How to Build a Post-Quantum Readiness Inventory

A post-quantum readiness inventory is a structured assessment of your blockchain ecosystem's exposure to quantum computing threats. The primary risk is that a sufficiently powerful quantum computer could break the Elliptic Curve Digital Signature Algorithm (ECDSA) and Schnorr signatures, which secure most blockchain wallets and transactions today. This process involves cataloging all cryptographic assets—from private keys and smart contract logic to node software and key management systems—to identify which components rely on vulnerable algorithms. The goal is not immediate migration, but establishing a clear baseline of risk to inform a strategic upgrade roadmap.

Begin by mapping your digital asset landscape. This includes: - Hot and cold wallet private keys (especially those securing significant funds or protocol treasuries). - Smart contracts that handle signature verification, such as multi-sig wallets, DeFi protocols, and cross-chain bridges. - Node infrastructure and validator client software that uses classical cryptography for consensus. - Off-chain systems like oracles, keeper networks, and backend services that sign transactions. Tools like blockchain explorers (Etherscan, Solscan) and static analysis frameworks (Slither, MythX) can help automate the discovery of on-chain dependencies.

For each identified component, classify its cryptographic criticality and quantum vulnerability. High-criticality items are those whose compromise would lead to irreversible fund loss or a total system failure. Assess vulnerability by determining if the component uses pre-quantum public-key cryptography (e.g., ECDSA, RSA) for signatures or key establishment, which is breakable by Shor's algorithm, or symmetric cryptography (e.g., AES-256, SHA-256) for hashing and encryption, which is considered quantum-resistant with larger key sizes. Document the specific algorithm, library (e.g., OpenSSL, libsecp256k1), and key lifecycle for each entry.

The final step is to create a prioritized action plan based on your inventory. Components should be triaged by their risk score, which combines criticality, vulnerability, and the asset's lifespan. For example, a long-lived smart contract treasury vault is a higher priority than a short-lived ephemeral key. This inventory becomes a living document, guiding decisions on when to adopt post-quantum cryptography (PQC) standards like CRYSTALS-Dilithium for signatures or to implement hash-based signatures (e.g., Lamport, SPHINCS+) in new smart contract designs. Regularly updating this inventory is crucial as your stack and the PQC landscape evolve.

A post-quantum readiness inventory is a comprehensive catalog of all cryptographic assets and dependencies within your blockchain application. This is not a theoretical exercise; it is a prerequisite for any meaningful quantum risk assessment. The goal is to identify every component that relies on public-key cryptography (like ECDSA or EdDSA), which is vulnerable to Shor's algorithm, and symmetric cryptography (like AES or SHA-256), which requires larger key sizes. Your inventory scope must include on-chain smart contracts, off-chain backend services, developer tooling, and third-party dependencies.

Begin by mapping your technology stack. For an Ethereum-based dApp, this includes your smart contract code (e.g., written in Solidity or Vyper), any off-chain indexers or oracles, wallet integration libraries (like ethers.js or web3.py), and key management systems. Use static analysis tools such as Slither or MythX to automatically scan smart contracts for cryptographic function calls (e.g., ecrecover, keccak256). For backend services, audit your code for libraries like libsecp256k1, tweetnacl, or TLS certificate implementations.

Next, document all key material and key lifecycle processes. This involves listing every type of key pair your system uses: validator keys, wallet seed phrases, API signing keys, and TLS certificates. For each, record the algorithm (e.g., secp256k1, Ed25519), key size, generation method, storage mechanism (hot wallet, HSM, env variable), and rotation policy. A key not properly inventoried is a vulnerability you cannot mitigate. Tools like Hashicorp Vault or AWS KMS can help manage and audit this data.

Finally, analyze your external dependencies and protocol-level exposures. Your application's security is intertwined with the underlying blockchain. You must inventory the consensus mechanism (Proof-of-Stake often uses BLS signatures), cross-chain bridge validators, and any governance contracts. Review the cryptographic assumptions of major DeFi protocols you integrate with, such as Uniswap or Aave. This broader scope reveals systemic risks beyond your direct control, informing your strategy for protocol upgrades or migration to post-quantum cryptography (PQC) standards like CRYSTALS-Dilithium.

A post-quantum readiness inventory is a structured audit of all cryptographic components within a blockchain system. Its primary goal is to identify assets—such as private keys, signature schemes, and encryption methods—that are susceptible to attacks from future quantum computers. For Web3 projects, this includes evaluating on-chain smart contracts, wallet infrastructure, consensus mechanisms, and off-chain key management systems. Building this inventory is the foundational first step in any quantum migration strategy, providing a clear roadmap for prioritization and remediation.

