𝐏𝐨𝐬𝐭-𝐪𝐮𝐚𝐧𝐭𝐮𝐦 𝐜𝐫𝐲𝐩𝐭𝐨𝐠𝐫𝐚𝐩𝐡𝐲 (𝐏𝐐𝐂) 𝐢𝐬 𝐦𝐚𝐢𝐧𝐥𝐲 𝐚𝐛𝐨𝐮𝐭 𝐬𝐞𝐜𝐮𝐫𝐢𝐭𝐲, 𝐧𝐨𝐭 𝐩𝐫𝐢𝐯𝐚𝐜𝐲. I've noticed some confusion around post-quantum technology in crypto, especially when people discuss it as though it automatically makes blockchain transactions private. That's not how it works. PQC and privacy technologies can complement each other, but they're designed to address different problems. Let me explain. ➊ 𝗪𝗵𝗮𝘁 𝗲𝘅𝗮𝗰𝘁𝗹𝘆 𝗶𝘀 𝗽𝗼𝘀𝘁-𝗾𝘂𝗮𝗻𝘁𝘂𝗺 𝗰𝗿𝘆𝗽𝘁𝗼𝗴𝗿𝗮𝗽𝗵𝘆? Today, many blockchains use cryptographic signatures to prove that someone has permission to move funds from a wallet. Bitcoin and Ethereum, for example, rely on elliptic-curve cryptography for important parts of their transaction security. These systems are considered secure against known practical attacks using classical computers. However, sufficiently powerful quantum computers could eventually break the mathematical problems protecting some of these systems. That's where PQC comes in. Post-quantum cryptography uses cryptographic methods designed to resist attacks from both classical computers and future quantum computers. For blockchains, one important application is replacing vulnerable digital signatures with quantum-resistant alternatives. The objective is to prevent unauthorized parties from forging signatures and spending funds they don't control. PQC also includes encryption and key-establishment methods designed to protect information against quantum attacks. ➋ 𝗗𝗼𝗲𝘀 𝘁𝗵𝗮𝘁 𝗺𝗲𝗮𝗻 𝗣𝗤𝗖 𝗺𝗮𝗸𝗲𝘀 𝘁𝗿𝗮𝗻𝘀𝗮𝗰𝘁𝗶𝗼𝗻𝘀 𝗽𝗿𝗶𝘃𝗮𝘁𝗲? No. And this is where the distinction becomes important. Imagine sending 5 $ETH to another wallet. On a transparent blockchain, anyone can potentially see: • The sending address • The receiving address • The amount transferred • The transaction history Even if the transaction uses a quantum-resistant signature, those details can remain publicly accessible. PQC can protect the authorization behind a transaction without hiding the transaction itself. In simple terms: PQC helps protect who can authorize a transaction. Privacy technology helps control what information others can see. Those are two different security properties. ➌ 𝗦𝗼 𝘄𝗵𝗮𝘁 𝘁𝗲𝗰𝗵𝗻𝗼𝗹𝗼𝗴𝗶𝗲𝘀 𝗮𝗰𝘁𝘂𝗮𝗹𝗹𝘆 𝗽𝗿𝗼𝘃𝗶𝗱𝗲 𝗯𝗹𝗼𝗰𝗸𝗰𝗵𝗮𝗶𝗻 𝗽𝗿𝗶𝘃𝗮𝗰𝘆? Several cryptographic approaches are used to protect sensitive information: > Zero-knowledge proofs (ZKPs): Allow someone to prove a statement is true without revealing all the information behind it. When combined with the right protocol design, they can support private transactions and confidential verification. > Fully homomorphic encryption (FHE): Allows computations to be performed on encrypted data without first decrypting it. This can support applications that process confidential information. > Multi-party computation (MPC): Allows multiple parties to jointly compute a result without each party revealing its private inputs to the others. > Trusted execution environments (TEEs): Use hardware-isolated environments to process sensitive information, although their security depends on hardware and implementation assumptions. > Privacy-focused transaction protocols: Use techniques such as shielded transactions, commitments, and other cryptographic mechanisms to conceal selected transaction details. However, using ZKPs, FHE, MPC, or TEEs doesn't automatically make an entire blockchain private. The level of confidentiality depends on what the protocol actually protects. Another technical distinction worth understanding: not every existing privacy system is quantum-resistant. Some privacy technologies rely on mathematical assumptions that sufficiently powerful quantum computers could eventually weaken. ➍ 𝗖𝗮𝗻 𝗣𝗤𝗖 𝗮𝗻𝗱 𝗽𝗿𝗶𝘃𝗮𝗰𝘆 𝘄𝗼𝗿𝗸 𝘁𝗼𝗴𝗲𝘁𝗵𝗲𝗿? Absolutely. Consider a future blockchain application handling confidential financial transactions. It could use: • post-quantum digital signatures to protect transaction authorization against quantum attacks • privacy-preserving cryptography to conceal sensitive transaction information • zero-knowledge proofs to verify transaction validity without exposing the underlying private data But the entire system would need to be designed and evaluated for quantum resistance. Adding a post-quantum signature alone doesn't make every other cryptographic component quantum-safe. This combination could become increasingly useful for institutional payments, private DeFi, confidential identity verification, and other financial applications. ➎ 𝗪𝗵𝘆 𝘀𝗵𝗼𝘂𝗹𝗱 𝗰𝗿𝘆𝗽𝘁𝗼 𝘂𝘀𝗲𝗿𝘀 𝘂𝗻𝗱𝗲𝗿𝘀𝘁𝗮𝗻𝗱 𝘁𝗵𝗶𝘀 𝗱𝗶𝘀𝘁𝗶𝗻𝗰𝘁𝗶𝗼𝗻? As