des文件加密损坏文件

Question

我用vb.net编写了一个用于加密/解密文件的类，但当我解密图像、zips或office文件等文件时，它们看起来已损坏。但如果我在记事本中打开解密的和原始的文件，它们是完全相同的。我能做些什么来阻止这一切？

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

Public Class Encrytion
Shared 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

Shared 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

End Class

Answer 1

我找到了this answer来解决这个问题。简而言之，在CreateEncryptor/CreateDecryptor调用之外，加密和解密函数应该完全相同：

Shared 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(DES.Key, DES.IV)

    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.Flush()

    cryptostream.Close()
End Sub

Shared Sub DecryptFile(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.CreateDecryptor(DES.Key, DES.IV)

    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.Flush()

    cryptostream.Close()
End Sub