### Reference Implementation Example

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/spec/erc-4361.md

A JavaScript example demonstrating the implementation of Sign-In with Ethereum.

```javascript
import { verifyMessage } from "@ethersproject/wallet";

const message = {
  domain: "localhost:3000",
  address: "0x0000000000000000000000000000000000000000",
  statement: "Please sign this message to confirm your identity.",
  uri: "http://localhost:3000/login",
  version: "1",
  chainId: 1,
  nonce: "3j4n89f3j4n89",
  issuedAt: "2021-09-30T13:37:00.000Z",
};

const formattedMessage = `${message.domain} wants you to sign in with your Ethereum account:
${message.address}

${message.statement}

URI: ${message.uri}
Version: ${message.version}
Chain ID: ${message.chainId}
Nonce: ${message.nonce}
Issued At: ${message.issuedAt}`;

const signature = "0x..."; // Signature from the user

// Verify the signature
const signerAddress = verifyMessage(formattedMessage, signature);

console.log(signerAddress === message.address); // true
```

--------------------------------

### Install @signinwithethereum/siwe-parser

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe-parser/README.md

Install the package using npm.

```bash
npm install @signinwithethereum/siwe-parser
```

--------------------------------

### Install @signinwithethereum/siwe

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Install the package and a required peer dependency like viem or ethers.

```bash
npm install @signinwithethereum/siwe
```

```bash
npm install viem    # recommended
# or
npm install ethers  # v5 or v6
```

--------------------------------

### Quick Start: Create and Verify SIWE Message

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Set up the configuration, create a SIWE message, prepare it for signing, and verify a signature. Ensure the client has signed the message.

```typescript
import { SiweMessage, configure, createConfig } from '@signinwithethereum/siwe'

// One-time setup — auto-detects viem or ethers
configure(await createConfig('https://eth.llamarpc.com'))

// Create a message
const message = new SiweMessage({
  domain: 'example.com',
  address: '0x...',
  statement: 'Sign in to Example',
  uri: 'https://example.com',
  version: '1',
  chainId: 1,
  nonce: 'abc12345defg78901',
  issuedAt: new Date().toISOString(),
})

// Get the EIP-4361 string to sign
const messageString = message.prepareMessage()

// Verify a signature (after signing on the client)
const { success, data, error } = await message.verify(
  { signature, domain: 'example.com', nonce: message.nonce },
  { suppressExceptions: true },
)
```

--------------------------------

### SIWE Message Example with Implicit Scheme

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/spec/erc-4361.md

An example of a SIWE message where the scheme is implicitly HTTPS, demonstrating the standard format for signing in.

```text
example.com wants you to sign in with your Ethereum account:
0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2

I accept the ExampleOrg Terms of Service: https://example.com/tos

URI: https://example.com/login
Version: 1
Chain ID: 1
Nonce: 32891756
Issued At: 2021-09-30T16:25:24Z
Resources:
- ipfs://bafybeiemxf5abjwjbikoz4mc3a3dla6ual3jsgpdr4cjr3oz3evfyavhwq/
- https://example.com/my-web2-claim.json
```

--------------------------------

### Configure Verification Backend: Auto-detect

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Configure the package to automatically detect and use either viem or ethers for message verification. This is the recommended one-time setup.

```typescript
import { configure, createConfig } from '@signinwithethereum/siwe'

configure(await createConfig('https://eth.llamarpc.com'))
```

--------------------------------

### SIWE Message Example with Explicit Scheme

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/spec/erc-4361.md

An example of a SIWE message that explicitly defines the scheme (e.g., 'https://') in the domain, demonstrating how to specify the protocol.

```text
https://example.com wants you to sign in with your Ethereum account:
0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2

I accept the ExampleOrg Terms of Service: https://example.com/tos

URI: https://example.com/login
Version: 1
Chain ID: 1
Nonce: 32891756
Issued At: 2021-09-30T16:25:24Z
Resources:
- ipfs://bafybeiemxf5abjwjbikoz4mc3a3dla6ual3jsgpdr4cjr3oz3evfyavhwq/
- https://example.com/my-web2-claim.json
```

--------------------------------

### SIWE Message Example with Implicit Scheme and Explicit Port

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/spec/erc-4361.md

An example of a SIWE message with an implicit HTTPS scheme but an explicit port specified in the domain, showing how to handle non-standard ports.

```text
example.com:3388 wants you to sign in with your Ethereum account:
0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2

I accept the ExampleOrg Terms of Service: https://example.com/tos

URI: https://example.com/login
Version: 1
Chain ID: 1
Nonce: 32891756
Issued At: 2021-09-30T16:25:24Z
Resources:
- ipfs://bafybeiemxf5abjwjbikoz4mc3a3dla6ual3jsgpdr4cjr3oz3evfyavhwq/
- https://example.com/my-web2-claim.json
```

--------------------------------

### Configure Verification Backend: Viem

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Configure the package specifically for viem. Ensure you have a viem public client set up.

```typescript
import { configure, createViemConfig } from '@signinwithethereum/siwe'
import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

const publicClient = createPublicClient({ chain: mainnet, transport: http() })
configure(await createViemConfig({ publicClient }))
```

--------------------------------

### Configuration Functions

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Functions to configure the verification backend, either automatically detecting viem or ethers, or explicitly using one of them.

```APIDOC
### `createConfig(rpcUrl)` — auto-detect

Detects whether viem or ethers is installed and creates the appropriate config with full EIP-1271 support.

