How to write the website verification code?

Classification: Computer/Network >> Internet

Problem description:

Who tells me how to do verification on the website? Thank you.

Analysis:

Let's first understand the basic idea of verification code from the simplest example.

In the first example, when the form is displayed, a 4-digit random number is generated as the verification code, and the verification code is transmitted through the session. On the data processing page, compare whether the verification code entered by the user is consistent with the value in the process. By the way, I met a confused guy who used hidden input controls to pass the verification code, but I didn't know that reading the page source code exposed the data. And the data in the password input is the same.

& lt%

''''''''**********************************

''''''' * Name: Post *

''''''' * code: ops(op.cc) *

''''' * Usage: verification code example 1: number *

''''''' * Time: July 2005 *

''''''''**********************************

Response. Buffer = true

Fuzzy check code

Response. Write "<& gt& lt text >

''''' = = * * After submitting the form: * = = = = =

If required. Server variables ("request _ method") = "post" and then

Dim founderr，callform，msg

Founderr = false''''' Is there an error?

Callform = false''''' Do you want to call the form?

Msg = ""'''''Prompt information

''''''' = = = = = = = Verification start of verification code = = = = = = = =

Dim session code

sessionCode = session("cCode ")

session("cCode") = " "

CheckCode = trim (request. Form ("ccode"))

If CheckCode = ""then

msg = msg+" & lt； Li> Please fill in the verification code. "

founderr = true

callform = true

else if CSTR(check code)& lt； & gtcstr(sessionCode)

msg = msg+" & lt； Li> verification code is incorrect "

founderr = true

callform = true

If ... it will be over.

''''''' = = = = = = = = = = Verification of verification code is over = = = = = = = = =

If founderr = true, then

Call message ("500")

If callform = true, myform () is called.

other

Msg = "< Li> operation succeeded! "

Call message ("500")

If ... it will be over.

''''''' = = * * Page initialization (before submitting the form) * * * = = = =

other

CheckCode = " "

Call myform ()

If ... it will be over.

Response. Write "& lt/body & gt；; & lt/>

REM subprocess, defining form

Child myform ()

Response. Write "< table width = 500 border =1cellspacing = 0 cellpadding = 5 align = center >" & amp_

“& ltform name = form 1 method = post action = post & gt；” & amp_

“& lttr height = 30 & gt& ltTD rowspan = 2 width = 100 align = center & gt。 Verification Code

“& lttd & gt& ltinput type = text name = ccode size = 10 >& amp_

getc code()& amp； “& lt/TD & gt； & lt/tr >； & amp_

"& lttr height = 30>& lttd & gt Please fill in the verification code on the right side of the text box.

“& lttr height = 30 & gt& lttd colspan=2 align=center >& amp_

"< input type = submission name = submission value = submission > & lt/TD & gt；; & lt/tr >； & amp_

“& lt/form & gt； & lt/table >

End joint

Rem subfunction, generating verification code (four-digit random number)

Function getCCode ()

Dimlannum

Irregular

ranNum = int(9000 * rnd)+ 1000

session("cCode") = ranNum

getCCode = ranNum

End function

Rem prompt information

Sub message (w)

Response. Write "< table width = & ampw & border =1cellspacing = 0cellpadding = 5align = center >" & amp_

"& lttr height = 30>& lttd & gt prompt information.

“& lttr valign=top>。 & lttdclass = "page _ speeder _ 327763530" Color: red; ""> & monosodium glutamate & amp“& lt/TD & gt；; & lt/tr & gt； & lt/table >

End joint

% & gt

The above code shows the general idea of generating verification code. Generating a four-digit random number as a verification code is the simplest and most insecure method.

Maybe you think that each number can correspond to a picture, and you can generate a picture verification code, just like a picture counter. This is not a good idea, it is not essentially different from numerical verification code, and it can't improve security.

Next, how to generate a picture verification code is introduced.

First of all, you can generate a verification code of xbm type through ASP, which is really a picture in xbm format, and you can set the size of the picture at will. For simplicity, let's take numbers as an example.

You can isolate the code that generates the verification code and name it checkcode:

& lt%

''''''''**********************************************

''''''' * Name: check code *

''''''' * code: ops(op.cc) *

''''' * Usage: generate verification code in xbm format *

''''''' * Time: July 2005 *

''''''''**********************************************

Continue to the next step when an error occurs.

dim i

dim countdata

countdata="*********** "

dim rou，ccode，clen

ccode= " "

clen = 4

Irregular

For i= 1 to 4

rou = int(rnd* 10)

ccode = ccode + cstr(rou)

then

Fuzzy structure

strDigits = Array(_

" 0 "、" 0x3c "、" 0x66 "、" 0x66 "、" 0x66 "、" 0x66 "、" 0x66 "、" 0x66 "、" 0x66 "、" 0x66 "、" 0x 66 "、" 0x3c "、_

" 1 "、" 0x30 "、" 0x38 "、" 0x30 "、" 0x30 "、" 0x30 "、" 0x30 "、" 0x30 "、" 0x30 "、" 0x30 "、" 0x30 "、" 0x 30 "、" 0x 30 "、_

