curve Diffie-Hellman Ephemeral) - Authentication: RSA-2048 or ECDSA P-256 (Kubernetes certificates) - Hashing: SHA-256, SHA-384

Configuration: - ✅ TLS 1.2+ required (TLS 1.0/1.1 disabled by Kubernetes) - ✅ Certificate validation enabled (no InsecureSkipVerify) - ✅ System CA certificate store used

Vulnerabilities: - None known in current versions - Regular updates via cargo audit

FIPS Compliance: - ⚠️ Requires FIPS-enabled TLS library (OpenSSL FIPS or AWS-LC) - See fips.md for deployment guide

Evidence: - Cargo.toml - dependency declaration - src/main.rs - client initialization

2. HMAC-SHA256 (DNS TSIG Keys)¶

Purpose: Transaction signatures for secure DNS zone transfers (AXFR/IXFR)

Library: - Name: BIND9 (via bind9 container image) - Version: BIND 9.18+ (see Dockerfile or container image) - Audit Status: ✅ Industry-standard DNS server, widely audited - FIPS Support: Yes (when compiled with FIPS-enabled OpenSSL)

Implementation:

// TSIG keys stored in Kubernetes Secrets
let secret = Secret {
    metadata: ObjectMeta {
        name: Some(format!("{}-tsig", instance_name)),
        ..Default::default()
    },
    string_data: Some({
        let mut data = BTreeMap::new();
        data.insert("transfer-key".to_string(), tsig_key_value);
        data
    }),
    ..Default::default()
};

Algorithms Supported: - FIPS-Approved: hmac-sha256 ✅ (default), hmac-sha384, hmac-sha512 - Not FIPS-Approved: hmac-md5 ❌ (not used)

Key Generation: - Method: tsig-keygen utility (part of BIND9) - Key Length: 256 bits (for HMAC-SHA256) - Randomness: System CSPRNG (/dev/urandom)

Key Storage: - ✅ Kubernetes Secrets (encrypted at rest in etcd) - ✅ Mounted as files (not environment variables) - ✅ RBAC-protected (only operator ServiceAccount can read)

Key Rotation: - ⚠️ Manual rotation required (not automated) - Documented procedure: Planned (see roadmap for key rotation automation)

FIPS Compliance: - ✅ HMAC-SHA256 is FIPS-approved (FIPS 198-1) - ✅ Default algorithm is FIPS-compliant

Evidence: - src/bind9_resources.rs - Secret generation - deploy/crds/bind9instances.crd.yaml - TSIG configuration

3. Kubernetes ServiceAccount Tokens (JWT)¶

Purpose: Authentication for operator to Kubernetes API

Library: - Name: Kubernetes (platform-level) - Version: Kubernetes 1.20+ (projected ServiceAccount tokens) - Audit Status: ✅ Core Kubernetes feature - FIPS Support: Inherits from cluster configuration

Implementation:

# Automatically mounted by Kubernetes
apiVersion: v1
kind: ServiceAccount
metadata:
  name: bindy-operator

Algorithms Used: - Signing: RSA-2048 or ECDSA P-256 (Kubernetes service account key) - Format: JWT (JSON Web Token, RFC 7519) - Encoding: Base64URL

Token Properties: - Expiration: Yes (default: 1 hour, automatically renewed) - Audience: Kubernetes API server - Rotation: Automatic (Kubernetes platform responsibility)

FIPS Compliance: - ✅ RSA-2048 and ECDSA P-256 are FIPS-approved - ⚠️ Requires FIPS-enabled Kubernetes control plane

Evidence: - deploy/rbac/serviceaccount.yaml

4. Container Image Signatures (Optional)¶

Purpose: Verify authenticity and integrity of container images

Library: - Name: Sigstore/Cosign - Version: Latest - Audit Status: ✅ CNCF project, widely adopted - FIPS Support: Yes (with FIPS-enabled Go runtime)

Implementation: - ⚠️ TODO: Image signing not yet automated - Planned in CI/CD pipeline

Algorithms (Future): - Signing: ECDSA P-256 (Sigstore Fulcio) - Hashing: SHA-256 (image digest) - Transparency: Sigstore Rekor (public log)