```ts
import { configure, createConfig } from '@signinwithethereum/siwe'

configure(await createConfig('https://eth.llamarpc.com'))
```

### `createViemConfig(opts)` — viem

```ts
import { configure, createViemConfig } from '@signinwithethereum/siwe'
import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

const publicClient = createPublicClient({ chain: mainnet, transport: http() })
configure(await createViemConfig({ publicClient }))
```

### `createEthersConfig(provider)` — ethers

```ts
import { configure, createEthersConfig } from '@signinwithethereum/siwe'
import { ethers } from 'ethers'

const provider = new ethers.JsonRpcProvider('https://eth.llamarpc.com')
configure(createEthersConfig(provider))
```

### Per-call config

Instead of setting a global config, you can pass `config` in verify options:

```ts
const config = await createViemConfig({ publicClient })
await message.verify({ signature, domain, nonce }, { config })
```
```

--------------------------------

### Configure Verification Backend: Ethers

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Configure the package specifically for ethers. Provide an ethers JsonRpcProvider instance.

```typescript
import { configure, createEthersConfig } from '@signinwithethereum/siwe'
import { ethers } from 'ethers'

const provider = new ethers.JsonRpcProvider('https://eth.llamarpc.com')
configure(createEthersConfig(provider))
```

--------------------------------

### Informal SIWE Message Template

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/spec/erc-4361.md

A Bash-like template illustrating the structure of a full SIWE message, useful for understanding field placement and optionality.

```bash
${scheme}:// ${domain} wants you to sign in with your Ethereum account:
${address}

${statement}

URI: ${uri}
Version: ${version}
Chain ID: ${chain-id}
Nonce: ${nonce}
Issued At: ${issued-at}
Expiration Time: ${expiration-time}
Not Before: ${not-before}
Request ID: ${request-id}
Resources:
- ${resources[0]}
- ${resources[1]}
...
- ${resources[n]}
```

--------------------------------

### SiweConfig Interface

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Defines the interface for custom verification backends, allowing users to provide their own implementations for message verification and related utilities.

```APIDOC
### `SiweConfig`

Interface for bringing your own verification backend:

```ts
interface SiweConfig {
  verifyMessage: (message: string, signature: string) => string | Promise<string>
  hashMessage: (message: string) => string
  getAddress: (address: string) => string
  checkContractWalletSignature?: (
    address: string, message: string, signature: string,
    chainId: number,
  ) => Promise<boolean>
}
```
```

--------------------------------

### Create SiweMessage from Object or String

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Instantiate a SiweMessage either by providing its fields as an object or by parsing a raw EIP-4361 formatted string.

```typescript
// From object
const msg = new SiweMessage({ domain, address, uri, version, chainId, nonce, issuedAt })

// From EIP-4361 string
const msg = new SiweMessage(rawMessageString)
```

--------------------------------

### Per-call Configuration for Verification

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Override the global configuration for a single verification call by passing a config object directly to the verify options.

```typescript
const config = await createViemConfig({ publicClient })
await message.verify({ signature, domain, nonce }, { config })
```

--------------------------------

### Utility Functions

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe-parser/README.md

Provides utility functions for validating Ethereum addresses and ISO8601 dates.

```APIDOC
## Utility Functions

### Description
Provides utility functions for validating Ethereum addresses and ISO8601 dates.

### Functions

- **isEIP55Address(address: string): boolean**
  Checks if the provided string is a valid EIP-55 checksummed Ethereum address.
  Example: `isEIP55Address('0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B') // true`

- **isValidISO8601Date(dateString: string): boolean**
  Checks if the provided string is a valid ISO 8601 formatted date string.
  Example: `isValidISO8601Date('2024-01-01T00:00:00Z') // true`
```

--------------------------------

### SiweMessage Class

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

The `SiweMessage` class allows you to create SIWE messages from an object or parse them from an EIP-4361 string. It exposes fields for message components and provides methods for preparing and verifying messages.

```APIDOC
## `SiweMessage`

Create from an object or parse from an EIP-4361 string:

```ts
// From object
const msg = new SiweMessage({ domain, address, uri, version, chainId, nonce, issuedAt })

