关于验证码
为了安全 ，现在的很多网站都采取了验证码，最原始的纯数字或字符的验证码毫无用处。网站使用的验证码 一般都是 图片+干扰像素的。
有那位大大知道是怎么做到的么？我不想用组件，最好是纯代码的。
[解决办法]
我提供一个ASP验证码！
<%
Const nMaxSaturation = 100' 最大色彩饱和度
Const nBlankNoisyDotOdds = 0.01 ' 空白处噪点率
Const nColorNoisyDotOdds = 0.05 '有色处噪点率
Const nCharCount = 4' 产生的字符个数
Const nPixelWidth = 25' 单个字符位图的宽度
Const nPixelHeight = 25' 单个字符位图的高度
Const nColorHue = -1' 显示验证码的色调(-1表示随机色调, -2表示灰度色调)'220
Const nAngleRandom = 5 ' 角度随机量
Const nLengthRandom = 30 ' 长度随机量(百分比)
Const cCharSet = "0123456789"
' 构成验证码的字符集
' 如果扩充了下边的字母矢量库，则可以相应扩充这个字符集
Dim Buf(), DigtalStr
Dim Lines(), LineCount
Dim CursorX, CursorY, DirX, DirY
Randomize
Call CreatValidCode("GetCode")
Sub CDGen_Reset()
' 复位矢量笔和环境变量
LineCount = 0
CursorX = 0
CursorY = 0
' 初始的光笔方向是垂直向下
DirX = 0
DirY = 1
End Sub
Sub CDGen_Clear()
' 清空位图阵列
Dim i, j
ReDim Buf(nPixelHeight - 1, nCharCount * nPixelWidth - 1)
For j = 0 To nPixelHeight - 1
For i = 0 To nCharCount * nPixelWidth - 1
Buf(j, i) = 0
Next
Next
End Sub
Sub CDGen_PSet(X, Y)
' 在位图阵列上画点
Buf(Y, X) = 1
End Sub
Sub CDGen_Line(X1, Y1, X2, Y2)
' 在位图阵列上画线
Dim DX, DY, DeltaT, i
DX = X2 - X1
DY = Y2 - Y1
If Abs(DX) > Abs(DY) Then DeltaT = Abs(DX) Else DeltaT = Abs(DY)
For i = 0 To DeltaT
CDGen_PSet X1 + DX * i / DeltaT, Y1 + DY * i / DeltaT
Next
End Sub
Sub CDGen_FowardDraw(nLength)
' 按当前光笔方向绘制指定长度并移动光笔，正数表示从左向右/从上向下绘制，负数表示从右向左/从下向上绘制
nLength = Sgn(nLength) * Abs(nLength) * (1 - nLengthRandom / 100 + Rnd * nLenghtRandom * 2 / 100)
ReDim Preserve Lines(3, LineCount)
Lines(0, LineCount) = CursorX
Lines(1, LineCount) = CursorY
CursorX = CursorX + DirX * nLength
CursorY = CursorY + DirY * nLength
Lines(2, LineCount) = CursorX
Lines(3, LineCount) = CursorY
LineCount = LineCount + 1
End Sub
Sub CDGen_SetDirection(nAngle)
' 按指定角度设定画笔方向, 正数表示相对当前方向顺时针改变方向，负数表示相对当前方向逆时针改变方向
Dim DX, DY
nAngle = Sgn(nAngle) * (Abs(nAngle) - nAngleRandom + Rnd * nAngleRandom * 2) / 180 * 3.1415926
DX = DirX
DY = DirY
DirX = DX * Cos(nAngle) - DY * Sin(nAngle)
DirY = DX * Sin(nAngle) + DY * Cos(nAngle)
End Sub
Sub CDGen_MoveToMiddle(nActionIndex, nPercent)
' 将画笔光标移动到指定动作的中间点上，nPercent为中间位置的百分比
Dim DeltaX, DeltaY
DeltaX = Lines(2, nActionIndex) - Lines(0, nActionIndex)
DeltaY = Lines(3, nActionIndex) - Lines(1, nActionIndex)
CursorX = Lines(0, nActionIndex) + Sgn(DeltaX) * Abs(DeltaX) * nPercent / 100
CursorY = Lines(1, nActionIndex) + Sgn(DeltaY) * Abs(DeltaY) * nPercent / 100
End Sub
Sub CDGen_MoveCursor(nActionIndex)
' 将画笔光标移动到指定动作的起始点上
CursorX = Lines(0, nActionIndex)
CursorY = Lines(1, nActionIndex)
End Sub
Sub CDGen_Close(nActionIndex)
' 将当前光笔位置与指定动作的起始点闭合并移动光笔
ReDim Preserve Lines(3, LineCount)
Lines(0, LineCount) = CursorX
Lines(1, LineCount) = CursorY
CursorX = Lines(0, nActionIndex)
