<%
  ' OPTION EXPLICIT
   const BASE_64_MAP_INIT = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
   dim newline
   dim Base64EncMap(63)
   dim Base64DecMap(127)
   '初始化函数
   PUBLIC SUB initCodecs()
     ' 初始化变量
     newline = "<P>" & chr(13) & chr(10)
     dim max, idx
       max = len(BASE_64_MAP_INIT)
     for idx = 0 to max - 1
        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
   'Base64加密函数
   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
     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
   'Base64解密函数
   PUBLIC FUNCTION base64Decode(scrambled)
     if len(scrambled) = 0 then
        base64Decode = ""
        exit function
     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 = 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
     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

%>

' 初始化
 call initCodecs
Response.Write(base64Encode("之我要加密的字符串"))
Response.Write(base64Decode("bWFyczIwMTAwMjIw0"))