Powershell 之加解密

9oijl1111

#################
# Powershell Allows The Loading of .NET Assemblies
# Load the Security assembly to use with this script  
#################
[Reflection.Assembly]::LoadWithPartialName("System.Security")
#################
# This function is to Encrypt A String.
# $string is the string to encrypt, $passphrase is a second security "password" that has to be passed to decrypt.
# $salt is used during the generation of the crypto password to prevent password guessing.
# $init is used to compute the crypto hash -- a checksum of the encryption
#################
function Encrypt-String($String, $Passphrase, $salt="SaltCrypto", $init="IV_Password", [switch]$arrayOutput)
{
    # Create a COM Object for RijndaelManaged Cryptography
    $r = new-Object System.Security.Cryptography.RijndaelManaged
    # Convert the Passphrase to UTF8 Bytes
    $pass = [Text.Encoding]::UTF8.GetBytes($Passphrase)
    # Convert the Salt to UTF Bytes
    $salt = [Text.Encoding]::UTF8.GetBytes($salt)
   
    # Create the Encryption Key using the passphrase, salt and SHA1 algorithm at 256 bits
    $r.Key = (new-Object Security.Cryptography.PasswordDeriveBytes $pass, $salt, "SHA1", 5).GetBytes(32) #256/8
    # Create the Intersecting Vector Cryptology Hash with the init
    $r.IV = (new-Object Security.Cryptography.SHA1Managed).ComputeHash( [Text.Encoding]::UTF8.GetBytes($init) )[0..15]
      
    # Starts the New Encryption using the Key and IV
    $c = $r.CreateEncryptor()
    # Creates a MemoryStream to do the encryption in
    $ms = new-Object IO.MemoryStream
    # Creates the new Cryptology Stream --> Outputs to $MS or Memory Stream
    $cs = new-Object Security.Cryptography.CryptoStream $ms,$c,"Write"
    # Starts the new Cryptology Stream
    $sw = new-Object IO.StreamWriter $cs
    # Writes the string in the Cryptology Stream
    $sw.Write($String)
    # Stops the stream writer
    $sw.Close()
    # Stops the Cryptology Stream
    $cs.Close()
    # Stops writing to Memory
    $ms.Close()
    # Clears the IV and HASH from memory to prevent memory read attacks
    $r.Clear()
    # Takes the MemoryStream and puts it to an array
    [byte[]]$result = $ms.ToArray()
    # Converts the array from Base 64 to a string and returns
    return [Convert]::ToBase64String($result)
}


function Decrypt-String($Encrypted, $Passphrase, $salt="SaltCrypto", $init="IV_Password")
{
    # If the value in the Encrypted is a string, convert it to Base64
    if($Encrypted -is [string]){
        $Encrypted = [Convert]::FromBase64String($Encrypted)
    }
   
    # Create a COM Object for RijndaelManaged Cryptography
    $r = new-Object System.Security.Cryptography.RijndaelManaged
    # Convert the Passphrase to UTF8 Bytes
    $pass = [Text.Encoding]::UTF8.GetBytes($Passphrase)
    # Convert the Salt to UTF Bytes
    $salt = [Text.Encoding]::UTF8.GetBytes($salt)
   
    # Create the Encryption Key using the passphrase, salt and SHA1 algorithm at 256 bits     
    $r.Key = (new-Object Security.Cryptography.PasswordDeriveBytes $pass, $salt, "SHA1", 5).GetBytes(32) #256/8     
    # Create the Intersecting Vector Cryptology Hash with the init     
    $r.IV = (new-Object Security.Cryptography.SHA1Managed).ComputeHash( [Text.Encoding]::UTF8.GetBytes($init) )[0..15]
   
    # Create a new Decryptor
    $d = $r.CreateDecryptor()
    # Create a New memory stream with the encrypted value.
    $ms = new-Object IO.MemoryStream @(,$Encrypted)
    # Read the new memory stream and read it in the cryptology stream
    $cs = new-Object Security.Cryptography.CryptoStream $ms,$d,"Read"
    # Read the new decrypted stream
    $sr = new-Object IO.StreamReader $cs
    # Return from the function the stream
    Write-Output $sr.ReadToEnd()
    # Stops the stream
    $sr.Close()
    # Stops the crypology stream
    $cs.Close()
    # Stops the memory stream
    $ms.Close()
    # Clears the RijndaelManaged Cryptology IV and Key
    $r.Clear()
}
# This clears the screen of the output from the loading of the assembly. cls
# $me will never = 1, so It will run indefinately $me = 0
    write-host "To End This Application, Close the Window"  
    Write-host ""
do
{
    # Prompt the user for the password
    $string = read-host "Please Enter User Password"
    # Encrypt the string and store it into the $encrypted variable
    $encrypted = Encrypt-String $string "MyStrongPassword"
    # Write result to the screen
    write-host "Encrypted Password is: $encrypted"
    write-host ""
   
    write-host "Testing Decryption of Password..."
      
    # Decrypts the string and stores the decrypted value in $decrypted
    $decrypted = Decrypt-String $encrypted "MyStrongPassword"
    # Writes the decrpted value to the screen
    write-host "Decrypted Password is: $decrypted"
    write-host ""
}
while ($me -ne 1)