blob: 7f52f5c6dd8e1c417bceebcebbac3d06e30da0dc (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
#!/usr/bin/env -S nim r -d:release --verbosity:0 --hints:off
# we can add C code directly to Nim source file with emit pragma
{.emit: """
char* hello_world() {
return "Hello, World!";
}
""".}
# this is a thin wrapper over C function with a new name
proc hello_C: cstring {.importc: "hello_world".}
# https://www.gnu.org/software/libc/manual/html_node/Obfuscating-Data.html
proc memfrob(mem: pointer, length: csize_t): pointer {.importc.}
# a proper wrapper
proc obfuscate*[T: char | byte](arr: var openarray[T]) =
## Reversibly obfuscates data. Each byte is bitwise xor-ed
## with the binary pattern 00101010 (hexadecimal 0x2A)
discard memfrob(arr.addr, csize_t(arr.len))
when isMainModule:
import std/unittest
const
Greeting = "Hello, World!"
Plain = "abcdefgh"
Obfuscated = "KHINOLMB"
suite "Calling C functions":
test "Custom C function":
check hello_C() == Greeting
test "GNU libc (glibc) function":
var a = Plain
a.obfuscate()
check a == Obfuscated
a.obfuscate()
check a == Plain
|
