如何用asp进行base64加密

March 25,2004

bigeagle 于 2000-11-9 10:48:18 加贴在 Joy ASP ↑：

<%
   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
%>