由于David Kahn的书《The Codebreakers》让我对古代密码学产生了兴趣,因此我正在尝试使用Ruby类来处理旧密码,例如Nihilist cipher和ADFGVX。对于这些密码,一个有用的工具是Straddling checkboard。我在Ruby中有以下实现,并欢迎任何改进。
Ruby/Python/Perl或伪代码都可以,谢谢任何想法。
class Key
是基类(如果您想要的话是虚拟类)。Key#condensed
是一种从给定单词中删除重复字母的方法。class SKey < Key
attr_reader :full_key
attr_reader :alpha, :ralpha
def initialize(key)
super(key)
@alpha = Hash.new
@ralpha = Hash.new
@full_key = checkboard()
gen_rings()
end
# === checkboard
#
# Shuffle the alphabet a bit to avoid sequential allocation of the
# code numbers
#
# Regular rectangle
# -----------------
# Key is ARABESQUE condensed into ARBESQU (len = 7) (height = 4)
# Let word be ARBESQUCDFGHIJKLMNOPTVWXYZ/-
#
# First passes will generate
#
# A RBESQUCDFGHIJKLMNOPTVWXYZ/- c=0 0 x 6
# AC RBESQUDFGHIJKLMNOPTVWXYZ/- c=6 1 x 6
# ACK RBESQUDFGHIJLMNOPTVWXYZ/- c=12 2 x 6
# ACKV RBESQUDFGHIJLMNOPTWXYZ/- c=18 3 x 6
# ACKVR BESQUDFGHIJLMNOPTWXYZ/- c=0 0 x 5
# ACKVRD BESQUFGHIJLMNOPTWXYZ/- c=5 1 x 5
# ...
# ACKVRDLWBFMXEGNYSHOZQIP/UJT-
#
# Irregular rectangle
# -------------------
# Key is SUBWAY condensed info SUBWAY (len = 6) (height = 5)
#
# S UBWAYCDEFGHIJKLMNOPQRTVXZ/- c=0 0 x 5
# SC UBWAYDEFGHIJKLMNOPQRTVXZ/- c=5 1 x 5
# SCI UBWAYDEFGHJKLMNOPQRTVXZ/- c=10 2 x 5
# SCIO UBWAYDEFGHJKLMNPQRTVXZ/- c=15 3 x 5
# SCIOX UBWAYDEFGHJKLMNPQRTVZ/- c=20 4 x 5
# SCIOXU BWAYDEFGHJKLMNPQRTVZ/- c=0 0 x 4
# ...
# SCIOXUDJPZBEKQ/WFLR-AG YHMNTV c=1 1 x 1
# SCIOXUDJPZBEKQ/WFLR-AGM YHNTV c=2 2 x 1
# SCIOXUDJPZBEKQ/WFLR-AGMT YHNV c=3 3 x 1
# SCIOXUDJPZBEKQ/WFLR-AGMTYHNV
#
def checkboard
word = (@key + BASE).condensed.dup
len = @key.condensed.length
height = BASE.length / len
# Odd rectangle
#
if (BASE.length % len) != 0
height = height + 1
end
print "\ncheckboard size is #{len} x #{height}\n"
res = ""
(len - 1).downto(0) do |i|
0.upto(height - 1) do |j|
if word.length <= (height - 1) then
return res + word
else
c = word.slice!(i * j)
if not c.nil? then
res = res + c.chr
end
end
end
end
return res
end
# == gen_rings
#
# Assign a code number for each letter. Each code number is
# sequentially allocated from two pools, one with 0..7 and
# the other with 80..99.
#
# Allocation is made on the following criterias
# - if letter is one of ESANTIRU assign a single code number
# - else assign of of the two letters ones
#
# Generate both the encoding and decoding rings.
#
# XXX FIXME Use of 80-99 is hardcoded
#
def gen_rings
ind_u = 0
ind_d = 80
word = @full_key.dup
word.scan(/./) do |c|
if c =~ /[ESANTIRU]/
@alpha[c] = ind_u
@ralpha[ind_u] = c
ind_u = ind_u + 1
else
@alpha[c] = ind_d
@ralpha[ind_d] = c
ind_d = ind_d + 1
end
end
end # -- gen_rings
Ruby/Python/Perl或伪代码都可以,谢谢任何想法。