performing-post-quantum-cryptography-migration skill (Anthropic-Cybersecurity-Skills)

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What it does. 'Assesses organizational readiness for post-quantum cryptography migration Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).
Upstream mukul975/Anthropic-Cybersecurity-Skills
Skill file skills/performing-post-quantum-cryptography-migration/SKILL.md
License Apache-2.0 (skill folder LICENSE)
Author mukul975
Fetched 2026-09-10

Install

  • npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill performing-post-quantum-cryptography-migration, or copy the skill folder into ~/.claude/skills/performing-post-quantum-cryptography-migration/.
  • Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/performing-post-quantum-cryptography-migration/SKILL.md

SKILL.md (verbatim)

name: performing-post-quantum-cryptography-migration
description: 'Assesses organizational readiness for post-quantum cryptography migration
  per NIST FIPS 203/204/205 standards. Performs cryptographic inventory scanning to
  identify quantum-vulnerable algorithms (RSA, ECDH, ECDSA), evaluates hybrid TLS
  configurations with X25519MLKEM768, and validates CRYSTALS-Kyber (ML-KEM) and CRYSTALS-Dilithium
  (ML-DSA) readiness. Implements crypto-agility assessment using oqs-provider for
  OpenSSL. Use when planning or executing the transition from classical to post-quantum
  cryptographic algorithms across enterprise infrastructure.

  '
domain: cybersecurity
subdomain: cryptography
tags:
- post-quantum
- PQC
- CRYSTALS-Kyber
- ML-KEM
- ML-DSA
- FIPS-203
- FIPS-204
- hybrid-TLS
- crypto-agility
version: '1.0'
author: mukul975
license: Apache-2.0
nist_csf:
- PR.DS-01
- PR.DS-02
- PR.DS-10
mitre_attack:
- T1600
- T1573
- T1553
- T1040

Performing Post-Quantum Cryptography Migration

When to Use

  • When assessing organizational readiness for the NIST post-quantum cryptography transition
  • When building a cryptographic inventory to identify quantum-vulnerable algorithms across infrastructure
  • When evaluating hybrid TLS 1.3 configurations using X25519MLKEM768 key exchange
  • When testing CRYSTALS-Kyber (ML-KEM) and CRYSTALS-Dilithium (ML-DSA) algorithm support
  • When implementing crypto-agility to support both classical and post-quantum algorithms
  • When preparing migration roadmaps aligned with NIST IR 8547 deprecation timelines
  • When configuring oqs-provider with OpenSSL 3.x for post-quantum algorithm support

Prerequisites

  • Python 3.8+ with cryptography, requests, pyOpenSSL libraries
  • OpenSSL 3.0+ (3.5+ recommended for native ML-KEM/ML-DSA support)
  • oqs-provider for OpenSSL (for hybrid TLS testing with older OpenSSL)
  • Network access to target servers for TLS assessment
  • Administrative access for infrastructure scanning
  • Familiarity with PKI, TLS, and cryptographic protocols

Core Concepts

NIST Post-Quantum Cryptography Standards

NIST published three finalized PQC standards on August 13, 2024:

Standard Algorithm Renamed To Purpose Based On
FIPS 203 CRYSTALS-Kyber ML-KEM Key Encapsulation Mechanism Module lattice
FIPS 204 CRYSTALS-Dilithium ML-DSA Digital Signatures Module lattice
FIPS 205 SPHINCS+ SLH-DSA Digital Signatures (backup) Stateless hash

ML-KEM (FIPS 203) -- Primary standard for key exchange and encryption. Replaces RSA and ECDH for key establishment. Three security levels: ML-KEM-512, ML-KEM-768, ML-KEM-1024.

ML-DSA (FIPS 204) -- Primary standard for digital signatures. Replaces RSA and ECDSA for signing. Three security levels: ML-DSA-44, ML-DSA-65, ML-DSA-87.

SLH-DSA (FIPS 205) -- Backup signature standard using hash-based approach. Intended as fallback if lattice-based ML-DSA is found vulnerable. Larger signatures but conservative security assumptions.

