TweenEncryptString

TweenEncryptString.vb

' Tween - Client of Twitter
' Copyright (c) 2007-2011 kiri_feather (@kiri_feather) <kiri.feather@gmail.com>
'           (c) 2008-2011 Moz (@syo68k)
'           (c) 2008-2011 takeshik (@takeshik) <http://www.takeshik.org/>
'           (c) 2010-2011 anis774 (@anis774) <http://d.hatena.ne.jp/anis774/>
'           (c) 2010-2011 fantasticswallow (@f_swallow) <http://twitter.com/f_swallow>
'           (c) 2011      Egtra (@egtra) <http://dev.activebasic.com/egtra/>
' All rights reserved.
' 
' This file is part of Tween.
' 
' This program is free software; you can redistribute it and/or modify it
' under the terms of the GNU General Public License as published by the Free
' Software Foundation; either version 3 of the License, or (at your option)
' any later version.
' 
' This program is distributed in the hope that it will be useful, but
' WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
' or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
' for more details. 
' 
' You should have received a copy of the GNU General Public License along
' with this program. If not, see <http://www.gnu.org/licenses/>, or write to
' the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
' Boston, MA 02110-1301, USA.
Module Test
    Public Sub Main()
        Dim s = Console.ReadLine
        Console.WriteLine(EncryptString(s))
    End Sub

    Public Function ResizeBytesArray(ByVal bytes() As Byte, _
                                ByVal newSize As Integer) As Byte()
        Dim newBytes(newSize - 1) As Byte
        If bytes.Length <= newSize Then
            Dim i As Integer
            For i = 0 To bytes.Length - 1
                newBytes(i) = bytes(i)
            Next i
        Else
            Dim pos As Integer = 0
            Dim i As Integer
            For i = 0 To bytes.Length - 1
                newBytes(pos) = newBytes(pos) Xor bytes(i)
                pos += 1
                If pos >= newBytes.Length Then
                    pos = 0
                End If
            Next i
        End If
        Return newBytes
    End Function
    Public Function EncryptString(ByVal str As String) As String
        If String.IsNullOrEmpty(str) Then Return ""

        '文字列をバイト型配列にする
        Dim bytesIn As Byte() = System.Text.Encoding.UTF8.GetBytes(str)

        'DESCryptoServiceProviderオブジェクトの作成
        Using des As New System.Security.Cryptography.DESCryptoServiceProvider

            '共有キーと初期化ベクタを決定
            'パスワードをバイト配列にする
            Dim bytesKey As Byte() = System.Text.Encoding.UTF8.GetBytes("_tween_encrypt_key_")
            '共有キーと初期化ベクタを設定
            des.Key = ResizeBytesArray(bytesKey, des.Key.Length)
            des.IV = ResizeBytesArray(bytesKey, des.IV.Length)

            '暗号化されたデータを書き出すためのMemoryStream
            Using msOut As New System.IO.MemoryStream
                'DES暗号化オブジェクトの作成
                Using desdecrypt As System.Security.Cryptography.ICryptoTransform = _
                    des.CreateEncryptor()

                    '書き込むためのCryptoStreamの作成
                    Using cryptStream As New System.Security.Cryptography.CryptoStream( _
                        msOut, desdecrypt, _
                        System.Security.Cryptography.CryptoStreamMode.Write)
                        '書き込む
                        cryptStream.Write(bytesIn, 0, bytesIn.Length)
                        cryptStream.FlushFinalBlock()
                        '暗号化されたデータを取得
                        Dim bytesOut As Byte() = msOut.ToArray()

                        '閉じる
                        cryptStream.Close()
                        msOut.Close()

                        'Base64で文字列に変更して結果を返す
                        Return System.Convert.ToBase64String(bytesOut)
                    End Using
                End Using
            End Using
        End Using
    End Function
End Module