FIPS Compliance: - ✅ ECDSA P-256 is FIPS-approved - ✅ SHA-256 is FIPS-approved

Evidence: - Planned: .github/workflows/release.yml (TODO)

5. Hashing (Non-Cryptographic)¶

Purpose: Data integrity checks, caching, non-security operations

Library: - Name: Rust standard library (std::collections::HashMap) - Algorithm: SipHash-1-3 (default Rust hasher) - Audit Status: ✅ Rust standard library - FIPS Relevance: ❌ Not used for security purposes (FIPS exemption)

Usage: - HashMap keys (in-memory data structures) - Cache keys - Non-authenticated checksums

FIPS Compliance: - ✅ Exempt (not used for security-critical operations)

Evidence: - Standard Rust collections throughout codebase

Cryptographic Security Controls¶

Secret Management¶

Kubernetes Secrets (Encrypted at Rest): - ✅ TSIG keys stored in Kubernetes Secrets - ✅ Secrets mounted as volumes (not environment variables) - ✅ RBAC restricts access to operator ServiceAccount - ⚠️ etcd encryption must be enabled (cluster-level)

Secret Rotation: - ⚠️ Manual TSIG key rotation (not automated) - ✅ ServiceAccount token rotation automatic (Kubernetes) - ✅ TLS certificates managed by Kubernetes (automatic rotation)

Evidence: - src/bind9_resources.rs - Secret volume mounts - deploy/rbac/role.yaml - RBAC for secrets

Secure Communication¶

TLS Everywhere: - ✅ Operator ↔ Kubernetes API: TLS 1.2+ (mutual TLS) - ✅ Pod ↔ DNS service: Optional mTLS via Linkerd service mesh - ❌ BIND9 ↔ BIND9: Cleartext DNS (zone transfers authenticated via TSIG)

Network Segmentation: - ✅ Kubernetes NetworkPolicies supported (user responsibility) - ✅ Namespace isolation enforced - ✅ No external network access required

Evidence: - Default Kubernetes TLS configuration - Network design: See Security Architecture

Key Generation¶

Randomness Source: - ✅ System CSPRNG (/dev/urandom on Linux) - ✅ No weak random number generators - ✅ No hardcoded keys or predictable seeds

Key Strength: - ✅ TSIG keys: 256 bits (HMAC-SHA256) - ✅ TLS keys: RSA-2048 or ECDSA P-256 (Kubernetes-managed)

Evidence: - BIND9 tsig-keygen uses system CSPRNG - Kubernetes certificate generation uses CSPRNG

Vulnerability Management¶

Dependency Scanning¶

Automated Scanning: - ✅ cargo audit in CI/CD pipeline (every commit) - ✅ Dependabot for automated dependency updates - ✅ Security advisories monitored

Scanning Tools: - RustSec Advisory Database: Checks for known CVEs in Rust crates - GitHub Dependabot: Automated PR creation for updates - Trivy/Grype: Container image scanning (optional)

Evidence: - .github/workflows/audit.yml - .github/dependabot.yml

Known Vulnerabilities¶

Current Status (as of 2025-12-17):

cargo audit
# Expected output: 0 vulnerabilities found

Historical Vulnerabilities: - None affecting cryptographic libraries (as of this audit)

Response Process: 1. Automated detection via cargo audit 2. Security advisory created (if critical) 3. Patch released within 48 hours (critical) or 7 days (high) 4. Changelog updated 5. Customers notified (if applicable)

Evidence: - SECURITY.md - vulnerability reporting process

Cryptographic Weaknesses and Mitigations¶

Identified Weaknesses¶

1. DNS Zone Transfers (Cleartext)¶

Issue: AXFR/IXFR zone transfers are not encrypted (industry standard)

Risk: Low (zones contain public DNS records, TSIG provides authentication)

Mitigation: - ✅ TSIG authentication prevents tampering - ✅ Kubernetes NetworkPolicies can restrict traffic - ✅ Optional mTLS via Linkerd service mesh

Recommendation: Use Linkerd mTLS for defense-in-depth

2. Manual TSIG Key Rotation¶

Issue: TSIG keys not automatically rotated

Risk: Medium (key compromise window)

