Sep45NoContractIdException

Exception thrown when the domain's stellar.toml is missing the WEB_AUTH_CONTRACT_ID.

SEP-45 requires the server's stellar.toml to contain a WEB_AUTH_CONTRACT_ID field that specifies the contract address (C...) used for authentication. This contract implements the web_auth_verify function that validates authentication requests.

The WEB_AUTH_CONTRACT_ID is critical for security validation:

• Clients verify the challenge targets this specific contract

• Prevents attacks where malicious servers direct auth to wrong contracts

• Ensures the authentication flow uses the intended contract implementation

To resolve this error:

1. Check the stellar.toml at https://{domain}/.well-known/stellar.toml

2. Look for WEB_AUTH_CONTRACT_ID field (should be a C... address)

3. Verify the WEB_AUTH_FOR_CONTRACTS_ENDPOINT is also present

4. Contact the service provider if the contract ID should be available

Example - Handle missing contract ID:

try {
    val webAuth = WebAuthForContracts.fromDomain("example.com", Network.PUBLIC)
} catch (e: Sep45NoContractIdException) {
    println("Domain ${e.domain} does not have WEB_AUTH_CONTRACT_ID configured")
    // Contact service provider or check configuration
}