Aes Encryption using powershell.

PowershellAes.ps1

function Create-AesManagedObject($key, $IV) {
    $aesManaged = New-Object "System.Security.Cryptography.AesManaged"
    $aesManaged.Mode = [System.Security.Cryptography.CipherMode]::CBC
    $aesManaged.Padding = [System.Security.Cryptography.PaddingMode]::Zeros
    $aesManaged.BlockSize = 128
    $aesManaged.KeySize = 256
    if ($IV) {
        if ($IV.getType().Name -eq "String") {
            $aesManaged.IV = [System.Convert]::FromBase64String($IV)
        }
        else {
            $aesManaged.IV = $IV
        }
    }
    if ($key) {
        if ($key.getType().Name -eq "String") {
            $aesManaged.Key = [System.Convert]::FromBase64String($key)
        }
        else {
            $aesManaged.Key = $key
        }
    }
    $aesManaged
}

function Create-AesKey() {
    $aesManaged = Create-AesManagedObject
    $aesManaged.GenerateKey()
    [System.Convert]::ToBase64String($aesManaged.Key)
}

function Encrypt-String($key, $unencryptedString) {
    $bytes = [System.Text.Encoding]::UTF8.GetBytes($unencryptedString)
    $aesManaged = Create-AesManagedObject $key
    $encryptor = $aesManaged.CreateEncryptor()
    $encryptedData = $encryptor.TransformFinalBlock($bytes, 0, $bytes.Length);
    [byte[]] $fullData = $aesManaged.IV + $encryptedData
    $aesManaged.Dispose()
    [System.Convert]::ToBase64String($fullData)
}

function Decrypt-String($key, $encryptedStringWithIV) {
    $bytes = [System.Convert]::FromBase64String($encryptedStringWithIV)
    $IV = $bytes[0..15]
    $aesManaged = Create-AesManagedObject $key $IV
    $decryptor = $aesManaged.CreateDecryptor();
    $unencryptedData = $decryptor.TransformFinalBlock($bytes, 16, $bytes.Length - 16);
    $aesManaged.Dispose()
    [System.Text.Encoding]::UTF8.GetString($unencryptedData).Trim([char]0)
}

$key = Create-AesKey
$key
$unencryptedString = "blahblahblah"
$encryptedString = Encrypt-String $key $unencryptedString
$backToPlainText = Decrypt-String $key $encryptedString

@wbrianwhite Glad I could help, good luck with your scriptwork.

Hey, just tried your functions today, and thanks, looks great. Good job

I did, however get an error after updating with your latest notes. The size of the key is invalid when I use $aesManaged.Key = [Text.Encoding]::UTF8.GetBytes($key) , but when I switch back to FromBase64String it works..

Pretty new to this whole encryption thing, so no idea why, but probably something I've forgotten.. Anyway, works with the first part.

@Zorahn , might have something to do with the characterset you are using. But that is the main reason when I make changes like this, I always put the old stuff in the comments. Please note I am not the original creator of this Example so all credits go to @ctigeek

Glad it works for you, Encryption is a very tricky thing. It took me a while as well to get it working for my purpose.

Very nice project in PowerShell.
As block cipher mode, I see that we can only use the following: CBC,ECB,OFB,CFB,CTS.
How can we implement the GCM in this code?

Up @ctigeek

@D3vil0p3r I created AES+GCM wrapper for my own purposes

You might find this helpful:
https://github.com/PowerShellLibrary/Crypto.AES

@D3vil0p3r I created AES+GCM wrapper for my own purposes

You might find this helpful: https://github.com/PowerShellLibrary/Crypto.AES

Thank you @alan-null I appreciate this. I will give a look to it in the next days.