Quantum-Vulnerable Algorithms

These classical algorithms are vulnerable to quantum attack via Shor's algorithm:

Algorithm Usage Quantum Threat Migration Priority
RSA-2048/4096 Key exchange, signatures, encryption Shor's algorithm breaks factoring Critical
ECDH (P-256, P-384) TLS key exchange Shor's algorithm breaks ECDLP Critical
ECDSA Code signing, TLS certificates Shor's algorithm breaks ECDLP Critical
DSA Legacy signatures Shor's algorithm breaks DLP Critical
DH (Diffie-Hellman) Key exchange Shor's algorithm breaks DLP Critical
AES-128 Symmetric encryption Grover's halves key strength Medium (upgrade to AES-256)
SHA-256 Hashing Grover's reduces to 128-bit Low (still adequate)

NIST Migration Timeline (IR 8547)

  • 2024: Standards published, migration planning should begin
  • 2030: Deprecation of quantum-vulnerable algorithms for most federal systems
  • 2035: Complete removal of quantum-vulnerable algorithms from NIST standards
  • Now: "Harvest now, decrypt later" attacks make early migration essential for long-lived secrets and data requiring long-term confidentiality

Hybrid TLS Key Exchange

During the transition period, hybrid key exchange combines a classical algorithm with a post-quantum algorithm. If either algorithm is secure, the connection remains protected.

Hybrid Key Exchange: X25519MLKEM768
  = X25519 (classical ECDH) + ML-KEM-768 (post-quantum)

Client Hello:
  supported_groups: X25519MLKEM768, X25519, secp256r1
  key_share: X25519MLKEM768

Server Hello:
  selected_group: X25519MLKEM768
  key_share: X25519MLKEM768

Shared Secret = KDF(X25519_shared || MLKEM768_shared)

Instructions

Phase 1: Cryptographic Inventory Scanning

The first step in PQC migration is discovering all cryptographic algorithm usage across the enterprise. This includes TLS configurations, certificates, code libraries, key stores, and protocol configurations.

# Scan TLS endpoints for quantum-vulnerable algorithms
python scripts/agent.py --action scan_tls \
    --targets targets.txt \
    --output tls_inventory.json

The scanner identifies:

  • TLS protocol versions in use
  • Key exchange algorithms (RSA, ECDH, DH -- all quantum-vulnerable)
  • Certificate signature algorithms (RSA, ECDSA)
  • Cipher suite configurations
  • Certificate key sizes and expiration dates

Phase 2: Crypto-Agility Assessment

Evaluate the organization's ability to swap cryptographic algorithms without major infrastructure changes:

# Assess crypto-agility readiness
python scripts/agent.py --action assess_agility \
    --scan-results tls_inventory.json \
    --output agility_report.json

Key assessment areas:

  1. Protocol flexibility: Can TLS configurations be updated without downtime?
  2. Library versions: Do deployed crypto libraries support PQC algorithms?
  3. Certificate infrastructure: Can CA issue PQC certificates?
  4. Key management: Can KMS handle larger PQC key sizes?
  5. Hardware constraints: Can HSMs support PQC operations?

Phase 3: Hybrid TLS Readiness Testing

Test whether infrastructure supports hybrid key exchange with X25519MLKEM768:

# Test hybrid TLS support on target servers
python scripts/agent.py --action test_hybrid_tls \
    --target server.example.com:443 \
    --output hybrid_tls_report.json

OpenSSL 3.5+ (native ML-KEM support):

# Test with native PQC support
openssl s_client -connect server.example.com:443 \
    -groups X25519MLKEM768

OpenSSL 3.0-3.4 with oqs-provider:

# Configure oqs-provider
# /etc/ssl/openssl-oqs.cnf
[openssl_init]
providers = provider_sect

[provider_sect]
default = default_sect
oqsprovider = oqsprovider_sect

[default_sect]
activate = 1

[oqsprovider_sect]
activate = 1
module = /usr/lib/oqs-provider/oqsprovider.so

# Test hybrid TLS
OPENSSL_CONF=/etc/ssl/openssl-oqs.cnf \
openssl s_client -connect server.example.com:443 \
    -groups x25519_mlkem768

Web Server Configuration for Hybrid TLS:

Apache httpd:

