<%
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
' 测试代码
dim inp, encode
inp = "mars20100220"
encode = base64Encode(inp)
'encode = "bWFyczIwMTAwMjIw0"
response.write "加密前为:" & inp & newline
response.write "加密后为:" & encode & newline
response.write "解密后为:" & base64Decode(encode) & newline
%>