Access 下Base64位加密（支持中文和特殊符号）

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这个Access类模块可实现功能： 

1.Access加密字符串函数 Base64编码函数（加密）

2.Access解密字符串函数 Base64解码函数（加密）

3.Access加密整个文件函数

4.Access解密整个文件函数

5.Access加密解密字节数组

6.Access二进制与字符串相互转换

7.去掉字符串尾等

此Access加密解密类模块如下

Option Explicit

' 1、加密字符串函数 Base64编码函数（加密）

' 参数：源字符串（明文）

' 返回：加密后的字符串

Public Function Base64StringEncode(InStr1 As String) As String

On Error GoTo Err2

    Dim mInByte(3) As Byte, mOutByte(4) As Byte

    Dim myByte As Byte

    Dim I As Integer, LenArray As Integer, J As Integer

    Dim myBArray() As Byte

    Dim OutStr1 As String

    myBArray() = StrConv(InStr1, vbFromUnicode)

    LenArray = UBound(myBArray) + 1

    For I = 0 To LenArray Step 3

        If LenArray - I = 0 Then

            Exit For

        End If

        If LenArray - I = 2 Then

            mInByte(0) = myBArray(I)

            mInByte(1) = myBArray(I + 1)

            Base64EncodeByte mInByte, mOutByte, 2

        ElseIf LenArray - I = 1 Then

            mInByte(0) = myBArray(I)

            Base64EncodeByte mInByte, mOutByte, 1

        Else

            mInByte(0) = myBArray(I)

            mInByte(1) = myBArray(I + 1)

            mInByte(2) = myBArray(I + 2)

            Base64EncodeByte mInByte, mOutByte, 3

        End If

        For J = 0 To 3

            OutStr1 = OutStr1 & Chr(mOutByte(J))

        Next J

    Next I

    Base64StringEncode = OutStr1

    Exit Function

Err2:

    Base64StringEncode = ""

    Debug.Print "函数(CBase64EnDeCode.Base64StringEncode) 出错 " & Err.Number & " (" & Err.Description & ")"

End Function

' 2、解密字符串函数 Base64解码函数（加密）

' 参数：源字符串（密文）

' 返回：解密后的字符串

Public Function Base64StringDecode(InStr1 As String) As String

On Error GoTo Err2

    Dim mInByte(4) As Byte, mOutByte(3) As Byte

    Dim I As Integer, LenArray As Integer, J As Integer

    Dim myBArray() As Byte

    Dim OutStr1 As String

    Dim tmpArray() As Byte

    myBArray() = StrConv(InStr1, vbFromUnicode)

    LenArray = UBound(myBArray)

    ReDim tmpArray(((LenArray + 1) / 4) * 3)

    J = 0

    For I = 0 To LenArray Step 4

        If LenArray - I = 0 Then

            Exit For

        Else

            mInByte(0) = myBArray(I)

            mInByte(1) = myBArray(I + 1)

            mInByte(2) = myBArray(I + 2)

            mInByte(3) = myBArray(I + 3)

            Base64DecodeByte mInByte, mOutByte, 4

        End If

        tmpArray(J * 3) = mOutByte(0)

        tmpArray(J * 3 + 1) = mOutByte(1)

        tmpArray(J * 3 + 2) = mOutByte(2)

        J = J + 1

    Next I

    Base64StringDecode = StripNulls(BinaryToString(tmpArray))

    Exit Function

Err2:

    Base64StringDecode = ""

    Debug.Print "函数(CBase64EnDeCode.Base64StringDecode) 出错 " & Err.Number & " (" & Err.Description & ")"

End Function

' 3、加密文件函数

' 参数：明文文件名，密文文件名

' 返回：无

Public Sub Base64FileEncode(PlaintextFileName As String, CiphertextFileName As String)

On Error GoTo Err2

    Dim Plaintext As String, Ciphertext As String   ' 明文和密文文字！

    ' 打开明文文件

    Open PlaintextFileName For Binary Access Read As #1

        Plaintext = Input(LOF(1), #1)

    Close #1

    ' 文件内容加密

    Ciphertext = Base64StringEncode(Plaintext)

    ' 写入密文到文件！

    Open CiphertextFileName For Binary Access Write As #1

        Put #1, , Ciphertext

    Close #1

    Exit Sub

Err2:

    Debug.Print "函数(CBase64EnDeCode.Base64FileEncode) 出错 " & Err.Number & " (" & Err.Description & ")"

End Sub

' 4、解密文件函数

' 参数：明文文件名，密文文件名

' 返回：无

Public Sub Base64FileDecode(PlaintextFileName As String, CiphertextFileName As String)

On Error GoTo Err2

    Dim Plaintext As String, Ciphertext As String   ' 明文和密文文字！

    ' 读入密文文件

    Open CiphertextFileName For Binary Access Read As #1

        Ciphertext = Input(LOF(1), #1)

    Close #1

    ' 解密密文

    Plaintext = Base64StringDecode(Ciphertext)

    ' 将解密后的文字写入文件

    Open PlaintextFileName For Binary Access Write As #1

        Put #1, , Plaintext

    Close #1

    Exit Sub

Err2:

    Debug.Print "函数(CBase64EnDeCode.Base64FileDecode) 出错 " & Err.Number & " (" & Err.Description & ")"