SSLEngine on
SSLCertificateFile /etc/ssl/certs/server.crt
SSLCertificateKeyFile /etc/ssl/private/server.key
SSLOpenSSLConfCmd Curves X25519MLKEM768:X25519:prime256v1
SSLProtocol -all +TLSv1.2 +TLSv1.3

NGINX:

ssl_ecdh_curve X25519MLKEM768:X25519:prime256v1;
ssl_protocols TLSv1.2 TLSv1.3;
ssl_prefer_server_ciphers on;

Phase 4: ML-KEM Key Encapsulation Validation

Validate that ML-KEM (CRYSTALS-Kyber) key encapsulation works correctly in your environment:

# Test ML-KEM key encapsulation at all security levels
python scripts/agent.py --action test_mlkem \
    --output mlkem_validation.json

ML-KEM parameter comparison:

Parameter ML-KEM-512 ML-KEM-768 ML-KEM-1024
Security Level NIST Level 1 NIST Level 3 NIST Level 5
Public Key Size 800 bytes 1,184 bytes 1,568 bytes
Ciphertext Size 768 bytes 1,088 bytes 1,568 bytes
Shared Secret 32 bytes 32 bytes 32 bytes
Comparable To AES-128 AES-192 AES-256

Phase 5: ML-DSA Digital Signature Validation

Validate ML-DSA (CRYSTALS-Dilithium) signature operations:

# Test ML-DSA digital signatures
python scripts/agent.py --action test_mldsa \
    --output mldsa_validation.json

ML-DSA parameter comparison:

Parameter ML-DSA-44 ML-DSA-65 ML-DSA-87
Security Level NIST Level 2 NIST Level 3 NIST Level 5
Public Key Size 1,312 bytes 1,952 bytes 2,592 bytes
Signature Size 2,420 bytes 3,293 bytes 4,595 bytes
Secret Key Size 2,560 bytes 4,032 bytes 4,896 bytes

Phase 6: Migration Roadmap Generation

Generate a prioritized migration roadmap based on inventory and assessment results:

# Generate complete migration roadmap
python scripts/agent.py --action roadmap \
    --scan-results tls_inventory.json \
    --agility-results agility_report.json \
    --output migration_roadmap.json

The roadmap prioritizes systems by:

  1. Data sensitivity: Systems handling long-lived secrets migrate first
  2. Exposure level: Internet-facing services before internal
  3. Crypto-agility: Systems that can easily swap algorithms first
  4. Compliance requirements: Federal/regulated systems per NIST IR 8547 timeline
  5. Dependency chains: Libraries and frameworks before applications

Examples

Full Assessment Pipeline

# Step 1: Scan all TLS endpoints
python scripts/agent.py --action scan_tls --targets hosts.txt --output scan.json

# Step 2: Assess crypto-agility
python scripts/agent.py --action assess_agility --scan-results scan.json --output agility.json

# Step 3: Test hybrid TLS on critical servers
python scripts/agent.py --action test_hybrid_tls --target critical.example.com:443

# Step 4: Validate ML-KEM support
python scripts/agent.py --action test_mlkem --output mlkem.json

# Step 5: Validate ML-DSA support
python scripts/agent.py --action test_mldsa --output mldsa.json

# Step 6: Generate migration roadmap
python scripts/agent.py --action roadmap --scan-results scan.json --agility-results agility.json --output roadmap.json

Quick Server Assessment

# Single server PQC readiness check
python scripts/agent.py --action scan_tls --target server.example.com:443

Validation Checklist

  • Cryptographic inventory covers all TLS endpoints, certificates, and key stores
  • All quantum-vulnerable algorithms (RSA, ECDH, ECDSA, DH, DSA) are identified
  • Crypto-agility assessment documents library versions and upgrade paths
  • Hybrid TLS (X25519MLKEM768) tested on representative server configurations
  • ML-KEM key encapsulation validated at target security level (768 recommended)
  • ML-DSA signature verification validated for certificate chain use
  • SLH-DSA (FIPS 205) evaluated as backup signature algorithm
  • Migration roadmap prioritizes by data sensitivity and compliance timeline
  • OpenSSL version and oqs-provider compatibility confirmed
  • Key size increases accounted for in network and storage capacity planning
  • HSM/KMS compatibility with PQC algorithms verified
  • Performance impact of PQC algorithms benchmarked under production load
  • "Harvest now, decrypt later" risk assessed for sensitive data channels
  • Certificate Authority PQC readiness confirmed for certificate issuance

References

Other files in this skill

references/api-reference.md (verbatim)

API Reference: Post-Quantum Cryptography Migration

NIST PQC Standards Summary

FIPS 203 -- ML-KEM (Module-Lattice-Based Key-Encapsulation Mechanism)

Formerly CRYSTALS-Kyber. Primary standard for key exchange and encryption.