CursorY = Lines(1, nActionIndex)
Lines(2, LineCount) = CursorX
Lines(3, LineCount) = CursorY
LineCount = LineCount + 1
End Sub
Sub CDGen_CloseToMiddle(nActionIndex, nPercent)
' 将当前光笔位置与指定动作的中间点闭合并移动光笔，nPercent为中间位置的百分比
Dim DeltaX, DeltaY
ReDim Preserve Lines(3, LineCount)
Lines(0, LineCount) = CursorX
Lines(1, LineCount) = CursorY
DeltaX = Lines(2, nActionIndex) - Lines(0, nActionIndex)
DeltaY = Lines(3, nActionIndex) - Lines(1, nActionIndex)
CursorX = Lines(0, nActionIndex) + Sgn(DeltaX) * Abs(DeltaX) * nPercent / 100
CursorY = Lines(1, nActionIndex) + Sgn(DeltaY) * Abs(DeltaY) * nPercent / 100
Lines(2, LineCount) = CursorX
Lines(3, LineCount) = CursorY
LineCount = LineCount + 1
End Sub
Sub CDGen_Flush(X0, Y0)
' 按照当前的画笔动作序列绘制位图点阵
Dim MaxX, MinX, MaxY, MinY
Dim DeltaX, DeltaY, StepX, StepY, OffsetX, OffsetY
Dim i
MaxX = MinX = MaxY = MinY = 0
For i = 0 To LineCount - 1
If MaxX < Lines(0, i) Then MaxX = Lines(0, i)
If MaxX < Lines(2, i) Then MaxX = Lines(2, i)
If MinX > Lines(0, i) Then MinX = Lines(0, i)
If MinX > Lines(2, i) Then MinX = Lines(2, i)
If MaxY < Lines(1, i) Then MaxY = Lines(1, i)
If MaxY < Lines(3, i) Then MaxY = Lines(3, i)
If MinY > Lines(1, i) Then MinY = Lines(1, i)
If MinY > Lines(3, i) Then MinY = Lines(3, i)
Next
DeltaX = MaxX - MinX
DeltaY = MaxY - MinY
If DeltaX = 0 Then DeltaX = 1
If DeltaY = 0 Then DeltaY = 1
MaxX = MinX
MaxY = MinY
If DeltaX > DeltaY Then
StepX = (nPixelWidth - 2) / DeltaX
StepY = (nPixelHeight - 2) / DeltaX
OffsetX = 0
OffsetY = (DeltaX - DeltaY) / 2
Else
StepX = (nPixelWidth - 2) / DeltaY
StepY = (nPixelHeight - 2) / DeltaY
OffsetX = (DeltaY - DeltaX) / 2
OffsetY = 0
End If
For i = 0 To LineCount - 1
Lines(0, i) = Round((Lines(0, i) - MaxX + OffsetX) * StepX, 0)
If Lines(0, i) < 0 Then Lines(0, i) = 0
If Lines(0, i) >= nPixelWidth - 2 Then Lines(0, i) = nPixelWidth - 3
Lines(1, i) = Round((Lines(1, i) - MaxY + OffsetY) * StepY, 0)
If Lines(1, i) < 0 Then Lines(1, i) = 0
If Lines(1, i) >= nPixelHeight - 2 Then Lines(1, i) = nPixelHeight - 3
Lines(2, i) = Round((Lines(2, i) - MinX + OffsetX) * StepX, 0)
If Lines(2, i) < 0 Then Lines(2, i) = 0
If Lines(2, i) >= nPixelWidth - 2 Then Lines(2, i) = nPixelWidth - 3
Lines(3, i) = Round((Lines(3, i) - MinY + OffsetY) * StepY, 0)
If Lines(3, i) < 0 Then Lines(3, i) = 0
If Lines(3, i) >= nPixelHeight - 2 Then Lines(3, i) = nPixelHeight - 3
CDGen_Line Lines(0, i) + X0 + 1, Lines(1, i) + Y0 + 1, Lines(2, i) + X0 + 1, Lines(3, i) + Y0 + 1
Next
End Sub
[解决办法]
我给你来一个简单一点的：
<%'生成验证码图片文件
Option Explicit
Response.buffer=true
Call Com_CreatValidCode("GetCode")
Sub Com_CreatValidCode(pSN)
Response.Expires = -1
Response.AddHeader "Pragma","no-cache"
Response.AddHeader "cache-ctrol","no-cache"
