1000이란 숫자를 암호화 하면 MTAwMCAg 란 값을 얻는다.

MTAwMCAg를 받아 암호를 풀면 1000 이란 값을 얻는다.

암호화하기

------------------------------------------------------------------

<!-- #include virtual='/include/asp/amount.asp' -->

<%

amount = Base64encode(1000)
response.write amount
%>

암호화 풀기

-------------------------------------------------------------------

<!-- #include virtual='/include/asp/amount.asp' -->

<%

amount = Base64decode("MTAwMCAg")

response.write amount
%>

amount.asp

--------------------------------------------------------------

<%
Const sBASE_64_CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

Function Base64decode(ByVal asContents)
Dim lsResult
Dim lnPosition
Dim lsGroup64, lsGroupBinary
Dim Char1, Char2, Char3, Char4
Dim Byte1, Byte2, Byte3
If Len(asContents) Mod 4 > 0 Then asContents = asContents & String(4 - (Len(asContents) Mod 4), " ")
lsResult = ""

For lnPosition = 1 To Len(asContents) Step 4
lsGroupBinary = ""
lsGroup64 = Mid(asContents, lnPosition, 4)
Char1 = INSTR(sBASE_64_CHARACTERS, Mid(lsGroup64, 1, 1)) - 1
Char2 = INSTR(sBASE_64_CHARACTERS, Mid(lsGroup64, 2, 1)) - 1
Char3 = INSTR(sBASE_64_CHARACTERS, Mid(lsGroup64, 3, 1)) - 1
Char4 = INSTR(sBASE_64_CHARACTERS, Mid(lsGroup64, 4, 1)) - 1
Byte1 = Chr(((Char2 And 48) /16) Or (Char1 * 4) And &HFF)
Byte2 = lsGroupBinary & Chr(((Char3 And 60) /4) Or (Char2 * 16) And &HFF)
Byte3 = Chr((((Char3 And 3) * 64) And &HFF) Or (Char4 And 63))
lsGroupBinary = Byte1 & Byte2 & Byte3
lsResult = lsResult + lsGroupBinary
Next
Base64decode = lsResult
End Function

Function Base64encode(ByVal asContents)
Dim lnPosition
Dim lsResult
Dim Char1
Dim Char2
Dim Char3
Dim Char4
Dim Byte1
Dim Byte2
Dim Byte3
Dim SaveBits1
Dim SaveBits2
Dim lsGroupBinary
Dim lsGroup64

If Len(asContents) Mod 3 > 0 Then asContents = asContents & String(3 - (Len(asContents) Mod 3), " ")
lsResult = ""

For lnPosition = 1 To Len(asContents) Step 3
lsGroup64 = ""
lsGroupBinary = Mid(asContents, lnPosition, 3)

Byte1 = Asc(Mid(lsGroupBinary, 1, 1)): SaveBits1 = Byte1 And 3
Byte2 = Asc(Mid(lsGroupBinary, 2, 1)): SaveBits2 = Byte2 And 15
Byte3 = Asc(Mid(lsGroupBinary, 3, 1))

Char1 = Mid(sBASE_64_CHARACTERS, ((Byte1 And 252) /4) + 1, 1)
Char2 = Mid(sBASE_64_CHARACTERS, (((Byte2 And 240) /16) Or (SaveBits1 * 16) And &HFF) + 1, 1)
Char3 = Mid(sBASE_64_CHARACTERS, (((Byte3 And 192) /64) Or (SaveBits2 * 4) And &HFF) + 1, 1)
Char4 = Mid(sBASE_64_CHARACTERS, (Byte3 And 63) + 1, 1)
lsGroup64 = Char1 & Char2 & Char3 & Char4
lsResult = lsResult + lsGroup64
Next

Base64encode = lsResult
End Function

%>