RC2CryptoServiceProvider.GenerateIV メソッド

.NET Framework クラス ライブラリ リファレンス

RC2CryptoServiceProvider.GenerateIV メソッド

アルゴリズムに使用するランダムな初期化ベクタ (IV) を生成します。

名前空間: System.Security.Cryptography
アセンブリ: mscorlib (mscorlib.dll 内)
構文

Visual Basic (宣言)

Public Overrides Sub GenerateIV

Visual Basic (使用法)

Dim instance As RC2CryptoServiceProvider

instance.GenerateIV

C#

public override void GenerateIV ()

C++

public:
virtual void GenerateIV () override

J#

public void GenerateIV ()

JScript

public override function GenerateIV ()

解説

指定されていない場合は、このメソッドを使用してランダムな IV を生成します。

使用例

次のコード例は、文字列を暗号化した後で復号化します。

Visual Basic

Imports System
Imports System.IO
Imports System.Text
Imports System.Security.Cryptography



Module MyMainModule

    Sub Main()

        ' Create a new instance of the RC2CryptoServiceProvider class
        ' and automatically generate a Key and IV.
        Dim rc2CSP As New
 RC2CryptoServiceProvider()

        Console.WriteLine("Effective key size is {0} bits.",
 rc2CSP.EffectiveKeySize)

        ' Get the key and IV.
        Dim key As Byte()
 = rc2CSP.Key
        Dim IV As Byte()
 = rc2CSP.IV

        ' Get an encryptor.
        Dim encryptor As ICryptoTransform =
 rc2CSP.CreateEncryptor(key, IV)

        ' Encrypt the data as an array of encrypted bytes in memory.
        Dim msEncrypt As New
 MemoryStream()
        Dim csEncrypt As New
 CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)

        ' Convert the data to a byte array.
        Dim original As String
 = "Here is some data to encrypt."
        Dim toEncrypt As Byte()
 = Encoding.ASCII.GetBytes(original)

        ' Write all data to the crypto stream and flush it.
        csEncrypt.Write(toEncrypt, 0, toEncrypt.Length)
        csEncrypt.FlushFinalBlock()

        ' Get the encrypted array of bytes.
        Dim encrypted As Byte()
 = msEncrypt.ToArray()

        '''''''''''''''''''''''''''''''''''''''''''''''''''''''''
        ' This is where the data could be transmitted or saved.    
      
        '''''''''''''''''''''''''''''''''''''''''''''''''''''''''

        'Get a decryptor that uses the same key and IV as the encryptor.
        Dim decryptor As ICryptoTransform =
 rc2CSP.CreateDecryptor(key, IV)

        ' Now decrypt the previously encrypted message using the decryptor
        ' obtained in the above step.
        Dim msDecrypt As New
 MemoryStream(encrypted)
        Dim csDecrypt As New
 CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)

        Dim fromEncrypt(toEncrypt.Length) As
 Byte

        ' Read the data out of the crypto stream.
        csDecrypt.Read(fromEncrypt, 0, toEncrypt.Length)

        ' Convert the byte array back into a string.
        Dim roundtrip As String
 = Encoding.ASCII.GetString(fromEncrypt)

        ' Display the original data and the decrypted data.
        Console.WriteLine("Original:   {0}", original)
        Console.WriteLine("Round Trip: {0}", roundtrip)

        Console.ReadLine()

    End Sub
End Module

C#

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

namespace RC2CryptoServiceProvider_Examples
{
    class MyMainClass
    {
        public static void
 Main()
        {

            // Create a new instance of the RC2CryptoServiceProvider
 class
            // and automatically generate a Key and IV.
            RC2CryptoServiceProvider rc2CSP = new RC2CryptoServiceProvider();

            Console.WriteLine("Effective key size is {0} bits.", rc2CSP.EffectiveKeySize);

            // Get the key and IV.
            byte[] key = rc2CSP.Key;
            byte[] IV = rc2CSP.IV;

            // Get an encryptor.
            ICryptoTransform encryptor = rc2CSP.CreateEncryptor(key, IV);

            // Encrypt the data as an array of encrypted bytes in memory.
            MemoryStream msEncrypt = new MemoryStream();
            CryptoStream csEncrypt = new CryptoStream(msEncrypt,
 encryptor, CryptoStreamMode.Write);

            // Convert the data to a byte array.
            string original = "Here is some data to encrypt.";
            byte[] toEncrypt = Encoding.ASCII.GetBytes(original);

            // Write all data to the crypto stream and flush it.
            csEncrypt.Write(toEncrypt, 0, toEncrypt.Length);
            csEncrypt.FlushFinalBlock();

            // Get the encrypted array of bytes.
            byte[] encrypted = msEncrypt.ToArray();

            ///////////////////////////////////////////////////////
            // This is where the data could be transmitted or saved.
          
            ///////////////////////////////////////////////////////

            //Get a decryptor that uses the same key and IV as the encryptor.
            ICryptoTransform decryptor = rc2CSP.CreateDecryptor(key, IV);

            // Now decrypt the previously encrypted message using the
 decryptor
            // obtained in the above step.
            MemoryStream msDecrypt = new MemoryStream(encrypted);
            CryptoStream csDecrypt = new CryptoStream(msDecrypt,
 decryptor, CryptoStreamMode.Read);

            byte[] fromEncrypt = new byte[toEncrypt.Length];

            // Read the data out of the crypto stream.
            csDecrypt.Read(fromEncrypt, 0, toEncrypt.Length);

            // Convert the byte array back into a string.
            String roundtrip = Encoding.ASCII.GetString(fromEncrypt);

            // Display the original data and the decrypted data.
            Console.WriteLine("Original:   {0}", original);
            Console.WriteLine("Round Trip: {0}", roundtrip);

            Console.ReadLine();
        }
    }
}

プラットフォーム

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework
サポート対象 : 2.0、1.1、1.0
.NET Compact Framework
サポート対象 : 2.0

参照

関連項目
RC2CryptoServiceProvider クラス
RC2CryptoServiceProvider メンバ
System.Security.Cryptography 名前空間
その他の技術情報
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