Begin the inventory process by mapping your cryptographic attack surface. Systematically catalog every component that uses public-key cryptography. Critical areas to examine include: wallet seed phrases and derived keys, validator signing keys in Proof-of-Stake networks, multi-signature scheme participants, and state channels or layer-2 solutions. For smart contracts, audit all functions that verify ECDSA or EdDSA signatures, such as those in popular libraries like OpenZeppelin. Document the location, purpose, and current algorithm (e.g., secp256k1, ed25519) for each asset.

Next, categorize assets by risk and liquidity. High-risk, high-value targets should be prioritized. This typically includes: - Hot wallet keys controlling significant treasury funds - Foundation or multisig keys governing protocol upgrades - Staking pool operator keys in delegated PoS systems - Bridge validator sets securing cross-chain assets. Assign a criticality score based on the asset's value and the feasibility of a quantum attack extracting the private key from its public on-chain footprint.

For a technical implementation, create an inventory database. Use a schema that tracks the asset type, associated address or identifier, cryptographic algorithm, key derivation path, and custodial model (self-custodied, MPC, custodian). Here is a simplified example structure for a smart contract signature verifier audit:

solidityCopy
// Inventory Finding: Contract `TokenVault`
// Location: verifyWithdrawalSignature() function
// Algorithm: ECDSA recovery using `ecrecover`
// Vulnerability: Public key exposed via signature on-chain
// Criticality: HIGH - guards all user deposits

Finally, integrate the inventory into a continuous monitoring pipeline. Cryptographic dependencies evolve; new contracts are deployed, and key rotation policies change. Automate the detection of new vulnerable assets by scanning transaction logs for signature operations and monitoring new contract deployments for known vulnerable patterns. Tools like static analyzers (e.g., Slither) and blockchain indexers can be configured to flag the use of non-quantum-safe primitives, ensuring your inventory remains current as your protocol develops.

Begin by scanning your application's source code for direct cryptographic function calls. Use static analysis tools like grep, semgrep, or CodeQL to search for patterns related to key algorithms. Focus on identifying uses of RSA, ECDSA, ECDH, and Schnorr signatures, which are vulnerable to Shor's algorithm. Also flag symmetric ciphers like AES-128 and hash functions like SHA-256 and SHA-3, which, while requiring larger key sizes, are threatened by Grover's algorithm. This creates your initial list of cryptographic primitives in use.

Next, audit your software dependencies, as most cryptographic logic is imported via libraries. For Node.js projects, run npm audit and manually inspect package-lock.json. For Rust, use cargo audit and cargo tree. Python developers should check requirements.txt and use safety or pip-audit. The goal is to identify every library that performs cryptography, such as libsecp256k1, tweetnacl, openssl, or @noble/curves. Create a manifest listing each dependency, its version, and the specific PQ-vulnerable algorithms it implements.

For smart contracts, the audit must examine both the contract bytecode and the development toolchain. Analyze Solidity or Vyper source code for built-in functions like ecrecover, which uses ECDSA. Also audit the dependencies in your hardhat.config.js or foundry.toml, as testing libraries and deployment scripts often bundle cryptographic utilities. Remember that oracles and cross-chain messaging protocols (like LayerZero or Chainlink CCIP) may also rely on vulnerable signature schemes within their on-chain verification.

Document your findings in a structured inventory. For each identified component, record its location (file path or dependency name), purpose (e.g., 'wallet signature', 'TLS handshake'), algorithm (e.g., 'ECDSA with secp256k1'), and criticality (e.g., 'high' for private key signing). This inventory is not a one-time task; it must be integrated into your CI/CD pipeline. Automate the audit with scripts that run on each commit, ensuring new vulnerabilities are not introduced as your codebase evolves.

Finally, prioritize the items in your inventory based on risk. Components that handle private keys, funds, or identity are highest priority. Systems with long-lived secrets, like root CA certificates or blockchain genesis keys, are especially critical. This prioritized list becomes the actionable roadmap for the next steps: researching replacements, testing new libraries, and planning the migration to post-quantum cryptography standards like CRYSTALS-Kyber for key exchange or CRYSTALS-Dilithium for digital signatures.

Begin by cataloging all systems that rely on public-key cryptography (PKC). This includes, but is not limited to, TLS/SSL certificates for web servers and APIs, SSH keys for server access, code-signing certificates for software distribution, and PGP/GPG keys for email and artifact signing. For blockchain projects, this audit must extend to wallet seed phrases, validator node keys, consensus mechanism signatures (e.g., BLS signatures in Ethereum 2.0), and smart contracts that perform cryptographic verification. Tools like nmap with SSL scripts or internal asset management databases can automate discovery of network-facing certificates.

Next, classify each identified key and certificate by its cryptographic algorithm and sensitivity level. Create a spreadsheet or database with columns for: Asset Name (e.g., 'api.production.tls'), Algorithm (e.g., 'RSA-2048', 'ECDSA secp256k1'), Location (e.g., 'HSM Cluster A', 'AWS Secrets Manager'), Purpose (e.g., 'Authentication', 'Transaction Signing'), and Cryptographic Agility score. Agility measures how easily the system can switch algorithms; a private key in a cloud KMS may be more agile than one burned into a hardware security module (HSM) firmware.

