加密 CAPICOM 中的訊息

[CAPICOM 是 32 位的僅限元件，可用於下列作業系統：Windows Server 2008、Windows Vista 和 Windows XP。 請改用.NET Framework來實作安全性功能。 如需詳細資訊，請參閱 使用 CAPICOM 的替代方案。]

這個副程式會採用要加密的字串、用來產生加密金鑰的密碼字串，以及將寫入加密訊息的檔案名。 所有參數都會依值傳遞至副程式。 若要解密訊息，必須使用相同的密碼字串。 如果密碼遺失，就無法解密文字。 如果非預期收件者取得密碼的存取權，郵件的隱私權就會遺失。

注意

CAPICOM 不支援 PKCS #7 EncryptedData 內容類型，但會針對 EncryptedData 使用非標準 ASN 結構。 因此，只有 CAPICOM 可以解密 CAPICOM EncryptedData 物件。

 

在任何 CAPICOM 錯誤上，會傳回 Err.Number 屬性的負十進位值。 如需詳細資訊，請參閱 CAPICOM_ERROR_CODE。 如需 Err.Number的正十進位值相關資訊，請參閱 Winerror.h。

Sub EncryptMessage(ByVal TobeEncrypted As String, ByVal hidden _
    As String, ByVal filename As String)

    On Error GoTo ErrorHandler

    ' Declare and initialize an EncryptedData object.
    ' Algorithm.Name and KeyLength do not need to be set.

    Dim message As New EncryptedData
    message.Content = Tobeencrypted
    message.SetSecret(hidden)
    ' Optionally, the encryption algorithm and key length can be set.
    ' If these properties are not set, the default algorithm and key 
    ' length are used.
    ' Information about the algorithm and key length is saved with 
    ' the encrypted string and the individual decrypting the message
    ' does not need to set these properties.

    message.Algorithm.Name = CAPICOM_ENCRYPTION_ALGORITHM_DES

    ' Declare the string that will hold the encrypted message.

    Dim encryptedmessage As String

    ' Encrypt the message storing the result in the encryptedmessage
    ' string.
    encryptedmessage = message.Encrypt

    ' Optionally, check the length of the encrypted string to 
    ' make sure that the encrypt method worked. 

    If Len(encryptedmessage) < 1 Then
        MsgBox("no message encrypted. ")
    Else
        MsgBox(" Message is " & Len(encryptedmessage) & " characters")

        ' Open an output file and write the encrypted message to the
        ' file. The file is not opened if there is no message
        ' to write.
    Open filename For Output As #1
    Write #1, encryptedmessage
    Close #1
        MsgBox("Encrypted message written to file ")
    End If

    ' Release the EncryptedData object.
    message = Nothing

    Exit Sub

ErrorHandler:
    If Err.Number > 0 Then
        MsgBox("Visual Basic error found:" & Err.Description)
    Else
        MsgBox("CAPICOM error found : " & Err.Number)
    End If
End Sub