encryptdecrypt

0.8.8

Private/DecryptFile.ps1

                                <#

    .SYNOPSIS 

    Decrypts a file using AES.

    .DESCRIPTION

    Decrypts a file using an AES key.

    .PARAMETER FileToDecrypt

    File(s) to be decrypted

    .PARAMETER Key

    AES key to be used for decryption.

    .EXAMPLE

    DecryptFile 'C:\file.ext.encrypted' $key

    This example decrypts C:\file.ext.encrypted with the key stored in the variable $key.

    .NOTES

    Author: Tyler Siegrist

    Date: 8/23/2016

    https://gallery.technet.microsoft.com/scriptcenter/EncryptDecrypt-files-use-65e7ae5d

#>

Function DecryptFile {

    Param(

       [Parameter(Mandatory=$true, Position=1)]

       [System.IO.FileInfo[]]$FileToDecrypt,

       [Parameter(Mandatory=$true, Position=2)]

       [String]$Key,

       [Parameter(Mandatory=$false, Position=3)]

       [String]$Suffix

    )

    #Load dependencies

    try {

        if ($PSVersionTable.PSEdition -eq "Core") {

            $SystemCoreAssemblyPath = $($(Get-Command pwsh).Source | Split-Path -Parent) + '\System.Core.dll'

            if (!$(Test-Path $SystemCoreAssemblyPath)) {

                Write-Error "The path '$SystemCoreAssemblyPath' was not found! Halting!"

                $global:FunctionResult = "1"

                return

            }

            $null = Add-Type -Path $SystemCoreAssemblyPath

        }

        else {

            [System.Reflection.Assembly]::LoadWithPartialName('System.Security.Cryptography')

        }

    }

    catch {

        Write-Error 'Could not load required assembly.'

        Return

    }

    #Configure AES

    try {

        $EncryptionKey = [System.Convert]::FromBase64String($Key)

        $KeySize = $EncryptionKey.Length*8

        $AESProvider = New-Object 'System.Security.Cryptography.AesManaged'

        $AESProvider.Mode = [System.Security.Cryptography.CipherMode]::CBC

        $AESProvider.BlockSize = 128

        $AESProvider.KeySize = $KeySize

        $AESProvider.Key = $EncryptionKey

    }

    catch {

        Write-Error 'Unable to configure AES, verify you are using a valid key.'

        Return

    }

    #Used to store successfully decrypted file names.

    $DecryptedFiles = @()

    $FailedToDecryptFiles = @()

    foreach ($File in $FileToDecrypt) {

        # Try to decrypt as long as the .decrypted file doesn't already exist

        $DestinationFile = "$($File.FullName).decrypted"

        if (!$(Test-Path $DestinationFile)) {

            #Open file to decrypt

            try {

                $FileStreamReader = New-Object System.IO.FileStream($File.FullName, [System.IO.FileMode]::Open)

            }

            catch {

                Write-Error "Unable to open $($File.FullName) for reading."

                Continue

            }

            #Create destination file

            try {

                $FileStreamWriter = New-Object System.IO.FileStream($DestinationFile, [System.IO.FileMode]::Create)

            }

            catch {

                $FileStreamReader.Close()

                $FileStreamWriter.Close()

                Remove-Item $DestinationFile -Force

                Write-Error "Unable to open $DestinationFile for writing."

                Continue

            }

            #Get IV

            try {

                [Byte[]]$LenIV = New-Object Byte[] 4

                $FileStreamReader.Seek(0, [System.IO.SeekOrigin]::Begin) | Out-Null

                $FileStreamReader.Read($LenIV,  0, 3) | Out-Null

                [Int]$LIV = [System.BitConverter]::ToInt32($LenIV,  0)

                [Byte[]]$IV = New-Object Byte[] $LIV

                $FileStreamReader.Seek(4, [System.IO.SeekOrigin]::Begin) | Out-Null

                $FileStreamReader.Read($IV, 0, $LIV) | Out-Null

                $AESProvider.IV = $IV

            }

            catch {

                $FileStreamReader.Close()

                $FileStreamWriter.Close()

                Remove-Item $DestinationFile -Force

                $FailedToDecryptFiles += $File

                Write-Error "Unable to read IV from $($File.FullName), verify this file was made using the included EncryptFile function."

