CryptoProvider.BlockSize Propiedad

Definición

Espacio de nombres:

System.Security.RightsManagement

Ensamblado:

WindowsBase.dll

Obtiene el tamaño del bloque cifrado, en bytes.

public:
 property int BlockSize { int get(); };

public int BlockSize { get; }

member this.BlockSize : int

Public ReadOnly Property BlockSize As Integer

Valor de propiedad

Int32

Tamaño del bloque cifrado, en bytes. El tamaño de bloque predeterminado para Advanced Encryption Standard (AES) es 8.

Ejemplos

En el ejemplo siguiente se muestra cómo usar la BlockSize propiedad para convertir datos de texto no cifrado en datos de texto cifrado.

WriteStatus("   Binding the author's UseLicense and");
WriteStatus("       obtaining the CryptoProvider.");
using (CryptoProvider cryptoProvider =
            authorsUseLicense.Bind(_secureEnv))
{
    WriteStatus("   Writing encrypted content.");
    using (Stream clearTextStream =
                File.OpenRead(contentFile) )
    {
        using (Stream cryptoTextStream =
                    File.OpenWrite(encryptedFile))
        {
            // Write the length of the source content file
            // as the first four bytes of the encrypted file.
            cryptoTextStream.Write(
                BitConverter.GetBytes(clearTextStream.Length),
                0, sizeof(Int32));

            // Allocate clearText buffer.
            byte[] clearTextBlock =
                new byte[cryptoProvider.BlockSize];

            // Encrypt clearText to cryptoText block by block.
            for(;;)
            {   // Read clearText block.
                int readCount = ReliableRead(
                                    clearTextStream,
                                    clearTextBlock, 0 ,
                                    cryptoProvider.BlockSize);
                // readCount of zero is end of data.
                if (readCount == 0)  break; // for

                // Encrypt clearText to cryptoText.
                byte[] cryptoTextBlock =
                    cryptoProvider.Encrypt(clearTextBlock);

                // Write cryptoText block.
                cryptoTextStream.Write(cryptoTextBlock, 0,
                                       cryptoTextBlock.Length);
            }
            WriteStatus("   Closing '" + encryptedFilename + "'.");
        }// end:using (Stream cryptoTextStream =
    }// end:using (Stream clearTextStream =
}// end:using (CryptoProvider cryptoProvider =
WriteStatus("   Done - Content encryption complete.");

WriteStatus("   Binding the author's UseLicense and")
WriteStatus("       obtaining the CryptoProvider.")
Using cryptoProvider As CryptoProvider = authorsUseLicense.Bind(_secureEnv)
    WriteStatus("   Writing encrypted content.")
    Using clearTextStream As Stream = File.OpenRead(contentFile)
        Using cryptoTextStream As Stream = File.OpenWrite(encryptedFile)
            ' Write the length of the source content file
            ' as the first four bytes of the encrypted file.
            Dim expression As Int32
            cryptoTextStream.Write(BitConverter.GetBytes(clearTextStream.Length), 0, Len(expression))

            ' Allocate clearText buffer.
            Dim clearTextBlock(cryptoProvider.BlockSize - 1) As Byte

            ' Encrypt clearText to cryptoText block by block.
            Do
                Dim readCount As Integer = ReliableRead(clearTextStream, clearTextBlock, 0, cryptoProvider.BlockSize)
                ' readCount of zero is end of data.
                If readCount = 0 Then ' for
                    Exit Do
                End If

                ' Encrypt clearText to cryptoText.
                Dim cryptoTextBlock() As Byte = cryptoProvider.Encrypt(clearTextBlock)

                ' Write cryptoText block.
                cryptoTextStream.Write(cryptoTextBlock, 0, cryptoTextBlock.Length)
            Loop
            WriteStatus("   Closing '" & encryptedFilename & "'.")
        End Using ' end:using (Stream cryptoTextStream =
    End Using ' end:using (Stream clearTextStream =
End Using ' end:using (CryptoProvider cryptoProvider =
WriteStatus("   Done - Content encryption complete.")

Comentarios

Los clearText búferes y pasados a Encrypt y cipherText Decrypt deben ser n*BlockSize bytes de longitud, donde 'n' es un entero mayor o igual que 1.

Si CanMergeBlocks es false, los búferes pasados a Encrypt deben tener la misma longitud que los búferes pasados a Decrypt.

Si CanMergeBlocks es true, los búferes pasados a Encrypt pueden ser una longitud diferente de los búferes pasados a Decrypt (todos los tamaños de búfer deben ser siempre un múltiplo de bytes de BlockSize longitud).

Un BlockSize de 1 indica que el cifrado es un cifrado de flujo; un BlockSize de 2 o superior indica un cifrado de bloque.