ASP'de bilgileri veritabanına kaydederken özellikle parolaları kaydederken tüm bilgiler açık bir şekilde yazmaktadır. Bu bilgilerin açık bir şekilde yazmasını engellemek amacıyla şifreleme yöntemi kullanılmaktadır. En çok kullanılan şifreleme yöntemi ise MD5'tir. Size MD5 ile verilerinizin şifrelendiğini anlatan bir ders yazacağım.
Öncelikle verileri kaydederken nasıl bir yöntem kullanıyoruz, ilk önce buradaki derse giderek onu hatırlayalım. Şimdi bir parola alanı oluşturduğumuzu varsayarak kaydetme işleminde yaptığımız kodlama şu şekilde oluyordu:
<%
parola=Request.Form("parola")
%>Bunu şu şekilde değiştiriyoruz:
<%
parola=MD5(Request.Form("parola"))
%>Bu şekilde formdan gelen bilgiyi şifrelemiş olduk. Fakat burada birde MD5 uygulamasının yapıldığı dosyayı ekliyoruz. Aşağıda paylaşacağım kodu isterseniz bir farklı dosya olarak yapılandırın ve bu dosyayı kaydetme işlemini yaptığınız sayfaya include edin. MD5 uygulamasına ait kodlar şu şekildedir:
<%
Private Const BITS_TO_A_BYTE = 8
Private Const BYTES_TO_A_WORD = 4
Private Const BITS_TO_A_WORD = 32
Private m_lOnBits(30)
Private m_l2Power(30)
m_lOnBits(0) = CLng(1)
m_lOnBits(1) = CLng(3)
m_lOnBits(2) = CLng(7)
m_lOnBits(3) = CLng(15)
m_lOnBits(4) = CLng(31)
m_lOnBits(5) = CLng(63)
m_lOnBits(6) = CLng(127)
m_lOnBits(7) = CLng(255)
m_lOnBits(8) = CLng(511)
m_lOnBits(9) = CLng(1023)
m_lOnBits(10) = CLng(2047)
m_lOnBits(11) = CLng(4095)
m_lOnBits(12) = CLng(8191)
m_lOnBits(13) = CLng(16383)
m_lOnBits(14) = CLng(32767)
m_lOnBits(15) = CLng(65535)
m_lOnBits(16) = CLng(131071)
m_lOnBits(17) = CLng(262143)
m_lOnBits(18) = CLng(524287)
m_lOnBits(19) = CLng(1048575)
m_lOnBits(20) = CLng(2097151)
m_lOnBits(21) = CLng(4194303)
m_lOnBits(22) = CLng(8388607)
m_lOnBits(23) = CLng(16777215)
m_lOnBits(24) = CLng(33554431)
m_lOnBits(25) = CLng(67108863)
m_lOnBits(26) = CLng(134217727)
m_lOnBits(27) = CLng(268435455)
m_lOnBits(28) = CLng(536870911)
m_lOnBits(29) = CLng(1073741823)
m_lOnBits(30) = CLng(2147483647)
m_l2Power(0) = CLng(1)
m_l2Power(1) = CLng(2)
m_l2Power(2) = CLng(4)
m_l2Power(3) = CLng(8)
m_l2Power(4) = CLng(16)
m_l2Power(5) = CLng(32)
m_l2Power(6) = CLng(64)
m_l2Power(7) = CLng(128)
m_l2Power(8) = CLng(256)
m_l2Power(9) = CLng(512)
m_l2Power(10) = CLng(1024)
m_l2Power(11) = CLng(2048)
m_l2Power(12) = CLng(4096)
m_l2Power(13) = CLng(8192)
m_l2Power(14) = CLng(16384)
m_l2Power(15) = CLng(32768)
m_l2Power(16) = CLng(65536)
m_l2Power(17) = CLng(131072)
m_l2Power(18) = CLng(262144)
m_l2Power(19) = CLng(524288)