Response.ContentType = "Image/BMP"
Randomize
Dim i, ii, iii
Const cOdds = 0 ' 杂点出现的机率
Const cAmount = 10 ' 文字数量
Const cCode = "0123456789"
' 颜色的数据(字符，背景)
Dim vColorData(1)
vColorData(0) = ChrB(155) & ChrB(58) & ChrB(48) ' 蓝0，绿0，红0（黑色）
vColorData(1) = ChrB(255) & ChrB(223) & ChrB(223) ' 蓝250，绿236，红211（浅蓝色）
' 随机产生字符
Dim vCode(4), vCodes
For i = 0 To 3
vCode(i) = Int(Rnd * cAmount)
vCodes = vCodes & Mid(cCode, vCode(i) + 1, 1)
Next
Session("pSN") = vCodes '记录入Session
' 字符的数据
Dim vNumberData(9)
vNumberData(0) = "1110000111110111101111011110111101001011110100101111010010111101001011110111101111011110111110000111"
vNumberData(1) = "1111011111110001111111110111111111011111111101111111110111111111011111111101111111110111111100000111"
vNumberData(2) = "1110000111110111101111011110111111111011111111011111111011111111011111111011111111011110111100000011"
vNumberData(3) = "1110000111110111101111011110111111110111111100111111111101111111111011110111101111011110111110000111"
vNumberData(4) = "1111101111111110111111110011111110101111110110111111011011111100000011111110111111111011111111000011"
vNumberData(5) = "1100000011110111111111011111111101000111110011101111111110111111111011110111101111011110111110000111"
vNumberData(6) = "1111000111111011101111011111111101111111110100011111001110111101111011110111101111011110111110000111"
vNumberData(7) = "1100000011110111011111011101111111101111111110111111110111111111011111111101111111110111111111011111"
vNumberData(8) = "1110000111110111101111011110111101111011111000011111101101111101111011110111101111011110111110000111"
vNumberData(9) = "1110001111110111011111011110111101111011110111001111100010111111111011111111101111011101111110001111"
' 输出图像文件头
Response.BinaryWrite ChrB(66) & ChrB(77) & ChrB(230) & ChrB(4) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) &_
ChrB(0) & ChrB(0) & ChrB(54) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(40) & ChrB(0) &_
ChrB(0) & ChrB(0) & ChrB(40) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(10) & ChrB(0) &_
ChrB(0) & ChrB(0) & ChrB(1) & ChrB(0)
' 输出图像信息头
Response.BinaryWrite ChrB(24) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(176) & ChrB(4) &_
ChrB(0) & ChrB(0) & ChrB(18) & ChrB(11) & ChrB(0) & ChrB(0) & ChrB(18) & ChrB(11) &_
ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) &_
ChrB(0) & ChrB(0)
For i = 9 To 0 Step -1 ' 历经所有行
For ii = 0 To 3 ' 历经所有字
For iii = 1 To 10 ' 历经所有像素
' 逐行、逐字、逐像素地输出图像数据
If Rnd * 99 + 1 < cOdds Then ' 随机生成杂点
Response.BinaryWrite vColorData(0)
Else
Response.BinaryWrite vColorData(Mid(vNumberData(vCode(ii)), i * 10 + iii, 1))
End If
Next
Next
Next
End Sub
%>
调用：
<img src="1.asp">
判断：
只要判断表单变量和SESSION表量是否一致就可以了