diff options
Diffstat (limited to 'tex/context')
| -rw-r--r-- | tex/context/third/enigma/enigma.lua | 100 | ||||
| -rw-r--r-- | tex/context/third/enigma/t-enigma.mkvi | 10 |
2 files changed, 80 insertions, 30 deletions
diff --git a/tex/context/third/enigma/enigma.lua b/tex/context/third/enigma/enigma.lua index 371ddd9..521c4b7 100644 --- a/tex/context/third/enigma/enigma.lua +++ b/tex/context/third/enigma/enigma.lua @@ -138,8 +138,8 @@ By default the output to \type{stdout} will be zero. The verbosity level can be adjusted in order to alleviate debugging. \stopparagraph --ichd]]-- -local verbose_level = 42 ---local verbose_level = 0 +--local verbose_level = 42 +local verbose_level = 0 --[[ichd-- \startparagraph @@ -575,10 +575,10 @@ accomplished, there will be an optional (re-)uppercasing. \stopparagraph \startparagraph -Substitutions are applied onto the lowercased input. You might want -to avoid some of these, above all the rules for numbers, because they -translate single digits only. The solution is to write out numbers above -ten. +Substitutions \reference[listing:preproc]{}are applied onto the +lowercased input. You might want to avoid some of these, above all the +rules for numbers, because they translate single digits only. The +solution is to write out numbers above ten. \stopparagraph --ichd]]-- @@ -737,9 +737,6 @@ local variable, \identifier{pb_char}. machine.step = machine.step + 1 machine:rotate() local pb = machine.plugboard - --if valid_char_p[char] == nil then -- skip unwanted characters - -- return char - --end char = letter_to_value[char] local pb_char = pb[char] -- first plugboard substitution emit(2, pprint_step, machine.step, char, pb_char) @@ -1078,8 +1075,34 @@ consists of three elements: return result or handle_day_key(nil, name, dk) end - new = function (name, setup_string, pattern) - --local raw_settings = lpegmatch(p_init, setup_string) +--[[ichd-- +\startparagraph +The enigma encoding is restricted to an input -- and, naturally, output +-- alphabet of exactly twenty-seven characters. Obviously, this would +severely limit the set of encryptable documents. For this reason the +plain text would be \emph{preprocessed} prior to encoding, removing +spaces and substituting a range of characters, e.\,g. punctuation, with +placeholders (“X”) from the encodable spectrum. See above +\at{page}[listing:preproc] for a comprehensive list of substitutions. +\stopparagraph + +\startparagraph +The above mentioned preprocessing, however, does not even nearly extend +to the whole unicode range that modern day typesetting is expected to +handle. Thus, sooner or later an Enigma machine will encounter +non-preprocessable characters and it will have to decide what to do with +them. The Enigma module offers two ways to handle this kind of +situation: \emph{drop} those characters, possibly distorting the +deciphered plain text, or to leave them in, leaving hints behind as to +the structure of the encrypted text. None of these is optional, so it is +nevertheless advisable to not include non-latin characters in the plain +text in the first place. The settings key \identifier{other_chars} (type +boolean) determines whether we will keep or drop offending characters. +\stopparagraph +--ichd]]-- + + new = function (name, args) + local setup_string, pattern = args.day_key, args.rotor_setting local raw_settings = handle_day_key(setup_string, name) local rotors, ring = get_rotors(raw_settings.rotors, raw_settings.ring) @@ -1096,6 +1119,7 @@ consists of three elements: rotors = rotors, ring = ring, state = init_state, + other_chars = args.other_chars, ---> a>1, b>2, c>3 reflector = letter_to_value[raw_settings.reflector], plugboard = plugboard, @@ -1225,7 +1249,7 @@ a sanitizer routine and, if so, apply it to its value. end local sanitizers = { - other_chars = toboolean, + other_chars = toboolean, -- true = keep, false = drop day_key = alphanum_or_space, rotor_setting = ensure_alpha, verbose = ensure_int, @@ -1294,20 +1318,24 @@ local new_callback = function (machine, name) if n.id == glyph_node then local chr = utf8char(n.char) local replacement = machine:encode(chr) - if replacement == false then - --noderemove(head, n) + --if replacement == false then + if not replacement then + if not machine.other_chars then + noderemove(head, n) + end elseif type(replacement) == "string" then local insertion = nodecopy(n) insertion.char = utf8byte(replacement) nodeinsert_before(head, n, insertion) + noderemove(head, n) elseif type(replacement) == "table" then for i=1, #replacement do local insertion = nodecopy(n) insertion.char = utf8byte(replacement[i]) nodeinsert_before(head, n, insertion) end + noderemove(head, n) end - noderemove(head, n) elseif n.id == glue_node then -- spaces are dropped noderemove(head, n) @@ -1334,6 +1362,18 @@ local new_callback = function (machine, name) end end +--[[ichd-- +\startparagraph +Enigma\reference[listing:retrieve]{} machines can be copied and derived +from one another at will, cf. the \texmacro{defineenigma} on +\at{page}[listing:define]. Two helper functions residing inside the +\identifier{thirddata.enigma} namespace take care of these actions: +\luafunction{save_raw_args} and \luafunction{retrieve_raw_args}. As soon +as a machine is defined, we store its parsed options inside the table +\identifier{configurations} for later reference. For further details on +the machine derivation mechanism see \at{page}[listing:inherit]. +\stopparagraph +--ichd]]-- local configurations = { } local save_raw_args = function (conf, name) local current = configurations[name] or { } @@ -1350,26 +1390,28 @@ enigma.save_raw_args = save_raw_args enigma.retrieve_raw_args = retrieve_raw_args -local new_machine = function (args, name) - verbose_level = args.verbose - local machine = new(name, args.day_key, args.rotor_setting) +--[[ichd-- +\startparagraph +The function \luafunction{new_machine} instantiates a table containing +the complete specification of a workable \emph{Enigma} machine and other +metadata. The result is intended to be handed over to the callback +creation mechanism (\luafunction{new_callback}). However, the arguments +table is usally stored away in the \identifier{thirddata.enigma} +namespace anyway (\luafunction{save_raw_args}), so that the +specification of any machine can be inherited by some new setup later +on. +\stopparagraph +--ichd]]-- +local new_machine = function (_, name) + local args = configurations[name] + verbose_level = args.verbose or verbose_level + local machine = new(name, args) return machine end enigma.new_machine = new_machine enigma.new_callback = new_callback ------------------------------------------------------------------------- - ---local teststring = [[B I IV III 16 26 08 AD CN ET FL GI JV KZ PU QY WX]] ---local teststring = [[B I II III 01 01 01 AD CN ET FL GI JV KZ PU QY WX]] ---local teststring = [[B I II III 01 01 01]] ---local teststring = [[B I II III 01 01 02]] ---local teststring = [[B I II III 02 02 02]] ---local teststring = [[B I IV III 16 26 08 AD CN ET FL GI JV KZ PU QY WX]] ---local teststring = [[B I IV III 16 26 08]] ---local teststring = [[B I IV III 01 01 02]] - --[[ichd-- \stopdocsection --ichd]]-- diff --git a/tex/context/third/enigma/t-enigma.mkvi b/tex/context/third/enigma/t-enigma.mkvi index 0d2d9bf..8bf0797 100644 --- a/tex/context/third/enigma/t-enigma.mkvi +++ b/tex/context/third/enigma/t-enigma.mkvi @@ -41,7 +41,7 @@ thirddata = thirddata or { } %D \startdocsection[title=Macro Generator] %D \startparagraph -%D The main setup. The \texmacro{defineenigma} macro does not adhere to +%D The main setup.\reference[listing:define]{} The \texmacro{defineenigma} macro does not adhere to %D the reommended practis of automatical macro derivation. Rather, we %D have our own parser do the job of setting globals. This is a %D consequence of the intention to offer the same behavior in any of the @@ -76,10 +76,18 @@ thirddata = thirddata or { } }% } +%D \startparagraph +%D The \texmacro{inherit_enigma}\reference[listing:inherit]{} is called as +%D an intermediate step when deriving one machine from an already existing +%D one. It gets the stored configuration of its ancestor, relying on the +%D \luafunction{retrieve_raw_args} function (see +%D \at{page}[listing:retrieve]. +%D \stopparagraph \def\inherit_enigma#to#from{% \ctxlua{% local enigma = thirddata.enigma local current_args = enigma.retrieve_raw_args(\!!bs#from\!!es) + enigma.save_raw_args(current_args, \!!bs#to\!!es) enigma.new_callback(enigma.new_machine(current_args, \!!bs#to\!!es), \!!bs#to\!!es) }% |