m_l2Power(20) = CLng(1048576)
m_l2Power(21) = CLng(2097152)
m_l2Power(22) = CLng(4194304)
m_l2Power(23) = CLng(8388608)
m_l2Power(24) = CLng(16777216)
m_l2Power(25) = CLng(33554432)
m_l2Power(26) = CLng(67108864)
m_l2Power(27) = CLng(134217728)
m_l2Power(28) = CLng(268435456)
m_l2Power(29) = CLng(536870912)
m_l2Power(30) = CLng(1073741824)
Private Function LShift(lValue, iShiftBits)
If iShiftBits = 0 Then
LShift = lValue
Exit Function
ElseIf iShiftBits = 31 Then
If lValue And 1 Then
LShift = &H80000000
Else
LShift = 0
End If
Exit Function
ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
Err.Raise 6
End If
If (lValue And m_l2Power(31 - iShiftBits)) Then
LShift = ((lValue And m_lOnBits(31 - (iShiftBits + 1))) * m_l2Power(iShiftBits)) Or &H80000000
Else
LShift = ((lValue And m_lOnBits(31 - iShiftBits)) * m_l2Power(iShiftBits))
End If
End Function
Private Function RShift(lValue, iShiftBits)
If iShiftBits = 0 Then
RShift = lValue
Exit Function
ElseIf iShiftBits = 31 Then
If lValue And &H80000000 Then
RShift = 1
Else
RShift = 0
End If
Exit Function
ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
Err.Raise 6
End If
RShift = (lValue And &H7FFFFFFE) \ m_l2Power(iShiftBits)
If (lValue And &H80000000) Then
RShift = (RShift Or (&H40000000 \ m_l2Power(iShiftBits - 1)))
End If
End Function
Private Function RotateLeft(lValue, iShiftBits)
RotateLeft = LShift(lValue, iShiftBits) Or RShift(lValue, (32 - iShiftBits))
End Function
Private Function AddUnsigned(lX, lY)
Dim lX4
Dim lY4
Dim lX8
Dim lY8
Dim lResult
lX8 = lX And &H80000000
lY8 = lY And &H80000000
lX4 = lX And &H40000000
lY4 = lY And &H40000000
lResult = (lX And &H3FFFFFFF) + (lY And &H3FFFFFFF)
If lX4 And lY4 Then
lResult = lResult Xor &H80000000 Xor lX8 Xor lY8
ElseIf lX4 Or lY4 Then
If lResult And &H40000000 Then
lResult = lResult Xor &HC0000000 Xor lX8 Xor lY8
Else
lResult = lResult Xor &H40000000 Xor lX8 Xor lY8
End If
Else
lResult = lResult Xor lX8 Xor lY8
End If
AddUnsigned = lResult
End Function
Private Function F(x, y, z)
F = (x And y) Or ((Not x) And z)
End Function
Private Function G(x, y, z)
G = (x And z) Or (y And (Not z))
End Function
Private Function H(x, y, z)
H = (x Xor y Xor z)
End Function
Private Function I(x, y, z)
I = (y Xor (x Or (Not z)))
End Function
Private Sub FF(a, b, c, d, x, s, ac)
a = AddUnsigned(a, AddUnsigned(AddUnsigned(F(b, c, d), x), ac))
a = RotateLeft(a, s)
a = AddUnsigned(a, b)
End Sub
Private Sub GG(a, b, c, d, x, s, ac)
a = AddUnsigned(a, AddUnsigned(AddUnsigned(G(b, c, d), x), ac))
