ASP验证码的程序及原理

sunlei

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##### 部分程序取自网络
##### 作者：扬子
##### Email: yangzinet@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

1. <%
2. '### To encrypt/decrypt include this code in your page
3. '### strMyEncryptedString = EncryptString(strString)
4. '### strMyDecryptedString = DeCryptString(strMyEncryptedString)
5. '### You are free to use this code as long as credits remain in place
6. '### also if you improve this code let me know.
8. Private Function EncryptString(strString)
9. '####################################################################
10. '### Crypt Function (C) 2001 by Slavic Kozyuk [email]grindkore@yahoo.com[/email] ###
11. '### Arguments: strString <--- String you wish to encrypt ###
12. '### Output: Encrypted HEX string ###
13. '####################################################################
15. Dim CharHexSet, intStringLen, strTemp, strRAW, i, intKey, intOffSet
16. Randomize Timer
18. intKey = Round((RND * 1000000) + 1000000) '##### Key Bitsize
19. intOffSet = Round((RND * 1000000) + 1000000) '##### KeyOffSet Bitsize
21. If IsNull(strString) = False Then
22. strRAW = strString
23. intStringLen = Len(strRAW)
25. For i = 0 to intStringLen - 1
26. strTemp = Left(strRAW, 1)
27. strRAW = Right(strRAW, Len(strRAW) - 1)
28. CharHexSet = CharHexSet & Hex(Asc(strTemp) * intKey)& Hex(intKey)
29. Next
31. EncryptString = CharHexSet & "|" & Hex(intOffSet + intKey) & "|" & Hex(intOffSet)
32. Else
33. EncryptString = ""
34. End If
35. End Function
38. Private Function DeCryptString(strCryptString)
39. '####################################################################
40. '### Crypt Function (C) 2001 by Slavic Kozyuk [email]grindkore@yahoo.com[/email] ###
41. '### Arguments: Encrypted HEX stringt ###
42. '### Output: Decrypted ASCII string ###
43. '####################################################################
44. '### Note this function uses HexConv() and get_hxno() functions ###
45. '### so make sure they are not removed ###
46. '####################################################################
48. Dim strRAW, arHexCharSet, i, intKey, intOffSet, strRawKey, strHexCrypData
50. strRawKey = Right(strCryptString, Len(strCryptString) - InStr(strCryptString, "|"))
51. intOffSet = Right(strRawKey, Len(strRawKey) - InStr(strRawKey,"|"))
52. intKey = HexConv(Left(strRawKey, InStr(strRawKey, "|") - 1)) - HexConv(intOffSet)
53. strHexCrypData = Left(strCryptString, Len(strCryptString) - (Len(strRawKey) + 1))
55. arHexCharSet = Split(strHexCrypData, Hex(intKey))
57. For i=0 to UBound(arHexCharSet)
58. strRAW = strRAW & Chr(HexConv(arHexCharSet(i))/intKey)
59. Next
61. DeCryptString = strRAW
62. End Function
65. Private Function HexConv(hexVar)
66. Dim hxx, hxx_var, multiply
67. IF hexVar <> "" THEN
68. hexVar = UCASE(hexVar)
69. hexVar = StrReverse(hexVar)
70. DIM hx()
71. REDIM hx(LEN(hexVar))
72. hxx = 0
73. hxx_var = 0
74. FOR hxx = 1 TO LEN(hexVar)
75. IF multiply = "" THEN multiply = 1
76. hx(hxx) = mid(hexVar,hxx,1)
77. hxx_var = (get_hxno(hx(hxx)) * multiply) + hxx_var
78. multiply = (multiply * 16)
79. NEXT
80. hexVar = hxx_var
81. HexConv = hexVar
82. END IF
83. End Function
85. Private Function get_hxno(ghx)
86. If ghx = "A" Then
87. ghx = 10
88. ElseIf ghx = "B" Then
89. ghx = 11
90. ElseIf ghx = "C" Then
91. ghx = 12
92. ElseIf ghx = "D" Then
93. ghx = 13
94. ElseIf ghx = "E" Then
95. ghx = 14
96. ElseIf ghx = "F" Then
97. ghx = 15
98. End If
99. get_hxno = ghx
100. End Function
101. %>
103. <%
104. randomize
105. num = int(7999*rnd+2000) '计数器的值
106. num2 = EncryptString(num)
107. session("pwdt")=num
108. %>
109. <form action="chk.asp" method=post>
110. 请输入验证码： <input type="text" name="pwds">
111. <img src="count.asp?sksid=<%=num2%>"> <input type=submit value=提交>
112. </form>

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chk.asp

1. <%
2. if trim(request.form("pwds"))<>trim(session("pwdt")) then
3. %>
4. 输入错误： 应该为：<%=session("pwdt")%>，可你输入的是:<%=request.form("pwds")%>
5. <%
6. else
7. %>
8. 输入正确
9. <%end if%>

