复制代码 代码如下:

Function fDecode(sStringToDecode)

'This function will decode a Base64 encoded string and returns the decoded string.

'This becomes usefull when attempting to hide passwords from prying eyes.

Const CharList = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

Dim iDataLength, sOutputString, iGroupInitialCharacter

sStringToDecode = Replace(Replace(Replace(sStringToDecode, vbCrLf, ""), vbTab, ""), " ", "")

iDataLength = Len(sStringToDecode)

If iDataLength Mod 4 <> 0 Then

fDecode = "Bad string passed to fDecode() function."

Exit Function

End If

For iGroupInitialCharacter = 1 To iDataLength Step 4

Dim iDataByteCount, iCharacterCounter, sCharacter, iData, iGroup, sPreliminaryOutString

iDataByteCount = 3

iGroup = 0

For iCharacterCounter = 0 To 3

sCharacter = Mid(sStringToDecode, iGroupInitialCharacter + iCharacterCounter, 1)

If sCharacter = "=" Then

iDataByteCount = iDataByteCount - 1

iData = 0

Else

iData = InStr(1, CharList, sCharacter, 0) - 1

If iData = -1 Then

fDecode = "Bad string passed to fDecode() function."

Exit Function

End If

End If

iGroup = 64 * iGroup + iData

Next

iGroup = Hex(iGroup)

iGroup = String(6 - Len(iGroup), "0") & iGroup

sPreliminaryOutString = Chr(CByte("&H" & Mid(iGroup, 1, 2))) & Chr(CByte("&H" & Mid(iGroup, 3, 2))) & Chr(CByte("&H" & Mid(iGroup, 5, 2)))

sOutputString = sOutputString & Left(sPreliminaryOutString, iDataByteCount)

Next

fDecode = sOutputString

End Function

base64 测试代码：

复制代码 代码如下:

Function fDecode(sStringToDecode)

'This function will decode a Base64 encoded string and returns the decoded string.

'This becomes usefull when attempting to hide passwords from prying eyes.

Const CharList = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

Dim iDataLength, sOutputString, iGroupInitialCharacter

sStringToDecode = Replace(Replace(Replace(sStringToDecode, vbCrLf, ""), vbTab, ""), " ", "")

iDataLength = Len(sStringToDecode)

If iDataLength Mod 4 <> 0 Then

fDecode = "Bad string passed to fDecode() function."

Exit Function

End If

For iGroupInitialCharacter = 1 To iDataLength Step 4

Dim iDataByteCount, iCharacterCounter, sCharacter, iData, iGroup, sPreliminaryOutString

iDataByteCount = 3

iGroup = 0

For iCharacterCounter = 0 To 3

sCharacter = Mid(sStringToDecode, iGroupInitialCharacter + iCharacterCounter, 1)

If sCharacter = "=" Then

iDataByteCount = iDataByteCount - 1

iData = 0

Else

iData = InStr(1, CharList, sCharacter, 0) - 1

If iData = -1 Then

fDecode = "Bad string passed to fDecode() function."

Exit Function

End If

End If

iGroup = 64 * iGroup + iData

Next

iGroup = Hex(iGroup)

iGroup = String(6 - Len(iGroup), "0") & iGroup

sPreliminaryOutString = Chr(CByte("&H" & Mid(iGroup, 1, 2))) & Chr(CByte("&H" & Mid(iGroup, 3, 2))) & Chr(CByte("&H" & Mid(iGroup, 5, 2)))

sOutputString = sOutputString & Left(sPreliminaryOutString, iDataByteCount)

Next

fDecode = sOutputString

End Function

msgbox fDecode("d3d3LmpiNTEubmV0")

需要测试加密的代码的朋友可以访问 http://www.jb51.net/tools/base64.htm