如何用asp进行base64加密

<%
'-------------------------------------------------
'函数功能：文字加密解密Base64算法
'加密函数：base64Encode(str) as String
'解密函数：base64Decode(str) as String
'-------------------------------------------------

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 = "test"
 encode = base64Encode(inp)
 response.write "Encoded value = " & encode & "<br/>"
 response.write "Decoded value = " & base64Decode(encode) & "<br/>"
%>