                Continue

            }

            Write-Verbose "Decrypting $($File.FullName) with an IV of $([System.Convert]::ToBase64String($AESProvider.IV))"

            #Decrypt

            try {

                $Transform = $AESProvider.CreateDecryptor()

                [Int]$Count = 0

                [Int]$BlockSizeBytes = $AESProvider.BlockSize / 8

                [Byte[]]$Data = New-Object Byte[] $BlockSizeBytes

                $CryptoStream = New-Object System.Security.Cryptography.CryptoStream($FileStreamWriter, $Transform, [System.Security.Cryptography.CryptoStreamMode]::Write)

                Do

                {

                    $Count = $FileStreamReader.Read($Data, 0, $BlockSizeBytes)

                    $CryptoStream.Write($Data, 0, $Count)

                }

                While ($Count -gt 0)

                $CryptoStream.FlushFinalBlock()

                $CryptoStream.Close()

                $FileStreamWriter.Close()

                $FileStreamReader.Close()

                #Delete encrypted file

                Remove-Item $File.FullName

                Write-Verbose "Successfully decrypted $($File.FullName)"

                $DecryptedFiles += $DestinationFile

            }

            catch {

                Write-Error "Failed to decrypt $($File.FullName)."

                $CryptoStream.Close()

                $FileStreamWriter.Close()

                $FileStreamReader.Close()

                Remove-Item $DestinationFile

                $FailedToDecryptFiles += $File

            }

        }        

    }

    $Result = New-Object -TypeName PSObject

    $Result | Add-Member -MemberType NoteProperty -Name Computer -Value $env:COMPUTERNAME

    $Result | Add-Member -MemberType NoteProperty -Name AESKey -Value $Key

    $Result | Add-Member -MemberType NoteProperty -Name FilesDecryptedwAESKey -Value $DecryptedFiles

    $Result | Add-Member -MemberType NoteProperty -Name FilesFailedToDecrypt -Value $FailedToDecryptFiles

