VB.net中的加密 - 解密文件大於源文件？

Question

你好我一直都試圖用System.Security.Cryptography加密和解密文件，但它不是爲我工作

這個代碼

Private 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() 
    DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey) 
    DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey) 
    Dim desencrypt As ICryptoTransform = DES.CreateEncryptor() 
    Dim cryptostream As New CryptoStream(fsEncrypted, desencrypt, CryptoStreamMode.Write) 
    Dim bytearrayinput(fsInput.Length - 1) As Byte 
    fsInput.Read(bytearrayinput, 0, bytearrayinput.Length) 
    cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length) 
    cryptostream.Close() 
End Sub 

調用

EncryptFile(OpenFileDialog1.FileName, SaveFileDialog1.FileName, "12345678")[/CODE] 

似乎工作好吧，我得到一個與源文件大小相同的文件

繼承人雖然出錯但是

此代碼

Private 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) 
    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) 
    Dim fsDecrypted As New StreamWriter(sOutputFilename) 
    fsDecrypted.Write(New StreamReader(cryptostreamDecr).ReadToEnd) 
    fsDecrypted.Flush() 
    fsDecrypted.Close() 
End Sub 

調用

DecryptFile(OpenFileDialog1.FileName, SaveFileDialog1.FileName, "12345678")[/CODE] 

輸出文件，該文件是一樣大的被加密的源文件幾乎2倍。

這是怎麼回事我確定這幾個星期前工作正常，我不能看到任何明顯的錯誤。

有什麼想法嗎？

Answer 1

主要問題是EncryptFile使用字節數組讀取數據，而DecryptFile使用數據流讀取數據。 EncryptFile和DecryptFile方法之間的唯一區別應該是您的ICryptoTransform分配。它會更容易有共同的代碼1個步驟：

Private Sub EncryptFile(ByVal sInputFilename As String, ByVal sOutputFilename As String, ByVal sKey As String) 
    Crypto(sInputFilename, sOutputFilename, sKey, True) 
End Sub 

Private Sub DecryptFile(ByVal sInputFilename As String, ByVal sOutputFilename As String, ByVal sKey As String) 
    Crypto(sInputFilename, sOutputFilename, sKey, False) 
End Sub 

Private Sub Crypto(ByVal sInputFileName As String, ByVal sOutputFileName As String, ByVal sKey As String, ByVal bEncrypt As Boolean) 
    'Define the service provider 
    Dim DES As New DESCryptoServiceProvider() 
    DES.Key() = ASCIIEncoding.ASCII.GetBytes(sKey) 
    DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey) 


    'Read the input file into array 
    Dim fsInput As New FileStream(sInputFileName, FileMode.Open, FileAccess.Read) 
    Dim bytearrayinput(fsInput.Length - 1) As Byte 
    fsInput.Read(bytearrayinput, 0, bytearrayinput.Length) 


    'Define the crypto transformer 
    Dim cryptoTransform As ICryptoTransform 

    If bEncrypt Then 
     cryptoTransform = DES.CreateEncryptor() 
    Else 
     cryptoTransform = DES.CreateDecryptor 
    End If 


    'Create the encrypting streams 
    Dim fsEncrypted As New FileStream(sOutputFileName, FileMode.Create, FileAccess.Write) 
    Dim cryptostream As New CryptoStream(fsEncrypted, cryptoTransform, CryptoStreamMode.Write) 

    'Write the output file 
    cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length) 
    cryptostream.Close() 
End Sub 

的加密過程幾乎是相同的東西EncryptFile曾經是。區別在於我根據您是加密還是解密來更改ICryptoTransform分配。