a = RotateLeft(a, s)
a = AddUnsigned(a, b)
End Sub
Private Sub HH(a, b, c, d, x, s, ac)
a = AddUnsigned(a, AddUnsigned(AddUnsigned(H(b, c, d), x), ac))
a = RotateLeft(a, s)
a = AddUnsigned(a, b)
End Sub
Private Sub II(a, b, c, d, x, s, ac)
a = AddUnsigned(a, AddUnsigned(AddUnsigned(I(b, c, d), x), ac))
a = RotateLeft(a, s)
a = AddUnsigned(a, b)
End Sub
Private Function ConvertToWordArray(sMessage)
Dim lMessageLength
Dim lNumberOfWords
Dim lWordArray()
Dim lBytePosition
Dim lByteCount
Dim lWordCount
Const MODULUS_BITS = 512
Const CONGRUENT_BITS = 448
lMessageLength = Len(sMessage)
lNumberOfWords = (((lMessageLength + ((MODULUS_BITS - CONGRUENT_BITS) \ BITS_TO_A_BYTE)) \ (MODULUS_BITS \ BITS_TO_A_BYTE)) + 1) * (MODULUS_BITS \ BITS_TO_A_WORD)
ReDim lWordArray(lNumberOfWords - 1)
lBytePosition = 0
lByteCount = 0
Do Until lByteCount >= lMessageLength
lWordCount = lByteCount \ BYTES_TO_A_WORD
lBytePosition = (lByteCount Mod BYTES_TO_A_WORD) * BITS_TO_A_BYTE
lWordArray(lWordCount) = lWordArray(lWordCount) Or LShift(Asc(Mid(sMessage, lByteCount + 1, 1)), lBytePosition)
lByteCount = lByteCount + 1
Loop
lWordCount = lByteCount \ BYTES_TO_A_WORD
lBytePosition = (lByteCount Mod BYTES_TO_A_WORD) * BITS_TO_A_BYTE
lWordArray(lWordCount) = lWordArray(lWordCount) Or LShift(&H80, lBytePosition)
lWordArray(lNumberOfWords - 2) = LShift(lMessageLength, 3)
lWordArray(lNumberOfWords - 1) = RShift(lMessageLength, 29)
ConvertToWordArray = lWordArray
End Function
Private Function WordToHex(lValue)
Dim lByte
Dim lCount
For lCount = 0 To 3
lByte = RShift(lValue, lCount * BITS_TO_A_BYTE) And m_lOnBits(BITS_TO_A_BYTE - 1)
WordToHex = WordToHex & Right("0" & Hex(lByte), 2)
Next
End Function
Public Function MD5(sMessage)
Dim x
Dim k
Dim AA
Dim BB
Dim CC
Dim DD
Dim a
Dim b
Dim c
Dim d
Const S11 = 7
Const S12 = 12
Const S13 = 17
Const S14 = 22
Const S21 = 5
Const S22 = 9
Const S23 = 14
Const S24 = 20
Const S31 = 4
Const S32 = 11
Const S33 = 16
Const S34 = 23
Const S41 = 6
Const S42 = 10
Const S43 = 15
Const S44 = 21
x = ConvertToWordArray(sMessage)
a = &H67452301
b = &HEFCDAB89
c = &H98BADCFE
d = &H10325476
For k = 0 To UBound(x) Step 16
AA = a
BB = b
CC = c
DD = d
FF a, b, c, d, x(k + 0), S11, &HD76AA478
FF d, a, b, c, x(k + 1), S12, &HE8C7B756
FF c, d, a, b, x(k + 2), S13, &H242070DB
FF b, c, d, a, x(k + 3), S14, &HC1BDCEEE
FF a, b, c, d, x(k + 4), S11, &HF57C0FAF
FF d, a, b, c, x(k + 5), S12, &H4787C62A
FF c, d, a, b, x(k + 6), S13, &HA8304613
FF b, c, d, a, x(k + 7), S14, &HFD469501
