Chapter II

Containing a Definition of the Term Cryptography  
and the Explanation of the same.

Cryptography is the art of revealing safely and without risk, by means of hidden writing, and without the knowledge of any third person, some fact, to some person to whom we wish that fact to be known.

This definition I will explain by expounding the Name, Class, End, Object and Medium.

As regards the Name, this appears in a variety of forms in different authors; as, Cryptography and Cryptology, Steganology and Steganography, Polygraphy, in Trithemius; the Art of writing by Notes and the Art of Cipher-writing, in Cardano, Scaliger (Exerc., 327), Porta and de Vigenère; Cryptomenytics, in the writer of the brief notes to Porta; and, finally Scotography, in Abram Colorno, the Jew of Mantua.  All these terms are commonly used synonymously; but examination shows that they differ not a little from one another.  For some are general, some are specific, and some combine both characteristics.  For example, the Art of writing by Notes, or Ciphers, is far too specific to embrace all branches of the art.  Properly it refers simply to the use of notes as distinguished from the use of letters; see Herman Hugo, De Prim. Scrib.Orig.,c.17, where he rightly  blames Suctomius for calling Julius Caesar’s method of hidden writing, Writing by Notes.  For writing by notes or short-hand writing is one thing, and writing by transposed letters is another.  Furthermore, not every method of writing by notes concerns us here.  For the art of writing by notes has two ends:  one, secrecy, which belongs to our present investigation; the other, abridgment of writing, which is not one of the ends of this art, but rather constitutes an art by itself which is called Tachography.  The Art of writing by Notes, therefore, to state distinctly what should be understood by the expression, is a specific term simply, and includes only a small part of the whole subject; as will appear in clearer light from what follows.  The term Polygraphy, however, accurately taken, is, as indeed the name itself indicates, far more general, and embraces a broader field than is covered by each and every method of secret writing; though Trithemius, in the title of his book Polygraphia, restricts the use of the word to hidden writing in general.  The terms Steganography and Steganology, as well as Scotography, are indefinite, and also too general.  Cryptology, however, would seem to answer our purpose.  But if we take the word in the general sense, of the theory of all that is hidden, it is too broad.  If, on the other hand, we restrict its application to the voice and its writing, it is too narrow to include every branch of the art.  But if even Cryptology is too narrow a term, most certainly Cryptography, which is included under Cryptology, can denote nothing more than a subdivision of the art; and this I do not deny.  There remains, therefore, the word Cryptomenytics, which embraces every conceivable method of secret communication, whether it be by the voice, by writing, or by signs.  So, then, Cryptomenytics is the most general term, embracing, as subdivisions in nearest line, Cryptology, which is of the voice, and Cryptography, which is of writing, and a third division which has to be sings, and follows in