That man Tony Gaffney has been at it again, shooting yet another cryptographic tin can down off Giovan Battista Bellaso’s fence: this time, it was Bellaso’s 1564 challenge cipher #7’s turn to fall.

What was particularly sweet about #7 was that it was a completely different type of cipher to the others Tony had previously broken: rather than being some kind of reciprocal rotating cipher (i.e. reciprocal = a cipher that both encodes and decodes, and rotating = a cipher alphabet whose order rotates every letter, every plaintext word, or every ciphertext word), this one was a fairly fiendish digram table (i.e. a table of pairs of letters).

Of course, you’d need a really substantial piece of ciphertext to stand any chance of filling out the contents of any such table: but because Bellaso wasn’t that sadistic, he used the same table he included in his book. The difficulty was therefore not so much of reconstructing the table, but of reconstructing the ksyphrase driving the table (i.e., the phrase permuting the rows and columns).

As regular Cipher Mysteries readers should know by know, classical (i.e. puzzle-based rather than statistics-based) code-breakers such as Tony look for words in the ciphertext with unusual properties, and see if they can use those to lever their way in. Here, the fact that nearly every word has an even number of letters is a strong indication that this is a digram-based cipher: and in Bellaso’s table (where each row of digrams is horizontally offset by one place relative to the row above it) the group CMYLDLELRL in line 4 of the ciphertext would appear to fall mostly along a diagonal.

Assuming that Y was “unlikely to be in the keyword or in the message“, Tony then “compared each of the 10 digrams in its row with those in their diagonals” – this let him hunt for candidate words to fit this basic kind of consonant-vowel-consonant pattern. “cifra” matched the first three pairs; “fantasie” matched the first four pairs; but by far the best 5-digram match for the group was “altramente“.

“This gave me a few rows and columns – the rest was a lot of trial & error & cups of tea & cigarettes!”

Post-caffeine and post-tobacco, here’s the resulting Italian cleartext that Tony ended up with – it appears to be explaining how to aim your cannon so that it hits the target:-

serom pera ilfestcon doi  sopresetireve  c onlavite perpe tova ilcanone
postoasegnn ousire delapaia faretirar e ilchanoneil quale sedeveretirar
inproporti onesetutiri inalto stsognache nel retirasecali chonlacoda
altramente dariaeo to d alsegnosetutirai baso bis na* elacoda retiran do
siassen ?da viran doperdrito bisognaseretiripesdritto etintutitreiquesuicasi
leretebisognache sesttiri noequal menteperchhe calan dounarotada rialap
ladaquellaban da

* YE = Il Signor Iddie, “The Lord God” (as per the table below – so almost certainly an error)
? An odd number of letters in this group (so almost certainly a typesetting error).

If you then insert plausible-looking spaces, you end up with text looking like this:-

Se rompera il fest con doi sopre se tireve con la vite perpetoua il canone
posto a segnn ousire della paia fare tirare il chanone il quale se devere tirar
in proportione se tutiri in alto st sogna che nel retira se cali chon la coda
altramente dariaeo to d'al segno se tutirai baso bis na ? el a coda retiran do
si assen ? da virando per drito bisogna se retire pes dritto et intuit tre I que
sui casi le rete bisogna che sesttiri no equalmente perchhe calando una rota dari
alap lada quella banda

As you can see from the final table (below), the keyphrase driving the row and column permutations appears to be “BARTOLOMEUS / PAN FILIUS”.

   B  A  R  T  O  L  M  E  U  S  C  D  F         G         H
P  pb pa pr pt po pl pm pe pu ps pc pd pf        pg        Ph
   aa ea ia oa ua A  aa ae ai ao au A  accio     altra     ancore
A  ah ab aa ar at ao al am ae au as ac ad        af        ag
   ab eb ib ob ub B  ba be bi bo bu B  benche    che       che
N  ng nh nb na nr nt no nl nm ne nu ns nc        nd        nf
   ac ec ic oc uc C  ca ce ci co cu Ch cosa      como      della
F  ff fg fh fb fa fr ft fo fl fm fe fu fs        fc        fd
   ad ed id od ud D  da de di do du D  debba     detto     doppe
I  id if ig ih ib ia ir it io il im ie iu        is        ic
   ae ee ie oe ue E  ea ee ei eo eu E  esso      essendo   essere
L  lc ld lf lg lh lb la lr lt lo ll lm le        lu        ls
   af ef if of uf F  fa fe fi fo fu F  forsi     fusse     finche
U  us uc ud uf ug uh ub ua ur ut uo ul um        ue        uu
   ag eg ig og ug G  ga ge gi go gu G  gratia    grave     grato
S  su ss sc sd sf sg sh sb sa sr st so sl        sm        se
   ah eh ih oh uh H  ha he hi ho hu H  abaiamo   avunto    hanno
B  be bu bs bc bd bf bg bh bb ba br bt bo        bl        bm
   ai ei ii oi ui I  ia ie ii io iu I  imperio   impo      impoche
C  cm ce cu cs cc cd cf cg ch cb ca cr ct        co        cl
   al el il ol ul L  la le li lo lu L  leqli     liquali   lettera
D  DL dm de du ds dc dd df dg dh db da dr        dt        do
   am em im om um M  ma me mi mo mu M  molto     modo      mondo
E  eo EL em ee eu es ec ed ef eg eh eb ea        er        et
   an en in on un N  na ne ni no nu N  non       nostra    nella
G  gt go gl gm ge gu gs gc gd gf gg gh gb        ga        gr
   ao eo io oo uo O  oa oe oi oo ou O  oltra     ogni      ognicosa
H  hr ht ho hl hm he hu hs hc hd hf hg hh        hb        ha
   ap ep ip op up P  pa pe pi po pu P  per       pero      perche
M  ma mr mt mo ml mm me mu ms mc md mf mg        mh        mb
   aq eq iq oq uq Q  st st st st qu Q  quali     quella    questa
O  ob oa or ot oo ol om oe ou os oc od of        og        oh
   ar er ir or ur R  ra re ri ro ru R  quato     quando    qualche
Q  qh qb qa qr qt qo ql qm qe qu qs qc qd        qf        qg
   as es is os us S  sa se si so su S  signor    signoria  scritto
R  rg rh rb ra rr rt ro RL rm re ru rs rc        rd        rf
   at et it ot ut T  ta te ti to tu T  scrisse   tutto     tanto
T  tf tg th tb ta tr tt to tl tm te tu ts        tc        td
   au eu iu ou uu V  ua ue iu uo uu V  vostro    vero      una
X  xd xf xg xh xb xa xr xt xo xl xm xe xu        xs        xc
   br dr gn lt nq X  pr rl rp rt st X  vostra    le vostra lquate piu
                                        Sig       lettere   presto
Y  yc yd yf yg yh yb ya yr yt yo YL ym ye        yu        ys
   ch fr gr mn nt Y  rc rm rs sc tr Y  Il Signor Le cose   Me
                                        Iddio     passano   racemande
Z  zs zc zd zf zg zh zb za zr zt zo zl zm        ze        zu
   cr gl lm nc pn Z  rd rn rt sp tr Z  habiamo   havemo    fatime
                                        recevute  apiacer   raccom.

All in all, I think this was another excellent result for Tony G., cracking an altogether harder challenge cipher than the previous ones – classy stuff, very well done! 🙂

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