hi,

     1. Use System.Security.Cryptography namespace.

    2. Decalre an object of MD5CryptoServiceProvider and compute hash keys for the variable.

1. Use namespace System.Security.Cryptography.

2.  declare an UTF8Encoding object.

3. declare an object of MD5CryptoServiceProvider compute hash keys and compute the hash key for the variable.

Hope this will suffice ur need.

u cannot decrypt a password from a string encrypted by MD5 as it takes a long time may be years 

the best way to do is convert  the password in MD5 and then compare both  by converting both in Base64String

Thank for your comments

Try This function.......for both Decrypt and  Encrypt also....

 Public Function psDecrypt(ByVal sQueryString As String) As String

        Dim buffer() As Byte
        Dim loCryptoClass As New TripleDESCryptoServiceProvider
        Dim loCryptoProvider As New MD5CryptoServiceProvider

        Try

            buffer = Convert.FromBase64String(sQueryString)
            loCryptoClass.Key = loCryptoProvider.ComputeHash(ASCIIEncoding.ASCII.GetBytes(lscryptoKey))
            loCryptoClass.IV = lbtVector
            Return Encoding.ASCII.GetString(loCryptoClass.CreateDecryptor().TransformFinalBlock(buffer, 0, buffer.Length()))
        Catch ex As Exception
            Throw ex
        Finally
            loCryptoClass.Clear()
            loCryptoProvider.Clear()
            loCryptoClass = Nothing
            loCryptoProvider = Nothing
        End Try

    End Function
    Public Function psEncrypt(ByVal sInputVal As String) As String
        Dim loCryptoClass As New TripleDESCryptoServiceProvider
        Dim loCryptoProvider As New MD5CryptoServiceProvider
        Dim lbtBuffer() As Byte

        Try
            lbtBuffer = System.Text.Encoding.ASCII.GetBytes(sInputVal)
            loCryptoClass.Key = loCryptoProvider.ComputeHash(ASCIIEncoding.ASCII.GetBytes(lscryptoKey))
            loCryptoClass.IV = lbtVector
            sInputVal = Convert.ToBase64String(loCryptoClass.CreateEncryptor().TransformFinalBlock(lbtBuffer, 0, lbtBuffer.Length()))
            psEncrypt = sInputVal
        Catch ex As CryptographicException
            Throw ex
        Catch ex As FormatException
            Throw ex
        Catch ex As Exception
            Throw ex
        Finally
            loCryptoClass.Clear()
            loCryptoProvider.Clear()
            loCryptoClass = Nothing
            loCryptoProvider = Nothing
        End Try
    End Function