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如何用asp进行base64加密

 2000-11-13 10:13:08 来源:WEB开发网   
核心提示:<% OPTION EXPLICIT const BASE_64_MAP_INIT ="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" dim nl ' zero based arrays dim Ba
<%
   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(13) & 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 64 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(plain) \ 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 63 )
        ret = ret & Base64EncMap( ((first * 16) AND 48) + ((second \ 16)
AND 15 ) )
        ret = ret & Base64EncMap( ((second * 4) AND 60) + ((third \ 64)
AND 3 ) )
        ret = ret & Base64EncMap( third AND 63)
        ndx = ndx + 3
     loop
     ' check for stragglers
     if by3 < len(plain) then
        first = asc(mid(plain, ndx+0, 1))
        ret = ret & Base64EncMap( (first \ 4) AND 63 )
        if (len(plain) MOD 3 ) = 2 then
          second = asc(mid(plain, ndx+1, 1))
          ret = ret & Base64EncMap( ((first * 16) AND 48) +
((second \
16) AND 15 ) )
          ret = ret & Base64EncMap( ((second * 4) AND 60) )
        else
          ret = ret & Base64EncMap( (first * 16) AND 48)
          ret = ret & "="
        end if
        ret = ret & "="
     end if

     base64Encode = ret
   END FUNCTION

   ' decode base 64 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, first, second, third, fourth
     ret = ""
     by4 = (realLen \ 4) * 4
     ndx = 1
     do while ndx <= by4
        first = Base64DecMap(asc(mid(scrambled, ndx+0, 1)))
        second = Base64DecMap(asc(mid(scrambled, ndx+1, 1)))
        third = Base64DecMap(asc(mid(scrambled, ndx+2, 1)))
        fourth = Base64DecMap(asc(mid(scrambled, ndx+3, 1)))
        ret = ret & chr( ((first * 4) AND 255) +  ((second \ 16) AND 3)
)
        ret = ret & chr( ((second * 16) AND 255) + ((third \ 4) AND
15) )
        ret = ret & chr( ((third * 64) AND 255) + (fourth AND 63) )
        ndx = ndx + 4
     loop
     ' check for stragglers, will be 2 or 3 characters
     if ndx < realLen then
        first = Base64DecMap(asc(mid(scrambled, ndx+0, 1)))
        second = Base64DecMap(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 * 16) 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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