" 2 "，" 0x3c "，" 0x66 "，" 0x60 "，" 0x60 "，" 0x30 "，" 0x 18 "，" 0x0c "，" 0x06 "，" 0x06 "，" 0x7e "，_

" 3 "，" 0x3c "，" 0x66 "，" 0x60 "，" 0x60 "，" 0x38 "，" 0x60 "，" 0x60 "，" 0x60 "，" 0x66 "，" 0x3c "，_

" 4 "，" 0x30 "，" 0x30 "，" 0x38 "，" 0x38 "，" 0x34 "，" 0x34 "，" 0x32 "，" 0x7e "，" 0x30 "，" 0x78 "，_

" 5 "、" 0x7e "、" 0x06 "、" 0x06 "、" 0x06 "、" 0x3e "、" 0x60 "、" 0x60 "、" 0x60 "、" 0x66 "、" 0x3c "、_

" 6 "，" 0x38 "，" 0x0c "，" 0x06 "，" 0x06 "，" 0x3e "，" 0x66 "，" 0x66 "，" 0x66 "，" 0x66 "，" 0x3c "，_

" 7 "，" 0x7e "，" 0x66 "，" 0x60 "，" 0x60 "，" 0x30 "，" 0x30 "，" 0x 18 "，" 0x 18 "，" 0x0c "，" 0x0c "，_

" 8 "、" 0x3c "、" 0x66 "、" 0x66 "、" 0x66 "、" 0x3c "、" 0x66 "、" 0x66 "、" 0x66 "、" 0x66 "、" 0x 66 "、" 0x3c "、_

“9”、“0x3c”、“0x66”、“0x66”、“0x66”、“0x66”、“0x7c”、“0x60”、“0x60”、“0x30”、“0x 1c”)

dim iCharWidth，iCharHeight，theBit，theNum，iRow，k，theOffset

Dim image string

imageStr = " "

iCharWidth = 8

iCharHeight= 10* 1

Response. ContentType ="image/x-xbitmap "

Response. Expired =0

Response. Write "# define counter width" & ampicharwidth * clen & amp chr (13) human rights center (10).

Response. Write "# Defining Counter Height" & AmpicharHeight & amp CHR (13) Center for Human Rights (10)

Response. Write "static unsigned character counter_bits[]={"

For iRow=0 to iCharHeight- 1

For i= 1 to clen

theBit=mid(ccode，I， 1)

k=0

do while k & ltubound(strDigits)

If strDigits(k) = theBit, then exit do.

k=k+iCharHeight+ 1

ring

If k & gt=ubound(strDigits), k=0.

Offset = k+1

imageStr = imageStr+(strDigits(the offset+iRow))& amp； ","

then

then

imageStr = left(imageStr，(len(imageStr)- 1))

Response. Write image string

Response. Write "};"

Session ("cCode") = ccode

% & gt

In post, when defining the form, the corresponding code is changed to:

REM subprocess, defining form

Child myform ()

Response. Write "< table width = 500 border =1cellspacing = 0 cellpadding = 5 align = center >" & amp_

“& ltform name = form 1 method = post action = default & gt；” & amp_

“& lttr height = 30 & gt& ltTD rowspan = 2 width = 100 align = center & gt。 Verification Code

“& lttd & gt& ltinput type = text name = ccode size = 10 >& amp_

“& ltimg src = check code width = 32 height = 10 border = 0 & gt； & lt/TD & gt； & lt/tr >； & amp_

"& lttr height = 30>& lttd & gt Please fill in the verification code on the right side of the text box.

“& lttr height = 30 & gt& lttd colspan=2 align=center >& amp_

"< input type = submission name = submission value = submission > & lt/TD & gt；; & lt/tr >； & amp_

“& lt/form & gt； & lt/table >

End joint

The above is the simplest verification code of xbm type. However, users of windows xp sp2 can't see the verification code in this format, because xp sp2 cancels the support for xbm format files. However, this problem can be solved by modifying the registry: open the registry, find HKEY _ local _ machine \ software \ Microsoft \ InterExplorer \ security, right-click to add a dword value, and rename it as BlockXBM, and its value is * * * * * * * *. After the change, just open the browser. You can also use the file editor to edit files containing:

Registry 4

[HKEY _ LOCAL _ MACHINE \ SOFTWARE \ Microsoft \ Inter Explorer \ Security]

" BlockXBM"=dword:*********

Save the file as a registry file with the extension reg, and then double-click the file.

In addition to the verification code in xbm format, we can also use the object of Adodb. To develop a more complex BMP verification code, and we can get the related program from op.cc/downloads/bmpccode.rar.. Using this program, you can generate a verification code that is a mixture of numbers and letters, colors and colored backgrounds.

For friends who rent space, the use of third-party components is greatly restricted. If you have your own server, you can try to use ASP drawing component shotgraph to generate verification code, which is in GIF format and has wide versatility. This component can be obtained from op.cc/downloads/shotgraph.zip., and there are detailed sample programs and documents in the compressed package.

In short, there are many ways to generate verification codes. There are many third-party components that can help you generate verification codes in various styles. Look for it on the internet.