DES 加密和解密文件,檔案型

Imports System
Imports System.IO
Imports System.Security
Imports System.Security.Cryptography
Imports System.Text

Module Encrypt
Private Const sSecretKey As String = "password"

Public Sub Main()
EncryptFile("c:\temp\test.txt", _
"c:\temp\Encrypted.txt", _
sSecretKey)
DecryptFile("c:\temp\Encrypted.txt", _
"c:\temp\Decrypted.txt", _
sSecretKey)
End Sub

Sub EncryptFile(ByVal sInputFilename As String, _
ByVal sOutputFilename As String, _
ByVal sKey As String)

Dim fsInput As New FileStream(sInputFilename, _
FileMode.Open, FileAccess.Read)
Dim fsEncrypted As New FileStream(sOutputFilename, _
FileMode.Create, FileAccess.Write)

Dim DES As New DESCryptoServiceProvider()

'為DES算法設置安全碼.
'必須是64位,8個字節
DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey)


DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey)

'創建DES加密碼實例
Dim desencrypt As ICryptoTransform = DES.CreateEncryptor()
'
Dim cryptostream As New CryptoStream(fsEncrypted, _
desencrypt, _
CryptoStreamMode.Write)

'讀取文件到數組
Dim bytearrayinput(fsInput.Length - 1) As Byte
fsInput.Read(bytearrayinput, 0, bytearrayinput.Length)
'寫到加密文件中
cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length)
cryptostream.Close()
End Sub

Sub DecryptFile(ByVal sInputFilename As String, _
ByVal sOutputFilename As String, _
ByVal sKey As String)

Dim DES As New DESCryptoServiceProvider()
DES.Key() = ASCIIEncoding.ASCII.GetBytes(sKey)
DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey)

'讀取加密文件
Dim fsread As New FileStream(sInputFilename, FileMode.Open, FileAccess.Read)
'
Dim desdecrypt As ICryptoTransform = DES.CreateDecryptor()
'
Dim cryptostreamDecr As New CryptoStream(fsread, desdecrypt, CryptoStreamMode.Read)
'輸出到解密文件
Dim fsDecrypted As New StreamWriter(sOutputFilename)
fsDecrypted.Write(New StreamReader(cryptostreamDecr).ReadToEnd)
fsDecrypted.Flush()
fsDecrypted.Close()
End Sub
End Module