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验证码的程序及原理
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##### 部分程序取自网络
##### 作者：扬子
##### email: yangz.net@hotmail.com
##### qq: 21112856
##### website: www.tingfo.net
一共4个页面：form.asp; chk.asp; num.asp; count.asp
得到一个随即数字。加密！
解密后成成xbm图片
利用session 判断
form.asp
<%
'### to encrypt/decrypt include this code in your page
'### strmyencryptedstring = encryptstring(strstring)
'### strmydecryptedstring = decryptstring(strmyencryptedstring)
'### you are free to use this code as long as credits remain in place
'### also if you improve this code let me know.
private function encryptstring(strstring)
'####################################################################
'### crypt function (c) 2001 by slavic kozyuk grindkore@yahoo.com ###
'### arguments: strstring <--- string you wish to encrypt ###
'### output: encrypted hex string ###
'####################################################################
dim charhexset, intstringlen, strtemp, strraw, i, intkey, intoffset
randomize timer
intkey = round((rnd * 1000000) + 1000000) '##### key bitsize
intoffset = round((rnd * 1000000) + 1000000) '##### keyoffset bitsize
if isnull(strstring) = false then
strraw = strstring
intstringlen = len(strraw)
for i = 0 to intstringlen - 1
strtemp = left(strraw, 1)
strraw = right(strraw, len(strraw) - 1)
charhexset = charhexset & hex(asc(strtemp) * intkey)& hex(intkey)
next
encryptstring = charhexset & "" & hex(intoffset + intkey) & "" & hex(intoffset)
else
encryptstring = ""
end if
end function
private function decryptstring(strcryptstring)
'####################################################################
'### crypt function (c) 2001 by slavic kozyuk grindkore@yahoo.com ###
'### arguments: encrypted hex stringt ###
'### output: decrypted ascii string ###
'####################################################################
'### note this function uses hexconv() and get_hxno() functions ###
'### so make sure they are not removed ###
'####################################################################
dim strraw, arhexcharset, i, intkey, intoffset, strrawkey, strhexcrypdata
strrawkey = right(strcryptstring, len(strcryptstring) - instr(strcryptstring, ""))
intoffset = right(strrawkey, len(strrawkey) - instr(strrawkey,""))
intkey = hexconv(left(strrawkey, instr(strrawkey, "") - 1)) - hexconv(intoffset)
strhexcrypdata = left(strcryptstring, len(strcryptstring) - (len(strrawkey) + 1))
arhexcharset = split(strhexcrypdata, hex(intkey))
for i=0 to ubound(arhexcharset)
strraw = strraw & chr(hexconv(arhexcharset(i))/intkey)
next
decryptstring = strraw
end function
private function hexconv(hexvar)
dim hxx, hxx_var, multiply
if hexvar <> "" then
hexvar = ucase(hexvar)
hexvar = strreverse(hexvar)
dim hx()
redim hx(len(hexvar))
hxx = 0
hxx_var = 0
for hxx = 1 to len(hexvar)
if multiply = "" then multiply = 1
hx(hxx) = mid(hexvar,hxx,1)
hxx_var = (get_hxno(hx(hxx)) * multiply) + hxx_var
multiply = (multiply * 16)
next
hexvar = hxx_var
hexconv = hexvar
end if
end function
private function get_hxno(ghx)
if ghx = "a" then
ghx = 10
elseif ghx = "b" then
ghx = 11
elseif ghx = "c" then
ghx = 12
elseif ghx = "d" then
ghx = 13
elseif ghx = "e" then
ghx = 14
elseif ghx = "f" then
ghx = 15
end if
get_hxno = ghx
end function
%>
<%
randomize
num = int(7999*rnd+2000) '计数器的值
num2 = encryptstring(num)
session("pwdt")=num
%>
<form action="chk.asp" method=post>
请输入验证码： <input type="text" name="pwds">
<img src="count.asp?sksid=<%=num2%>"> <input type=submit value=提交>
</form>
chk.asp
<%
if trim(request.form("pwds"))<>trim(session("pwdt")) then
%>
输入错误： 应该为：<%=session("pwdt")%>，可你输入的是:<%=request.form("pwds")%>
<%
else
%>
输入正确
<%end if%>
count.asp
<!--#include file="num.asp"-->
<%
'### to encrypt/decrypt include this code in your page
'### strmyencryptedstring = encryptstring(strstring)
'### strmydecryptedstring = decryptstring(strmyencryptedstring)
'### you are free to use this code as long as credits remain in place
'### also if you improve this code let me know.
