# OpenSSL Configuration for Hybrid Root CA
# Classical Path: ECDSA P-256 (universal compatibility, resource-efficient)
# Post-Quantum Path: ML-DSA-87/Dilithium5 (quantum-resistant, future-proof)

[ req ]
default_days           = 7300
default_md             = sha256
distinguished_name     = req_distinguished_name
x509_extensions        = v3_ca
string_mask            = utf8only
prompt                 = no

[ req_distinguished_name ]
CN                     = Hybrid Root CA

[ v3_ca ]
# Basic constraints - critical for CA certificates
basicConstraints       = critical, CA:TRUE
keyUsage               = critical, digitalSignature, keyCertSign, cRLSign

# Subject Key Identifier
subjectKeyIdentifier   = hash

# Certificate policies (optional)
certificatePolicies    = @ca_policies

[ ca_policies ]
policyIdentifier       = 2.5.29.32.0 # wildcard issue all.
# CPS.1                = "https://example.com/cps"


# =============================================================================
# HYBRID CERTIFICATE STRATEGY
# =============================================================================
#
# Your approach is excellent! By using ECDSA P-256 for both IoT and browsers,
# you get universal compatibility while the ML-DSA-87 root provides quantum
# resistance for future-ready intermediate certificates.
#
# DEPLOYMENT MODEL:
#
# 1. ECDSA P-256 Root CA → Issues intermediates for current use
#    ├─ IoT Intermediate CA → Issues device certificates
#    └─ VPS Intermediate CA → Issues server certificates (browser-compatible)
#
# 2. ML-DSA-87 Root CA → Issues quantum-safe intermediates
#    ├─ PQ IoT Intermediate CA → For future IoT with PQ support
#    └─ PQ VPS Intermediate CA → For browsers when ML-DSA support arrives
#
# BENEFITS:
# - Single ECDSA key serves all current needs efficiently
# - ML-DSA root is ready when ecosystem supports it
# - Intermediate certificates can be cross-signed by both roots
# - No redundant security overlap between the two paths
# - Clear migration path as PQ support becomes available
#
# =============================================================================
# GENERATION COMMANDS
# =============================================================================
#
# 1. CLASSICAL PATH: ECDSA P-256 ROOT CA
#
#    Generate P-256 private key:
#      openssl ecparam -name prime256v1 -genkey -noout -out root-ca-p256.key
#
#    Protect the private key (highly recommended):
#      chmod 400 root-ca-p256.key
#
#    Create self-signed root certificate:
#      openssl req -new -x509 -days 7300 -sha256 -config root-ca.cnf \
#        -key root-ca-p256.key -out root-ca-p256.crt
#
#    Verify the certificate:
#      openssl x509 -in root-ca-p256.crt -text -noout
#
#    Extract public key (for verification):
#      openssl x509 -in root-ca-p256.crt -pubkey -noout > root-ca-p256.pub
#
#
# 2. POST-QUANTUM PATH: ML-DSA-87 ROOT CA
#
#    Prerequisites:
#    - OpenSSL 3.2+ with OQS provider
#    - Install: https://github.com/open-quantum-safe/oqs-provider
#
#    Install OQS provider (Ubuntu/Debian):
#      sudo apt update
#      sudo apt install cmake ninja-build
#      git clone https://github.com/open-quantum-safe/liboqs.git
#      cd liboqs && mkdir build && cd build
#      cmake -GNinja -DCMAKE_INSTALL_PREFIX=/usr/local ..
#      ninja && sudo ninja install
#
#      cd ../..
#      git clone https://github.com/open-quantum-safe/oqs-provider.git
#      cd oqs-provider && mkdir build && cd build
#      cmake -GNinja -DCMAKE_INSTALL_PREFIX=/usr/local ..
#      ninja && sudo ninja install
#
#    Generate ML-DSA-87 (Dilithium5) private key:
#      openssl genpkey -algorithm mldsa87 -out root-ca-mldsa87.key
#
#    Protect the private key:
#      chmod 400 root-ca-mldsa87.key
#
#    Create self-signed root certificate:
#      openssl req -new -x509 -days 7300 -sha256 -config root-ca.cnf \
#        -key root-ca-mldsa87.key -out root-ca-mldsa87.crt
#
#    Verify the certificate:
#      openssl x509 -in root-ca-mldsa87.crt -text -noout
#
#    Extract public key:
#      openssl x509 -in root-ca-mldsa87.crt -pubkey -noout > root-ca-mldsa87.pub
#
#
# 3. VERIFY BOTH ROOTS
#
#    Check P-256 certificate details:
#      openssl x509 -in root-ca-p256.crt -text -noout | grep -A3 "Public Key"
#      # Should show: Public Key Algorithm: id-ecPublicKey
#      #              Public-Key: (256 bit)
#
#    Check ML-DSA-87 certificate details:
#      openssl x509 -in root-ca-mldsa87.crt -text -noout | grep -A3 "Public Key"
#      # Should show: Public Key Algorithm: ML-DSA-87
#
#    Verify certificate validity periods:
#      openssl x509 -in root-ca-p256.crt -noout -dates
#      openssl x509 -in root-ca-mldsa87.crt -noout -dates
#
# =============================================================================
# ISSUING INTERMEDIATE CERTIFICATES
# =============================================================================
#
# You'll need to create intermediate CA configurations and sign them with
# both roots. Here's the workflow:
#
# 1. Create intermediate CA private key (P-256 for compatibility):
#      openssl ecparam -name prime256v1 -genkey -noout \
#        -out intermediate-ca.key
#
# 2. Create intermediate CSR:
#      openssl req -new -key intermediate-ca.key \
#        -out intermediate-ca.csr -config intermediate-ca.cnf
#
# 3. Sign with P-256 root (for current use):
#      openssl x509 -req -in intermediate-ca.csr -days 3650 \
#        -CA root-ca-p256.crt -CAkey root-ca-p256.key \
#        -CAcreateserial -out intermediate-ca-p256-signed.crt \
#        -extfile intermediate-ca.cnf -extensions v3_intermediate_ca
#
# 4. Sign with ML-DSA-87 root (for future PQ use):
#      openssl x509 -req -in intermediate-ca.csr -days 3650 \
#        -CA root-ca-mldsa87.crt -CAkey root-ca-mldsa87.key \
#        -CAcreateserial -out intermediate-ca-mldsa87-signed.crt \
#        -extfile intermediate-ca.cnf -extensions v3_intermediate_ca
#
# Now you have the same intermediate CA signed by both roots!
