Sep45InvalidServerSignatureException

Exception thrown when the server's signature on an authorization entry is invalid.

SEP-45 Security Requirement: The server's authorization entry MUST contain a valid Ed25519 signature that can be verified against the server's signing key from stellar.toml.

This is the MOST CRITICAL security check in SEP-45 validation. It protects against:

• Man-in-the-middle attacks (attacker intercepting and modifying challenges)

• Phishing attacks (fake server generating invalid challenges)

• Challenge tampering (modification of challenge after server signing)

Signature verification process:

1. Build HashIDPreimageSorobanAuthorization from the entry's values:

• networkId (hash of network passphrase)

• nonce (from entry's credentials)

• signatureExpirationLedger (from entry's credentials)

• invocation (rootInvocation)

2. Hash the preimage with SHA-256

3. Extract public_key and signature from credentials.addressCredentials.signature

4. Verify public_key matches serverSigningKey

5. Verify signature using Ed25519

Security warning: NEVER sign authorization entries with an invalid server signature. An invalid signature means:

• The challenge did not come from the legitimate server

• The challenge may have been modified in transit

• You may be communicating with an attacker

If you receive this error:

1. Verify you're connecting to the correct domain (check HTTPS certificate)

2. Verify the server signing key matches the stellar.toml

3. Report the incident if it persists (possible security breach)

Example - Handle invalid server signature:

try {
    webAuth.validateChallenge(authEntries, accountId)
} catch (e: Sep45InvalidServerSignatureException) {
    logger.error("CRITICAL SECURITY: Invalid server signature!")
    logger.error(e.message)
    // DO NOT proceed - possible MITM attack
    // Alert security team if in production
}

Parameters