I'm encrypting my Lua code with this script.
local script = string.dump(
function()
local function h4x(strtbl)
buffer=""
for v in strtbl do
buffer=buffer..strtbl[v]
end
return buffer
end
print("encrypted")
end
)
buff=""
for v=1,string.len(script) do --Convert our string into a hex string.
buff=buff..'\\'..string.byte(script,v)
end
file=io.open('encrypted.txt','w') --Output our bytecode into ascii format to encrypted.txt
file:write(buff)
file:flush()
file:close()
The output of encrypted.txt is like "00/12/46/4/2/6/4/62/". How do I decrypt bytecode?
This text is not encrypted. It's just Lua bytecode in hexadecimal.
Discussion of means of disassembling this bytecode into human-readable opcodes is in another question: Lua equivalent to Python dis()?
Obviously its printing out each BYTE as a value (which is decimal, even though its stated its converted to hex) delimited by a '/'.
All you need to do then is fill an array using the bytes you pull from the string, using tonumber to convert them back to their byte value. this will help with parsing the formatted output
Related
I am trying to convert a text source into an HTML readable page.
The code I have have tried:
local newstr=string.gsub(str,"±", "±")
local newstr=string.gsub(str,"%±", "±")
However, the character shows up as  in the output.
I can't seem to find any other documentation on how to handle this specific special character. How do I handle this character when reading in so that it will output properly?
Edit: After trying suggestions I'm able to determine this:
local function sanitizeheader(str)
if not(str)then return "" end
str2 = "Depth ±"
local newstr=string.gsub(str2, string.char(177), "±")
return newstr
end
In the testing, if I use str2 ± does show up in the output. However, when I try to use str as it is passed in from reading the excel file, it doesn't pick up the character and still returns the  character.
Lua string assume strings as sequence of bytes. You are trying utf8 multi byte character. The code you are trying should work as it just replacing a sequence of bytes. However, Lua 5.3 has utf8 library to handle unicode character
local str="±®ª"
for code in str:gmatch(utf8.charpattern) do
print("&#" .. utf8.codepoint(code) .. ";")
end
Output:
±
®
ª
Check Lua Reference Manual for more info.
I am trying to write custom dissector for Wireshark, which will change byte/hex output to ASCII string.
I was able to write the body of this dissector and it works. My only problem is conversion of this data to ASCII string.
Wireshark declares this data to be sequence of bytes.
To Lua the data type is userdata (tested using type(data)).
If I simply convert it to string using tostring(data) my dissector returns 24:50:48, which is the exact hex representation of bytes in an array.
Is there any way to directly convert this byte sequence to ascii, or can you help me convert this colon separated string to ascii string? I am totally new to Lua. I've tried something like split(tostring(data),":") but this returns Lua Error: attempt to call global 'split' (a nil value)
Using Jakuje's answer I was able to create something like this:
function isempty(s)
return s == nil or s == ''
end
data = "24:50:48:49:4A"
s = ""
for i in string.gmatch(data, "[^:]*") do
if not isempty( i ) then
print(string.char(tonumber(i,16)))
s = s .. string.char(tonumber(i,16))
end
end
print( s )
I am not sure if this is effective, but at least it works ;)
There is no such function as split in Lua (consulting reference manual is a good start). You should use probably string.gmatch function as described on wiki:
data = "24:50:48"
for i in string.gmatch(data, "[^:]*") do
print(i)
end
(live example)
Further you are searching for string.char function to convert bytes to ascii char.
You need to mark range of bytes in the buffer that you're interested in and convert it to the type you want:
data:range(offset, length):string()
-- or just call it, which works the same thanks to __call metamethod
data(offset, length):string()
See TvbRange description in https://wiki.wireshark.org/LuaAPI/Tvb for full list of available methods of converting buffer range data to different types.
I'm trying to take HEX bytes and display them as their ASCII values. If someone could point me reasonably firmly in the right direction I'd be obliged. Tried any number of uint-type commands, and working with buffer(x, 2) as an argument.
I'm not sure what you mean by hex bytes, but the relevant functions are:
string.byte, which converts chars to numerical codes
string.char, which converts numerical codes to chars
For a single character in hexadecimal, you can use string.byte as mentioned by lhf. For longer sequences, you can create a loop in Lua, but that is not very efficient since it involves a lot of copying.
Since Wireshark 1.11.3 there is a Struct.fromhex function that converts a string of hexadecimal characters to the binary equivalent.
Example:
-- From hex to bytes (with no separators)
assert(Struct.fromhex("5753") == "WS")
-- From hex to bytes (using a single space as separator)
assert(Struct.fromhex("57 53", " ") == "WS")
Similarly, there is a Struct.tohex function that converts from bytes to hex.
i need to store a string of bytes in a table in lua, how I can do it
thanks
Jp
Is that what you mean?
s="some string"
t={s:byte(1,#s)}
A Lua string is exactly what you wrote - a string of bytes. Lua is different from C-like languages in that it is 8-bit clean, meaning that you can even store embedded zero '\0' inside strings - the length of the string is held separately and is not based on where '\0' is.
You did not write where you want those bytes from (what is the source), so let's assume you are reading from a file. In the following example, f is a file handle obtained by calling io.open(filename), and t is a table (t = {}).
local str = f:read(100) -- will read up to 100 bytes from file handle f
t[#t + 1] = str -- will append the string to the end of table t
table.insert(t, str) -- alternative way of achieving the same
In Erlang how do I convert a string to a binary value?
String = "Hello"
%% should be
Binary = <<"Hello">>
In Erlang strings are represented as a list of integers. You can therefore use the list_to_binary (built-in-function, aka BIF). Here is an example I ran in the Erlang console (started with erl):
1> list_to_binary("hello world").
<<"hello world">>
the unicode (utf-8/16/32) character set needs more number of bits to express characters that are greater than 1-byte in length:
this is why the above call failed for any byte value > 255 (the limit of information that a byte can hold, and which is sufficient for IS0-8859/ASCII/Latin1)
to correctly handle unicode characters you'd need to use
unicode:characters_to_binary() R1[(N>3)]
instead, which can handle both Latin1 AND unicode encoding.
HTH ...