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# Signatures and SIWE

## Overview

Viem supports raw hashes, EIP-191 messages, EIP-712 typed data, and EIP-4361 Sign-In with Ethereum.
A Local Account can sign each format. A JSON-RPC Account supports message and typed data signing.

Verification supports EOAs and compatible contract Accounts through
[`verifyHash`](/docs/actions/public/verifyHash).

## Recipes

These recipes assume you have [set up a Client](/docs) with public and wallet Actions.

### Sign and Verify a Raw Hash

A [Local Account](/docs/accounts/local/private-key) can sign a 32-byte hash directly with
`account.sign`. Verify the signature against the same hash and address with
[`verifyHash`](/docs/actions/public/verifyHash).

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

const hash =
  '0xd9eba16ed0ecae432b71fe008c98cc872bb4cc214d3220a36f365326cf807d68'
const signature = await client.account.sign({ hash }) // [!code focus]

const valid = await client.verifyHash({ // [!code focus]
  address: client.account.address, // [!code focus]
  hash, // [!code focus]
  signature, // [!code focus]
}) // [!code focus]
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/viem.config.ts:setup]
```
:::

:::warning
Raw signing adds no message prefix or domain separation. Use it only when a protocol defines the
exact hash to sign.
:::

### Sign and Verify a Message

[`signMessage`](/docs/actions/wallet/signMessage) signs the EIP-191 payload. Verify the same string,
signature, and expected address with [`verifyMessage`](/docs/actions/public/verifyMessage).

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

const message = 'Confirm account ownership'
const signature = await client.signMessage({ message }) // [!code focus]

const valid = await client.verifyMessage({ // [!code focus]
  address: client.account.address, // [!code focus]
  message, // [!code focus]
  signature, // [!code focus]
}) // [!code focus]
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/viem.config.ts:setup]
```
:::

### Sign and Verify Typed Data

[`typedData.sign`](/docs/actions/wallet/typedData/sign) binds structured data to a domain. Use
[`typedData.verify`](/docs/actions/public/typedData/verify) with the same domain, types, and message.

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

const typedData = {
  domain: { chainId: 1, name: 'Example', version: '1' },
  message: { contents: 'Hello' },
  primaryType: 'Mail',
  types: { Mail: [{ name: 'contents', type: 'string' }] },
} as const

const signature = await client.typedData.sign(typedData) // [!code focus]
const valid = await client.typedData.verify({ // [!code focus]
  address: client.account.address, // [!code focus]
  signature, // [!code focus]
  ...typedData, // [!code focus]
}) // [!code focus]
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/viem.config.ts:setup]
```
:::

### Verify Sign-In with Ethereum

Create a message with [`Siwe.createMessage`](/docs/utilities/siwe/createMessage), sign it, then
validate the expected domain and nonce with
[`siwe.verify`](/docs/actions/public/siwe/verify).

:::code-group
```ts twoslash [example.ts]
import { Siwe } from 'viem/utils'
import { client } from './viem.config'

const message = Siwe.createMessage({
  address: client.account.address,
  chainId: 1,
  domain: 'example.com',
  nonce: 'foobarbaz12',
  uri: 'https://example.com/login',
  version: '1',
})
const signature = await client.signMessage({ message }) // [!code focus]

const valid = await client.siwe.verify({ // [!code focus]
  domain: 'example.com', // [!code focus]
  message, // [!code focus]
  nonce: 'foobarbaz12', // [!code focus]
  signature, // [!code focus]
}) // [!code focus]
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/viem.config.ts:setup]
```
:::

## Best Practices

### Bind Signatures to Context

Use a nonce, domain, Chain ID, expiry, and human-readable purpose where the format supports them.
Never treat an unscoped signature as permanent authentication.

### Verify on the Intended Chain

Contract Account verification can depend on deployed code and state. Verify against the Chain and
block context where the signature is meant to be valid.

## See More

<Cards>
  <Card icon="lucide:log-in" title="SIWE Utilities" description="Create, parse, validate, and inspect EIP-4361 messages." to="/docs/utilities/siwe" />

  <Card icon="lucide:shield-check" title="verifyHash" description="Verify EOA and contract Account signatures over a hash." to="/docs/actions/public/verifyHash" />
</Cards>