omemo_dart/lib/src/errors.dart

abstract class OmemoError {}

/// Triggered during X3DH if the signature if the SPK does verify to the actual SPK.
class InvalidSignatureException extends OmemoError implements Exception {
  String errMsg() =>
      'The signature of the SPK does not match the provided signature';
}

/// Triggered by the Double Ratchet if the computed HMAC does not match the attached HMAC.
class InvalidMessageHMACError extends OmemoError {}

/// Triggered by the Double Ratchet if skipping messages would cause skipping more than
/// MAXSKIP messages
class SkippingTooManyKeysError extends OmemoError {}

/// Triggered by the Session Manager if the message key is not encrypted for the device.
class NotEncryptedForDeviceError extends OmemoError {}

/// Triggered by the Session Manager when there is no key for decrypting the message.
class NoDecryptionKeyException extends OmemoError implements Exception {
  String errMsg() => 'No key available for decrypting the message';
}

/// Triggered by the Session Manager when the identifier of the used Signed Prekey
/// is neither the current SPK's identifier nor the old one's.
class UnknownSignedPrekeyError extends OmemoError {}

/// Triggered by the Session Manager when the received Key Exchange message does not meet
/// the requirement that a key exchange, given that the ratchet already exists, must be
/// sent after its creation.
class InvalidKeyExchangeException extends OmemoError implements Exception {
  String errMsg() => 'The key exchange was sent before the last kex finished';
}

/// Triggered by the OmemoManager when we could not encrypt a message as we have
/// no key material available. That happens, for example, when we want to create a
/// ratchet session with a JID we had no session with but fetching the device bundle
/// failed.
class NoKeyMaterialAvailableException extends OmemoError
    implements Exception {
  String errMsg() =>
      'No key material available to create a ratchet session with';
}

/// A non-key-exchange message was received that was encrypted for our device, but we have no ratchet with
/// the device that sent the message.
class NoSessionWithDeviceError extends OmemoError {}