Security Levels:

Parameter Set NIST Level Public Key Ciphertext Shared Secret
ML-KEM-512 Level 1 800 B 768 B 32 B
ML-KEM-768 Level 3 1,184 B 1,088 B 32 B
ML-KEM-1024 Level 5 1,568 B 1,568 B 32 B

Operations:

  • KeyGen() -> (ek, dk) -- Generate encapsulation/decapsulation key pair
  • Encaps(ek) -> (K, c) -- Encapsulate: produce shared secret K and ciphertext c
  • Decaps(dk, c) -> K -- Decapsulate: recover shared secret K from ciphertext

Python (mlkem library):

from mlkem.ml_kem import ML_KEM

ml_kem = ML_KEM(768)  # ML-KEM-768
ek, dk = ml_kem.key_gen()
shared_secret, ciphertext = ml_kem.encaps(ek)
recovered_secret = ml_kem.decaps(dk, ciphertext)
assert shared_secret == recovered_secret

OpenSSL 3.5+ (native):

# Generate ML-KEM-768 key pair
openssl genpkey -algorithm mlkem768 -out mlkem768_key.pem

# Display key details
openssl pkey -in mlkem768_key.pem -text -noout

# Extract public key
openssl pkey -in mlkem768_key.pem -pubout -out mlkem768_pub.pem

FIPS 204 -- ML-DSA (Module-Lattice-Based Digital Signature Algorithm)

Formerly CRYSTALS-Dilithium. Primary standard for digital signatures.

Security Levels:

Parameter Set NIST Level Public Key Secret Key Signature
ML-DSA-44 Level 2 1,312 B 2,560 B 2,420 B
ML-DSA-65 Level 3 1,952 B 4,032 B 3,293 B
ML-DSA-87 Level 5 2,592 B 4,896 B 4,595 B

Operations:

  • KeyGen() -> (pk, sk) -- Generate signing/verification key pair
  • Sign(sk, M) -> sigma -- Sign message M with secret key
  • Verify(pk, M, sigma) -> bool -- Verify signature on message

OpenSSL 3.5+ (native):

# Generate ML-DSA-65 key pair
openssl genpkey -algorithm mldsa65 -out mldsa65_key.pem

# Extract public key
openssl pkey -in mldsa65_key.pem -pubout -out mldsa65_pub.pem

# Sign a file
openssl dgst -sign mldsa65_key.pem -out signature.bin message.txt

# Verify signature
openssl dgst -verify mldsa65_pub.pem -signature signature.bin message.txt

FIPS 205 -- SLH-DSA (Stateless Hash-Based Digital Signature Algorithm)

Formerly SPHINCS+. Backup signature standard using conservative hash-based approach.

Parameter Sets (SHA2 variants):

Parameter Set NIST Level Public Key Signature (fast) Signature (small)
SLH-DSA-128 Level 1 32 B 17,088 B 7,856 B
SLH-DSA-192 Level 3 48 B 35,664 B 16,224 B
SLH-DSA-256 Level 5 64 B 49,856 B 29,792 B

Variants: Each level has fast (f) and small (s) variants with SHA2 or SHAKE hash.

Hybrid TLS Configuration

X25519MLKEM768 Key Exchange

The hybrid key exchange combines classical X25519 ECDH with ML-KEM-768 post-quantum KEM. Both must be broken for the handshake to be compromised.

