实现该功能的程序代码如下：

Private Sub Command1_Click()

    Dim i As Integer，ch As String，s As String

    Dim my(0 To 127)As Boolean  ‘0～127表示128个ASCII字符的ASCII值

    s=Text1．Text

    For i=0 To 127

        my(i)=False

    Next i

    If    ①   then

        Text2．Text=”密钥长度不足26个字符!”

    Else

        For i=1 To 26

           ch=Mid(s，i，1)

           t=    ②    

           If my(t)=False Then

              my(t)=True

           Else

             Text2．Text=“密钥中有重复字符!”

             Exit Sub

           EndIf

        Next i

        Text2．Text=“密钥正确!”

    EndIf

End Sub

Dim a(1 To 15) As Integer

Private Sub Form_Load()

  Dim i As Integer, t As Integer

  Dim s1 As String, s2 As String

  Randomize

  s1 = ""

  For i = 1 To 15

    a(i) =  ①    

    s1 = s1 + Str(a(i))

  Next i

  Text1.Text = s1

End Sub

Private Sub Com1_Click()

  s2 = ""

  For i = 1 To 15

    s2 =  ②    

  Next i

  Text2.Text = s2

End Sub