加密密钥大小和算法

Question

下面是一些代码，我有一个完美的作品：

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() 

    'Set secret key for DES algorithm. 
    'A 64-bit key and an IV are required for this provider. 
    DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey) 

    'Set the initialization vector. 
    DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey) 

    'Create the DES encryptor from this instance. 
    Dim desencrypt As ICryptoTransform = DES.CreateEncryptor() 
    'Create the crypto stream that transforms the file stream by using DES encryption. 
    Dim cryptostream As New CryptoStream(fsEncrypted, _ 
             desencrypt, _ 
             CryptoStreamMode.Write) 

    'Read the file text to the byte array. 
    Dim bytearrayinput(fsInput.Length - 1) As Byte 
    fsInput.Read(bytearrayinput, 0, bytearrayinput.Length) 
    'Write out the DES encrypted file. 
    cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length) 
    cryptostream.Close() 

末次

是否有可能改变密钥长度，甚至MD5和SHA1加密之间选择使用此代码？如果没有，有人能指出我正确的方向来找到一些这样做吗？

感谢

西蒙

Answer 1

DES是一种加密算法。如果你想使用别的东西，你应该看看TripleDESCryptoServiceProvider或者AesCryptoServiceProvider（在System.Security.Cryptography命名空间中）。

MD5和SHA1实际上是哈希算法。实际上，它们是特殊情况下的单向加密算法，不能解密（所以我不认为它们就是你要找的）。

只看了TripleDes的和AES类的文档，它看起来像你应该能够取代线：任何提供了一个CreateEncryptor功能的其他CryptoServiceProvider类

Dim DES As New DESCryptoServiceProvider() 

。它们还支持您可以设置的KeySize属性。你可以尝试这样的：

Sub EncryptFile(ByVal sInputFilename As String, _ 
      ByVal sOutputFilename As String, _ 
      ByVal sKey As String, _ 
      ByVal keysize as integer, _ 
      ByVal algorithm as String) 

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

    Dim algorithm As SymmetricAlgorithm 
    Select Case algorithm 
     Case "DES": algorithm = New DESCryptoServiceProvider() 
     Case "3DES": algorithm = New TripleDESCryptoServiceProvider() 
     Case "AES": algorithm = New AESCryptoServiceProvider() 
    End Select 
    algorithm.KeySize = keysize 

    'Set secret key for the algorithm. 
    'A 64-bit key and an IV are required for this provider. 
    algorithm.Key = ASCIIEncoding.ASCII.GetBytes(sKey) 

    'Set the initialization vector. 
    algorithm.IV = ASCIIEncoding.ASCII.GetBytes(sKey) 

    'Create the encryptor from this instance. 
    Dim desencrypt As ICryptoTransform = algorithm.CreateEncryptor() 
    'Create the crypto stream that transforms the file stream by using encryption. 
    Dim cryptostream As New CryptoStream(fsEncrypted, _ 
            desencrypt, _ 
            CryptoStreamMode.Write) 

    'Read the file text to the byte array. 
    Dim bytearrayinput(fsInput.Length - 1) As Byte 
    fsInput.Read(bytearrayinput, 0, bytearrayinput.Length) 
    'Write out the DES encrypted file. 
    cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length) 
    cryptostream.Close() 
End Sub 

我没试过编译上面的示例，但你让你开始希望。