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Added encrypt-file.ps1 and decrypt-file.ps1
This commit is contained in:
Markus Fleschutz
197
Scripts/decrypt-file.ps1
Executable file
197
Scripts/decrypt-file.ps1
Executable file
@ -0,0 +1,197 @@
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#!/snap/bin/powershell
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<#
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.SYNTAX ./decrypt-file.ps1 [<path>] [<password>]
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.DESCRIPTION decrypts the given file
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.LINK https://github.com/fleschutz/PowerShell
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.NOTES Author: Markus Fleschutz / License: CC0
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#>
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param([string]$Path = "", [string]$Password = "")
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Set-StrictMode -Version Latest
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Function Unprotect-File
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{
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<#
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.SYNOPSIS
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Decrypts a file encrypted with Protect-File.
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.DESCRIPTION
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Decrypts a file using a provided cryptography key.
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.PARAMETER FileName
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File(s) to be decrypted.
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.PARAMETER Key
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Cryptography key as a SecureString be used for decryption.
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.PARAMETER KeyAsPlainText
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Cryptography key as a String to be used for decryption.
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.PARAMETER CipherMode
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Specifies the block cipher mode that was used for encryption.
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.PARAMETER PaddingMode
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Specifies the type of padding that was applied when the message data block was shorter than the full number of bytes needed for a cryptographic operation.
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.PARAMETER Suffix
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Suffix of the encrypted file to be removed.
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.PARAMETER RemoveSource
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Removes the source (encrypted) file after decrypting.
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.OUTPUTS
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System.IO.FileInfo. Unprotect-File will return FileInfo with the SourceFile as an added NoteProperty
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.EXAMPLE
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Unprotect-File 'C:\secrets.txt.AES' $key
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This example decrypts C:\secrets.txt.AES using the key stored in the variable $key. The decrypted file would remove the default extension of '.AES' and the source (encrypted) file would not be removed.
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.EXAMPLE
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Unprotect-File 'C:\secrets.txt.Encrypted' -Algorithm DES -Key $key -Suffix '.Encrypted' -RemoveSource
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This example decrypts C:\secrets.txt.Encrypted using DES and the key stored in the variable $key. The decrypted file would remove the extension of '.Encrypted' and the source (encrypted) file would be removed.
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.EXAMPLE
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Get-ChildItem 'C:\Files' -Recurse | Unprotect-File -Algorithm AES -Key $key -RemoveSource
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This example decrypts all of the files under the C:\Files directory using the key stored in the variable $key. The decrypted files would remove the default extension of '.AES' and the source (encrypted) files would be removed.
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.NOTES
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Author: Tyler Siegrist
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Date: 9/22/2017
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#>
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[CmdletBinding(DefaultParameterSetName='SecureString')]
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[OutputType([System.IO.FileInfo[]])]
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Param(
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[Parameter(Mandatory=$true, Position=1, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true)]
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[Alias('PSPath','LiteralPath')]
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[string[]]$FileName,
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[Parameter(Mandatory=$false, Position=2, ValueFromPipelineByPropertyName=$true)]
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[ValidateSet('AES','DES','RC2','Rijndael','TripleDES')]
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[String]$Algorithm = 'AES',
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[Parameter(Mandatory=$true, Position=3, ValueFromPipelineByPropertyName=$true, ParameterSetName='SecureString')]
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[System.Security.SecureString]$Key,
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[Parameter(Mandatory=$true, Position=3, ParameterSetName='PlainText')]
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[String]$KeyAsPlainText,
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[Parameter(Mandatory=$false, Position=4, ValueFromPipelineByPropertyName=$true)]
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[System.Security.Cryptography.CipherMode]$CipherMode = 'CBC',
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[Parameter(Mandatory=$false, Position=5, ValueFromPipelineByPropertyName=$true)]
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[System.Security.Cryptography.PaddingMode]$PaddingMode = 'PKCS7',
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[Parameter(Mandatory=$false, Position=6)]
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[String]$Suffix, #Assigning default value in code due to it not processing ".$Algorithm" properly when Algorithm is ValueFromPipelineByPropertyName
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[Parameter()]
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[Switch]$RemoveSource
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)
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Process
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{
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#Configure cryptography
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try
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{
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if($PSCmdlet.ParameterSetName -eq 'PlainText')
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{
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$Key = $KeyAsPlainText | ConvertTo-SecureString -AsPlainText -Force
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}
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#Decrypt cryptography Key from SecureString
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$BSTR = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($Key)
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$EncryptionKey = [System.Convert]::FromBase64String([System.Runtime.InteropServices.Marshal]::PtrToStringAuto($BSTR))
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$Crypto = [System.Security.Cryptography.SymmetricAlgorithm]::Create($Algorithm)
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$Crypto.Mode = $CipherMode
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$Crypto.Padding = $PaddingMode
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$Crypto.KeySize = $EncryptionKey.Length*8
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$Crypto.Key = $EncryptionKey
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}
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Catch
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{
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Write-Error $_ -ErrorAction Stop
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}
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if(-not $PSBoundParameters.ContainsKey('Suffix'))
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{
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$Suffix = ".$Algorithm"
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}
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#Used to store successfully decrypted file names.
