Windows File Encryption

Import

# Requires [Invoke-AESEncryption.ps1] PowerShell Script
# Import the PowerShell Script
Import-Module .\Invoke-AESEncryption.ps1

Target

# Encrypt File
Invoke-AESEncryption.ps1 -Mode Encrypt -Key "<Password>" -Path <File To Encrypt>

# Decrypt File
Invoke-AESEncryption -Mode Decrypt -Key "<Password>" -Path <File To Decrypt>

PowerShell Script

<#
.SYNOPSIS
Encryptes or Decrypts Strings or Byte-Arrays with AES
 
.DESCRIPTION
Takes a String or File and a Key and encrypts or decrypts it with AES256 (CBC)
 
.PARAMETER Mode
Encryption or Decryption Mode
 
.PARAMETER Key
Key used to encrypt or decrypt
 
.PARAMETER Text
String value to encrypt or decrypt
 
.PARAMETER Path
Filepath for file to encrypt or decrypt
 
.EXAMPLE
Invoke-AESEncryption -Mode Encrypt -Key "p@ssw0rd" -Text "Secret Text"
 
Description
-----------
Encrypts the string "Secret Test" and outputs a Base64 encoded cipher text.
 
.EXAMPLE
Invoke-AESEncryption -Mode Decrypt -Key "p@ssw0rd" -Text "LtxcRelxrDLrDB9rBD6JrfX/czKjZ2CUJkrg++kAMfs="
 
Description
-----------
Decrypts the Base64 encoded string "LtxcRelxrDLrDB9rBD6JrfX/czKjZ2CUJkrg++kAMfs=" and outputs plain text.
 
.EXAMPLE
Invoke-AESEncryption -Mode Encrypt -Key "p@ssw0rd" -Path file.bin
 
Description
-----------
Encrypts the file "file.bin" and outputs an encrypted file "file.bin.aes"
 
.EXAMPLE
Invoke-AESEncryption -Mode Encrypt -Key "p@ssw0rd" -Path file.bin.aes
 
Description
-----------
Decrypts the file "file.bin.aes" and outputs an encrypted file "file.bin"
#>
function Invoke-AESEncryption {
    [CmdletBinding()]
    [OutputType([string])]
    Param
    (
        [Parameter(Mandatory = $true)]
        [ValidateSet('Encrypt', 'Decrypt')]
        [String]$Mode,

        [Parameter(Mandatory = $true)]
        [String]$Key,

        [Parameter(Mandatory = $true, ParameterSetName = "CryptText")]
        [String]$Text,

        [Parameter(Mandatory = $true, ParameterSetName = "CryptFile")]
        [String]$Path
    )

    Begin {
        $shaManaged = New-Object System.Security.Cryptography.SHA256Managed
        $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
    }

    Process {
        $aesManaged.Key = $shaManaged.ComputeHash([System.Text.Encoding]::UTF8.GetBytes($Key))

        switch ($Mode) {
            'Encrypt' {
                if ($Text) {$plainBytes = [System.Text.Encoding]::UTF8.GetBytes($Text)}
                
                if ($Path) {
                    $File = Get-Item -Path $Path -ErrorAction SilentlyContinue
                    if (!$File.FullName) {
                        Write-Error -Message "File not found!"
                        break
                    }
                    $plainBytes = [System.IO.File]::ReadAllBytes($File.FullName)
                    $outPath = $File.FullName + ".aes"
                }

                $encryptor = $aesManaged.CreateEncryptor()
                $encryptedBytes = $encryptor.TransformFinalBlock($plainBytes, 0, $plainBytes.Length)
                $encryptedBytes = $aesManaged.IV + $encryptedBytes
                $aesManaged.Dispose()

                if ($Text) {return [System.Convert]::ToBase64String($encryptedBytes)}
                
                if ($Path) {
                    [System.IO.File]::WriteAllBytes($outPath, $encryptedBytes)
                    (Get-Item $outPath).LastWriteTime = $File.LastWriteTime
                    return "File encrypted to $outPath"
                }
            }

            'Decrypt' {
                if ($Text) {$cipherBytes = [System.Convert]::FromBase64String($Text)}
                
                if ($Path) {
                    $File = Get-Item -Path $Path -ErrorAction SilentlyContinue
                    if (!$File.FullName) {
                        Write-Error -Message "File not found!"
                        break
                    }
                    $cipherBytes = [System.IO.File]::ReadAllBytes($File.FullName)
                    $outPath = $File.FullName -replace ".aes"
                }

                $aesManaged.IV = $cipherBytes[0..15]
                $decryptor = $aesManaged.CreateDecryptor()
                $decryptedBytes = $decryptor.TransformFinalBlock($cipherBytes, 16, $cipherBytes.Length - 16)
                $aesManaged.Dispose()

                if ($Text) {return [System.Text.Encoding]::UTF8.GetString($decryptedBytes).Trim([char]0)}
                
                if ($Path) {
                    [System.IO.File]::WriteAllBytes($outPath, $decryptedBytes)
                    (Get-Item $outPath).LastWriteTime = $File.LastWriteTime
                    return "File decrypted to $outPath"
                }
            }
        }
    }

    End {
        $shaManaged.Dispose()
        $aesManaged.Dispose()
    }
}

Linux File Encryption

Encrypt

:: Encrypt with [OpenSSL] using AES256
openssl enc -aes256 -iter 100000 -pbkdf2 -in <File To Encrypt> -out <Output>

Decrypt

openssl enc -d -aes256 -iter 100000 -pbkdf2 -in <File To Decrypt> -out <Output>