Base64 addition and decryption function in ASP

 

<% OPTION EXPLICIT Const BASE_64_MAP_INIT = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789+/" Dim NL ' Zero based arrays Dim Base64encmap (+) Dim base64decmap (127) ' must be called before using anything else public SUB I Nitcodecs () ' init vars nl = ' <P> ' & chr & chr ' Setup base ' Dim max, idx max = Len (base_64_map_in IT) for idx = 0 to Max-1 ' one based string base64encmap (idx) = Mid (Base_64_map_init, IDX + 1, 1) next-to-idx = 0 to Ma X-1 Base64decmap (ASC (Base64encmap (idx))) = idx next END SUB ' encode base encoded string public FUNCTION Base64Encode (plain) If len (plain) = 0 Then Base64Encode = "" "Exit Function End If Dim ret, Ndx, By3, first, second, third by3 = (Len (p Lain)/3) * 3 NDX = 1 Do While ndx <= by3 first = ASC (Mid (Plain, ndx+0, 1)) Second = ASC (Mid (Plain, ndx+1, 1)) Third = ASC (Mid (Plain, ndx+2, 1)) ret = ret & Base64encmap ((FIRST/4) and () ret = ret & Base64encmap ((First * 16) and () + ((SECOND/16) anD) ret = ret & Base64encmap (((Second * 4) and + ((THIRD/64) and 3)) ret = ret & Base64encmap (third and ndx = ndx + 3 loop if by3 < Len (plain) then first = ASC (Mid (Plain, ndx+0, 1)) ret = ret & Base64encmap ((f IRST/4) if (Len (plain) MOD 3) = 2 Then second = ASC (Mid (Plain, ndx+1, 1)) ret = ret & Base64encmap (((Firs T * +) + ((SECOND/16) and)) ret = ret & Base64encmap ((((second * 4) and) ELSE ret = ret & Bas E64encmap (First *) and () ret = ret & "=" End If ret = ret & "=" End If Base64Encode = Ret end FUNCTION ' de Code base encoded string public FUNCTION Base64decode (scrambled) if Len (scrambled) = 0 Then Base64decode = "" Exit func tion End If Dim reallen Reallen = Len (scrambled) Do while mid (scrambled, Reallen, 1) = "=" Reallen = RealLen-1 Loop Dim RET, NDX, By4, first, second, third, fourth ret = "" By4 = (REALLEN/4) * 4 NDX = 1 Do While ndx <= by4 first = Base64 Decmap (ASC (Mid (scrambled, ndx+0, 1))) Second = Base64decmap (ASC (Scrambled, ndx+1, 1)) Third = Base64decmap (ASC (Mid (Scrambled, ndx+2, 1))) Fou Rth = Base64decmap (ASC (Mid (Scrambled, ndx+3, 1)) ret = ret & Chr ((First * 4) and 255) + ((SECOND/16) and 3) RET = RET & Chr (((second *) and 255) + ((THIRD/4) and ()) ret = ret & Chr (((third *) and 255) + (fourth an D)) Ndx = ndx + 4 loop if ndx < Reallen then first = BASE64DECMAP (ASC (Mid (Scrambled, ndx+0, 1))) Second = Base64dec MAP (ASC (Mid (Scrambled, ndx+1, 1)) ret = ret & Chr ((First * 4) and 255) + ((SECOND/16) and 3)) if Reallen MOD 4 = 3 Then third = BASE64DECMAP (ASC (Mid (scrambled,ndx+2,1))) ret = ret & Chr (((second *) and 255) + ((THIRD/4) and 1 5) End If End If Base64decode = Ret End FUNCTION ' Initialize call Initcodecs ' Testing code Dim InP, Encode ' INP = req Uest. QueryString ("input") encode = Base64Encode (INP) Response.Write "Encoded value =" & Encode & nl Response.Write "De Coded value = "&amP Base64decode (encode) & NL%>