private function encryptstring(strstring)
'####################################################################
'### crypt function (c) 2001 by slavic kozyuk grindkore@yahoo.com ###
'### arguments: strstring <--- string you wish to encrypt ###
'### output: encrypted hex string ###
'####################################################################
dim charhexset, intstringlen, strtemp, strraw, i, intkey, intoffset
randomize timer
intkey = round((rnd * 1000000) + 1000000) '##### key bitsize
intoffset = round((rnd * 1000000) + 1000000) '##### keyoffset bitsize
if isnull(strstring) = false then
strraw = strstring
intstringlen = len(strraw)
for i = 0 to intstringlen - 1
strtemp = left(strraw, 1)
strraw = right(strraw, len(strraw) - 1)
charhexset = charhexset & hex(asc(strtemp) * intkey)& hex(intkey)
next
encryptstring = charhexset & "" & hex(intoffset + intkey) & "" & hex(intoffset)
else
encryptstring = ""
end if
end function
private function decryptstring(strcryptstring)
'####################################################################
'### crypt function (c) 2001 by slavic kozyuk grindkore@yahoo.com ###
'### arguments: encrypted hex stringt ###
'### output: decrypted ascii string ###
'####################################################################
'### note this function uses hexconv() and get_hxno() functions ###
'### so make sure they are not removed ###
'####################################################################
dim strraw, arhexcharset, i, intkey, intoffset, strrawkey, strhexcrypdata
strrawkey = right(strcryptstring, len(strcryptstring) - instr(strcryptstring, ""))
intoffset = right(strrawkey, len(strrawkey) - instr(strrawkey,""))
intkey = hexconv(left(strrawkey, instr(strrawkey, "") - 1)) - hexconv(intoffset)
strhexcrypdata = left(strcryptstring, len(strcryptstring) - (len(strrawkey) + 1))
arhexcharset = split(strhexcrypdata, hex(intkey))
for i=0 to ubound(arhexcharset)
strraw = strraw & chr(hexconv(arhexcharset(i))/intkey)
next
decryptstring = strraw
end function
private function hexconv(hexvar)
dim hxx, hxx_var, multiply
if hexvar <> "" then
hexvar = ucase(hexvar)
hexvar = strreverse(hexvar)
dim hx()
redim hx(len(hexvar))
hxx = 0
hxx_var = 0
for hxx = 1 to len(hexvar)
if multiply = "" then multiply = 1
hx(hxx) = mid(hexvar,hxx,1)
hxx_var = (get_hxno(hx(hxx)) * multiply) + hxx_var
multiply = (multiply * 16)
next
hexvar = hxx_var
hexconv = hexvar
end if
end function
private function get_hxno(ghx)
if ghx = "a" then
ghx = 10
elseif ghx = "b" then
ghx = 11
elseif ghx = "c" then
ghx = 12
elseif ghx = "d" then
ghx = 13
elseif ghx = "e" then
