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# Post-Quantum

## Overview

[`MlDsa44`](/docs/utilities/mldsa44) implements the ML-DSA-44 digital signature scheme from
[FIPS 204](https://csrc.nist.gov/pubs/fips/204/final). ML-DSA is designed to resist attacks from
classical and quantum computers.

ML-DSA-44 private keys are 32-byte seeds. Public keys are 1,312 bytes and signatures are 2,420
bytes, so protocols and storage formats must account for their size.

## Recipes

These recipes assume you have [installed and set up Viem](/docs).

### Create a Key Pair

Use [`MlDsa44.createKeyPair`](/docs/utilities/mldsa44/createKeyPair) to create a private seed and
its corresponding public key.

```ts twoslash
import { MlDsa44 } from 'viem/utils'

const { privateKey, publicKey } = MlDsa44.createKeyPair()
```

Keep the private key secret. Store or distribute the public key to verifiers.

### Sign and Verify Data

Use [`MlDsa44.sign`](/docs/utilities/mldsa44/sign) and
[`MlDsa44.verify`](/docs/utilities/mldsa44/verify) with the same payload and optional context.

```ts twoslash
import { Hex, MlDsa44 } from 'viem/utils'

const { privateKey, publicKey } = MlDsa44.createKeyPair()
const payload = Hex.fromString('Approve document 42')
const context = Hex.fromString('example.com:documents')

const signature = MlDsa44.sign({ context, payload, privateKey })
const valid = MlDsa44.verify({ context, payload, publicKey, signature })
```

A different payload, public key, signature, or context causes verification to return `false`.

## Best Practices

### Separate Protocols with a Context

Use a stable context to separate signatures created for different protocols. FIPS 204 limits the
context to 255 bytes.

### Protect Private Keys

Treat the 32-byte seed as secret key material. Generate it with a cryptographically secure random
source, avoid logging it, and keep it outside long-lived application state when possible.

### Plan for Larger Values

Check every transport, database field, contract, and message format that stores public keys or
signatures. ML-DSA-44 values are much larger than common elliptic-curve keys and signatures.

## See More

<Cards>
  <Card icon="lucide:fingerprint" title="Post-Quantum Passkeys" description="Derive an ML-DSA-44 key from a WebAuthn PRF." to="/docs/guides/post-quantum/passkeys" />

  <Card icon="lucide:braces" title="MlDsa44 Reference" description="Browse the complete ML-DSA-44 utility API." to="/docs/utilities/mldsa44" />
</Cards>