quantum-resistant blockchain infrastructure develops, we’ll probably see more projects describing themselves as post-quantum secure. That claim needs to be examined carefully: ▸ does the project protect wallet signatures? ▸ does it address exposed public keys? ▸ are its privacy proofs also quantum-resistant? ▸ what about its encryption and other cryptographic components? These are different questions, and a project can solve one without solving the others. For example, a blockchain could implement quantum-resistant signatures while still exposing every transaction publicly. Another could offer private transactions using cryptographic components that may eventually require quantum-resistant upgrades. Neither property automatically guarantees the other. ➏ 𝗠𝘆 𝗽𝗼𝘀𝘁-𝗾𝘂𝗮𝗻𝘁𝘂𝗺 𝗰𝗿𝘆𝗽𝘁𝗼 𝘄𝗮𝘁𝗰𝗵𝗹𝗶𝘀𝘁 These are projects I'm following for quantum-resistant cryptography, blockchain security upgrades, and long-term cryptographic research. Quantum-focused networks and infrastructure • $QANX → @QANplatform • $CELL → @cellframenet • $QRL → @QRLedger • $ABEL → @PQabelian • $NAORIS → @NaoXprotocol Established networks and other projects exploring quantum-resistant technology • $ALGO → @Algorand • $XDC → @XDCNetwork • $STRK → @Starknet • $HBAR → @hedera • $IOTA → @iota • $CKB → @NervosNetwork • $XNT → @NeptunePrivacy QRL and Abelian are particularly relevant because quantum-resistant cryptography is central to their network designs. @Starknet is another example worth examining. Its STARK-based proof technology relies on quantum-resistant cryptographic assumptions, and the ecosystem has explored post-quantum wallet authentication. However, quantum-resistant proofs don’t automatically make an entire network quantum-safe. The same caution applies to other projects on this watchlist: » Some have implemented specific quantum-resistant components. » Others are researching or developing upgrades. ➐ 𝗠𝘆 𝗽𝗿𝗶𝘃𝗮𝗰𝘆 𝗰𝗿𝘆𝗽𝘁𝗼 𝘄𝗮𝘁𝗰𝗵𝗹𝗶𝘀𝘁 For privacy, I'm tracking projects across confidential transactions, private smart contracts, zero-knowledge systems, encrypted computation, and confidential computing infrastructure. Privacy-focused blockchains and applications • $SCRT → @SecretNetwork • $ROSE → @OasisProtocol • $RAIL → @RAILGUN_Project • $AZTEC → @aztecnetwork • @0xMiden • $NEAR → @NEARProtocol • $ZEC → @Zcash • $ALEO → @AleoHQ • $FIRO → @firoorg • $ZEN → @horizenglobal • $NOCK → @Nockchain Confidential computing and privacy infrastructure • $ZAMA → @zama • @fhenix • @inconetwork • @partisiampc • @nillion • @Arcium • @mindnetwork_xyz • @PhalaNetwork • @TACEO_IO • @primus_labs These projects are building different parts of the privacy infrastructure. For example: • RAILGUN uses zero-knowledge cryptography to support private DeFi interactions. • Zama focuses on FHE, enabling applications to perform computations on encrypted information. • Arcium develops confidential computation infrastructure using MPC. • Aztec focuses on programmable privacy and private smart-contract execution. • Primus develops privacy-preserving verification and computation technologies, including zkTLS and FHE-related infrastructure. The important distinction is that these systems don't all provide the same type or level of privacy. Some focus on hiding transaction information. Others protect data during computation or allow information to be verified without exposing the underlying records. Their security assumptions and deployment maturity also differ. ✦ Conclusion Post-quantum cryptography is about preparing cryptographic security for a future where quantum computers could threaten today's widely used systems. Privacy technology is about protecting sensitive information from unnecessary exposure. A blockchain can have one without the other: » A blockchain can be quantum-resistant without being private. » A blockchain can be private without being quantum-resistant. Understanding that distinction is essential before evaluating either category. As these technologies develop, I'll be paying attention to: ▸ actual implementations ▸ independent security reviews ▸ whether their protections extend beyond individual components The long-term objective should be systems that provide both strong cryptographic security against future threats and meaningful privacy for users. Note: These are research watchlists, not claims that every listed project has deployed fully quantum-resistant or privacy-preserving infrastructure.