> ## Documentation Index
> Fetch the complete documentation index at: https://docs.quantumapi.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Quantum safety

> Why Quantum Chain uses post-quantum cryptography and what it means for your integration.

## Why post-quantum?

Traditional blockchains use signature schemes that are secure today but vulnerable to future quantum computers. A sufficiently powerful quantum computer could recover private keys from public keys, breaking the fundamental security assumption of digital asset custody.

Quantum Chain is built from the ground up with **quantum-safe cryptography**, using a post-quantum signature scheme **aligned with NIST** Post-Quantum Cryptography guidance. This means:

* **No migration needed.** Your keys and transactions are quantum-resistant from day one
* **Future-proof.** Security guarantees hold even as quantum computing advances
* **Standards-aligned.** Built on algorithms vetted by the global cryptographic community and aligned with the NIST Post-Quantum Cryptography process

## What this means for integrators

<CardGroup cols={2}>
  <Card title="Signing works the same way" icon="pen-nib">
    The signing flow is identical to traditional blockchains: you receive a
    hash, sign it with your private key, and submit the signature. The
    quantum-safe layer is transparent to your integration.
  </Card>

  <Card title="Addresses are compatible" icon="link">
    Quantum Chain addresses use the same `0x`-prefixed, 20-byte format as
    Ethereum. Your existing address handling code works without modification.
  </Card>

  <Card title="Larger signatures" icon="expand">
    Post-quantum signatures are significantly larger than classical ECDSA signatures. This is
    the primary trade-off for quantum resistance. Quantum Chain's network
    parameters are tuned to handle this natively.
  </Card>

  <Card title="Key management" icon="key">
    Your private keys must be generated using Quantum Chain's quantum-safe
    scheme. Key generation tooling and SDKs are provided during onboarding.
  </Card>
</CardGroup>

## The quantum threat

Quantum computers exploit **Shor's algorithm** to solve the mathematical problems that underpin traditional public-key cryptography (ECDSA, RSA, etc.) in polynomial time. While large-scale quantum computers don't exist yet, the threat is real:

* **Harvest now, decrypt later.** Adversaries can record encrypted data and signed transactions today, then break them when quantum computers arrive
* **Long-lived assets.** Digital assets and keys that must remain secure for years or decades are especially at risk
* **Regulatory pressure.** Global regulators and standards bodies are mandating migration timelines for post-quantum readiness

## Standards alignment

Quantum Chain's signature scheme is **aligned with the NIST** Post-Quantum Cryptography process and reflects the multi-year global review of post-quantum candidates:

| Phase           | Year | Milestone                                   |
| --------------- | ---- | ------------------------------------------- |
| Round 1         | 2017 | 69 candidate algorithms submitted           |
| Round 2         | 2019 | Narrowed to 26 candidates                   |
| Round 3         | 2020 | 7 finalists and 8 alternates                |
| Standardization | 2024 | Final standards published as FIPS documents |

The selected scheme is based on **post-quantum mathematical foundations** with no known efficient quantum attacks.

## Security model

<AccordionGroup>
  <Accordion title="What is protected">
    All transaction signatures and wallet key pairs use quantum-safe
    cryptography. An attacker with a quantum computer cannot forge signatures or
    derive private keys from public keys.
  </Accordion>

  <Accordion title="What is not changed">
    Hash functions (Keccak256/SHA-3) used for address derivation and transaction
    hashing are already quantum-resistant. They require Grover's algorithm,
    which only provides a quadratic speedup, easily countered by using
    sufficient hash lengths.
  </Accordion>

  <Accordion title="Key generation">
    Keys must be generated using Quantum Chain's quantum-safe tooling. Standard
    ECDSA key generation tools will not produce compatible keys. SDKs and
    documentation for key generation are provided during onboarding.
  </Accordion>
</AccordionGroup>

## Further reading

<CardGroup cols={2}>
  <Card title="External signing guide" icon="pen-nib" href="/guides/external-signing">
    How to sign transactions with your quantum-safe key, the core integration
    flow.
  </Card>

  <Card title="PQC reference" icon="landmark" href="https://csrc.nist.gov/projects/post-quantum-cryptography">
    Reference material on the global Post-Quantum Cryptography standardization process Quantum Chain aligns with.
  </Card>
</CardGroup>