Mitigation: - ✅ Keys stored in Kubernetes Secrets (encrypted at rest) - ✅ RBAC limits access - ⚠️ Manual rotation process documented (TODO)

Recommendation: Implement automated key rotation (future enhancement)

3. FIPS Mode Not Enforced¶

Issue: FIPS mode requires manual deployment configuration

Risk: Medium (regulatory compliance)

Mitigation: - ✅ FIPS deployment guide provided (fips.md) - ✅ Default algorithms are FIPS-compatible - ⚠️ Requires FIPS-enabled cluster or container image

Recommendation: Provide FIPS-enabled container images

Compliance Matrix¶

Control	Requirement	Status	Evidence
NIST 800-53 SC-13	FIPS-validated crypto	⚠️ Deployment-specific	fips.md
NIST 800-53 SC-12	Key management	✅ Implemented	Kubernetes Secrets
NIST 800-53 SC-8	Transmission confidentiality	✅ Implemented	TLS 1.2+
SOX ITGC	Encryption at rest	⚠️ Cluster-level	etcd encryption
SOX ITGC	Encryption in transit	✅ Implemented	TLS
PCI-DSS 3.4	Key storage security	✅ Implemented	Kubernetes Secrets
FIPS 140-2	Approved algorithms	✅ Compatible	HMAC-SHA256, AES-GCM

Cryptographic Best Practices¶

✅ Followed¶

Use standard libraries - No custom crypto implementations
Defense in depth - Multiple layers (TLS + TSIG + RBAC)
Least privilege - Minimal secret access
Fail secure - TLS certificate validation always enabled
Auditability - All crypto operations logged

⚠️ Recommendations¶

Automate key rotation - Implement periodic TSIG key updates
FIPS by default - Provide FIPS-enabled container images
Mutual TLS - Enable Linkerd mTLS for pod-to-pod communication
Image signing - Sign container images with Sigstore/Cosign
HSM integration - Support Hardware Security Modules for key storage (future)

Audit Trail¶

Cryptographic Events Logged¶

Logged: - ✅ TLS connection establishment (Kubernetes audit logs) - ✅ Secret creation/updates (Kubernetes audit logs) - ✅ RBAC denials (Kubernetes audit logs) - ✅ Reconciliation events (application logs)

Not Logged: - ❌ Actual TSIG key values (correct - secrets not logged) - ❌ TLS handshake details (platform-level)

Log Retention: - ⚠️ Kubernetes audit logs: Cluster-level configuration - ✅ Application logs: Stdout (user configures retention)

Third-Party Cryptographic Dependencies¶

Dependency	Purpose	Version	Audit Status	FIPS
`rustls` or `openssl`	TLS library	See Cargo.lock	✅ Audited	⚠️ Conditional
BIND9	DNS server + TSIG	9.18+	✅ ISC official	⚠️ Conditional
Kubernetes	Platform crypto	1.20+	✅ CNCF	⚠️ Cluster-level

Audit Process: 1. Annual review of all cryptographic dependencies 2. Quarterly cargo audit scans 3. CVE monitoring via GitHub Security Advisories 4. Dependency updates via Dependabot

Cryptographic Configuration Hardening¶

Recommended Settings¶

Kubernetes API Server (Cluster-Level):

# /etc/kubernetes/manifests/kube-apiserver.yaml
spec:
  containers:
  - command:
    - kube-apiserver
    - --tls-min-version=VersionTLS12
    - --tls-cipher-suites=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384

Bindy Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: bindy-operator
spec:
  template:
    spec:
      containers:
      - name: bindy
        env:
        # Enable FIPS mode (if using OpenSSL)
        - name: OPENSSL_FORCE_FIPS_MODE
          value: "1"

TSIG Configuration:

apiVersion: dns.firestoned.io/v1beta1
kind: Bind9Instance
metadata:
  name: primary
spec:
  # Ensure FIPS-approved algorithm (default)
  # tsigAlgorithm: hmac-sha256  # Explicitly set if needed

Cryptographic Incident Response¶

Trigger Events: - CVE published for cryptographic library - TSIG key compromise suspected - TLS certificate expiration - FIPS validation failure

Response Procedure: 1. Assess Impact: - Identify affected components - Determine if keys/certificates compromised - Check if FIPS compliance broken

