Golang : Embed secret text string into binary(executable) file



Tags : golang embed-include-data executable-binary-file secret-text-string hex

Problem:

You want to hide certain plain text string that you plan to embed(include) in your executable or binary file. There are few reasons to do this, such as you don't want to the plain text information to be viewed from a hex editor, cat or more command. How to hide a plain text string that you plan to embed?

Solution:

Use the encoding/hex package EncodeToString() function to convert plain text string into hexadecimal value and use it in your code as constant. The code below will demonstrate how to read a plain text string from a file and convert it with EncodeToString() function before converting it back to plain text with DecodeString() function.

The code is only an example, in your production code, you need to embed the hexadecimal value as constant.


 package main

 import (
  "encoding/hex"
  "fmt"
  "io/ioutil"
  "os"
 )

 func ConvertFileToHexString(filepath string) (string, error) {
  byteString, err := ioutil.ReadFile(filepath)
  if err != nil {
 return "", err
  }
  return hex.EncodeToString(byteString), nil
 }

 func main() {

  if len(os.Args) != 2 {
 fmt.Printf("Usage : %s <filename>\n", os.Args[0])
 os.Exit(0)
  }

  filename := os.Args[1]

  hexDataString, err := ConvertFileToHexString(filename)

  // will display
  // 746869732069732061207365637265742066696c652077697468207365637265742064617461210a
  // for this example string "this is a secret file with secret data!"
  //fmt.Println(hexDataString)

  if err != nil {
 panic(err)
  }

  bytesDataString, err := hex.DecodeString(hexDataString)

  if err != nil {
 panic(err)
  }

  fmt.Println("This is generated from reading : ", filename)
  fmt.Print(string(bytesDataString))

  // ok, we translated the data from file, but that's not what we want to achieve.
  // we want to embed the data inside this executable.

  // we will assign a constant with a slightly different message to indicate that it is NOT from file
  const secretMessageInsideExecutable = "746869732069732061207365637265742066696c652077697468207365637265742064617461210a"

  bytesDataString2, _ := hex.DecodeString(secretMessageInsideExecutable)

  fmt.Println("------------------------------------")
  fmt.Println("This is generated from embedded hexadecimal string found inside this executable")
  fmt.Println(string(bytesDataString2))
 }

Sample output:

secret.txt file content:

this is a secret text message from a file!


$ ./embedtext secret.txt

This is generated from reading : secret.txt

this is a secret text message from a file!

------------------------------------

This is generated from embedded hexadecimal string found inside this executable

this is a secret file with secret data!

References:

https://www.socketloop.com/tutorials/golang-how-to-protect-your-source-code-from-client-hosting-company-or-hacker

http://stackoverflow.com/questions/17796043/embedding-text-file-into-compiled-executable

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  See also : Golang : Embedded or data bundling example



Tags : golang embed-include-data executable-binary-file secret-text-string hex

By Adam Ng

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