FF a, b, c, d, x(k + 8), S11, &H698098D8
FF d, a, b, c, x(k + 9), S12, &H8B44F7AF
FF c, d, a, b, x(k + 10), S13, &HFFFF5BB1
FF b, c, d, a, x(k + 11), S14, &H895CD7BE
FF a, b, c, d, x(k + 12), S11, &H6B901122
FF d, a, b, c, x(k + 13), S12, &HFD987193
FF c, d, a, b, x(k + 14), S13, &HA679438E
FF b, c, d, a, x(k + 15), S14, &H49B40821
GG a, b, c, d, x(k + 1), S21, &HF61E2562
GG d, a, b, c, x(k + 6), S22, &HC040B340
GG c, d, a, b, x(k + 11), S23, &H265E5A51
GG b, c, d, a, x(k + 0), S24, &HE9B6C7AA
GG a, b, c, d, x(k + 5), S21, &HD62F105D
GG d, a, b, c, x(k + 10), S22, &H2441453
GG c, d, a, b, x(k + 15), S23, &HD8A1E681
GG b, c, d, a, x(k + 4), S24, &HE7D3FBC8
GG a, b, c, d, x(k + 9), S21, &H21E1CDE6
GG d, a, b, c, x(k + 14), S22, &HC33707D6
GG c, d, a, b, x(k + 3), S23, &HF4D50D87
GG b, c, d, a, x(k + 8), S24, &H455A14ED
GG a, b, c, d, x(k + 13), S21, &HA9E3E905
GG d, a, b, c, x(k + 2), S22, &HFCEFA3F8
GG c, d, a, b, x(k + 7), S23, &H676F02D9
GG b, c, d, a, x(k + 12), S24, &H8D2A4C8A
HH a, b, c, d, x(k + 5), S31, &HFFFA3942
HH d, a, b, c, x(k + 8), S32, &H8771F681
HH c, d, a, b, x(k + 11), S33, &H6D9D6122
HH b, c, d, a, x(k + 14), S34, &HFDE5380C
HH a, b, c, d, x(k + 1), S31, &HA4BEEA44
HH d, a, b, c, x(k + 4), S32, &H4BDECFA9
HH c, d, a, b, x(k + 7), S33, &HF6BB4B60
HH b, c, d, a, x(k + 10), S34, &HBEBFBC70
HH a, b, c, d, x(k + 13), S31, &H289B7EC6
HH d, a, b, c, x(k + 0), S32, &HEAA127FA
HH c, d, a, b, x(k + 3), S33, &HD4EF3085
HH b, c, d, a, x(k + 6), S34, &H4881D05
HH a, b, c, d, x(k + 9), S31, &HD9D4D039
HH d, a, b, c, x(k + 12), S32, &HE6DB99E5
HH c, d, a, b, x(k + 15), S33, &H1FA27CF8
HH b, c, d, a, x(k + 2), S34, &HC4AC5665
II a, b, c, d, x(k + 0), S41, &HF4292244
II d, a, b, c, x(k + 7), S42, &H432AFF97
II c, d, a, b, x(k + 14), S43, &HAB9423A7
II b, c, d, a, x(k + 5), S44, &HFC93A039
II a, b, c, d, x(k + 12), S41, &H655B59C3
II d, a, b, c, x(k + 3), S42, &H8F0CCC92
II c, d, a, b, x(k + 10), S43, &HFFEFF47D
II b, c, d, a, x(k + 1), S44, &H85845DD1
II a, b, c, d, x(k + 8), S41, &H6FA87E4F
II d, a, b, c, x(k + 15), S42, &HFE2CE6E0
II c, d, a, b, x(k + 6), S43, &HA3014314
II b, c, d, a, x(k + 13), S44, &H4E0811A1
II a, b, c, d, x(k + 4), S41, &HF7537E82
II d, a, b, c, x(k + 11), S42, &HBD3AF235
II c, d, a, b, x(k + 2), S43, &H2AD7D2BB
II b, c, d, a, x(k + 9), S44, &HEB86D391
a = AddUnsigned(a, AA)
b = AddUnsigned(b, BB)
c = AddUnsigned(c, CC)
d = AddUnsigned(d, DD)
Next
MD5 = LCase(WordToHex(a) & WordToHex(b) & WordToHex(c) & WordToHex(d))
End Function
%>
