form1.frm

一个较为简单的维吉尼亚算法

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "维吉尼亚密码"
   ClientHeight    =   3360
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   5325
   LinkTopic       =   "Form1"
   MaxButton       =   0   'False
   ScaleHeight     =   3360
   ScaleWidth      =   5325
   StartUpPosition =   2  'CenterScreen
   Begin VB.TextBox txtKey 
      Height          =   375
      Left            =   840
      MultiLine       =   -1  'True
      TabIndex        =   7
      Top             =   1200
      Width           =   3855
   End
   Begin VB.CommandButton cmdDecryption 
      Caption         =   "解密"
      BeginProperty Font 
         Name            =   "MS Sans Serif"
         Size            =   12
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   495
      Left            =   3000
      TabIndex        =   3
      Top             =   2640
      Width           =   1095
   End
   Begin VB.CommandButton cmdEncrtption 
      Caption         =   "加密"
      BeginProperty Font 
         Name            =   "MS Sans Serif"
         Size            =   12
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   495
      Left            =   1200
      TabIndex        =   2
      Top             =   2640
      Width           =   1095
   End
   Begin VB.TextBox txtCiphertext 
      Height          =   855
      Left            =   840
      MultiLine       =   -1  'True
      TabIndex        =   1
      Top             =   1680
      Width           =   3855
   End
   Begin VB.TextBox txtPlaintext 
      Height          =   855
      Left            =   840
      MultiLine       =   -1  'True
      TabIndex        =   0
      Top             =   240
      Width           =   3855
   End
   Begin VB.Label Label3 
      Caption         =   "密文："
      BeginProperty Font 
         Name            =   "MS Sans Serif"
         Size            =   12
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   255
      Left            =   120
      TabIndex        =   6
      Top             =   1800
      Width           =   615
   End
   Begin VB.Label Label2 
      Caption         =   "密钥："
      BeginProperty Font 
         Name            =   "MS Sans Serif"
         Size            =   12
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   255
      Left            =   120
      TabIndex        =   5
      Top             =   1200
      Width           =   615
   End
   Begin VB.Label Label1 
      Caption         =   "明文："
      BeginProperty Font 
         Name            =   "MS Sans Serif"
         Size            =   12
         Charset         =   0
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   495
      Left            =   120
      TabIndex        =   4
      Top             =   480
      Width           =   855
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
 Option Explicit
 
Private Sub cmdDecryption_Click() '解密功能
    Dim Cipher
    Dim Key, iLenKey
    Key = Trim(Me.txtKey.Text)
    Cipher = Trim(Me.txtCiphertext.Text)
    If Len(Cipher) = 0 Then MsgBox "密文不能为空！", vbOKOnly + vbQuestion, "警告": Exit Sub
    If Len(Key) = 0 Then MsgBox "密钥不能为空！", vbOKOnly + vbQuestion, "警告": Exit Sub
    Call DecryptionAlgorithm(Cipher, Key)
End Sub

Private Sub cmdEncrtption_Click() '加密功能
    Dim Plain
    Dim Key, iLenKey
    Key = Trim(Me.txtKey.Text)
    Plain = Trim(Me.txtPlaintext.Text)
    If Len(Plain) = 0 Then MsgBox "明文不能为空！", vbOKOnly + vbQuestion, "警告": Exit Sub
    If Len(Key) = 0 Then MsgBox "密钥不能为空！", vbOKOnly + vbQuestion, "警告": Exit Sub
    Call EncryptionAlgorithm(Plain, Key)
End Sub

