<% '============================================================ ' MODULE: Captcha.asp ' AUTHOR: © www.u229.no ' CREATED: July 2005 ' HOME PAGE: http://www.u229.no/stuff/Captcha/ ' LICENSE: http://www.u229.no/stuff/license/ '============================================================ ' COMMENT: This is a CAPTCHA made with Classic ASP, some CSS and some javascript. ' You may want to move the user checking to other parts of your own code. See ' info somewhere near line 150. ' Save this file as Captcha.asp '============================================================ ' TODO: ' 1) Include numbers? ' 2) If above = True Then: Add more human questions like doing some basic math on the numbers? ' 3) Limit the number of log in attemps based on the visitors IP Number? ' 4) The yellow color might be hard to read. It could have been gray instead. '============================================================ ' ROUTINES: ' - Function CreateCAPTCHA() ' - Sub InitArrays() ' - Sub CreateStyleSheet() ' - Sub CreateJavascript() ' - Function RandomizeArrayUnique(arr, arrNew) ' - Function RandomizeArray(arr, arrNew) ' - Function RandomNumber(iMax) ' - Function RandomString(iMax) '============================================================ 'Option Explicit On Error Resume Next Response.CacheControl = "no-cache" Response.AddHeader "Pragma", "no-cache" Response.Expires = -1 '// YOUR PREFERENCES Const MAX_NUMBER_OF_CHARACTERS = 3 '// How many characters in our CAPTCHA? Const MAX_LENGTH_CSS_CLASSES = 12 '// How many characters in the CSS class names? Const CAPTCHA_CHARACTER_FACTOR = 40 '// How many pixels are we moving each new character from left? Const CAPTCHA_BOX_BORDER = "border: 2px solid #ccc;" '// Style the div box holding the CAPTCHA. Const CAPTCHA_BOX_WIDTH = 160 '// Width. This value should balance the number of characters and size. Const CAPTCHA_BOX_HEIGHT = 40 '// Same as above. Const NAME_OF_CAPTCHA_TEXTBOX = "CaptchaBox" '// Name of CAPTCHA text box. Rename this!! Dim m_arrCaptcha() '// Array holding our CAPTCHA charaters. Hold in session variable. Dim m_arrCaptchaScreen() '// Parallell array where some items migth be hex/decimal encoded for display on screen. Dim m_sCSS '// Our CSS Dim m_sJavascript '// Our Javascript Dim m_sUserResult '// Return a response to client/demo if success or failure Dim m_sNameOfWrapperDiv '// Holding the id name attribute for the div wrapping the CAPTCHA? Dim m_arrColor(4) '// Array of colors for the characters Dim m_arrColorNew(4) '// Same colors randomized Dim m_arrFontFamily(4) '// Array of font family strings Dim m_arrFontFamilyNew(4) '// Same fonts randomized Dim m_arrFontSize(4) '// Array of font sizes Dim m_arrFontSizeNew(4) '// Same font sizes now randomized Dim m_arrTopPosition(4) '// Array of top position values Dim m_arrTopPositionNew(4) '// Same values randomized Dim m_arrClassNames() '// Array of names for the CSS classes Dim m_arrQuestions(3) '// Array of questions for the human visitor Dim m_lngQuestionIndex '// This number between 0 - 3 defines what question to ask the human visitor Dim m_arrCaptchaColor(2) '// Array holding the color of the character we are asking the visitor for Dim m_arrCSSStrings(4) '// Array holding our CSS elements/strings Dim m_arrCSSStringsNew(4) '// Same strings now randomly and uniquely sorted Dim TestColor , newstemp,spliter dim sJScript123 dim colorval '// START UP THE MODULE ARRAYS m_arrColor(0) = "green" m_arrColor(1) = "blue" m_arrColor(2) = "red" m_arrColor(3) = "black" m_arrColor(4) = "red" m_arrFontFamily(0) = "Verdana" m_arrFontFamily(1) = "Arial" m_arrFontFamily(2) = "Tahoma" m_arrFontFamily(3) = "Courier" m_arrFontFamily(4) = "Georgia" m_arrFontSize(0) = 24 m_arrFontSize(1) = 21 m_arrFontSize(2) = 22 m_arrFontSize(3) = 25 m_arrFontSize(4) = 20 m_arrTopPosition(0) = 5 m_arrTopPosition(1) = 10 m_arrTopPosition(2) = 15 m_arrTopPosition(3) = 5 m_arrTopPosition(4) = 10 m_arrQuestions(0) = "Before submitting this form, please type the characters displayed above:" m_arrQuestions(1) = "Before submitting this form, please type the color of the first character:" m_arrQuestions(2) = "Before submitting this form, please type the color of the second character:" m_arrQuestions(3) = "Before submitting this form, please type the color of the third character:" m_arrCSSStrings(0) = "position: absolute;" m_arrCSSStrings(1) = "top: " m_arrCSSStrings(2) = "left: " m_arrCSSStrings(3) = "color: " m_arrCSSStrings(4) = "font: bold " '------------------------------------------------------------------------------------------------------------ ' Comment: Call this function from where you want to include the CAPTCHA. '------------------------------------------------------------------------------------------------------------ Function CreateCAPTCHA() On Error Resume Next Dim i, iTmp, sTmp '---------------------------- Create our CAPTCHA! '// This holds plain text characters. They are stored in a session variable and compared with the user input. ReDim m_arrCaptcha(MAX_NUMBER_OF_CHARACTERS - 1) '// This holds the decimal and hexified characters displayed on screen. ReDim m_arrCaptchaScreen(MAX_NUMBER_OF_CHARACTERS - 1) For i = 0 To (MAX_NUMBER_OF_CHARACTERS - 1) sTmp = UCase(RandomString(1)) iTmp = RandomNumber(101) m_arrCaptcha(i) = sTmp If iTmp < 33 Then m_arrCaptchaScreen(i) = "&#" & Asc(UCase(sTmp)) & ";" '// Decimal If iTmp > 66 Then m_arrCaptchaScreen(i) = "&#x" & Hex(Asc(UCase(sTmp))) & ";" '// Hexify If iTmp < 67 And iTmp > 32 Then m_arrCaptchaScreen(i) = UCase(sTmp) '// Plain Ascii Next '---------------------------- What question will we ask the human visitor? m_lngQuestionIndex = RandomNumber(MAX_NUMBER_OF_CHARACTERS + 1) '// Default max number of questions is 4 If m_lngQuestionIndex > 4 Then m_lngQuestionIndex = RandomNumber(4) '---------------------------- Create CSS and javascript Call CreateStyleSheet Call CreateJavascript '---------------------------- Check to see if someone submitted CAPTCHA, machine or human '// You may want to move this code to another part of your own application and do the testing there. '// Nothing was submitted, so just set a new session value which is our CAPTCHA characters or a color Session("CAPTCHA") = Replace(Join(m_arrCaptcha), " ", "") '// We will ask visitor for a color! Reduce m_lngQuestionIndex by 1 to match the m_arrCaptchaColor array If (m_lngQuestionIndex > 0) Then Session("CAPTCHA") = m_arrCaptchaColor(m_lngQuestionIndex - 1) '---------------------------- Return the html CreateCAPTCHA = m_sCSS & m_sJavascript End Function 'response.Write "Cap :" & Session("CAPTCHA") '------------------------------------------------------------------------------------------------------------ ' Comment: Randomize our module arrays holding the CSS values. '------------------------------------------------------------------------------------------------------------ Sub InitArrays() On Error Resume Next '// First 4 arrays are randomly sorted meaning that all characters might have the same color. response.Write "m_arrColor: "& m_arrColor &"
" Call RandomizeArray(m_arrColor, m_arrColorNew) Call RandomizeArray(m_arrFontFamily, m_arrFontFamilyNew) Call RandomizeArray(m_arrFontSize, m_arrFontSizeNew) Call RandomizeArray(m_arrTopPosition, m_arrTopPositionNew) Call RandomizeArrayUnique(m_arrCSSStrings, m_arrCSSStringsNew) End Sub '------------------------------------------------------------------------------------------------------------ ' Comment: Build the CSS. '------------------------------------------------------------------------------------------------------------ Sub CreateStyleSheet() On Error Resume Next Dim sCSS, i, l, iLeft, sTmp, sTmpClassName '---------------------------- Create the CSS for the div box '// First create a random name for the wrapper div. m_sNameOfWrapperDiv = RandomString(MAX_LENGTH_CSS_CLASSES) sCSS = "" End Sub '------------------------------------------------------------------------------------------------------------ ' Comment: Create the javascript with our unique css class names and the CAPTCHA characters. '------------------------------------------------------------------------------------------------------------ Sub CreateJavascript() On Error Resume Next Dim i, sJScript sJScript = "" & vbCrLf sJScript = sJScript & "