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$Files = Get-Item -LiteralPath $FileName
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ForEach($File in $Files)
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{
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#Verify file ends with supplied suffix
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If(-not $File.Name.EndsWith($Suffix))
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{
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Write-Error "$($File.FullName) does not have an extension of '$Suffix'."
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Continue
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}
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$DestinationFile = $File.FullName -replace "$Suffix$"
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Try
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{
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$FileStreamReader = New-Object System.IO.FileStream($File.FullName, [System.IO.FileMode]::Open)
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$FileStreamWriter = New-Object System.IO.FileStream($DestinationFile, [System.IO.FileMode]::Create)
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#Get IV from file
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[Byte[]]$LenIV = New-Object Byte[] 4
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$FileStreamReader.Seek(0, [System.IO.SeekOrigin]::Begin) | Out-Null
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$FileStreamReader.Read($LenIV, 0, 3) | Out-Null
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[Int]$LIV = [System.BitConverter]::ToInt32($LenIV, 0)
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[Byte[]]$IV = New-Object Byte[] $LIV
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$FileStreamReader.Seek(4, [System.IO.SeekOrigin]::Begin) | Out-Null
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$FileStreamReader.Read($IV, 0, $LIV) | Out-Null
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$Crypto.IV = $IV
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#Peform Decryption
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$Transform = $Crypto.CreateDecryptor()
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$CryptoStream = New-Object System.Security.Cryptography.CryptoStream($FileStreamWriter, $Transform, [System.Security.Cryptography.CryptoStreamMode]::Write)
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$FileStreamReader.CopyTo($CryptoStream)
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#Close open files
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$CryptoStream.FlushFinalBlock()
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$CryptoStream.Close()
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$FileStreamReader.Close()
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$FileStreamWriter.Close()
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#Delete encrypted file
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if($RemoveSource){Remove-Item $File.FullName}
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#Output decrypted file
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Get-Item $DestinationFile | Add-Member –MemberType NoteProperty –Name SourceFile –Value $File.FullName -PassThru
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}
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Catch
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{
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Write-Error $_
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If($FileStreamWriter)
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{
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#Remove failed file
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$FileStreamWriter.Close()
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Remove-Item -LiteralPath $DestinationFile -Force
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}
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Continue
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}
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Finally
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{
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if($CryptoStream){$CryptoStream.Close()}
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if($FileStreamReader){$FileStreamReader.Close()}
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if($FileStreamWriter){$FileStreamWriter.Close()}
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}
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}
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}
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}
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try {
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if ($Path -eq "" ) {
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$Path = read-host "Enter path to file"
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}
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if ($Password -eq "" ) {
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$Password = read-host "Enter password"
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}
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$PasswordBase64 = [System.Convert]::ToBase64String($Password)
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Unprotect-File "$Path" -algorithm AES -keyAsPlainText $PasswordBase64 -removeSource
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write-output "OK."
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exit 0
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} catch {
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write-error "ERROR in line $($_.InvocationInfo.ScriptLineNumber): $($Error[0])"
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exit 1
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}
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