He was the third of four sons and the second to survive childhood, having an older brother Gian Vincenzo and a younger brother Gian Ferrante. His father had a thirst for learning, a trait he would pass on to all of his children. He surrounded himself with distinguished people and entertained the likes of philosophers, mathematicians, poets, and musicians. The atmosphere of the house resembled an academy for his sons. The members of the learned circle of friends stimulated the boys, tutoring and mentoring them, under strict guidance of their father. In addition to having talents for the sciences and mathematics, all the brothers were also extremely interested in the arts, music in particular.
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Editions In , Porta published a classic work on cryptology De furtivis literarum notis, vulgo de ziferis. In , a pirated edition made "almost to perfection" Kahn p. A legitimate edition titled De occultis literarum notis Google added an appendix.
The term occultis secret, occluded, hidden and furtivis secret, furtive are more or less synonymous and furtivis in the title of some chapters was replaced with occultis seu furtivis in the edition. An enlarged and reorganized edition Google is reorganized into five books. An English translation On secret notations for letters commonly called ciphers in typescript by Mrs. Porta, gentilhomme napolitain, , pp. Book 1 Book 1 deals with ancient ciphers.
Note that the illustration of the scytale below taken from the appendix of the edition is different from transposition cipher as commonly understood today see another article.
Chapter Titles of Book 1 1-I. Quid sint furtivae literarum notae 1-II. Quid his etiam notis scribunt, qui velint compendiose scribere 1-IIII. Multa tacitis ambagibus posse indicari 1-IX. Per notas Hieroglyphicas, atque; per rerum animaliumque figuras tacite sermonem exprimi posse 1-X.
Noctu igne, interdiu vero pulvere posse significari 1-XI. De literis clandestinis ex veterum scriptis 1-XIII. Transposition Cipher 2-II and 2-III deal with transposition, the latter seeming to describe a way not to arouse suspicion.
The drawing of the cipher disk below shows the inner movable disk pasted at the initial position. Referring to the enciphering example further below, the first letter "H" is enciphered with this initial position. Then, the inner disk is rotated clockwise by one place for enciphering "O", and so on.
Although a cipher disk had been described by Alberti before, Porta incorporated the idea of letter-by-letter encipherment which per se had been anticipated by Trithemius. Porta provides several measures to enhance secrecy.
The second example below suppresses word breaks and the symbol disk includes more symbols than the letters of the alphabet, which makes the cycle of the disk positions unequal to the number of letters in the alphabet.
With the first cipher disk, every twentieth letter is enciphered with the same disk position. See "m" in "Iam" and "Milite". When this second cipher disk is used, the first example text is enciphered as follows. In 2-XI, Porta points out that the cipher disk is equivalent to the following table. The edition has a new chapter 4-III discussing use of a key phrase rather than progressive rotation after enciphering each letter.
If only four letters should be used, "DD" may be used instead of "E. Use of three symbols without such combinations is also described.
According to the example given in the edition 4-XVIII , it appears to distinguish the seven positions in each row by the amount of space before the letter A, B, C , which must be filled with insignificant letters those other than A, B, C. Porta was aware that the fewer symbols used, the longer the ciphertext would be.
In a new chapter 5-VI of the edition, a biliteral cipher with only A, B is presented but it requires representing the plaintext with only eight letters of the alphabet: a, e, r, u, o, i, f, t by replacing the other less frequent letters with these.
As with Bacon, Porta was also concerned about avoiding suspicion, for which he proposes writing a word having a number of syllables corresponding to the number of A or B occurring without interruption. For example, if there is a succession of four Bs, some four-syllable word e. The following forms a symbol with four substitution elements. Porta sneers pigpen cipher as used by "rustics, women and children" Kahn p.
P for O. Keyed Transposition 2-XV discusses an intricate transposition cipher. The enciphering with this key proceeds as follows. First, one letter after another from the key phrase is written under the letters of the plaintext to be enciphered Post Bello Each key letter indicates a number corresponding to its position in the alphabet 3 for "c", 1 for "a", etc. The number specifies a place counting from the letter after the current position at which the corresponding plaintext letter is to be written.
For example, the first number "3" for the key letter "c" indicates the corresponding first plaintext letter "p" should be written at the third place. The second number "1" indicates the next "o" should be written at the first place after it.
The third number "17" indicates the third letter "s" should be written at the 17th place after that. Such a reciprocal table had been described by Bellaso in Wikipedia. The top row headed "AB" indicates a pairwise reciprocal transposition. That is, "A" in plaintext is enciphered as "N" and "N" in plaintext is enciphered as "A", and so on. The row to be used is switched according to a key. Although the above table is illustrated with the regular alphabet, Porta points out that "The order [of the letters in the tableau] Letter-by-letter progression of the key had been anticipated by Trithemius.
