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Rijndael管理的:纯文本长度偏差

rijndaelmanaged

3

J. Polfer · 技术社区 · 14 年前

我花了一些时间学习如何在.NET中使用RijndaelManaged库,并开发了以下功能,通过对msdn库的细微修改来测试加密文本:

Function encryptBytesToBytes_AES(ByVal plainText As Byte(), ByVal Key() As Byte, ByVal IV() As Byte) As Byte()
        ' Check arguments.
        If plainText Is Nothing OrElse plainText.Length <= 0 Then
            Throw New ArgumentNullException("plainText")
        End If
        If Key Is Nothing OrElse Key.Length <= 0 Then
            Throw New ArgumentNullException("Key")
        End If
        If IV Is Nothing OrElse IV.Length <= 0 Then
            Throw New ArgumentNullException("IV")
        End If

        ' Declare the RijndaelManaged object
        ' used to encrypt the data.
        Dim aesAlg As RijndaelManaged = Nothing

        ' Declare the stream used to encrypt to an in memory
        ' array of bytes.
        Dim msEncrypt As MemoryStream = Nothing

        Try
            ' Create a RijndaelManaged object
            ' with the specified key and IV.
            aesAlg = New RijndaelManaged()
            aesAlg.BlockSize = 128
            aesAlg.KeySize = 128
            aesAlg.Mode = CipherMode.ECB
            aesAlg.Padding = PaddingMode.None
            aesAlg.Key = Key
            aesAlg.IV = IV

                ' Create a decrytor to perform the stream transform.
                Dim encryptor As ICryptoTransform = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV)

                ' Create the streams used for encryption.
                msEncrypt = New MemoryStream()
                Using csEncrypt As New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)
                    Using swEncrypt As New StreamWriter(csEncrypt)

                        'Write all data to the stream.
                        swEncrypt.Write(plainText)
                    End Using
                End Using

        Finally
            ' Clear the RijndaelManaged object.
            If Not (aesAlg Is Nothing) Then
                aesAlg.Clear()
            End If
        End Try
        ' Return the encrypted bytes from the memory stream.
        Return msEncrypt.ToArray()

    End Function

下面是我调用encryptbytestobytes_aes()的实际代码:

Private Sub btnEncrypt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEncrypt.Click
    Dim bZeroKey As Byte() = {&H0, &H0, &H0, &H0, &H0, &H0, &H0, &H0, &H0, &H0, &H0, &H0, &H0, &H0, &H0, &H0}
    PrintBytesToRTF(encryptBytesToBytes_AES(bZeroKey, bZeroKey, bZeroKey))
End Sub

但是,我得到了一个例外 swEncrypt.Write(plainText) 声明“要加密的数据长度无效”。

但是,我知道我的密钥、IV和纯文本的大小是16字节==128位==aesalg.blocksize。 为什么会抛出这个异常? 是因为streamwriter试图创建一个字符串(表面上使用某种编码)而不喜欢将&h0作为值吗?

编辑:我想我需要想出一种新的方法来加密字节数组,而不是使用流作者。一个勇敢的人 MSDN page 显示这将首先执行某种类型的字符串转换,我不希望这样做。有什么想法吗?

1 回复 | 直到 14 年前

1

Sani Huttunen 14 年前

在这种情况下,您不能也不需要使用streamwriter。
StreamWriter不接受byte()作为参数。

您可以将加密功能修改为以下内容:

Function encryptBytesToBytes_AES(ByVal plainText As Byte(), ByVal Key() As Byte, ByVal IV() As Byte) As Byte()
    ' Check arguments.'
    If plainText Is Nothing OrElse plainText.Length <= 0 Then
        Throw New ArgumentNullException("plainText")
    End If
    If Key Is Nothing OrElse Key.Length <= 0 Then
        Throw New ArgumentNullException("Key")
    End If
    If IV Is Nothing OrElse IV.Length <= 0 Then
        Throw New ArgumentNullException("IV")
    End If

    ' Declare the RijndaelManaged object'
    ' used to encrypt the data.'
    Dim aesAlg As RijndaelManaged = Nothing

    Dim encryptedData As Byte()

    Try
        ' Create a RijndaelManaged object'
        ' with the specified key and IV.'
        aesAlg = New RijndaelManaged()
        aesAlg.BlockSize = 128
        aesAlg.KeySize = 128
        aesAlg.Mode = CipherMode.ECB
        aesAlg.Padding = PaddingMode.None
        aesAlg.Key = Key
        aesAlg.IV = IV

        ' Create a decrytor to perform the stream transform.'
        Dim encryptor As ICryptoTransform = aesAlg.CreateEncryptor()

        ' Create the streams used for encryption.'
        Using msEncrypt As New MemoryStream()

            Using csEncrypt As New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)
                csEncrypt.Write(plainText, 0, plainText.Length)
                csEncrypt.FlushFinalBlock()
            End Using
            encryptedData = msEncrypt.ToArray()
        End Using

    Finally
        ' Clear the RijndaelManaged object.'
        If Not (aesAlg Is Nothing) Then
            aesAlg.Clear()
        End If
    End Try
    ' Return the encrypted bytes from the memory stream.'
    Return encryptedData
End Function