ghx = 14
elseif ghx = "f" then
ghx = 15
end if
get_hxno = ghx
end function
%>
<%
dim image
dim width, height
dim num
dim digtal
dim length
dim sort
length = 4 '自定计数器长度
redim sort( length )
num=cint(decryptstring(request.querystring("sksid")))
digital = ""
for i = 1 to length -len( num ) '补0
digital = digital & "0"
next
for i = 1 to len( num )
digital = digital & mid( num, i, 1 )
next
for i = 1 to len( digital )
sort(i) = mid( digital, i, 1 )
next
width = 8 * len( digital ) '图像的宽度
height = 10 '图像的高度，在本例中为固定值
response.contenttype="image/x-xbitmap"
hc=chr(13) & chr(10)
image = "#define counter_width " & width & hc
image = image & "#define counter_height " & height & hc
image = image & "static unsigned char counter_bits[]={" & hc
for i = 1 to height
for j = 1 to length
image = image & a(sort(j),i) & ","
next
next
image = left( image, len( image ) - 1 ) '去掉最后一个逗号
image = image & "};" & hc
%>
<%
response.write image
%>
num.asp
<%
dim a(10,10)
a(0,1) = "0x3c" '数字0
a(0,2) = "0x66"
a(0,3) = "0xc3"
a(0,4) = "0xc3"
a(0,5) = "0xc3"
a(0,6) = "0xc3"
a(0,7) = "0xc3"
a(0,8) = "0xc3"
a(0,9) = "0x66"
a(0,10)= "0x3c"
a(1,1) = "0x18" '数字1
a(1,2) = "0x1c"
a(1,3) = "0x18"
a(1,4) = "0x18"
a(1,5) = "0x18"
a(1,6) = "0x18"
a(1,7) = "0x18"
a(1,8) = "0x18"
a(1,9) = "0x18"
a(0,10)= "0x7e"
a(2,1) = "0x3c" '数字2
a(2,2) = "0x66"
a(2,3) = "0x60"
a(2,4) = "0x60"
a(2,5) = "0x30"
a(2,6) = "0x18"
a(2,7) = "0x0c"
a(2,8) = "0x06"
a(2,9) = "0x06"
a(2,10)= "0x7e"
a(3,1) = "0x3c" '数字3
a(3,2) = "0x66"
a(3,3) = "0xc0"
a(3,4) = "0x60"
a(3,5) = "0x1c"
a(3,6) = "0x60"
a(3,7) = "0xc0"
a(3,8) = "0xc0"
a(3,9) = "0x66"
a(3,10)= "0x38"
a(4,1) = "0x38" '数字4
a(4,2) = "0x3c"
a(4,3) = "0x36"
a(4,4) = "0x33"
a(4,5) = "0x33"
a(4,6) = "0x33"
a(4,7) = "0xff"
a(4,8) = "0x30"
a(4,9) = "0x30"
a(4,10)= "0xfe"
a(5,1) = "0xfe" '数字5
a(5,2) = "0xfe"
a(5,3) = "0x06"
a(5,4) = "0x06"
a(5,5) = "0x3e"
a(5,6) = "0x60"
a(5,7) = "0xc0"
a(5,8) = "0xc3"
a(5,9) = "0x66"
a(5,10)= "0x3c"
a(6,1) = "0x60" '数字6
a(6,2) = "0x30"
a(6,3) = "0x18"
a(6,4) = "0x0c"
a(6,5) = "0x3e"
a(6,6) = "0x63"
a(6,7) = "0xc3"
a(6,8) = "0xc3"
a(6,9) = "0x66"
a(6,10) ="0x3c"
a(7,1) = "0xff" '数字7
a(7,2) = "0xc0"
a(7,3) = "0x60"
a(7,4) = "0x30"
a(7,5) = "0x18"
a(7,6) = "0x18"
a(7,7) = "0x18"
a(7,8) = "0x18"
a(7,9) = "0x18"
a(7,10)= "0x18"
a(8,1) = "0x3c" '数字8
a(8,2) = "0x66"
a(8,3) = "0xc3"
a(8,4) = "0x66"
a(8,5) = "0x3c"
a(8,6) = "0x66"
a(8,7) = "0xc3"
a(8,8) = "0xc3"
a(8,9) = "0x66"
a(8,10)= "0x3c"
a(9,1) = "0x3c" '数字9
a(9,2) = "0x66"
a(9,3) = "0xc3"
a(9,4) = "0xc3"
a(9,5) = "0x66"
a(9,6) = "0x3c"
a(9,7) = "0x18"
a(9,8) = "0x0c"
a(9,9) = "0x06"
a(9,10)= "0x03"
%>