    return $Result

}

# SIG # Begin signature block

# MIIMiAYJKoZIhvcNAQcCoIIMeTCCDHUCAQExCzAJBgUrDgMCGgUAMGkGCisGAQQB

# gjcCAQSgWzBZMDQGCisGAQQBgjcCAR4wJgIDAQAABBAfzDtgWUsITrck0sYpfvNR

# AgEAAgEAAgEAAgEAAgEAMCEwCQYFKw4DAhoFAAQU+Qq9ZQVraxaAi3yRRRoZ2Tzj

# brygggn9MIIEJjCCAw6gAwIBAgITawAAAB/Nnq77QGja+wAAAAAAHzANBgkqhkiG

# 9w0BAQsFADAwMQwwCgYDVQQGEwNMQUIxDTALBgNVBAoTBFpFUk8xETAPBgNVBAMT

# CFplcm9EQzAxMB4XDTE3MDkyMDIxMDM1OFoXDTE5MDkyMDIxMTM1OFowPTETMBEG

# CgmSJomT8ixkARkWA0xBQjEUMBIGCgmSJomT8ixkARkWBFpFUk8xEDAOBgNVBAMT

# B1plcm9TQ0EwggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDCwqv+ROc1

# bpJmKx+8rPUUfT3kPSUYeDxY8GXU2RrWcL5TSZ6AVJsvNpj+7d94OEmPZate7h4d

# gJnhCSyh2/3v0BHBdgPzLcveLpxPiSWpTnqSWlLUW2NMFRRojZRscdA+e+9QotOB

# aZmnLDrlePQe5W7S1CxbVu+W0H5/ukte5h6gsKa0ktNJ6X9nOPiGBMn1LcZV/Ksl

# lUyuTc7KKYydYjbSSv2rQ4qmZCQHqxyNWVub1IiEP7ClqCYqeCdsTtfw4Y3WKxDI

# JaPmWzlHNs0nkEjvnAJhsRdLFbvY5C2KJIenxR0gA79U8Xd6+cZanrBUNbUC8GCN

# wYkYp4A4Jx+9AgMBAAGjggEqMIIBJjASBgkrBgEEAYI3FQEEBQIDAQABMCMGCSsG

# AQQBgjcVAgQWBBQ/0jsn2LS8aZiDw0omqt9+KWpj3DAdBgNVHQ4EFgQUicLX4r2C

# Kn0Zf5NYut8n7bkyhf4wGQYJKwYBBAGCNxQCBAweCgBTAHUAYgBDAEEwDgYDVR0P

# AQH/BAQDAgGGMA8GA1UdEwEB/wQFMAMBAf8wHwYDVR0jBBgwFoAUdpW6phL2RQNF

# 7AZBgQV4tgr7OE0wMQYDVR0fBCowKDAmoCSgIoYgaHR0cDovL3BraS9jZXJ0ZGF0

# YS9aZXJvREMwMS5jcmwwPAYIKwYBBQUHAQEEMDAuMCwGCCsGAQUFBzAChiBodHRw

# Oi8vcGtpL2NlcnRkYXRhL1plcm9EQzAxLmNydDANBgkqhkiG9w0BAQsFAAOCAQEA

# tyX7aHk8vUM2WTQKINtrHKJJi29HaxhPaHrNZ0c32H70YZoFFaryM0GMowEaDbj0

# a3ShBuQWfW7bD7Z4DmNc5Q6cp7JeDKSZHwe5JWFGrl7DlSFSab/+a0GQgtG05dXW

# YVQsrwgfTDRXkmpLQxvSxAbxKiGrnuS+kaYmzRVDYWSZHwHFNgxeZ/La9/8FdCir

# MXdJEAGzG+9TwO9JvJSyoGTzu7n93IQp6QteRlaYVemd5/fYqBhtskk1zDiv9edk

# mHHpRWf9Xo94ZPEy7BqmDuixm4LdmmzIcFWqGGMo51hvzz0EaE8K5HuNvNaUB/hq

# MTOIB5145K8bFOoKHO4LkTCCBc8wggS3oAMCAQICE1gAAAH5oOvjAv3166MAAQAA

# AfkwDQYJKoZIhvcNAQELBQAwPTETMBEGCgmSJomT8ixkARkWA0xBQjEUMBIGCgmS

# JomT8ixkARkWBFpFUk8xEDAOBgNVBAMTB1plcm9TQ0EwHhcNMTcwOTIwMjE0MTIy

# WhcNMTkwOTIwMjExMzU4WjBpMQswCQYDVQQGEwJVUzELMAkGA1UECBMCUEExFTAT

# BgNVBAcTDFBoaWxhZGVscGhpYTEVMBMGA1UEChMMRGlNYWdnaW8gSW5jMQswCQYD

# VQQLEwJJVDESMBAGA1UEAxMJWmVyb0NvZGUyMIIBIjANBgkqhkiG9w0BAQEFAAOC

# AQ8AMIIBCgKCAQEAxX0+4yas6xfiaNVVVZJB2aRK+gS3iEMLx8wMF3kLJYLJyR+l

# rcGF/x3gMxcvkKJQouLuChjh2+i7Ra1aO37ch3X3KDMZIoWrSzbbvqdBlwax7Gsm

