"On Secret Writing, Commonly Called Ciphers"

CRYPTOGRAPHY. Porta, Giovan Battista della (1535-1615)

De furtiuis literarum notis vulgo, De ziferis libri IIII. Ioan. Baotista Porta Neapolitano autore.

London: John Wolf, 1591


Quarto: 19.3 x 14 cm. [20], 228 p. Collation: †6, 4, A-Z4, Aa-Dd4, Ee6, π1

ONE OF TWO PIRATED EDITIONS, both printed by Wolfe in 1591. The original edition was printed in 1563 at Naples.

Bound in 17thc. stiff vellum. A nice copy with minor blemishes and a light damp-stain, with some mild discoloration, to the bottom of the leaves in the second half. With numerous woodcut diagrams, tables and cipher specimens, including three full-page woodcuts and a separate leaf of volvelles (π1) at end to accompany them.

The Italian natural philosopher Giovanni Battista Della Porta was the most accomplished cryptographer of the Renaissance. In 1610 Della Porta joined the Accademia dei Lincei (Academy of the Lynx), the renowned scientific society founded by Federico Cesi. Galileo joined the following year.

Della Porta's treatise on cryptography 'De furtivis literarum notis vulgo de ziferis' (Notes on Secret Writing, Commonly Called Ciphers), first published in Naples in 1563, ranks as one of the earliest and most important works on cryptography after Johann Trithemius’'Polygraphie'.

This work includes a set of movable cipher disks to code and decode messages. The cipher disk, or code wheel, rotates to align corresponding characters for the code on the inner and outer dials. The leaf with the printed volvelles (the moveable centerpieces meant to be attached to the cipher wheels) is intact and bound at the end of the book.

"Della Porta's was a seeker of patterns, codes, systems, and keys… His cryptographic manual, 'De Furtivis literarum' is a striking example of this search for pattern and meaning… The work has a claim to an important cryptographic first: the digraphic cipher, a code that uses a single symbol of cipher text to represent two different letters of plain text."(Saiber)The recipient deciphers the text by performing the inverse substitution.

"According to David Kahn, Porta's work was pirated by the Englishman John Wolfe, who in 1591 issued two versions at the same time, one falsely imprinted as Naples, 1563, and the other correctly identified as London, 1591. Both issues were unauthorized and circumvented the rights of the author and the regulations of the Stationers’ Company" (Tomash & Williams).

Tomash & Williams P101; ESTC S101179; STC 20118; Tomita 195; Luborsky and Ingram, English Illustrated Books, 20118