Pay special attention to long-term secrets. A wallet's seed phrase, which generates a hierarchical deterministic (HD) key tree, is a prime target. If this seed is secured by today's cryptography (like the elliptic curve secp256k1), a future quantum computer could derive all past and future private keys. Similarly, static smart contract addresses derived from a single private key are perpetually at risk. Document these high-value, immutable assets separately as they will require the most careful migration strategy, potentially involving moving funds to new, quantum-resistant addresses.

For development and DevOps teams, audit your software supply chain. Identify libraries and dependencies that perform cryptography, such as OpenSSL, libsodium, or blockchain SDKs like ethers.js or web3.py. Check their versions and supported algorithms. You must also inventory key storage and management systems: cloud KMS (AWS KMS, GCP Cloud KMS), HSMs, and software-based keystores. Assess their current capabilities for algorithm support and whether they offer a migration path or APIs for key rotation, which will be critical for the transition.

Finally, prioritize your inventory. Assign a risk score based on the asset's lifetime, value, and exposure. A TLS certificate renewed every year is lower priority than a blockchain foundation's multi-signature wallet key intended to exist for decades. This prioritized list becomes your actionable roadmap for Step 3, where you will evaluate and select concrete post-quantum cryptography (PQC) algorithms like CRYSTALS-Kyber for key encapsulation or CRYSTALS-Dilithium for digital signatures to replace each vulnerable asset.

The goal of the data model is to capture the cryptographic context of every asset in a machine-readable format. This transforms a simple list into a structured database that can be queried, analyzed, and integrated with automation tools. At a minimum, each inventory entry should include fields for the asset name, system/application, cryptographic algorithm, key length or parameters, library/provider, and purpose (e.g., TLS, digital signature, data encryption).

For interoperability, adopt or extend an existing schema. The NIST Post-Quantum Cryptography Migration Project provides data models, as do frameworks like the ETSI Quantum-Safe Cryptography (QSC) framework. Using a standard schema ensures your inventory can be shared with partners or integrated with future compliance tools. Define your model in a simple format like JSON Schema or YAML for easy validation and tooling support.

Here is a practical JSON example for a single inventory entry:

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{
  "assetId": "web-api-tls-001",
  "system": "Customer Portal API",
  "component": "TLS Termination (Load Balancer)",
  "cryptoAlgorithm": "RSA",
  "algorithmType": "Asymmetric Encryption",
  "keySize": 2048,
  "cryptoProvider": "OpenSSL 1.1.1",
  "purpose": "TLS Handshake (Key Exchange)",
  "pqReadiness": "Vulnerable",
  "migrationPriority": "High",
  "notes": "Scheduled for upgrade in Q3."
}

This structured record allows you to filter all assets using RSA-2048 or flag all components with a "migrationPriority" of "High".

Beyond basic attributes, consider adding fields for ownership (team responsible), dependencies (upstream/downstream systems), discovery method (how it was found), and validation status. This metadata is crucial for planning and executing the migration. The model should also support versioning to track changes as assets are upgraded from classical to post-quantum algorithms over time.

Finally, document the data model and its field definitions in a central location accessible to all inventory contributors. Consistency in data entry is critical; use dropdowns for enumerated fields (like algorithmType) in your collection tool to prevent errors. This standardized foundation enables the next step: populating the inventory through systematic discovery.

Begin by mapping your cryptographic inventory, which includes all systems and components that rely on public-key cryptography vulnerable to quantum attacks. This primarily targets asymmetric algorithms like ECDSA (used for digital signatures in Bitcoin and Ethereum), RSA, and Diffie-Hellman. Key assets to catalog are: wallet private keys, validator signing keys, node identity keys, and the cryptographic libraries (e.g., OpenSSL, libsecp256k1) your applications depend on. For smart contracts, identify functions that perform signature verification, such as ecrecover in Solidity.

Next, assess the data sensitivity and exposure lifecycle. Not all cryptographic assets have the same risk profile. Classify data and keys based on their exposure to future decryption. Store-now, decrypt-later attacks are a primary threat, where encrypted data intercepted today could be decrypted once a large-scale quantum computer exists. Inventory long-lived, highly sensitive data like: encrypted private messages on-chain, state secrets in confidential smart contracts, and the public keys associated with large, static cryptocurrency holdings.

Finally, document your system dependencies and ownership. Create a registry that details where each cryptographic component resides, its current algorithm, its software version, and the responsible team or owner. For decentralized systems, this includes on-chain contracts, off-chain relayers, oracle networks, and bridge validators. Use tools like Slither or Foundry's cast to analyze smart contracts for cryptographic calls. This inventory is not a one-time task; it must be a living document updated with new deployments, forming the essential data layer for your migration plan.