Asp 加密解密字符串

<%
'const BASE_64_MAP_INIT = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
const BASE_64_MAP_INIT = "ABCD0EFGH1IJKLMNO2PQRSTUV3WXYZab4cdefg5hij6klmnop7qrstu8vwxyz9"
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

'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

'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
call initCodecs
abc="131"
response.write(base64Encode(abc))'加密字符串abc
'解密加密的字符串
response.Write("<br>")
response.Write(base64Decode(base64Encode(abc)))
response.End()
%>