Public Function md5(ByVal a As String) As String
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Dim tempmd5 As System.Security.Cryptography.MD5 = New System.Security.Cryptography.MD5CryptoServiceProvider()
Dim bytResult() As Byte = tempmd5.ComputeHash(System.Text.Encoding.Default.GetBytes(a))
Dim strResult As String = BitConverter.ToString(bytResult)
strResult = strResult.Replace("-", "")
Return strResult
End Function
如果要计算文件的就把参数改成字节数组就可以了，然后获取文件GetBytes（）传进去就可以了。
md5加密运算是不可逆的，就是说不能通过那一串古古怪怪的东西算出它原始的样子。
以下提供VB可用的16位和32位MD5加密函数代码：
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)
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 md5_F(x, y, z)
md5_F = (x And y) Or ((Not x) And z)
End Function
Private Function md5_G(x, y, z)
md5_G = (x And z) Or (y And (Not z))
End Function
Private Function md5_H(x, y, z)
md5_H = (x Xor y Xor z)
End Function
Private Function md5_I(x, y, z)
md5_I = (y Xor (x Or (Not z)))
End Function
Private Sub md5_FF(a, b, c, d, x, s, ac)
a = AddUnsigned(a, AddUnsigned(AddUnsigned(md5_F(b, c, d), x), ac))
a = RotateLeft(a, s)
a = AddUnsigned(a, b)
End Sub
Private Sub md5_GG(a, b, c, d, x, s, ac)
a = AddUnsigned(a, AddUnsigned(AddUnsigned(md5_G(b, c, d), x), ac))
a = RotateLeft(a, s)
a = AddUnsigned(a, b)
End Sub
Private Sub md5_HH(a, b, c, d, x, s, ac)
a = AddUnsigned(a, AddUnsigned(AddUnsigned(md5_H(b, c, d), x), ac))
a = RotateLeft(a, s)
a = AddUnsigned(a, b)
End Sub
Private Sub md5_II(a, b, c, d, x, s, ac)
a = AddUnsigned(a, AddUnsigned(AddUnsigned(md5_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, stype)
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)
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
md5_FF a, b, c, d, x(k + 0), S11, HD76AA478
md5_FF d, a, b, c, x(k + 1), S12, HE8C7B756
md5_FF c, d, a, b, x(k + 2), S13, H242070DB
md5_FF b, c, d, a, x(k + 3), S14, HC1BDCEEE
md5_FF a, b, c, d, x(k + 4), S11, HF57C0FAF
md5_FF d, a, b, c, x(k + 5), S12, H4787C62A
md5_FF c, d, a, b, x(k + 6), S13, HA8304613
md5_FF b, c, d, a, x(k + 7), S14, HFD469501
md5_FF a, b, c, d, x(k + 8), S11, H698098D8
md5_FF d, a, b, c, x(k + 9), S12, H8B44F7AF
md5_FF c, d, a, b, x(k + 10), S13, HFFFF5BB1
md5_FF b, c, d, a, x(k + 11), S14, H895CD7BE
md5_FF a, b, c, d, x(k + 12), S11, H6B901122
md5_FF d, a, b, c, x(k + 13), S12, HFD987193
md5_FF c, d, a, b, x(k + 14), S13, HA679438E
md5_FF b, c, d, a, x(k + 15), S14, H49B40821
md5_GG a, b, c, d, x(k + 1), S21, HF61E2562
md5_GG d, a, b, c, x(k + 6), S22, HC040B340
md5_GG c, d, a, b, x(k + 11), S23, H265E5A51
md5_GG b, c, d, a, x(k + 0), S24, HE9B6C7AA
md5_GG a, b, c, d, x(k + 5), S21, HD62F105D
md5_GG d, a, b, c, x(k + 10), S22, H2441453
md5_GG c, d, a, b, x(k + 15), S23, HD8A1E681
md5_GG b, c, d, a, x(k + 4), S24, HE7D3FBC8
md5_GG a, b, c, d, x(k + 9), S21, H21E1CDE6
md5_GG d, a, b, c, x(k + 14), S22, HC33707D6
md5_GG c, d, a, b, x(k + 3), S23, HF4D50D87
md5_GG b, c, d, a, x(k + 8), S24, H455A14ED
md5_GG a, b, c, d, x(k + 13), S21, HA9E3E905
md5_GG d, a, b, c, x(k + 2), S22, HFCEFA3F8
md5_GG c, d, a, b, x(k + 7), S23, H676F02D9
md5_GG b, c, d, a, x(k + 12), S24, H8D2A4C8A
md5_HH a, b, c, d, x(k + 5), S31, HFFFA3942
md5_HH d, a, b, c, x(k + 8), S32, H8771F681
md5_HH c, d, a, b, x(k + 11), S33, H6D9D6122
md5_HH b, c, d, a, x(k + 14), S34, HFDE5380C
md5_HH a, b, c, d, x(k + 1), S31, HA4BEEA44
md5_HH d, a, b, c, x(k + 4), S32, H4BDECFA9
md5_HH c, d, a, b, x(k + 7), S33, HF6BB4B60
md5_HH b, c, d, a, x(k + 10), S34, HBEBFBC70
