Sep45NoSigningKeyException

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

SEP-45 requires the server's stellar.toml to contain a SIGNING_KEY field that specifies the server's Ed25519 public key (G... address). This key is used to:

• Sign the server's authorization entry in the challenge

• Allow clients to verify the challenge came from the legitimate server

The SIGNING_KEY is critical for security:

• Clients verify the server's signature on the challenge entries

• Without verification, man-in-the-middle attacks would be possible

• The same SIGNING_KEY is used for both SEP-10 and SEP-45

This exception is also thrown when requesting client domain authentication and the client domain's stellar.toml is missing SIGNING_KEY.

To resolve this error:

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

2. Look for SIGNING_KEY field (should be a G... address)

3. Contact the service provider if the signing key should be available

Example - Handle missing signing key:

try {
    val webAuth = WebAuthForContracts.fromDomain("example.com", Network.PUBLIC)
} catch (e: Sep45NoSigningKeyException) {
    println("Domain ${e.domain} does not have SIGNING_KEY configured")
    // Cannot proceed with authentication - contact service provider
}