Powershell encode with powershell commands

Question

I have below powershell commands,

$tmp = Get-Content 'C:\Users\username\Documents\emp_details.txt'
$tmp[0..75], ':tech emp details', $tmp[76.. ($tmp.Count -1)] | 
    Set-Content 'C:\Users\username\Documents\emp_details.txt'

which I want to encode and this entire commands as string and store it to variable and then will decode and execute it whenever I needed. But when I tried to decode using below which internally executes the Get-Content command as well.

$Bytes = [System.Text.Encoding]::Unicode.GetBytes("$tmp = Get-Content 'C:\Users\username\Documents\emp_details.txt'
$tmp[0..75], ':tech emp details', $tmp[76.. ($tmp.Count -1)] | 
    Set-Content 'C:\Users\username\Documents\emp_details.txt'")
$EncodedText =[Convert]::ToBase64String($Bytes)
$EncodedText

Any idea please to encode those commands as strings without executing those commands internally.

On another note, the first code block appears to be reading and writing to the same file. Has this worked well? — lit
– lit, Commented May 6, 2017 at 16:55

lit · Accepted Answer · 2017-05-06 17:24:09Z

2

Phil's suggestion of making a script block is a good one. Here is how to store the command into a variable $thecmd.

$thecmd = {$tmp = Get-Content "C:\Users\$Env:USERNAME\Documents\$emp_details.txt"
    $tmp[0..75], ':tech emp details', $tmp[76.. ($tmp.Count -1)] | 
    Set-Content "C:\Users\$Env:USERNAME\Documents\emp_details_out.txt"}

The value of $thecmd will be the scriptblock text. In order to run it, use the invocation operator (&).

& $thecmd

I changed your hardcoded path to use the $Env:USERNAME variable. Also, what happens if the source text file does not have at least 75 lines?

answered May 6, 2017 at 17:24

lit

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6 Comments

Karthi1234 Over a year ago

Am pretty sure the content would be there on all file, since it was copied myself only but missed to add one line. It works perfect. But its not working when I try to encode and decode and then execute it. Below the syntax which I attempted

$readbytes = [System.Text.Encoding]::Unicode.GetBytes($thecmd) $ecryptString =[Convert]::ToBase64String($readbytes) $decryptString = [System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String($ecryptString)) & $decryptString

Karthi1234 Over a year ago

Getting below error,

The term '$tmp = Get-Content "C:\Users\$Env:USERNAME\Documents\$emp_details.txt"     $tmp[0..75], ':tech emp details', $tmp[76.. ($tmp.Count -1)] |      Set-Content "C:\Users\$Env:USERNAME\Documents\emp_details_out.txt"' is not recognized as the name of a cmdlet, func tion, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path  is correct and try again.

lit Over a year ago

I do not see the invocation operator before $thecmd. Please edit code into the question. It is too difficult to read in a comment.

Karthi1234 Over a year ago

Found the issue, When we encrypt and decrypt the ScriptBlock is converted to String type, so had to convert back to ScriptBlock to make it work, Thanks

lit Over a year ago

My guess is that the invocation operator (`&) converts the string to a scriptblock. It would be helpful if you could edit the working code into the question.

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