CRYPTOGRAPHY (ante), secret writing, or writing to understand which the recipient must know the key. Such modes of communication have been in use from the earliest times, The Laccdmmonians, according to Plutarch, had a method which has been called the scytale, from the staff employed in constructing and deciphering the message. When the Spartan ephors wished to forward their orders to their commander abroad, they ;wound slantwise a narrow slip of parchment upon the staff so that the edges met close together, and the message was then added in such a way that the center of the line of writing was on the edge of parchment. When unwound, the scroll con sisted of broken letters; and in that condition it was dispatched to its destination; the general to whose hands it came deciphering it by means of a staff exactly corresponding to that used by the ephors. Polybius has enumerated other methods of cryptography. The art was in use also among the Romans. Upon the revival of letters, methods of secret correspondence were introduced into private business, diplomacy, plots, etc.; and as the study of this art has always presented attractions to the ingenious, a curious body of literature has been the result. John Trithemius, the abbot of Spanheim, was the first important writer on cryptography. His Poligraphia, published in 1500, has passed through many editions, and has supplied the basis upon which subsequent writers have worked. It was begun at the desire of the duke of Bavaria; but Trithemius did not at first intend to publish it, on the ground that it would be injurious to public interests. The next treatises of importance were those of John Baptist Porte, a Neapolitan mathe matician, who wrote De Furtiris Literarum, Noels, 1563; and of Blaise de Vigenere, whose Traitg des Ch Tres appeared in Paris in 1587. Lord Vernlam proposed an ingenious system of cryptography on the plan of what is called the double cipher; but while thus lending to the art the influence of his great name, he gave an intimation as to the general opinion formed of it and as to the classes of men who used it; for when prose cuting the earl of Somerset in the matter of the poisoning of Overbury, he urged itt as an aggravation of the crime that the earl and Overbury "had ciphers and jargons for the king and queen and all the great men—things seldom used but either by princes and their ambassadors and ministers, or by such as work or practice against or, at least, uponprinces." Other eminent Englishmen were afterwards connected with the art.
John Wilkins, subsequently bishop of Chester, published in 1641 an anonymous treatise entitled Mercury, or The Secret and Swift _Messenger, a small hut comprehensive work on the subject, and a timely gift to the diplomatists and leaders of the civil war. The deciphering of many of the royalist papers of that period, such as the letters that fell into the hands of the parliament at the battle of Naseby, has by Henry Stubbe been charged on the celebrated' mathematician, Dr. John Wallis. whose connection with the subject of cipher-writing is referred to in the Oxford edition of his mathematical works, 1689; as also by John Davys, Dr. Wallis states that this art, formerly scarcely known to any but the secretaries of princes, etc., had grown very common and familiar during the civil commotion, "so that now there is scarcely a person of quality but is more or less acquainted with it, and cloth, as there is occasion, make use of it." Subsequent writers on the subject arc John Falconer, Cryptomenysis Patefacta, 1685; John Davys, An Essay on the Art of Deciphering in which is inserted a Discourse of Dr. Wallis, 1737; Philip Thieknesse, A Treatise on the Art of Deciphering and of Writing in Cipher, 1772; William Blair (the writer of the comprehensive article "Cipher" in Rees's Cyclopaedia), 1819: and C. von Marten, Cours Diplomatique,1801, a fourth edition of which appeared in 1851. Perhaps the best modern work on this subject is the Kryptographik of J. L. Kluber, who was drawn into the investigation by inclination and official circumstances. In this work the different methods of cryptography are classified. Amongst others of less merit who have treated on,this art, may bc named Gustavus Sclenus (i.e. Augustus, duke of Brunswick), 1621; Cospi, translated by Niedron in 1641, the marquis of Worces ter, 1659; Kircher, 1663; Schoot, 1665; Hiller, 1682; Comiers, 1690, Baring, 1737; Con rad, 1739, etc.