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147 lines
5.2 KiB
PowerShell
Executable File
147 lines
5.2 KiB
PowerShell
Executable File
<#
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.SYNOPSIS
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Decrypts a file
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.DESCRIPTION
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This PowerShell script decrypts a file using the given password and AES encryption.
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.PARAMETER Path
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Specifies the path to the file to decrypt
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.PARAMETER Password
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Specifies the password
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.EXAMPLE
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PS> ./decrypt-file.ps1 C:\MyFile.txt "123"
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.LINK
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https://github.com/fleschutz/PowerShell
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.NOTES
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Author: Markus Fleschutz | License: CC0
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#>
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param([string]$Path = "", [string]$Password = "")
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function DecryptFile {
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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,
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[Parameter()]
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[Switch]$RemoveSource
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)
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Process
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{
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try
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{
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if($PSCmdlet.ParameterSetName -eq 'PlainText')
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{
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$Key = $KeyAsPlainText | ConvertTo-SecureString -AsPlainText -Force
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}
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$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 = ".$Algorithm"
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}
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$Files = Get-Item -LiteralPath $FileName
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ForEach($File in $Files)
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{
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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($DestinationFile, [System.IO.FileMode]::Create)
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[Byte[]]$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 = $IV
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$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($CryptoStream)
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$CryptoStream.FlushFinalBlock()
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$CryptoStream.Close()
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$FileStreamReader.Close()
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$FileStreamWriter.Close()
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if($RemoveSource){Remove-Item $File.FullName}
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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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$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 "" ) { $Path = read-host "Enter path to file" }
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if ($Password -eq "" ) { $Password = read-host "Enter password" }
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$StopWatch = [system.diagnostics.stopwatch]::startNew()
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$PasswordBase64 = [System.Convert]::ToBase64String($Password)
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DecryptFile "$Path" -Algorithm AES -KeyAsPlainText $PasswordBase64 -RemoveSource
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[int]$Elapsed = $StopWatch.Elapsed.TotalSeconds
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"✔️ file decrypted in $Elapsed sec"
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exit 0 # success
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} catch {
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"⚠️ Error in line $($_.InvocationInfo.ScriptLineNumber): $($Error[0])"
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exit 1
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}
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