What is SIWS?

A standard message format and verification process for authenticating Solana wallet owners.

Sign In With Solana (SIWS) is a standard for authenticating users with their Solana wallets -- no on-chain transactions required. It follows the pattern established by EIP-4361 (Sign-In with Ethereum).

Key Features

  • Human-readable messages -- Users see what they're signing before approval
  • Ed25519 signatures -- Native Solana signing, no transactions needed
  • Replay protection -- Server-generated nonces prevent reuse
  • Domain binding -- Messages bound to the requesting origin
  • Expiration support -- Configurable message lifetime
  • Cluster awareness -- Prevents cross-cluster replay (mainnet-beta, devnet, testnet)

Quick Example

server.ts
server.ts
import { SiwsMessageBuilder, generateNonce, verifySignature } from '@siws/core'
 
// 1. Build a message for the user to sign
const message = new SiwsMessageBuilder()
  .domain('example.com')
  .address(walletAddress)
  .uri('https://example.com/auth')
  .nonce(generateNonce())
  .issuedAt(new Date())
  .cluster('mainnet-beta')
  .statement('Sign in to Example')
  .build()
 
// 2. Send message.toMessage() to the client for signing
 
// 3. Verify the signature
const result = await verifySignature(
  messageString,
  signature,
  walletAddress,
  { domain: 'example.com' }
)
 
if (result.success) {
  // Authenticated! result.data contains parsed message fields
}

Packages

PackageDescription
@siws/coreMessage building, parsing, and Ed25519 signature verification
@siws/better-authDrop-in plugin for better-auth with server and client support

Links