Containment:
Rotate compromised keys immediately
Update vulnerable dependencies
Deploy patches
Recovery:
Verify new keys/certificates deployed
Test connectivity and functionality
Confirm FIPS compliance restored
Post-Incident:
Update CHANGELOG.md
Publish security advisory (if customer-facing)
Document lessons learned

Evidence: - SECURITY.md - incident reporting - Incident Response Guide

Recommendations for Future Enhancements¶

High Priority¶

Automated TSIG key rotation - Reduce key compromise window
FIPS-enabled container images - Simplify FIPS deployment
Container image signing - Complete supply chain security

Medium Priority¶

Mutual TLS documentation - Linkerd integration guide
HSM support - Hardware-backed key storage for high-security environments
Certificate management - Automate DNS server TLS certificates

Low Priority¶

Quantum-resistant algorithms - Future-proofing (when standardized)
Zero-knowledge proofs - Privacy-preserving DNS (research)

Cryptographic Compliance Statement¶

For Auditors:

The Bindy DNS Operator uses only industry-standard, widely-audited cryptographic libraries and algorithms. No custom cryptographic implementations are present. All algorithms used are approved for U.S. federal government use under FIPS 140-2/140-3 when deployed in FIPS mode.

Cryptographic Algorithms in Use: - TLS 1.2+ (AES-GCM, ECDHE, RSA-2048/ECDSA P-256, SHA-256) - HMAC-SHA256 (DNS TSIG) - JWT (ServiceAccount tokens, RSA-2048/ECDSA P-256)

Libraries: - rustls or OpenSSL (TLS) - BIND9 (HMAC-SHA256) - Kubernetes (JWT signing)

FIPS Compliance: - Deployment guide provided: fips.md - All algorithms FIPS-compatible - Requires FIPS-enabled runtime environment

Signed: _______________________ Date: _____________ Title: Principal Engineer, Bindy Project

Audit Conclusion¶

Overall Assessment: ✅ PASS

The Bindy DNS Operator demonstrates strong cryptographic hygiene: - Industry-standard libraries only - FIPS-compatible algorithms - Proper secret management - Regular vulnerability scanning - Documented compliance controls

Areas for Improvement: - Automate TSIG key rotation - Provide FIPS-enabled container images - Implement container image signing

Next Audit: 2026-12-17 (Annual)

References¶

NIST SP 800-52 Rev 2 - TLS Guidelines
NIST SP 800-57 - Key Management
FIPS 140-2 - Cryptographic Module Security
FIPS 198-1 - Keyed-Hash Message Authentication Code (HMAC)
RFC 2845 - DNS TSIG
RustSec Advisory Database - Rust CVE tracking

Document Control¶

Version	Date	Author	Changes
1.0	2025-12-17	Erick Bourgeois	Initial cryptographic audit

Next Review Date: 2026-12-17

Cryptographic Implementation Audit¶

Executive Summary¶

Cryptographic Inventory¶

1. TLS/mTLS (Transport Layer Security)¶

2. HMAC-SHA256 (DNS TSIG Keys)¶

3. Kubernetes ServiceAccount Tokens (JWT)¶

4. Container Image Signatures (Optional)¶

5. Hashing (Non-Cryptographic)¶

Cryptographic Security Controls¶

Secret Management¶

Secure Communication¶

Key Generation¶

Vulnerability Management¶

Dependency Scanning¶

Known Vulnerabilities¶

Cryptographic Weaknesses and Mitigations¶

Identified Weaknesses¶

1. DNS Zone Transfers (Cleartext)¶

2. Manual TSIG Key Rotation¶

3. FIPS Mode Not Enforced¶

Compliance Matrix¶

Cryptographic Best Practices¶

✅ Followed¶

⚠️ Recommendations¶

Audit Trail¶

Cryptographic Events Logged¶

Third-Party Cryptographic Dependencies¶

Cryptographic Configuration Hardening¶

Recommended Settings¶

Cryptographic Incident Response¶

Crypto-Related Incidents¶

Recommendations for Future Enhancements¶

High Priority¶

Medium Priority¶

Low Priority¶

Cryptographic Compliance Statement¶

Audit Conclusion¶

References¶

Document Control¶