SIWE

The SIWE utilities provide functions for creating and formatting Sign in with Ethereum (SIWE) messages according to the EIP-4361 standard.

Import

import { createSiweMessageString } from 'ethereum-identity-kit'
 
// For server side usage
import { createSiweMessageString } from 'ethereum-identity-kit/utils'

Functions

createSiweMessageString

Creates a properly formatted SIWE message string from the provided parameters according to the EIP-4361 specification.

const message = createSiweMessageString({
  domain: 'example.com',
  address: '0x1234567890123456789012345678901234567890',
  uri: 'https://example.com',
  version: '1',
  chainId: 1,
  nonce: 'abcd1234',
  issuedAt: '2023-10-01T12:00:00.000Z',
  statement: 'Sign in to access your account',
  expirationTime: '2023-10-01T12:05:00.000Z',
})

Parameters

Parameter	Type	Description	Required
`domain`	string	The domain that is requesting the signing	Yes
`address`	string	Ethereum address performing the signing	Yes
`uri`	string	A URI the user is signing in to	Yes
`version`	string	Current version of the SIWE Message (should be “1”)	Yes
`chainId`	number	EIP-155 Chain ID to which the session is bound	Yes
`nonce`	string	Randomized token to prevent replay attacks	Yes
`issuedAt`	string	ISO 8601 datetime string of when the message was generated	Yes
`statement`	string	Human-readable ASCII assertion that the user will sign	No
`expirationTime`	string	ISO 8601 datetime string of when the signed authentication expires	No
`notBefore`	string	ISO 8601 datetime string of when the signed authentication becomes valid	No
`requestId`	string	System-specific identifier that may be used to refer back to the request	No
`resources`	string[]	List of information or references to information the user wishes to have resolved	No
`scheme`	string	The scheme of the URI (typically omitted for web applications)	No

Return Value

Returns a string containing the properly formatted SIWE message that conforms to the EIP-4361 standard.

Example Output

example.com wants you to sign in with your Ethereum account:
0x1234567890123456789012345678901234567890

Sign in to access your account

URI: https://example.com
Version: 1
Chain ID: 1
Nonce: abcd1234
Issued At: 2023-10-01T12:00:00.000Z
Expiration Time: 2023-10-01T12:05:00.000Z

Example with All Parameters

const message = createSiweMessageString({
  scheme: 'https',
  domain: 'example.com',
  address: '0x1234567890123456789012345678901234567890',
  statement: 'I accept the ExampleOrg Terms of Service: https://example.com/tos',
  uri: 'https://example.com/login',
  version: '1',
  chainId: 1,
  nonce: 'abcd1234',
  issuedAt: '2023-10-01T12:00:00.000Z',
  expirationTime: '2023-10-01T12:05:00.000Z',
  notBefore: '2023-10-01T11:55:00.000Z',
  requestId: 'request-123',
  resources: ['https://example.com/my-web2-claim.json', 'https://example.com/my-web3-claim.json'],
})

Technical Details

The function formats the message according to the exact specification in EIP-4361
Required fields are always included in a specific order
Optional fields are only included if provided and non-empty
Resources are formatted as a bulleted list if provided
The message structure ensures compatibility with SIWE verification libraries

Use Cases

Authentication: Creating messages for wallet-based authentication
Session Management: Generating time-bound authentication tokens
Access Control: Creating signed messages for resource access
Integration: Building SIWE-compatible authentication flows

Generate Slot Followers You Know