#
# =============================================================================
# COMPARISON: ECDSA P-256 vs ML-DSA-87
# =============================================================================
#
# Property              | ECDSA P-256    | ML-DSA-87 (Dilithium5)
# ----------------------|----------------|------------------------
# Security Level        | 128-bit        | 256-bit (NIST Level 5)
# Quantum Resistant     | NO             | YES
# Key Size              | 256 bits       | 4656 bits
# Public Key Size       | ~64 bytes      | ~2592 bytes
# Signature Size        | ~64 bytes      | ~4595 bytes
# Certificate Size      | ~600 bytes     | ~5 KB
# Sign Time             | ~0.5ms         | ~2ms
# Verify Time           | ~0.3ms         | ~1.5ms
# Browser Support       | Universal      | Not yet (planned 2028-2030)
# IoT Compatibility     | Excellent      | Limited (high memory)
# TLS 1.3 Support       | Yes            | Yes (with OQS provider)
# OpenSSL Version       | 1.0.1+         | 3.2+ with OQS
#
# =============================================================================
# SECURITY CONSIDERATIONS
# =============================================================================
#
# ECDSA P-256 Root:
# - Provides 128-bit classical security (equivalent to RSA-3072)
# - Vulnerable to Shor's algorithm on quantum computers
# - Expected to remain secure until ~2030-2035 (optimistic estimates)
# - NIST-approved curve (FIPS 186-4)
# - No known classical attacks that reduce security
#
# ML-DSA-87 Root:
# - Provides NIST security level 5 (highest available)
# - Resistant to both classical and quantum attacks
# - Based on lattice cryptography (module lattices)
# - NIST-standardized as FIPS 204 (August 2024)
# - Conservative parameter set (Dilithium5 → ML-DSA-87)
#
# Hash Algorithm:
# - SHA-256 is sufficient for P-256 (matching security levels)
# - SHA-256 also works for ML-DSA-87 (ML-DSA has internal security)
#
# Key Storage:
# - CRITICAL: Store both root private keys in HSM or offline storage
# - Never expose root private keys to internet-connected systems
# - Use intermediate CAs for day-to-day certificate issuance
# - Consider geographic separation of P-256 and ML-DSA-87 keys
# - Implement key ceremony procedures for root key access
#
# Certificate Validity:
# - 20 years (7300 days) for root CAs is industry standard
# - Intermediate CAs: 10 years maximum
# - End-entity certificates: 1 year (current browser requirements)
#
# =============================================================================
# DEPLOYMENT TIMELINE
# =============================================================================
#
# Phase 1 (2026-2027): Current State
# - Deploy ECDSA P-256 root for all production use
# - Issue intermediate CAs for IoT and VPS services
# - Store ML-DSA-87 root securely offline
# - Monitor browser/client PQ support development
#
# Phase 2 (2028-2029): Hybrid Transition
# - Begin issuing dual-signed intermediates (P-256 + ML-DSA-87)
# - Test ML-DSA-87 certificates with compatible clients
# - Gradually enable PQ support for VPS services
# - Keep P-256 chain active for legacy compatibility
#
# Phase 3 (2030+): Post-Quantum Migration
# - Primary use of ML-DSA-87 intermediates for new certificates
# - P-256 chain remains for legacy IoT devices that cannot update
# - Full PQ protection for all VPS and modern IoT traffic
# - Consider rotating ML-DSA-87 root if cryptanalysis advances
#
# =============================================================================
# TROUBLESHOOTING
# =============================================================================
#
# If ML-DSA-87 generation fails:
# 1. Verify OQS provider installation:
#      openssl list -providers
#      # Should show "oqsprovider" in the list
#
# 2. Check available PQ algorithms:
#      openssl list -signature-algorithms -provider oqsprovider
#      # Should show mldsa44, mldsa65, mldsa87
#
# 3. Test OQS provider:
#      openssl genpkey -algorithm mldsa87 -provider oqsprovider \
#        -out test.key && echo "Success!" || echo "Failed"
#
# 4. Check OpenSSL version:
#      openssl version
#      # Must be 3.2 or higher
#
# If intermediate signing fails:
# - Ensure intermediate config has proper v3_intermediate_ca extensions
# - Verify pathlen constraints allow intermediate issuance
# - Check that CA:TRUE is set in the intermediate certificate
#
# =============================================================================