How to decrypt password from database in vb.net?

[Prathap]

Could someone please help me to decrypt password from database.
Here is my code to encrypt password

 Dim a, enc As String
    Private Sub encrypt(ByVal a)
        Try
            Dim encData_byte() As Byte = System.Text.Encoding.ASCII.GetBytes(a)
            enc = Convert.ToBase64String(encData_byte)
            TextBox4.Text = enc
        Catch ex As Exception
            MsgBox("Error in Creating Encryption")
        End Try
    End Sub
 Dim str As String = "Data Source=NET3\SQLEXPRESS;Initial Catalog=pos;Persist Security Info=True;User ID=sa;Password=password"
    Dim ds As New DataSet
    Dim adp As New SqlClient.SqlDataAdapter
    Dim con As New SqlClient.SqlConnection
 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 
        If TextBox3.Text <> "" Then
            Call encrypt(TextBox3.Text)
        Else
            MsgBox("Field Missing", MsgBoxStyle.OkOnly, "Error")
 Try
                con.ConnectionString = str
                adp = New SqlClient.SqlDataAdapter("insert into Login(userid,username,password) values ('" + TextBox1.Text + "','" + TextBox2.Text + "','" + TextBox4.Text + "') ", con)
                adp.Fill(ds)
                 MsgBox("Inserted", MsgBoxStyle.OkOnly, "Message")
            Catch ex As Exception
                MsgBox(ex.Message)
            End Try
        End If
    End Sub
End Class

[Rabbit]

You converted to a base 64 string. To decrypt, just convert from a base 64 string. Also, that's a bad way to store passwords, it's only one step up from storing it as plaintext. The preferred method is to use a hash with a salt.

[kadghar]

Using a simple hash, like sha1 in VB.net is quite simple, since the libraries are already in your framework:

Dim sha1 As New System.Security.Cryptography.SHA1Cng
Dim str2 As String = Convert.ToBase64String(sha1.ComputeHash(Encoding.Unicode.GetBytes(myPassword)))

Adding some salt is not much harder. And as you can see here, the hash has been converted into a B64 string, so you can store it as plain text.