// From EIP-4361 string
const msg = new SiweMessage(rawMessageString)
```

**Fields:** `domain`, `address`, `uri`, `version`, `chainId`, `nonce`, `issuedAt` (required) and `scheme`, `statement`, `expirationTime`, `notBefore`, `requestId`, `resources` (optional).

### `prepareMessage(): string`

Returns the EIP-4361 formatted message string, ready for EIP-191 signing.

### `verify(params, opts?): Promise<SiweResponse>`

Verifies a signed message. Returns `{ success, data, error }`.

**`params` (VerifyParams):**

| Field | Required | Description |
|---|---|---|
| `signature` | yes | The wallet signature |
| `domain` | yes | Expected domain (origin binding) |
| `nonce` | yes | Expected nonce (replay protection) |
| `scheme` | no | Expected URI scheme |
| `uri` | no | Expected URI (required in strict mode) |
| `chainId` | no | Expected chain ID (required in strict mode) |
| `requestId` | no | Expected request ID |
| `time` | no | ISO 8601 time to check against (defaults to now) |

**`opts` (VerifyOpts):**

| Field | Description |
|---|---|
| `config` | Per-call `SiweConfig` (overrides global) |
| `suppressExceptions` | Return errors in response instead of throwing (default: `false`) |
| `strict` | Require `uri` and `chainId` in params |
| `verificationFallback` | Custom verification function run alongside EIP-1271 |
```

--------------------------------

### Utility Functions for SIWE

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe-parser/README.md

Provides utility functions for validating EIP-55 addresses and ISO 8601 dates.

```typescript
import {
  isEIP55Address,
  isValidISO8601Date,
} from '@signinwithethereum/siwe-parser'

isEIP55Address('0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B') // true
isValidISO8601Date('2024-01-01T00:00:00Z') // true
```

--------------------------------

### ParsedMessage Constructor

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe-parser/README.md

Instantiate a ParsedMessage object by passing a raw SIWE message string. The constructor will throw an error if the message does not conform to the EIP-4361 specification.

```APIDOC
## ParsedMessage Constructor

### Description
Instantiate a `ParsedMessage` object by passing a raw SIWE message string. The constructor will throw an error if the message does not conform to the EIP-4361 specification.

### Usage
```typescript
import { ParsedMessage } from '@signinwithethereum/siwe-parser'

const message = new ParsedMessage(rawMessage)

console.log(message.domain)
console.log(message.address)
console.log(message.uri)
console.log(message.version)
console.log(message.chainId)
console.log(message.nonce)
console.log(message.issuedAt)
```

### Fields

| Field            | Type       | Required |
| ---------------- | ---------- | -------- |
| `domain`         | `string`   | Yes      |
| `address`        | `string`   | Yes      |
| `uri`            | `string`   | Yes      |
| `version`        | `string`   | Yes      |
| `chainId`        | `number`   | Yes      |
| `nonce`          | `string`   | Yes      |
| `issuedAt`       | `string`   | Yes      |
| `scheme`         | `string`   | No       |
| `statement`      | `string`   | No       |
| `expirationTime` | `string`   | No       |
| `notBefore`      | `string`   | No       |
| `requestId`      | `string`   | No       |
| `resources`      | `string[]` | No       |
```

--------------------------------

### Generate a Cryptographically Secure Nonce

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Generate a unique and secure nonce for use in SIWE messages to prevent replay attacks. The nonce has 96 bits of entropy and is alphanumeric.

```typescript
import { generateNonce } from '@signinwithethereum/siwe'

const nonce = generateNonce()
```

--------------------------------

### Check for EIP-6492 Signature

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Use `isEIP6492Signature` to determine if a signature originates from a pre-deployed smart contract wallet.

```typescript
import { isEIP6492Signature, EIP6492_MAGIC_SUFFIX } from '@signinwithethereum/siwe'

if (isEIP6492Signature(sig)) {
  // Signature is from a pre-deployed smart contract wallet
}
```

--------------------------------

### Parse a SIWE Message

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe-parser/README.md

Instantiate ParsedMessage with a raw SIWE message string. The constructor will throw an error if the message is not EIP-4361 compliant. Access parsed fields like domain, address, etc.

```typescript
import { ParsedMessage } from '@signinwithethereum/siwe-parser'

const message = new ParsedMessage(rawMessage)

console.log(message.domain)
console.log(message.address)
console.log(message.uri)
console.log(message.version)
console.log(message.chainId)
console.log(message.nonce)
console.log(message.issuedAt)
```

--------------------------------

### generateNonce Function

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe/README.md

Generates a cryptographically secure random nonce for use in SIWE messages to prevent replay attacks.

```APIDOC
### `generateNonce(): string`

Returns a cryptographically secure random nonce (96 bits of entropy, alphanumeric).

```ts
import { generateNonce } from '@signinwithethereum/siwe'

const nonce = generateNonce()
```
```

--------------------------------

### isUri Function

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe-parser/README.md

Validates if a given string is a valid URI.

```APIDOC
## isUri Function

### Description
Validates if a given string is a valid URI.

### Usage
```typescript
import { isUri } from '@signinwithethereum/siwe-parser'

isUri('https://example.com') // true
```
```

--------------------------------

### Validate a URI

Source: https://github.com/signinwithethereum/siwe/blob/main/packages/siwe-parser/README.md

Use the isUri function to check if a given string is a valid URI.

```typescript
import { isUri } from '@signinwithethereum/siwe-parser'

isUri('https://example.com') // true
```

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