Edited sentence: Shannon theory about the Unicity distance states that, in theory, the text's length is sufficient for reaching only one decipherment that makes sense.The problem is, however, that once there are reasons to think that a valid solution has been found, it is necessary to verify this solution by a way or another, generally by deciphering another text in the same script, to be sure about it.This general opinion is nevertheless disputed by several scholars on the basis of the work of the mathematician Claude Shannon