Public Sub EncryptionAlgorithm(Plaintext, Key) '加密算法

    Dim i, j, iStart, iKey
    Dim c, k, s
    If Len(Plaintext) = 0 Then MsgBox "明文不能为空！", vbOKOnly + vbQuestion, "警告": Exit Sub
    If Len(Key) = 0 Then MsgBox "密钥不能为空！", vbOKOnly + vbQuestion, "警告": Exit Sub
    j = 1
    For i = 1 To Len(Plaintext)
        c = Mid(Plaintext, i, 1)
        If (Asc(c) >= Asc("a") And Asc(c) <= Asc("z")) Then iKey = 1
        If (Asc(c) >= Asc("A") And Asc(c) <= Asc("Z")) Then iKey = 2
        If j > Len(Key) Then
            iStart = 1: j = 1
        Else
            iStart = j
        End If
        j = j + 1
        k = Mid(LCase(Trim(Key)), iStart, 1)
        s = s & IIf(iKey = 1, LCase(Chr(Asc(c) + (Asc(k) - Asc("a")))), UCase(Chr(Asc(c) + _
        (Asc(k) - Asc("a")))))
    Next i
    Me.txtCiphertext.Text = s
End Sub

Public Sub DecryptionAlgorithm(Ciphertext, Key) '解密算法
    Dim i, j, iStart, iKey
    Dim c, k, s
    If Len(Ciphertext) = 0 Then MsgBox "密文不能为空！", vbOKOnly + vbQuestion, "警告": Exit Sub
    If Len(Key) = 0 Then MsgBox "密钥不能为空！", vbOKOnly + vbQuestion, "警告": Exit Sub
    j = 1
    For i = 1 To Len(Ciphertext)
        c = Mid(Ciphertext, i, 1)
        If (Asc(c) >= Asc("a") And Asc(c) <= Asc("z")) Then iKey = 1
        If (Asc(c) >= Asc("A") And Asc(c) <= Asc("Z")) Then iKey = 2
        If j > Len(Key) Then
            iStart = 1: j = 1
        Else
            iStart = j
        End If
        j = j + 1
        k = Mid(LCase(Trim(Key)), iStart, 1)
        s = s & IIf(iKey = 1, LCase(Chr(Asc(c) - (Asc(k) - Asc("a")))), UCase(Chr(Asc(c) - _
        (Asc(k) - Asc("a")))))
    Next i
    Me.txtPlaintext.Text = s
End Sub

Private Sub txtCiphertext_Change()
    Dim Cipher
    Cipher = Trim(Me.txtCiphertext.Text)
    If Len(Cipher) = 0 Then Exit Sub
    If Not (Asc(Right(Cipher, 1)) >= Asc("a") And Asc(Right(Cipher, 1)) <= Asc("z")) And Not _
    (Asc(Right(Cipher, 1)) >= Asc("A") And Asc(Right(Cipher, 1)) <= Asc("Z")) Then
        MsgBox "输入大小写英文字符！", vbCritical, "警告"
        Me.txtCiphertext.SelStart = Len(Cipher) - 1
        Me.txtCiphertext.SelLength = 1
    End If
End Sub

Private Sub txtKey_Change()
    Dim Key
    Key = Trim(Me.txtKey.Text)
    If Len(Key) = 0 Then Exit Sub
    If Not (Asc(Right(Key, 1)) >= Asc("a") And Asc(Right(Key, 1)) <= Asc("z")) And Not _
    (Asc(Right(Key, 1)) >= Asc("A") And Asc(Right(Key, 1)) <= Asc("Z")) Then
        MsgBox "输入大小写英文字符！", vbCritical, "警告"
        Me.txtKey.SelStart = Len(Key) - 1
        Me.txtKey.SelLength = 1
    End If
End Sub

Private Sub txtPlaintext_Change()
    Dim Plain
    Plain = Trim(Me.txtPlaintext.Text)
    If Len(Plain) = 0 Then Exit Sub
    If Not (Asc(Right(Plain, 1)) >= Asc("a") And Asc(Right(Plain, 1)) <= Asc("z")) And Not _
    (Asc(Right(Plain, 1)) >= Asc("A") And Asc(Right(Plain, 1)) <= Asc("Z")) Then
        MsgBox "输入大小写英文字符！", vbCritical, "警告"
        Me.txtPlaintext.SelStart = Len(Plain) - 1
        Me.txtPlaintext.SelLength = 1
    End If
End Sub