" & m_arrQuestions(m_lngQuestionIndex) & "

" & vbCrLf m_sJavascript = sJScript 'response.Write "JS: " &m_sNameOfWrapperDiv End Sub '------------------------------------------------------------------------------------------------------------ ' Comment: Randomize array but make sure all values are present in the new array. '------------------------------------------------------------------------------------------------------------ Function RandomizeArrayUnique(arr, arrNew) On Error Resume Next Dim i, l, sBuf, sTmp, iMax iMax = UBound(arr) ReDim arrNew(iMax) For i = 0 To iMax '// This should be enough looping For l = 1 To (iMax * 20) sTmp = arr(RandomNumber(iMax + 1)) If InStr(sBuf, sTmp) = 0 Then sBuf = (sBuf & sTmp) 'response.Write "sBuf & sTmp : " & sBuf & sTmp &"
" arrNew(i) = sTmp Exit For End If Next Next ' response.Write "sTmp: " & sTmp &"
" End Function '------------------------------------------------------------------------------------------------------------ ' Comment: Randomize our module arrays holding the CSS. One value might appear several times. '------------------------------------------------------------------------------------------------------------ Function RandomizeArray(arr, arrNew) On Error Resume Next Dim i ReDim arrNew(UBound(arr)) For i = LBound(arr) To UBound(arr) arrNew(i) = arr(RandomNumber(UBound(arr) + 1)) ' response.Write "arrnew: " &arrNew(i) & "
" Next End Function '------------------------------------------------------------------------------------------------------------ ' Comment: Return a random number not bigger than the input parameter. '------------------------------------------------------------------------------------------------------------ Function RandomNumber(iMax) On Error Resume Next Randomize RandomNumber = Int(iMax * Rnd) 'response.Write "RandomNumber: "& RandomNumber End Function '------------------------------------------------------------------------------------------------------------ ' Comment: Create a random string of lower case letters [a-z] for the css class names. '------------------------------------------------------------------------------------------------------------ Function RandomString(iMax) On Error Resume Next Dim i, sTmp For i = 1 To iMax sTmp = sTmp & Chr(97 + RandomNumber(26)) '// Return a random number between 97 and 122, ascii values for [a-z] Next RandomString = sTmp ' response.Write "RandomString: " & RandomString End Function '============================================================ END OF ASP CODE %>
 
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<%Response.Write CreateCAPTCHA%>  <%if request.QueryString("Msg")="error" then %>* Invalid code<%end if %>
 
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