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count.asp

1. <!--#include file="num.asp"-->
2. <%
3. '### To encrypt/decrypt include this code in your page
4. '### strMyEncryptedString = EncryptString(strString)
5. '### strMyDecryptedString = DeCryptString(strMyEncryptedString)
6. '### You are free to use this code as long as credits remain in place
7. '### also if you improve this code let me know.
9. Private Function EncryptString(strString)
10. '####################################################################
11. '### Crypt Function (C) 2001 by Slavic Kozyuk [email]grindkore@yahoo.com[/email] ###
12. '### Arguments: strString <--- String you wish to encrypt ###
13. '### Output: Encrypted HEX string ###
14. '####################################################################
16. Dim CharHexSet, intStringLen, strTemp, strRAW, i, intKey, intOffSet
17. Randomize Timer
19. intKey = Round((RND * 1000000) + 1000000) '##### Key Bitsize
20. intOffSet = Round((RND * 1000000) + 1000000) '##### KeyOffSet Bitsize
22. If IsNull(strString) = False Then
23. strRAW = strString
24. intStringLen = Len(strRAW)
26. For i = 0 to intStringLen - 1
27. strTemp = Left(strRAW, 1)
28. strRAW = Right(strRAW, Len(strRAW) - 1)
29. CharHexSet = CharHexSet & Hex(Asc(strTemp) * intKey)& Hex(intKey)
30. Next
32. EncryptString = CharHexSet & "|" & Hex(intOffSet + intKey) & "|" & Hex(intOffSet)
33. Else
34. EncryptString = ""
35. End If
36. End Function
39. Private Function DeCryptString(strCryptString)
40. '####################################################################
41. '### Crypt Function (C) 2001 by Slavic Kozyuk [email]grindkore@yahoo.com[/email] ###
42. '### Arguments: Encrypted HEX stringt ###
43. '### Output: Decrypted ASCII string ###
44. '####################################################################
45. '### Note this function uses HexConv() and get_hxno() functions ###
46. '### so make sure they are not removed ###
47. '####################################################################
49. Dim strRAW, arHexCharSet, i, intKey, intOffSet, strRawKey, strHexCrypData
51. strRawKey = Right(strCryptString, Len(strCryptString) - InStr(strCryptString, "|"))
52. intOffSet = Right(strRawKey, Len(strRawKey) - InStr(strRawKey,"|"))
53. intKey = HexConv(Left(strRawKey, InStr(strRawKey, "|") - 1)) - HexConv(intOffSet)
54. strHexCrypData = Left(strCryptString, Len(strCryptString) - (Len(strRawKey) + 1))
56. arHexCharSet = Split(strHexCrypData, Hex(intKey))
58. For i=0 to UBound(arHexCharSet)
59. strRAW = strRAW & Chr(HexConv(arHexCharSet(i))/intKey)
60. Next
62. DeCryptString = strRAW
63. End Function
66. Private Function HexConv(hexVar)
67. Dim hxx, hxx_var, multiply
68. IF hexVar <> "" THEN
69. hexVar = UCASE(hexVar)
70. hexVar = StrReverse(hexVar)
71. DIM hx()
72. REDIM hx(LEN(hexVar))
73. hxx = 0
74. hxx_var = 0
75. FOR hxx = 1 TO LEN(hexVar)
76. IF multiply = "" THEN multiply = 1
77. hx(hxx) = mid(hexVar,hxx,1)
78. hxx_var = (get_hxno(hx(hxx)) * multiply) + hxx_var
79. multiply = (multiply * 16)
80. NEXT
81. hexVar = hxx_var
82. HexConv = hexVar
83. END IF
84. End Function
86. Private Function get_hxno(ghx)
87. If ghx = "A" Then
88. ghx = 10
89. ElseIf ghx = "B" Then
90. ghx = 11
91. ElseIf ghx = "C" Then
92. ghx = 12
93. ElseIf ghx = "D" Then
94. ghx = 13
95. ElseIf ghx = "E" Then
96. ghx = 14
97. ElseIf ghx = "F" Then
98. ghx = 15
99. End If
100. get_hxno = ghx
101. End Function
102. %>
105. <%
106. Dim Image
107. Dim Width, Height
108. Dim num
109. Dim digtal
110. Dim Length
111. Dim sort
112. Length = 4 '自定计数器长度
114. Redim sort( Length )
116. num=cint(DeCryptString(request.querystring("sksid")))
117. digital = ""
118. For I = 1 To Length -Len( num ) '补0
119. digital = digital & "0"
120. Next
121. For I = 1 To Len( num )
122. digital = digital & Mid( num, I, 1 )
123. Next
124. For I = 1 To Len( digital )
125. sort(I) = Mid( digital, I, 1 )
126. Next
127. Width = 8 * Len( digital ) '图像的宽度
128. Height = 10 '图像的高度，在本例中为固定值
130. Response.ContentType="image/x-xbitmap"
132. hc=chr(13) & chr(10)
134. Image = "#define counter_width " & Width & hc
135. Image = Image & "#define counter_height " & Height & hc
136. Image = Image & "static unsigned char counter_bits[]={" & hc
138. For I = 1 To Height
139. For J = 1 To Length
140. Image = Image & a(sort(J),I) & ","
141. Next
142. Next
144. Image = Left( Image, Len( Image ) - 1 ) '去掉最后一个逗号
145. Image = Image & "};" & hc
146. %>
147. <%
148. Response.Write Image
149. %>

