#!/bin/sh
<<DOC
Cryptogram Engine: v0.2 - Michael Sanders 2017
about...
. simple cryptogram creation using awk
. logic & data embedded within a single container
. example limited to three cryptograms for brevity
. for an archive containing 500+ cryptograms visit:
http://busybox.hypermart.net/cryptogram.html
tips...
. no letter represents itself (X never equals X)
. multiple instances of a letter always have the
same value (if B equals N, then all B's equal N)
. decipher smaller words first (thereby quickly
exposing letters for reuse)
. only two single-letter words exist in the
english language: A & I
. relax - its just a fun script because that's all
it has to be =)
letter frequency by usage...
e: 12.702% m: 02.406%
t: 09.056% w: 02.360%
a: 08.167% f: 02.228%
o: 07.507% g: 02.015%
i: 06.966% y: 01.974%
n: 06.749% p: 01.929%
s: 06.327% b: 01.492%
h: 06.094% v: 00.978%
r: 05.987% k: 00.772%
d: 04.253% j: 00.153%
l: 04.025% x: 00.150%
c: 02.782% q: 00.095%
u: 02.758% z: 00.074%
further reading...
https://en.wikipedia.org/wiki/Cryptogram
https://en.wikipedia.org/wiki/Caesar_cipher
https://www.rosettacode.org/wiki/Caesar_cipher#AWK
https://en.wikipedia.org/wiki/Letter_frequency
DOC
#e=$(dd if=/dev/urandom bs=9 count=1)
e=$RANDOM
awk -v e=$e '
/^exit/{q=1}
{if (q && $0 !~ /exit/ && length($0) > 0) d[++j] = $0}
END{
srand(e)
p = toupper(d[rndnum(1, j)])
m = mask(p)
do {
c = caesarshift(rndnum(1, 26), p)
} while (substr(p, 1, 1) == substr(c, 1, 1))
print "cryptogram..."
print "encoded: " c
print "decoded: " m
print "solution: " p
}
function caesarshift(k, m, p, c, x, y, z, s) {
p = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
c = substr(p, k + 1) substr(p, 1, k)
x = length(m)
for (y = 1; y <= x; y++) {
z = index(p, substr(m, y, 1))
s = (z) ? s substr(c, z, 1) : s substr(m, y, 1)
}
return s
}
function mask(m, x,y,z,r,s) {
x = length(m)
y = int(x / 2) + 1
for (z = 1; z <= y; z++) {
do {
r = rndnum(1, x)
} while (r in a || substr(m, r, 1) !~ /[A-Z]/)
a[r] = r
}
for (z = 1; z <= x; z++) s = (a[z]) ? s "_" : s substr(m, z, 1)
return s
}
function rndnum(lo, hi) {return int(lo + rand() * (hi - lo + 1))}
' < $0
exit
hunky-dory
say goodnight gracie
willy nilly
--
later on,
Mike
http://busybox.hypermart.net
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