London: Printed for Daniel Brown at the Black Swan and Bible without Temple-Bar, 1685.
Octavo: 17 x 11 cm. , 180 pp. Collation: A-M8 (with blank leaves A1, A8, and N8).
A fine, complete copy of this important book, bound in contemporary speckled sheepskin (some wear to corners and spine). Edges of text block sprinkled red. Generous outer margins (lvs. E5-6, E7-8, I7-8 uncut). A very pale dampstain to a few leaves.
The scarce first edition of Falconer's book on cryptography which constitutes the first adequate English handbook of cryptology; it furthermore seems to present the earliest illustration of keyed columnar transposition. It is the second English publication on the subject but the first work containing practical information.
"The second English book on the subject excelled, and its high quality is all the more surprising when one considers that John Falconer had written ‘Cryptomenysis Patefacta’ in France some thirty years before its first publication in 1685." (Leeuw, The History of Information Security, p. 303).
It has been stated that Falconer was greatly influenced by John Wilkins's ‘Mercury’ , the first English work on the subject. This is, however, not entirely true; Wilkins' work has "a certain air of unreality" about it; he borrowed knowledge from earlier volumes and puffed it out with his own hypothesizing, which seems never to have been deflated by contact with the bruising actuality of solving cryptograms that he himself had not made up. Up until Falconer the literature was all theory and no practice (Kahn, The Code Breakers, P. 156).
"Falconer also gave what seems to be the earliest illustration of keyed columnar transposition, a cipher that is today the primary and most widely used transposition cipher, having served (with modifications) for French military ciphers, Japanese diplomatic superencipherments, and Soviet spy ciphers." (Leeuw, p. 303).
Falconer's approach was that of practical coding and cryptography, which probably was a product of his profession as the private cipher of King James II.
"In the middle of the 17th-century, the first adequate English handbook of cryptology was finally written [The present work]; the second edition in 1692 may be an indication that Falconer's work was in demand even forty years after its redaction." (Leeuw, p. 303). Only very little is known about John Falconer except that he was a distant relative of the Scottish philosopher David Hume and "was reportedly entrusted with the private cipher of the future King James II, and died in France while following James into temporary exile there." (Kahn, The Code Breakers, P. 155).