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[VBA]Base64编码和Base64解码

March 26th, 2019 No comments

VBA实现Base64编码和Base64解码,用于处理加密的URL非常方便。

VBA Base64 编码/加密函数:

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'VBA Base64 编码/加密函数:
Function Base64Encode(StrA As String) As String                                  'Base64 编码
    On Error GoTo over                                                          '排错
    Dim buf() As Byte, length As Long, mods As Long
    Dim Str() As Byte
    Dim i, kk As Integer
    kk = Len(StrA) - 1
    ReDim Str(kk)
    For i = 0 To kk
        Str(i) = Asc(Mid(StrA, i + 1, 1))
    Next i
    Const B64_CHAR_DICT = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
    mods = (UBound(Str) + 1) Mod 3   '除以3的余数
    length = UBound(Str) + 1 - mods
    ReDim buf(length / 3 * 4 + IIf(mods <> 0, 4, 0) - 1)
    For i = 0 To length - 1 Step 3
        buf(i / 3 * 4) = (Str(i) And &HFC) / &H4
        buf(i / 3 * 4 + 1) = (Str(i) And &H3) * &H10 + (Str(i + 1) And &HF0) / &H10
        buf(i / 3 * 4 + 2) = (Str(i + 1) And &HF) * &H4 + (Str(i + 2) And &HC0) / &H40
        buf(i / 3 * 4 + 3) = Str(i + 2) And &H3F
    Next
    If mods = 1 Then
        buf(length / 3 * 4) = (Str(length) And &HFC) / &H4
        buf(length / 3 * 4 + 1) = (Str(length) And &H3) * &H10
        buf(length / 3 * 4 + 2) = 64
        buf(length / 3 * 4 + 3) = 64
    ElseIf mods = 2 Then
        buf(length / 3 * 4) = (Str(length) And &HFC) / &H4
        buf(length / 3 * 4 + 1) = (Str(length) And &H3) * &H10 + (Str(length + 1) And &HF0) / &H10
        buf(length / 3 * 4 + 2) = (Str(length + 1) And &HF) * &H4
        buf(length / 3 * 4 + 3) = 64
    End If
    For i = 0 To UBound(buf)
        Base64Encode = Base64Encode + Mid(B64_CHAR_DICT, buf(i) + 1, 1)
    Next
over:
End Function

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