1. A method for encoding steganographic messages comprising: parsing, from a code segment, a sequence of invariants, the invariants corresponding to fixed values in a microprocessor instruction sequence, each invariant defined by an invariant symbol; selecting a message from a sequence of message symbols from an alphabet; and defining a translation alphabet by mapping each message symbol in the selected message to a successive invariant in the sequence of invariants, the mapping associating each of the invariant symbols to a subset of the message symbols from which the message is composed, the mapping defining the message in the unmodified sequence of invariants from the code segments that leaves the instruction sequence unchanged, each occurrence of an invariant symbol associated with a plurality of message symbols in the subset of symbols.