powershell XOR encoder / decoder and hex / byte - byte / hex conversions

snippet-pwsh_xorhexbyte.ps1

# powershell XOR encoder / decoder and hex / byte - byte / hex conversions
# usage: execute & see output

# xor encoder / decoder
function xor($bytes, $string) {
    $newBytes = @();
    for ($i = 0; $i -lt $bytes.Count; $i++) {
        $newBytes += $bytes[$i] -bxor $string[$i % $string.Length];
    } 
    return $newBytes;
}

# hex string to byte array conversion
function hexStringToBytes($hexString) {
    $newBytes = @();
    for ($i = 0; $i -lt $hexString.Length; $i += 2) {
        $newBytes += [Byte]::Parse($hexString.Substring($i, 2), [System.Globalization.NumberStyles]::HexNumber);
    }
    return $newBytes;
}

# byte array to hex string conversion
function bytesToHexString($bytes) {
    $hexString = @();
    for ($i = 0; $i -lt $bytes.Count; $i++) {
        $hexString += $bytes[$i].ToString("X2");
    }
    return $hexString;
}

# various byte / hex conversion methods + xor test
function test($bytes) {

    $test = "super xor conversion test string";
    $key = "supersecret";

    write-host "XOR encoder / decoder with various byte / hex conversions";    
    write-host "Plain Variable";
    write-host $test;
    
    # XOR bytes with key
    $xor = xor ([system.Text.Encoding]::UTF8.getBytes($test)) $key;
    
    write-host "XOR String (maybe not all character displayed)";    
    write-host "wild bytes: no conversion";
    write-host ([system.Text.Encoding]::UTF8.getString($xor));
    
    write-host "--------------------";
    write-host "[System.BitConverter]::ToString(); string conversion";
    $hex = [System.BitConverter]::ToString($xor) -replace '-', ''; 
    write-host $hex;
    
    write-host "--------------------";
    write-host "(|ForEach-Object ToString X2) -join '' string conversion";
    $hex2 = ($xor|ForEach-Object ToString X2) -join ''
    write-host $hex2;
    
    write-host "--------------------";
    write-host "bytesToHexString() byte array conversion";
    $hexByte = bytesToHexString($xor);
    write-host $hexByte;
    write-host "bytesToHexString() string conversion";
    $hex3 = ($hexByte -join '');
    write-host $hex3;
    
    write-host "--------------------";
    write-host "hexStringToBytes() and bytesToHexString() string conversion";
    $bytes = hexStringToBytes($hex3);
    $hexByte = bytesToHexString($bytes);
    write-host ($hexByte -join '');
    
    write-host "--------------------";
    write-host "XOR String again with key";
    $deXor = xor $xor $key; # xor with same key to get old value
    write-host ([system.Text.Encoding]::UTF8.getString($deXor));   
}

test;