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。
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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
MD5实际一种单向的算法，是散列，很多人认为是加密，实际有误
比如说winxp、win7各版本都有MD5值，那么是否可依据这个值还原出个正版的winxp或win7呢？
况且MD5“加密”的密钥长度又是多少呢?比如des的不同版本有64位、128位、192位等
这个是我之前写的。在需要时调用即可。
Public Shared Function Encrypt(ByVal Text As String, ByVal sKey As String) As String
Dim provider As New DESCryptoServiceProvider()
Dim bytes As Byte() = Encoding.[Default].GetBytes(Text)
provider.Key = Encoding.ASCII.GetBytes(FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8))
provider.IV = Encoding.ASCII.GetBytes(FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8))
Dim stream As New MemoryStream()
Dim stream2 As New CryptoStream(stream, provider.CreateEncryptor(), CryptoStreamMode.Write)
stream2.Write(bytes, 0, bytes.Length)
stream2.FlushFinalBlock()
Dim builder As New StringBuilder()
For Each num As Byte In stream.ToArray()
builder.AppendFormat("{0:X2}", num)
Next
Return builder.ToString()
End Function
希望能帮到你