A cipher disk with a mixed alphabet had been described by Alberti. An easy-to-remember key had been proposed by Bellaso. Still, David Kahn appreciates that Porta was the first to enunciate "the modern concept of polyalphabeticity" p. Preconcerted Words? Grille 2-XVIII describes a so-called Cardan grille, a board with openings, which allows a reader to pick up significant letters of the true plaintext among a superficial text.
Chapter Titles of Book 2 2-I. Quid sit furtivis literarum notis scribere 2-II. Quod per literarum transpositionem occulte scribi possit 2-III. Occulta literarum transpositione aliter sine suspicione interpretem deludi posse 2-IIII. De furtivis characterum notis effingendis 2-V. De simplici occultarum sive furtivarum literarum modo 2-VI. Qua ratione ad scribendum instrumento uti possumus 2-IX. An liceat experiri utrum scribendo Rotam peccatum sit 2-X.
Eodem Rotae artificio quomodo aliter literis per tabulam expandis uti possimus 2-XII. Probable Words Porta was the first to mention using "probable words" words likely to be present in the plaintext for cryptanalysis Kahn p.
Frequency Analysis For simple substitution of Latin plaintext , Porta appears to point out vowels can be easily recognized from their position and consonants can be identified by their frequency.
According to Kahn p. At the time, codebreakers often depended on such word divisions. Although his examples were contrived and his methodology is not generally applicable, Kahn highly appreciates his bold attitude p.
A shrewd reader would have noticed sequences of three identical symbols in the example ciphertexts given in Book 2 above. The edition has a new chapter 4-XVII dealing with solution of a polyalphabetic cipher with a standard alphabet but with a literal key rather than progressive switching Kahn p. In this variant, succession of the same letter in the ciphertext indicates that the corresponding letters in the key are consecutive in alphabetical order and those in the plaintext are consecutive in reverse alphabetical order.
At one point, Porta went very close to a general solution: "Since there are Specifically, the ciphertext contrived by Porta to be decipherable is as follows. If so, the occurrence of "CCCC" suggests the corresponding key letters might also be consecutive in alphabetical order.
Table 4 is a similar list of four-letter words. The following table appears to help identifying word divisions by providing examples of consecutive vowels etc. There are also tables of words including consecutive two letters in alphabetical order, etc.
Appendix The edition includes an appendix including additional information. This table was not included in the edition. In particular, the original division of Book 2 enciphering and Book 3 cryptanalysis was abandoned and codebreaking techniques are described right after the relevant enciphering method.
It was substantially enlarged with additional techniques and examples. Among others, a solution to a polyalphabetic cipher with a literal key see above is described albeit for rather an artificial example.
Chapter Titles of Book 1 of the edition 1-I. Per notas Hieroglyphicas, atque per rerum animaliumque figuras tacite sermonem exprimi posse 1-X. Chapter Titles of Book 2 of the edition 2-I. De literis clandestinis ex veterum scriptis orig. Chapter Titles of Book 3 of the edition 3-I. Furtivae literarum notae, quibus maiores in scribendo usi sint orig. Quid sit furtivis literarum notis scribere orig.
Quomodo per literarum transpositionem occulte scribi possit orig. Quomodo aliter transposito literarum ordine scriptum indissolubile fiat orig. De simplici furtivarum literarum modo orig. Quae novisse interpretem conveniat, antequam ad scripti interpretationem accedat orig. Distincta literarum nomina, quibus saepenumero suis oportune locis uti debemus orig.
Simplex commutatae figurae modus quomodo deprehendatur orig. Consonantes quot modis in simplici permutati characteris scripto a vocalibus dignoscantur orig.
De Furtivis Literarum notis, vulgo de Ziferis libri IIII
Editions In , Porta published a classic work on cryptology De furtivis literarum notis, vulgo de ziferis. In , a pirated edition made "almost to perfection" Kahn p. A legitimate edition titled De occultis literarum notis Google added an appendix. The term occultis secret, occluded, hidden and furtivis secret, furtive are more or less synonymous and furtivis in the title of some chapters was replaced with occultis seu furtivis in the edition. An enlarged and reorganized edition Google is reorganized into five books. An English translation On secret notations for letters commonly called ciphers in typescript by Mrs. Porta, gentilhomme napolitain, , pp.
DE FURTIVIS LITERARUM NOTIS PDF
Ad Lectores Praefatio. Eorum quae in opere tractantur index. Liber Primus. Quid sint furtivae literarum notae.