Apache httpd:

# httpd.conf or ssl.conf
SSLEngine on
SSLProtocol -all +TLSv1.2 +TLSv1.3
SSLOpenSSLConfCmd Curves X25519MLKEM768:X25519:prime256v1
SSLCertificateFile /etc/ssl/certs/server.crt
SSLCertificateKeyFile /etc/ssl/private/server.key

NGINX:

server {
    listen 443 ssl;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ecdh_curve X25519MLKEM768:X25519:prime256v1;
    ssl_prefer_server_ciphers on;
    ssl_certificate /etc/ssl/certs/server.crt;
    ssl_certificate_key /etc/ssl/private/server.key;
}

Verification:

# Test hybrid TLS connection
openssl s_client -connect server.example.com:443 -groups X25519MLKEM768

# Verify negotiated group
# Look for "Server Temp Key: X25519MLKEM768" in output

oqs-provider for OpenSSL 3.0+

Installation

# Clone and build oqs-provider
git clone https://github.com/open-quantum-safe/oqs-provider.git
cd oqs-provider
mkdir build && cd build
cmake -DCMAKE_INSTALL_PREFIX=/usr/local ..
make -j$(nproc)
sudo make install

Configuration

# /etc/ssl/openssl-oqs.cnf
openssl_conf = openssl_init

[openssl_init]
providers = provider_sect
ssl_conf = ssl_sect

[provider_sect]
default = default_sect
oqsprovider = oqsprovider_sect

[default_sect]
activate = 1

[oqsprovider_sect]
activate = 1
module = /usr/lib/oqs-provider/oqsprovider.so

[ssl_sect]
system_default = system_default_sect

[system_default_sect]
Groups = x25519_mlkem768:X25519:P-256:P-384
MinProtocol = TLSv1.2

Usage

# Set environment variable
export OPENSSL_CONF=/etc/ssl/openssl-oqs.cnf

# List available PQC algorithms
openssl list -kem-algorithms | grep -i ml
openssl list -signature-algorithms | grep -i ml

# Generate PQC key pair
openssl genpkey -algorithm mlkem768 -out key.pem

# Test hybrid TLS
openssl s_client -connect server:443 -groups x25519_mlkem768

Cryptographic Inventory Scanning

NIST SP 1800-38 Discovery Architecture

+------------------+     +------------------+     +------------------+
| Source Code Scan | --> |                  | --> | Risk Assessment  |
+------------------+    | Central Analysis |     +------------------+
+------------------+    |     Engine       |            |
| Binary Analysis  | -->|  (Normalization  |     +------------------+
+------------------+    |  & Correlation)  |     | Migration        |
+------------------+    |                  |     | Prioritization   |
| Network Traffic  | -->|                  |     +------------------+
+------------------+    +------------------+
+------------------+
| Certificate Scan | -->
+------------------+

Discovery Domains

Domain What to Scan Tools
CI/CD Pipeline Source code, build configs, dependencies SCA tools, Semgrep
Operational Systems Running services, installed libraries, key stores NIST SP 1800-38B tools
Network Services TLS endpoints, VPN configs, IPsec tunnels This agent, sslyze, testssl
Certificates CA chains, code signing certs, TLS certificates cert-manager, openssl

Quantum-Vulnerable Algorithm Reference

Algorithm NIST Status (IR 8547) Quantum Threat Replacement
RSA (all sizes) Deprecated 2030, removed 2035 Shor's algorithm ML-KEM (encryption), ML-DSA (signing)
ECDH / ECDHE Deprecated 2030, removed 2035 Shor's algorithm ML-KEM / X25519MLKEM768 hybrid
ECDSA Deprecated 2030, removed 2035 Shor's algorithm ML-DSA
DSA Already deprecated Shor's algorithm ML-DSA
DH / DHE Deprecated 2030, removed 2035 Shor's algorithm ML-KEM
AES-128 Acceptable with caveat Grover's halves to 64-bit AES-256
AES-256 Quantum-safe Grover's reduces to 128-bit No change needed
SHA-256 Quantum-safe Grover's reduces to 128-bit No change needed
SHA-3 Quantum-safe Grover's reduces to 128-bit No change needed

MITRE ATT&CK Relevance

Technique ID PQC Relevance
Adversary-in-the-Middle T1557 Quantum computers can break key exchange in recorded sessions
Encrypted Channel T1573 Harvest-now-decrypt-later targets encrypted C2 traffic
Steal Application Access Token T1528 Quantum computers can forge digital signatures
Forge Web Credentials T1606 Quantum computers can break certificate private keys

References

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