md5_HH a, b, c, d, x(k + 13), S31, H289B7EC6
md5_HH d, a, b, c, x(k + 0), S32, HEAA127FA
md5_HH c, d, a, b, x(k + 3), S33, HD4EF3085
md5_HH b, c, d, a, x(k + 6), S34, H4881D05
md5_HH a, b, c, d, x(k + 9), S31, HD9D4D039
md5_HH d, a, b, c, x(k + 12), S32, HE6DB99E5
md5_HH c, d, a, b, x(k + 15), S33, H1FA27CF8
md5_HH b, c, d, a, x(k + 2), S34, HC4AC5665
md5_II a, b, c, d, x(k + 0), S41, HF4292244
md5_II d, a, b, c, x(k + 7), S42, H432AFF97
md5_II c, d, a, b, x(k + 14), S43, HAB9423A7
md5_II b, c, d, a, x(k + 5), S44, HFC93A039
md5_II a, b, c, d, x(k + 12), S41, H655B59C3
md5_II d, a, b, c, x(k + 3), S42, H8F0CCC92
md5_II c, d, a, b, x(k + 10), S43, HFFEFF47D
md5_II b, c, d, a, x(k + 1), S44, H85845DD1
md5_II a, b, c, d, x(k + 8), S41, H6FA87E4F
md5_II d, a, b, c, x(k + 15), S42, HFE2CE6E0
md5_II c, d, a, b, x(k + 6), S43, HA3014314
md5_II b, c, d, a, x(k + 13), S44, H4E0811A1
md5_II a, b, c, d, x(k + 4), S41, HF7537E82
md5_II d, a, b, c, x(k + 11), S42, HBD3AF235
md5_II c, d, a, b, x(k + 2), S43, H2AD7D2BB
md5_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
If stype = 32 Then
MD5 = LCase(WordToHex(a) WordToHex(b) WordToHex(c) WordToHex(d))
Else
MD5 = LCase(WordToHex(b) WordToHex(c))
End If
End Function
'下面是测试代码
Sub test()
MsgBox MD5("a", 16) '16位加密
MsgBox MD5("a", 32) '32位加密
End Sub
下面是完整的类，可以设置任意密码
'DES及md5加密解密----添加引用中添加对system.web的引用。
Imports System.Security.Cryptography
Imports System
Imports System.Text
Imports System.Web
''' summary
''' DES加密类
''' /summary
''' remarks/remarks
Public Class DESEncrypt
Public Sub DESEncrypt()
End Sub
Public Shared Function Encrypt(ByVal Text As String) As String
Return Encrypt(Text, "12345678")
End Function
Public Shared Function Encrypt(ByVal Text As String, ByVal sKey As String) As String
Dim des As New DESCryptoServiceProvider()
Dim inputByteArray As Byte()
inputByteArray = Encoding.Default.GetBytes(Text)
des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8))
des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8))
Dim ms As New System.IO.MemoryStream()
Dim cs As New CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write)
cs.Write(inputByteArray, 0, inputByteArray.Length)
cs.FlushFinalBlock()
Dim ret As New StringBuilder()
Dim b As Byte
For Each b In ms.ToArray()
ret.AppendFormat("{0:X2}", b)
Next
Return ret.ToString()
End Function
Public Shared Function Decrypt(ByVal Text As String) As String
Return Decrypt(Text, "12345678")
End Function
Public Shared Function Decrypt(ByVal Text As String, ByVal sKey As String) As String
Dim des As New DESCryptoServiceProvider()
Dim len As Integer
len = Text.Length / 2
Dim inputByteArray(len - 1) As Byte
Dim x, i As Integer
For x = 0 To len - 1
i = Convert.ToInt32(Text.Substring(x * 2, 2), 16)
inputByteArray(x) = CType(i, Byte)
Next
des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8))
des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8))
Dim ms As New System.IO.MemoryStream()
Dim cs As New CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write)
cs.Write(inputByteArray, 0, inputByteArray.Length)
cs.FlushFinalBlock()
Return Encoding.Default.GetString(ms.ToArray())
End Function
End Class
'以下是调用方法
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click '加密
Dim str_Encrypt As String = DESEncrypt.Encrypt("你要加密的文本，可以是任意长度", "密码，可以很长，如果省略这个参数就是默认的12345678")
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click '解密
Dim str_Decrypt As String = DESEncrypt.Decrypt("你要解密的文本, 可以是任意长度", "加密时用到的密码，如果省略这个参数就是默认的12345678")
End Sub