End Sub

' 加密字节数组

Private Sub Base64EncodeByte(mInByte() As Byte, mOutByte() As Byte, Num As Integer)

   Dim tByte As Byte

   Dim I As Integer

   If Num = 1 Then

       mInByte(1) = 0

       mInByte(2) = 0

   ElseIf Num = 2 Then

       mInByte(2) = 0

   End If

   tByte = mInByte(0) And &HFC

   mOutByte(0) = tByte / 4

   tByte = ((mInByte(0) And &H3) * 16) + (mInByte(1) And &HF0) / 16

   mOutByte(1) = tByte

   tByte = ((mInByte(1) And &HF) * 4) + ((mInByte(2) And &HC0) / 64)

   mOutByte(2) = tByte

   tByte = (mInByte(2) And &H3F)

   mOutByte(3) = tByte

   For I = 0 To 3

       If mOutByte(I) >= 0 And mOutByte(I) <= 25 Then

           mOutByte(I) = mOutByte(I) + Asc("A")

       ElseIf mOutByte(I) >= 26 And mOutByte(I) <= 51 Then

           mOutByte(I) = mOutByte(I) - 26 + Asc("a")

       ElseIf mOutByte(I) >= 52 And mOutByte(I) <= 61 Then

           mOutByte(I) = mOutByte(I) - 52 + Asc("0")

       ElseIf mOutByte(I) = 62 Then

           mOutByte(I) = Asc("+")

       Else

           mOutByte(I) = Asc("/")

       End If

   Next I

   If Num = 1 Then

       mOutByte(2) = Asc("=")

       mOutByte(3) = Asc("=")

   ElseIf Num = 2 Then

       mOutByte(3) = Asc("=")

   End If

End Sub

' 解密字节数组

Private Sub Base64DecodeByte(mInByte() As Byte, mOutByte() As Byte, ByteNum As Integer)

    Dim tByte As Byte

    Dim I As Integer

    ByteNum = 0

    For I = 0 To 3

        If mInByte(I) >= Asc("A") And mInByte(I) <= Asc("Z") Then

            mInByte(I) = mInByte(I) - Asc("A")

        ElseIf mInByte(I) >= Asc("a") And mInByte(I) <= Asc("z") Then

            mInByte(I) = mInByte(I) - Asc("a") + 26

        ElseIf mInByte(I) >= Asc("0") And mInByte(I) <= Asc("9") Then

            mInByte(I) = mInByte(I) - Asc("0") + 52

        ElseIf mInByte(I) = Asc("+") Then

            mInByte(I) = 62

        ElseIf mInByte(I) = Asc("/") Then

            mInByte(I) = 63

        Else '"="

            ByteNum = ByteNum + 1

            mInByte(I) = 0

        End If

    Next I

    '取前六位

    tByte = (mInByte(0) And &H3F) * 4 + (mInByte(1) And &H30) / 16

    '0的六位和1的前两位

    mOutByte(0) = tByte

    tByte = (mInByte(1) And &HF) * 16 + (mInByte(2) And &H3C) / 4

    '1的后四位和2的前四位

    mOutByte(1) = tByte

    tByte = (mInByte(2) And &H3) * 64 + (mInByte(3) And &H3F)

    mOutByte(2) = tByte

    '2的后两位和3的六位

End Sub

' 二进制转换为字符串

Private Function BinaryToString(ByVal BinaryStr As Variant) As String

  Dim lnglen As Long

  Dim tmpBin As Variant

  Dim strC As String

  Dim skipflag As Long

  Dim I As Long

  skipflag = 0

  strC = ""

  If Not IsNull(BinaryStr) Then

      lnglen = LenB(BinaryStr)

      For I = 1 To lnglen

          If skipflag = 0 Then

            tmpBin = MidB(BinaryStr, I, 1)

            If AscB(tmpBin) > 127 Then

                strC = strC & Chr(AscW(MidB(BinaryStr, I + 1, 1) & tmpBin))

                skipflag = 1

            Else

                strC = strC & Chr(AscB(tmpBin))

            End If

          Else

            skipflag = 0

          End If

      Next

    End If

    BinaryToString = strC

End Function

' 字符串转成二进制

Private Function StringToBinary(ByVal VarString As String) As Variant

  Dim strBin As Variant

  Dim varchar As Variant

  Dim varasc As Long

  Dim varlow, varhigh

  Dim I As Long

  strBin = ""

  For I = 1 To Len(VarString)

      varchar = Mid(VarString, I, 1)

      varasc = Asc(varchar)

      If varasc < 0 Then

          varasc = varasc + 65535

      End If

      If varasc > 255 Then

          varlow = Left(Hex(Asc(varchar)), 2)

          varhigh = Right(Hex(Asc(varchar)), 2)

          strBin = strBin & ChrB("&H" & varlow) & ChrB("&H" & varhigh)

      Else

          strBin = strBin & ChrB(AscB(varchar))

      End If

  Next

  StringToBinary = strBin

End Function

' 去掉字符串尾

Private Function StripNulls(OriginalStr As String) As String

    ' This removes the extra Nulls so String comparisons will work

    If (InStr(OriginalStr, Chr$(0)) > 0) Then

        OriginalStr = Left$(OriginalStr, InStr(OriginalStr, Chr$(0)) - 1)

    End If

    StripNulls = OriginalStr

End Function