# BdLH9HZimSMCVgux0IfkClvnOlrc7Wpv1jqgvseRku5YKnNm1JD+91JDp/hBWRxR

# 3Qg2OR667FJd1Q/5FWwAdrzoQbFUuvAyeVl7TNW0n1XUHRgq9+ZYawb+fxl1ruTj

# 3MoktaLVzFKWqeHPKvgUTTnXvEbLh9RzX1eApZfTJmnUjBcl1tCQbSzLYkfJlJO6

# eRUHZwojUK+TkidfklU2SpgvyJm2DhCtssFWiQIDAQABo4ICmjCCApYwDgYDVR0P

# AQH/BAQDAgeAMBMGA1UdJQQMMAoGCCsGAQUFBwMDMB0GA1UdDgQWBBS5d2bhatXq

# eUDFo9KltQWHthbPKzAfBgNVHSMEGDAWgBSJwtfivYIqfRl/k1i63yftuTKF/jCB

# 6QYDVR0fBIHhMIHeMIHboIHYoIHVhoGubGRhcDovLy9DTj1aZXJvU0NBKDEpLENO

# PVplcm9TQ0EsQ049Q0RQLENOPVB1YmxpYyUyMEtleSUyMFNlcnZpY2VzLENOPVNl

# cnZpY2VzLENOPUNvbmZpZ3VyYXRpb24sREM9emVybyxEQz1sYWI/Y2VydGlmaWNh

# dGVSZXZvY2F0aW9uTGlzdD9iYXNlP29iamVjdENsYXNzPWNSTERpc3RyaWJ1dGlv

# blBvaW50hiJodHRwOi8vcGtpL2NlcnRkYXRhL1plcm9TQ0EoMSkuY3JsMIHmBggr

# BgEFBQcBAQSB2TCB1jCBowYIKwYBBQUHMAKGgZZsZGFwOi8vL0NOPVplcm9TQ0Es

# Q049QUlBLENOPVB1YmxpYyUyMEtleSUyMFNlcnZpY2VzLENOPVNlcnZpY2VzLENO

# PUNvbmZpZ3VyYXRpb24sREM9emVybyxEQz1sYWI/Y0FDZXJ0aWZpY2F0ZT9iYXNl

# P29iamVjdENsYXNzPWNlcnRpZmljYXRpb25BdXRob3JpdHkwLgYIKwYBBQUHMAKG

# Imh0dHA6Ly9wa2kvY2VydGRhdGEvWmVyb1NDQSgxKS5jcnQwPQYJKwYBBAGCNxUH

# BDAwLgYmKwYBBAGCNxUIg7j0P4Sb8nmD8Y84g7C3MobRzXiBJ6HzzB+P2VUCAWQC

# AQUwGwYJKwYBBAGCNxUKBA4wDDAKBggrBgEFBQcDAzANBgkqhkiG9w0BAQsFAAOC

# AQEAszRRF+YTPhd9UbkJZy/pZQIqTjpXLpbhxWzs1ECTwtIbJPiI4dhAVAjrzkGj

# DyXYWmpnNsyk19qE82AX75G9FLESfHbtesUXnrhbnsov4/D/qmXk/1KD9CE0lQHF

# Lu2DvOsdf2mp2pjdeBgKMRuy4cZ0VCc/myO7uy7dq0CvVdXRsQC6Fqtr7yob9NbE

# OdUYDBAGrt5ZAkw5YeL8H9E3JLGXtE7ir3ksT6Ki1mont2epJfHkO5JkmOI6XVtg

# anuOGbo62885BOiXLu5+H2Fg+8ueTP40zFhfLh3e3Kj6Lm/NdovqqTBAsk04tFW9

# Hp4gWfVc0gTDwok3rHOrfIY35TGCAfUwggHxAgEBMFQwPTETMBEGCgmSJomT8ixk

# ARkWA0xBQjEUMBIGCgmSJomT8ixkARkWBFpFUk8xEDAOBgNVBAMTB1plcm9TQ0EC

# E1gAAAH5oOvjAv3166MAAQAAAfkwCQYFKw4DAhoFAKB4MBgGCisGAQQBgjcCAQwx

# CjAIoAKAAKECgAAwGQYJKoZIhvcNAQkDMQwGCisGAQQBgjcCAQQwHAYKKwYBBAGC

# NwIBCzEOMAwGCisGAQQBgjcCARUwIwYJKoZIhvcNAQkEMRYEFAVKUt0aaWVeOO5F

# K0L1FXSaVv5JMA0GCSqGSIb3DQEBAQUABIIBAL7J3MAF2xCHrzHUDc1rpDKZutwZ

# ZP15297MUWskw1gwW8m5vUPsisercLEQKo8S6MwCLMyG3LFZ+hhF1Bx/XQUw+oq1

# pU+FcCzS1eqrF4NMsnB4gCivmHMGAZskxoiyEiesDiqMqZbxO8X78NhMsb0J6jyB

# 4Dxy2xbUvKRRmHjaQnAlFMQwglvIeQuJfVWMNEVaTCDUCCqr0oy68IarFv0+COPn

# ng6YCriLOYWgoLHYEJCe39lxtmVH/WoYB8RtzRw/0ByMAf+aCiADXDXapD2PEqDT

# 5DkK3aup1VaMj8s5uE8vZ2x9hwOu7mdVPnZ7cC6KOum44dxZEVp+U5BfkKI=

# SIG # End signature block