Getting all strings in a lua script - string

Question

I'm trying to encode some strings in my lua script, and since that I have a lua script with over 200k characters, encrypting each string query in the script with a function such as this example below
local string = "stackoverflow"
local string = [[stackoverflow]]
local string = [==[stackoverflow]==]
local string = 'stackoverflow'
to
local string=decode("jkrtbfmviwcfn",519211)
Trying to provide all above results to thread through a gsub and have the gsub encode the string text with a random offset number.
So far, I was only capable of gsubbing full quotation marks through.
function encode(x,offset,a)
for char in string.gmatch(x, "%a") do
local encrypted = string.byte(char) + offset
while encrypted > 122 do
encrypted = encrypted - 26
end
while encrypted < 97 do
encrypted = encrypted + 26
end
a[#a+1] = string.char(encrypted)
end
return table.concat(a)
end
luacode=[==[thatstring.Value="Encryptme!" testvalue.Value=[[string with
a linebreak]] string.Text="STOP!"]==]
luacode=luacode:gsub([=["(.-)"]=],function(s)
print("Caught "..s)
local offset=math.random(1,4)
local encoded=encode(s,offset,{})
return [[decode("]]..encoded..[[",]]..offset..[[)]]
end)
print("\n"..luacode)
With its output being
Caught Encryptme!
Caught STOP!
thatstring.Value=decode("crgvctxqi",4) testvalue.Value=[[string with
a linebreak]] string.Text=decode("opkl",2)
Any better solutions?

Answer 1

local function strings_and_comments(lua_code, callback)
-- lua_code must be valid Lua code (an error may be raised on syntax error)
-- callback will be invoked as callback(object_type, value, start_pos, end_pos)
-- callback("comment", comment_text, start_pos, end_pos) -- for comments
-- callback("string", string_value, start_pos, end_pos) -- for string literals
local objects = {} -- possible comments and string literals in the code
-- search for all start positions of comments (with false positives)
for pos, br1, eq, br2 in lua_code:gmatch"()%-%-(%-*%[?)(=*)(%[?)" do
table.insert(objects, {start_pos = pos,
terminator = br1 == "[" and br2 == "[" and "]"..eq.."]" or "\n"})
end
-- search for all start positions of string literals (with false positives)
for pos, eq in lua_code:gmatch"()%[(=*)%[[%[=]*" do
table.insert(objects, {is_string = true, start_pos = pos,
terminator = "]"..eq.."]"})
end
for pos, quote in lua_code:gmatch"()(['\"])" do
table.insert(objects, {is_string = true, start_pos = pos, quote = quote})
end
table.sort(objects, function(a, b) return a.start_pos < b.start_pos end)
local end_pos = 0
for _, object in ipairs(objects) do
local start_pos, ok, symbol = object.start_pos
if start_pos > end_pos then
if object.terminator == "\n" then
end_pos = lua_code:find("\n", start_pos + 1, true) or #lua_code
-- exclude last spaces and newline
while lua_code:sub(end_pos, end_pos):match"%s" do
end_pos = end_pos - 1
end
elseif object.terminator then
ok, end_pos = lua_code:find(object.terminator, start_pos + 1, true)
assert(ok, "Not a valid Lua code")
else
end_pos = start_pos
repeat
ok, end_pos, symbol = lua_code:find("(\\?.)", end_pos + 1)
assert(ok, "Not a valid Lua code")
until symbol == object.quote
end
local value = lua_code:sub(start_pos, end_pos):gsub("^%-*%s*", "")
if object.terminator ~= "\n" then
value = assert((loadstring or load)("return "..value))()
end
callback(object.is_string and "string" or "comment", value, start_pos, end_pos)
end
end
end
local inv256
local function encode(str)
local seed = math.random(0x7FFFFFFF)
local result = '",'..seed..'))'
if not inv256 then
inv256 = {}
for M = 0, 127 do
local inv = -1
repeat inv = inv + 2
until inv * (2*M + 1) % 256 == 1
inv256[M] = inv
end
end
repeat
seed = seed * 3
until seed > 2^43
local K = 8186484168865098 + seed
result = '(decode("'..str:gsub('.',
function(m)
local L = K % 274877906944 -- 2^38
local H = (K - L) / 274877906944
local M = H % 128
m = m:byte()
local c = (m * inv256[M] - (H - M) / 128) % 256
K = L * 21271 + H + c + m
return ('%02x'):format(c)
end
)..result
return result
end
function hide_strings_in_lua_code(lua_code)
local text = { [[
local function decode(str, seed)
repeat
seed = seed * 3
until seed > 2^43
local K = 8186484168865098 + seed
return (str:gsub('%x%x',
function(c)
local L = K % 274877906944 -- 2^38
local H = (K - L) / 274877906944
local M = H % 128
c = tonumber(c, 16)
local m = (c + (H - M) / 128) * (2*M + 1) % 256
K = L * 21271 + H + c + m
return string.char(m)
end
))
end
]] }
local pos = 1
strings_and_comments(lua_code,
function (object_type, value, start_pos, end_pos)
if object_type == "string" then
table.insert(text, lua_code:sub(pos, start_pos - 1))
table.insert(text, encode(value))
pos = end_pos + 1
end
end)
table.insert(text, lua_code:sub(pos))
return table.concat(text)
end
Usage:
math.randomseed(os.time())
-- This is the program to be converted
local luacode = [===[
print"Hello world!"
print[[string with
a linebreak]]
local str1 = "stackoverflow"
local str2 = [[stackoverflow]]
local str3 = [==[stackoverflow]==]
local str4 = 'stackoverflow'
print(str1)
print(str2)
print(str3)
print(str4)
]===]
-- Conversion
print(hide_strings_in_lua_code(luacode))
Output (converted program)
local function decode(str, seed)
repeat
seed = seed * 3
until seed > 2^43
local K = 8186484168865098 + seed
return (str:gsub('%x%x',
function(c)
local L = K % 274877906944 -- 2^38
local H = (K - L) / 274877906944
local M = H % 128
c = tonumber(c, 16)
local m = (c + (H - M) / 128) * (2*M + 1) % 256
K = L * 21271 + H + c + m
return string.char(m)
end
))
end
print(decode("ef869b23b69b7fbc7f89bbe7",2686976))
print(decode("c2dc20f7061c452db49302f8a1d9317aad1009711e0984",1210253312))
local str1 = (decode("84854df4599affe9c894060431",415105024))
local str2 = (decode("a5d7db792f0b514417827f34e3",1736704000))
local str3 = (decode("6a61bcf9fd6f403ed1b4846e58",1256259584))
local str4 = (decode("cad56d9dea239514aca9c8b8e0",1030488064))
print(str1)
print(str2)
print(str3)
print(str4)
Output of output (output produced by the converted program)
Hello world!
string with
a linebreak
stackoverflow
stackoverflow
stackoverflow
stackoverflow