TripleDES クラスとは何？わかりやすく解説 Weblio辞書

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TripleDES クラス

すべての TripleDES の実装の派生元となる TDES (Triple Data Encryption Standard) アルゴリズムの基本クラスを表します。

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

Visual Basic (宣言)

<ComVisibleAttribute(True)> _
Public MustInherit Class
 TripleDES
    Inherits SymmetricAlgorithm

Visual Basic (使用法)

Dim instance As TripleDES

[ComVisibleAttribute(true)] 
public abstract class TripleDES : SymmetricAlgorithm

C++

[ComVisibleAttribute(true)] 
public ref class TripleDES abstract : public
 SymmetricAlgorithm

/** @attribute ComVisibleAttribute(true) */ 
public abstract class TripleDES extends SymmetricAlgorithm

JScript

ComVisibleAttribute(true) 
public abstract class TripleDES extends
 SymmetricAlgorithm

解説

TripleDES では、3 つの連続した DES アルゴリズムの反復を使用します。2 つまたは 3 つの 56 ビットキーを使用できます。

このアルゴリズムは、128 ビットから 192 ビットのキー長を 64 ビット単位でサポートしています。

使用例

指定したキー (Key) と初期化ベクタ (IV) で TripleDESCryptoServiceProvider を使用して、inName で指定したファイルを暗号化するメソッドを次のコード例に示します。このメソッドは、暗号化の結果を outName で指定したファイルに出力します。

Visual Basic

Private Shared Sub EncryptData(inName
 As String, outName As
 String, _
   tdesKey() As Byte, tdesIV() As
 Byte)
   
    'Create the file streams to handle the input and output files.
    Dim fin As New FileStream(inName,
 FileMode.Open, FileAccess.Read)
    Dim fout As New FileStream(outName,
 FileMode.OpenOrCreate, _
       FileAccess.Write)
    fout.SetLength(0)
        
    'Create variables to help with read and write.
    Dim bin(100) As Byte
 'This is intermediate storage for the encryption.
    Dim rdlen As Long =
 0 'This is the total number of bytes written.
    Dim totlen As Long =
 fin.Length 'This is the total length of the input file.
    Dim len As Integer 'This
 is the number of bytes to be written at a time.
    Dim tdes As New TripleDESCryptoServiceProvider()
    Dim encStream As New
 CryptoStream(fout, _
       tdes.CreateEncryptor(tdesKey, tdesIV), CryptoStreamMode.Write)
        
    Console.WriteLine("Encrypting...")
        
    'Read from the input file, then encrypt and write to the output
 file.
    While rdlen < totlen
        len = fin.Read(bin, 0, 100)
        encStream.Write(bin, 0, len)
        rdlen = rdlen + len
        Console.WriteLine("{0} bytes processed", rdlen)
    End While
        
    encStream.Close()
End Sub

private static void EncryptData(String
 inName, String outName, byte[] tdesKey, byte[] tdesIV)
{    
    //Create the file streams to handle the input and output files.
    FileStream fin = new FileStream(inName, FileMode.Open, FileAccess.Read);
    FileStream fout = new FileStream(outName, FileMode.OpenOrCreate
,
 FileAccess.Write);
    fout.SetLength(0);
      
    //Create variables to help with read and write.
    byte[] bin = new byte[100]; //This is intermediate
 storage for the encryption.
    long rdlen = 0;              //This is the total number of bytes
 written.
    long totlen = fin.Length;    //This is the total length of the input
 file.
    int len;                     //This is the number
 of bytes to be written at a time.

    TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
          
    CryptoStream encStream = new CryptoStream(fout, tdes.CreateEncryptor(tdesKey,
 tdesIV), CryptoStreamMode.Write);
               
    Console.WriteLine("Encrypting...");

    //Read from the input file, then encrypt and write to the output
 file.
    while(rdlen < totlen)
    {
        len = fin.Read(bin, 0, 100);
        encStream.Write(bin, 0, len);
        rdlen = rdlen + len;
        Console.WriteLine("{0} bytes processed", rdlen);
    }

    encStream.Close();                     
}

C++

void EncryptData( String^ inName, String^ outName, array<Byte>^tdesKey,
 array<Byte>^tdesIV )
{
   
   //Create the file streams to handle the input and output files.
   FileStream^ fin = gcnew FileStream( inName,FileMode::Open,FileAccess::Read );
   FileStream^ fout = gcnew FileStream( outName,FileMode::OpenOrCreate,FileAccess::Write
 );
   fout->SetLength( 0 );
   
   //Create variables to help with read and write.
   array<Byte>^bin = gcnew array<Byte>(100);
   long rdlen = 0; //This is the total number of bytes written.

   long totlen = (long)fin->Length; //This is the total length of
 the input file.

   int len; //This is the number of bytes to be written
 at a time.

   TripleDESCryptoServiceProvider^ tdes = gcnew TripleDESCryptoServiceProvider;
   CryptoStream^ encStream = gcnew CryptoStream( fout,tdes->CreateEncryptor( tdesKey,
 tdesIV ),CryptoStreamMode::Write );
   Console::WriteLine( "Encrypting..." );
   
   //Read from the input file, then encrypt and write to the output
 file.
   while ( rdlen < totlen )
   {
      len = fin->Read( bin, 0, 100 );
      encStream->Write( bin, 0, len );
      rdlen = rdlen + len;
      Console::WriteLine( "{0} bytes processed", rdlen );
   }

   encStream->Close();
}

private static void EncryptData(String
 inName, String outName, 
    ubyte tdesKey[],ubyte tdesIV[])
{
    //Create the file streams to handle the input and output files.
    FileStream fin = new FileStream(inName, FileMode.Open,
        FileAccess.Read);
    FileStream fout = new FileStream(outName, FileMode.OpenOrCreate
,
        FileAccess.Write);
    fout.SetLength(0);

    //Create variables to help with read and write.
    ubyte bin[] = new ubyte[100];//This is intermediate
 storage for the 
                                 //encryption.
    long rdlen = 0; //This is the total number of bytes written.
    long totlen = fin.get_Length(); //This is the total length 
                                    //of the input file.
    int len; //This is the number of bytes to be written
 at a time.

    TripleDESCryptoServiceProvider tdes =
            new TripleDESCryptoServiceProvider();
    CryptoStream encStream = new CryptoStream(fout,
        tdes.CreateEncryptor(tdesKey, tdesIV), CryptoStreamMode.Write);
    Console.WriteLine("Encrypting...");

    //Read from the input file, then encrypt and write to the output
 file.
    while ((rdlen < totlen)) {
        len = fin.Read(bin, 0, 100);
        encStream.Write(bin, 0, len);
        rdlen = rdlen + len;
        Console.WriteLine("{0} bytes processed",
            System.Convert.ToString(rdlen));
    }
    encStream.Close();
} //EncryptData

復号化も同じ方法で処理できます。ただし、その場合は CreateEncryptor の代わりに CreateDecryptor を使用します。復号化では、ファイルの暗号化に使用したものと同じキー (Key) と初期化ベクタ (IV) を使用する必要があります。

継承階層

System.Object
   System.Security.Cryptography.SymmetricAlgorithm
    System.Security.Cryptography.TripleDES
       System.Security.Cryptography.TripleDESCryptoServiceProvider

スレッドセーフ

この型の public static (Visual Basic では Shared) メンバはすべて、スレッドセーフです。インスタンスメンバの場合は、スレッドセーフであるとは限りません。

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