File encoding and decoding

Other
#1

I am using these function a plugin coming soon, thought they could be helpful for share files to another device with services like gamkit, autolan( it does technical have a file send service build in), or one signal. You also can store files inside your lua code. Of course these functions generate long strings so beware of size limits on some services.

local function encodeFile( filename,dir ) local base64 = require("base64") local myDir = system.ResourceDirectory if (dir) then myDir = dir end local path = system.pathForFile( filename, myDir ) local fileHandle = io.open( path, "rb" ) local tempString=base64.encode(fileHandle:read( "\*a" )) local tempTable = filename:split("%.") local tempTable2 = tempTable[1]:split("/") local tempString3 = "" if (tempTable2 and tempTable2[1]) then tempString3= tempTable2[#tempTable2] else tempString3= tempTable[1] end local tempString2 = tempString.."\_"..tempString3.."\_"..tempTable[2] return tempString2 end local function decodeFile( txt, dir ) local base64 = require("base64") local myDir = system.DocumentsDirectory if (dir) then myDir = dir end local tempTable= txt:split("\_") local tempString2 = "" for i=1,#tempTable-2 do tempString2 = tempString2..tempTable[i] end local path local file, errorString if (path) then path = system.pathForFile( path2.."/"..tempTable[#tempTable-1].."."..tempTable[#tempTable], myDir ) file, errorString= io.open( path, "w" ) else path = system.pathForFile( tempTable[#tempTable-1].."."..tempTable[#tempTable], myDir) file, errorString= io.open( path, "w" ) end if not file then else -- Write data to file file:write( base64.decode(tempString2) ) -- Close the file handle io.close( file ) end return tempTable[#tempTable-1].."."..tempTable[#tempTable], dir end

You also need to include this lua file

local mime=require('mime') local socket=require('socket') local base64 = {} function base64.encode(data) local len = data:len() local t = {} for i=1,len,384 do local n = math.min(384, len+1-i) if n \> 0 then local s = data:sub(i, i+n-1) local enc, \_ = mime.b64(s) t[#t+1] = enc end end return table.concat(t) end function base64.decode(data) local len = data:len() local t = {} for i=1,len,384 do local n = math.min(384, len+1-i) if n \> 0 then local s = data:sub(i, i+n-1) local dec, \_ = mime.unb64(s) t[#t+1] = dec end end return table.concat(t) end return base64
#2

I’m trying to obfuscate some images in my app using a similar method, and wondered if you or anyone else know how to get around one thing that’s stopping us. 

I’m encrypting some images, saving the string to a txt file and then I’m putting those files into my app prior to building instead of the jpg files. Then at runtime, when I need to use an image (I only ever need one at any one time) I read the file, decrypt it, save it to a jpg in the DocumentsDirectory and then open that file using newImageRect.

The problem is that saving it to a jpg defeats the point of encrypting the image in the first place. The perfect workaround would be if the decrypted string could be passed into newImageRect. Is there anyway to pass that kind of data into an image or texture or anything like that?

I could do what I’m currently doing and delete the jpg file once the image loads, but I can see that causing problems where the image goes out of memory if the app sleeps or something like that so would prefer a better solution if there is one.

#3

You might try using bitmap

#4

Do you mean using BitmapPaint or am I overlooking something? As far as I can tell that takes a filename as well.

#5

You could try converting your images to a bitmaps and place them inside the lua file

#6

I’m trying to obfuscate some images in my app using a similar method, and wondered if you or anyone else know how to get around one thing that’s stopping us. 

I’m encrypting some images, saving the string to a txt file and then I’m putting those files into my app prior to building instead of the jpg files. Then at runtime, when I need to use an image (I only ever need one at any one time) I read the file, decrypt it, save it to a jpg in the DocumentsDirectory and then open that file using newImageRect.

The problem is that saving it to a jpg defeats the point of encrypting the image in the first place. The perfect workaround would be if the decrypted string could be passed into newImageRect. Is there anyway to pass that kind of data into an image or texture or anything like that?

I could do what I’m currently doing and delete the jpg file once the image loads, but I can see that causing problems where the image goes out of memory if the app sleeps or something like that so would prefer a better solution if there is one.

#7

You might try using bitmap

#8

Do you mean using BitmapPaint or am I overlooking something? As far as I can tell that takes a filename as well.

#9

You could try converting your images to a bitmaps and place them inside the lua file