errors.go

package itb

import "errors"

// ErrEmptyInput is returned by Low-Level Cfg entry points
// (Single Message and Streaming, plain and authenticated) when the
// supplied plaintext or wire payload is nil or zero-length.
//
// This sentinel is the Low-Level surface's peer to
// [github.com/everanium/itb/triple.ErrEmptyInput]; both signal the
// same policy, kept as two distinct package-scoped vars because the
// root itb package cannot import triple (triple depends on itb).
// The policy itself is uniform across every ITB cipher entry point:
// no zero-payload wire exists on the shipped surface — an empty
// message has no cover story in any cryptographic construction and
// is always distinguishable at some layer (wire length, timing,
// traffic count). Callers who need to signal "no data" send a
// marker byte instead.
var ErrEmptyInput = errors.New("itb: empty input")