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VMs: What if Alberti wasn't so smart...?
Here's a question I've been pondering for a while: what if Leon Battista
Alberti wasn't so smart?
AFAIK, the "standard" rendering of pre-polyalpha crypto history goes like
(1) crypto guys make monoalphabetic ciphers
(2) crypto guys add nomenclators (extra shapes) for frequent words
(3) crypto guys add homomorphs (alternative shapes) for vowels
(4) crypto guys add extra symbols for (vowel, consonant) pairs
(5) 1466/7: Alberti invents the code-wheel
(6) 1470: Alberti writes about his code-wheel, but no-one reads about for years
(7) 1472: Alberti dies
(8) 1500-ish: Trithemius develops progressive key (cycling) polyalphabetic
But... perhaps it's not quite that simple. First of all, (AIUI) Alberti
never intended the code-wheel to be "clicked round" after every character
(in the modern sense of polyalphabetic), but instead after every three or
four words. Given that modern cryptanalysts reckon that a simple cipher
needs something like 30 characters to be consistently breakable, that's
actually bang on the money. :-) This means it's not quite the precursor to
modern polyalpha you might think.
Secondly, looking again at the Tranchedino cipher ledger, I think there's
another possibility. From ciphers like the one on page 3r (Cum Francisco
Isulano de Tricio) which has three homomorphs for consonants (and four
homomorphs for a/e/i/o/u), I wonder whether some encipherers in 1450 used
only one row of such ciphers at a time (and perhaps used the extra
homomorph for subsequent occurrences of vowels that appear twice within a
That is, I wonder whether Alberti, rather than *inventing* a kind of
multi-cipher crypto practice, was in fact merely *technologising* an
existing crypto practice? This would fit the "darker" modern view of
Alberti (as discussed by Anthony Grafton in his recent book).
If there are some encrypted letters still extant in the Milanese archives
(which we can link up to actual codes in the cipher ledger), then this
could be explored further (and possibly falsified, if you subscribe to a
Popperian view of science).
Alternatively, it might be an interesting idea to re-read Alberti's 1470
"Trattati In Cifra", AKA "Dello scrivere in cifra Roma", 27, 29, 41-42,
46-47, according to:
BTW: does anyone know of a facsimile copy or transcription of this?
Also: for a good-length excerpt from Anthony Grafton's recent book on Alberti:
Cheers, .....Nick Pelling.....
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