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num.asp

1. <%
2. Dim a(10,10)
4. a(0,1) = "0x3c" '数字0
5. a(0,2) = "0x66"
6. a(0,3) = "0xc3"
7. a(0,4) = "0xc3"
8. a(0,5) = "0xc3"
9. a(0,6) = "0xc3"
10. a(0,7) = "0xc3"
11. a(0,8) = "0xc3"
12. a(0,9) = "0x66"
13. a(0,10)= "0x3c"
15. a(1,1) = "0x18" '数字1
16. a(1,2) = "0x1c"
17. a(1,3) = "0x18"
18. a(1,4) = "0x18"
19. a(1,5) = "0x18"
20. a(1,6) = "0x18"
21. a(1,7) = "0x18"
22. a(1,8) = "0x18"
23. a(1,9) = "0x18"
24. a(0,10)= "0x7e"
27. a(2,1) = "0x3c" '数字2
28. a(2,2) = "0x66"
29. a(2,3) = "0x60"
30. a(2,4) = "0x60"
31. a(2,5) = "0x30"
32. a(2,6) = "0x18"
33. a(2,7) = "0x0c"
34. a(2,8) = "0x06"
35. a(2,9) = "0x06"
36. a(2,10)= "0x7e"
38. a(3,1) = "0x3c" '数字3
39. a(3,2) = "0x66"
40. a(3,3) = "0xc0"
41. a(3,4) = "0x60"
42. a(3,5) = "0x1c"
43. a(3,6) = "0x60"
44. a(3,7) = "0xc0"
45. a(3,8) = "0xc0"
46. a(3,9) = "0x66"
47. a(3,10)= "0x38"
49. a(4,1) = "0x38" '数字4
50. a(4,2) = "0x3c"
51. a(4,3) = "0x36"
52. a(4,4) = "0x33"
53. a(4,5) = "0x33"
54. a(4,6) = "0x33"
55. a(4,7) = "0xff"
56. a(4,8) = "0x30"
57. a(4,9) = "0x30"
58. a(4,10)= "0xfe"
60. a(5,1) = "0xfe" '数字5
61. a(5,2) = "0xfe"
62. a(5,3) = "0x06"
63. a(5,4) = "0x06"
64. a(5,5) = "0x3e"
65. a(5,6) = "0x60"
66. a(5,7) = "0xc0"
67. a(5,8) = "0xc3"
68. a(5,9) = "0x66"
69. a(5,10)= "0x3c"
71. a(6,1) = "0x60" '数字6
72. a(6,2) = "0x30"
73. a(6,3) = "0x18"
74. a(6,4) = "0x0c"
75. a(6,5) = "0x3e"
76. a(6,6) = "0x63"
77. a(6,7) = "0xc3"
78. a(6,8) = "0xc3"
79. a(6,9) = "0x66"
80. a(6,10) ="0x3c"
82. a(7,1) = "0xff" '数字7
83. a(7,2) = "0xc0"
84. a(7,3) = "0x60"
85. a(7,4) = "0x30"
86. a(7,5) = "0x18"
87. a(7,6) = "0x18"
88. a(7,7) = "0x18"
89. a(7,8) = "0x18"
90. a(7,9) = "0x18"
91. a(7,10)= "0x18"
93. a(8,1) = "0x3c" '数字8
94. a(8,2) = "0x66"
95. a(8,3) = "0xc3"
96. a(8,4) = "0x66"
97. a(8,5) = "0x3c"
98. a(8,6) = "0x66"
99. a(8,7) = "0xc3"
100. a(8,8) = "0xc3"
101. a(8,9) = "0x66"
102. a(8,10)= "0x3c"
104. a(9,1) = "0x3c" '数字9
105. a(9,2) = "0x66"
106. a(9,3) = "0xc3"
107. a(9,4) = "0xc3"
108. a(9,5) = "0x66"
109. a(9,6) = "0x3c"
110. a(9,7) = "0x18"
111. a(9,8) = "0x0c"
112. a(9,9) = "0x06"
113. a(9,10)= "0x03"
115. %>

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bsuc

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sinhu

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