How to use ASP for base64 encryption

<%
OPTION EXPLICIT
Const BASE_64_MAP_INIT =
"abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789+/"
Dim nl
' Zero based arrays
Dim Base64encmap (63)
Dim Base64decmap (127)

' must be called before using anything else
Public SUB Initcodecs ()
' Init VARs
NL = "<P>" & Chr (+) & Chr (10)
' Setup Base 64
Dim max, IDX
max = Len (base_64_map_init)
For idx = 0 to Max-1
' One based string
Base64encmap (IDX) = Mid (Base_64_map_init, IDX + 1, 1)
Next
For idx = 0 to Max-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, second, third
By3 = (len (plain) \ 3) * 3
NDX = 1
Do While Ndx <= by3
A = ASC (Mid (Plain, ndx+0, 1))
Second = ASC (Mid (Plain, ndx+1, 1))
Third = ASC (Mid (Plain, ndx+2, 1))
RET = ret & Base64encmap ((4) and 63)
RET = ret & Base64encmap (((A) ((a) +) + ((second \ 16)
and 15))
RET = ret & Base64encmap ((Second * 4) and) + ((third \ 64)
and 3))
RET = ret & Base64encmap (third and 63)
NDX = ndx + 3
Loop
' Check for stragglers
If By3 < Len (plain) Then
A = ASC (Mid (Plain, ndx+0, 1))
RET = ret & Base64encmap ((4) and 63)
if (Len (plain) MOD 3) = 2 Then
Second = ASC (Mid (Plain, ndx+1, 1))
RET = ret & Base64encmap (((a) and 48) +
((Second \
) and 15))
RET = ret & Base64encmap ((Second * 4) and 60))
Else
RET = ret & Base64encmap ((a) and 48)
RET = ret & "="
End If
RET = ret & "="
End If

Base64Encode = RET
End FUNCTION

' Decode base encoded string
Public FUNCTION Base64decode (scrambled)

If Len (scrambled) = 0 Then
Base64decode = ""
Exit function
End If

' Ignore padding
Dim Reallen
Reallen = Len (scrambled)
Do while mid (scrambled, Reallen, 1) = "="
Reallen = realLen-1
Loop
Dim ret, Ndx, By4, A, second, third, fourth
ret = ""
By4 = (reallen \ 4) * 4
NDX = 1
Do While Ndx <= by4
i = BASE64DECMAP (ASC (Scrambled, ndx+0, 1))
Second = BASE64DECMAP (ASC (Scrambled, ndx+1, 1))
Third = Base64decmap (ASC (Scrambled, ndx+2, 1))
Fourth = BASE64DECMAP (ASC (Scrambled, ndx+3, 1))
RET = ret & Chr (((4) and 255) + ((second) and 3)
)
RET = ret & Chr ((second *) and 255) + ((third \ 4) and
15))
RET = ret & Chr ((third *) and 255) + (fourth and 63))
NDX = ndx + 4
Loop
' Check for stragglers, would be 2 or 3 characters
If Ndx < Reallen Then
i = BASE64DECMAP (ASC (Scrambled, ndx+0, 1))
Second = BASE64DECMAP (ASC (Scrambled, ndx+1, 1))
RET = ret & Chr (((4) and 255) + ((second) 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
15))
End If
End If

Base64decode = RET
End FUNCTION

' Initialize
Call Initcodecs

' Testing code
' Dim inp, Encode
' INP = Request. QueryString ("Input")
' Encode = Base64Encode (INP)
' Response.Write ' encoded value = ' & Encode & NL
' Response.Write ' decoded value = ' & Base64decode (encode) & NL
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