How to use powershell to reorder a string to obfuscate a hidden message? - powershell

Question

Just for fun a friend and I are trying to find a creative way to send coded messages to eachother using steganography.I stumbled upon doing something like whats shown below and I have been struggling trying to write a function to automate the process.
this is a secret message
can be turned into:
("{2}{1}{0}{3}"-f'ecret m','is a s','this ','essage')
splitting the string and using reordering seems to be the way to go.
So the string needs to be split in random splits between 5-10 characters
.
The index of the original positions need to be saved
the splits need to be swapped around
and the new indexes sorted as to reorder the message properly
i've just really been struggling
help is appreciated

Answer 1

Just for fun .... 😉🤡
$InputMessage = 'this is a secret message'
$SplittedString = $InputMessage -split '' | Select-Object -Skip 1 | Select-Object -SkipLast 1
[array]::Reverse($SplittedString)
foreach ($Character in $SplittedString) {
if ($Character -notin $CharacterList) {
[array]$CharacterList += $Character
}
}
foreach ($Character in ($InputMessage -split '' | Select-Object -Skip 1 | Select-Object -SkipLast 1)) {
$Index = [array]::indexof($CharacterList, $Character)
$Output += "{$Index}"
}
$Result = "'$Output' -f $(($CharacterList | ForEach-Object {"'$_'"}) -join ',')"
$Result
And the output of this would be:
'{6}{10}{9}{3}{5}{9}{3}{5}{2}{5}{3}{0}{8}{7}{0}{6}{5}{4}{0}{3}{3}{2}{1}{0}' -f 'e','g','a','s','m',' ','t','r','c','i','h'
And the output of this would be:
this is a secret message
And now if you want to go fancy with it you remove the curly braces and the quotes and the commas and the -f and add only the numbers and characters to the data. ;-)

Answer 2

Not exactly what you're looking for but this might give you something to start with:
class Encode {
[string] $EncodedMessage
[int[]] $Map
[int] $EncodingComplexity = 3
Encode ([string] $Value) {
$this.Shuffle($Value)
}
Encode ([string] $Value, [int] $Complexity) {
$this.EncodingComplexity = $Complexity
$this.Shuffle($Value)
}
[void] Shuffle([string] $Value) {
$set = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!##$%^&*()_-+=[{]};:<>|./?'
$ref = [Collections.Generic.HashSet[int]]::new()
$ran = [random]::new()
$enc = [char[]]::new($Value.Length * $this.EncodingComplexity)
for($i = 0; $i -lt $enc.Length; $i++) {
$enc[$i] = $set[$ran.Next($set.Length)]
}
for($i = 0; $i -lt $Value.Length; $i++) {
do {
$x = $ran.Next($enc.Length)
} until($ref.Add($x))
$enc[$x] = $Value[$i]
}
$this.EncodedMessage = [string]::new($enc)
$this.Map = $ref
}
}
class Decode {
static [string] DecodeMessage ([Encode] $Object) {
return [Decode]::DecodeMessage($Object.EncodedMessage, $Object.Map, $Object.EncodingComplexity)
}
static [string] DecodeMessage ([string] $EncodedMessage, [int[]] $Map) {
return [Decode]::DecodeMessage($EncodedMessage, $Map, 3)
}
static [string] DecodeMessage ([string] $EncodedMessage, [int[]] $Map, [int] $Complexity) {
$decoded = [char[]]::new($EncodedMessage.Length / $Complexity)
for($i = 0; $i -lt $decoded.Length; $i++) {
$decoded[$i] = $EncodedMessage[$Map[$i]]
}
return [string]::new($decoded)
}
}
Encoding a message:
PS /> $message = 'this is a secret message'
PS /> $encoded = [Encode] $message
PS /> $encoded
EncodingComplexity EncodedMessage Map
------------------ -------------- ---
3 B$h^elu2w#CeeHH^qa siQJ)t}es:.a3 ema=eN(GiIcsO;tst1 .fsg}eSUk7ms4 N>rfe# {49, 2, 41, 27…}
For decoding the message you can either use the object of the type Encode or you can give your friend the Encoded Message and the Map to decode it ;)
PS /> [Decode]::DecodeMessage($encoded)
this is a secret message
PS /> [Decode]::DecodeMessage('B$h^elu2w#CeeHH^qa siQJ)t}es:.a3 ema=eN(GiIcsO;tst1 .fsg}eSUk7ms4 N>rfe#', $encoded.Map)
this is a secret message