使用“Cryptography.HMACSHA1”加密，如何解密（VBA）

我有一個在 VBA 中執行良好的加密常式。但現在我需要編寫解密程序，我被困住了。對於加密，我使用 HMACSHA1 並將加密字節傳輸到 base 64。我可以解碼 base 64 並返回相同的字節數組，但是關於如何使用 HMACSHA1 解密有什麼建議嗎？到目前為止，這是我所擁有的（抱歉，如果這不是提出此類問題的合適場所）：

Private Function fDecrypto(sText As String, sPass As String) As String

Dim encoder As Object
Dim crypto As Object
Dim bEncrypted() As Byte
Dim i As Integer

' base64 to encrypted byte array

Dim objXML As MSXML2.DOMDocument
Dim objNode As MSXML2.IXMLDOMElement
Set objXML = New MSXML2.DOMDocument
Set objNode = objXML.createElement("b64")

objNode.DataType = "bin.base64"
objNode.Text = sText
bEncrypted = objNode.nodeTypedValue

Set objNode = Nothing
Set objXML = Nothing

' decrypt using HMACSHA1

Set encoder = CreateObject("System.Text.UTF8Encoding")
Set crypto = CreateObject("System.Security.Cryptography.HMACSHA1")

' **TODO - decrypt here**

Set encoder = Nothing
Set crypto = Nothing

End Function


Private Function fEncrypto(sText As String, sPass As String) As String

Dim encoder  As Object
Dim crypto As Object
Dim i As Integer
Dim bPass() As Byte
Dim bText() As Byte
Dim bEncrypted() As Byte

Set encoder = CreateObject("System.Text.UTF8Encoding")
Set crypto = CreateObject("System.Security.Cryptography.HMACSHA1")

bText = encoder.Getbytes_4(sText)
bPass = encoder.Getbytes_4(sPass)
crypto.key = bPass

bEncrypted = crypto.ComputeHash_2(bText)

Set encoder = Nothing
Set crypto = Nothing

' encrypted byte array to base64

Dim objXML As MSXML2.DOMDocument
Dim objNode As MSXML2.IXMLDOMElement
Set objXML = New MSXML2.DOMDocument
Set objNode = objXML.createElement("b64")

objNode.DataType = "bin.base64"
objNode.nodeTypedValue = bEncrypted
EncodeBase64 = objNode.Text

Set objNode = Nothing
Set objXML = Nothing

End Function

HMAC 是消息認證碼 (MAC)。MAC 產生“標籤”，可用於防止消息被篡改（有點像數字簽名）。沒有辦法“解密”一個 HMAC 標籤來取回原始消息，所以聽起來 HMAC 不是你要找的。

我建議改用 AES-GCM，因為它旨在用於加密。我不確定如何使用 VBA 中的 AES-GCM：我建議在 StackOverflow 上提出這個問題（這個問題在這裡是題外話）。

引用自：https://crypto.stackexchange.com/questions/35097