TripleDES クラス

定義

public ref class TripleDES abstract : System::Security::Cryptography::SymmetricAlgorithm

public abstract class TripleDES : System.Security.Cryptography.SymmetricAlgorithm

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public abstract class TripleDES : System.Security.Cryptography.SymmetricAlgorithm

[System.Runtime.InteropServices.ComVisible(true)]
public abstract class TripleDES : System.Security.Cryptography.SymmetricAlgorithm

type TripleDES = class
    inherit SymmetricAlgorithm

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
type TripleDES = class
    inherit SymmetricAlgorithm

[<System.Runtime.InteropServices.ComVisible(true)>]
type TripleDES = class
    inherit SymmetricAlgorithm

Public MustInherit Class TripleDES
Inherits SymmetricAlgorithm

継承

Object

SymmetricAlgorithm

TripleDES

派生

System.Security.Cryptography.TripleDESCng

System.Security.Cryptography.TripleDESCryptoServiceProvider

属性

UnsupportedOSPlatformAttribute ComVisibleAttribute

例

次のコード例は、 TripleDES オブジェクトを作成して使用して、ファイル内のデータを暗号化および復号化する方法を示しています。

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

class TripleDESSample
{
    static void Main()
    {
        try
        {
            byte[] key;
            byte[] iv;

            // Create a new TripleDES object to generate a random key
            // and initialization vector (IV).
            using (TripleDES tripleDes = TripleDES.Create())
            {
                key = tripleDes.Key;
                iv = tripleDes.IV;
            }

            // Create a string to encrypt.
            string original = "Here is some data to encrypt.";
            // The name/path of the file to write.
            string filename = "CText.enc";

            // Encrypt the string to a file.
            EncryptTextToFile(original, filename, key, iv);

            // Decrypt the file back to a string.
            string decrypted = DecryptTextFromFile(filename, key, iv);

            // Display the decrypted string to the console.
            Console.WriteLine(decrypted);
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
    }

    public static void EncryptTextToFile(string text, string path, byte[] key, byte[] iv)
    {
        try
        {
            // Create or open the specified file.
            using (FileStream fStream = File.Open(path, FileMode.Create))
            // Create a new TripleDES object.
            using (TripleDES tripleDes = TripleDES.Create())
            // Create a TripleDES encryptor from the key and IV
            using (ICryptoTransform encryptor = tripleDes.CreateEncryptor(key, iv))
            // Create a CryptoStream using the FileStream and encryptor
            using (var cStream = new CryptoStream(fStream, encryptor, CryptoStreamMode.Write))
            {
                // Convert the provided string to a byte array.
                byte[] toEncrypt = Encoding.UTF8.GetBytes(text);

                // Write the byte array to the crypto stream.
                cStream.Write(toEncrypt, 0, toEncrypt.Length);
            }
        }
        catch (CryptographicException e)
        {
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message);
            throw;
        }
    }

    public static string DecryptTextFromFile(string path, byte[] key, byte[] iv)
    {
        try
        {
            // Open the specified file
            using (FileStream fStream = File.OpenRead(path))
            // Create a new TripleDES object.
            using (TripleDES tripleDes = TripleDES.Create())
            // Create a TripleDES decryptor from the key and IV
            using (ICryptoTransform decryptor = tripleDes.CreateDecryptor(key, iv))
            // Create a CryptoStream using the FileStream and decryptor
            using (var cStream = new CryptoStream(fStream, decryptor, CryptoStreamMode.Read))
            // Create a StreamReader to turn the bytes back into text
            using (StreamReader reader = new StreamReader(cStream, Encoding.UTF8))
            {
                // Read back all of the text from the StreamReader, which receives
                // the decrypted bytes from the CryptoStream, which receives the
                // encrypted bytes from the FileStream.
                return reader.ReadToEnd();
            }
        }
        catch (CryptographicException e)
        {
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message);
            throw;
        }
    }
}

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

Module TripleDESSample

    Sub Main()
        Try
            Dim key As Byte()
            Dim iv As Byte()

            ' Create a new TripleDES object to generate a key
            ' and initialization vector (IV).
            Using tripleDes As TripleDES = TripleDES.Create
                key = tripleDes.Key
                iv = tripleDes.IV
            End Using

            ' Create a string to encrypt.
            Dim original As String = "Here is some data to encrypt."
            ' The name/path of the file to write.
            Dim filename As String = "CText.enc"

            ' Encrypt the string to a file.
            EncryptTextToFile(original, filename, key, iv)

            ' Decrypt the file back to a string.
            Dim decrypted As String = DecryptTextFromFile(filename, key, iv)

            ' Display the decrypted string to the console.
            Console.WriteLine(decrypted)
        Catch e As Exception
            Console.WriteLine(e.Message)
        End Try
    End Sub


    Sub EncryptTextToFile(text As String, path As String, key As Byte(), iv As Byte())
        Try
            ' Create or open the specified file.
            ' Create a new TripleDES object,
            ' Create a TripleDES encryptor from the key and IV,
            ' Create a CryptoStream using the MemoryStream And encryptor
            Using fStream As FileStream = File.Open(path, FileMode.Create),
                tripleDes As TripleDES = TripleDES.Create,
                encryptor As ICryptoTransform = tripleDes.CreateEncryptor(key, iv),
                cStream = New CryptoStream(fStream, encryptor, CryptoStreamMode.Write)

                ' Convert the passed string to a byte array.
                Dim toEncrypt As Byte() = Encoding.UTF8.GetBytes(text)

                ' Write the byte array to the crypto stream.
                cStream.Write(toEncrypt, 0, toEncrypt.Length)
            End Using

        Catch e As CryptographicException
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message)
            Throw
        End Try
    End Sub


    Function DecryptTextFromFile(path As String, key As Byte(), iv As Byte()) As String
        Try
            ' Open the specified file
            ' Create a new TripleDES object.
            ' Create a TripleDES decryptor from the key and IV
            ' Create a CryptoStream using the MemoryStream and decryptor
            ' Create a StreamReader to turn the bytes back into text
            Using mStream As FileStream = File.OpenRead(path),
                tripleDes As TripleDES = TripleDES.Create,
                decryptor As ICryptoTransform = tripleDes.CreateDecryptor(key, iv),
                cStream = New CryptoStream(mStream, decryptor, CryptoStreamMode.Read),
                reader = New StreamReader(cStream, Encoding.UTF8)

                ' Read back all of the text from the StreamReader, which receives
                ' the decrypted bytes from the CryptoStream, which receives the
                ' encrypted bytes from the FileStream.
                Return reader.ReadToEnd()
            End Using
        Catch e As CryptographicException
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message)
            Return Nothing
        End Try
    End Function
End Module

次のコード例は、 TripleDES オブジェクトを作成して使用して、メモリ内のデータを暗号化および復号化する方法を示しています。

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

class TripleDESSample2
{
    static void Main()
    {
        try
        {
            byte[] key;
            byte[] iv;

            // Create a new TripleDES object to generate a random key
            // and initialization vector (IV).
            using (TripleDES tripleDes = TripleDES.Create())
            {
                key = tripleDes.Key;
                iv = tripleDes.IV;
            }

            // Create a string to encrypt.
            string original = "Here is some data to encrypt.";

            // Encrypt the string to an in-memory buffer.
            byte[] encrypted = EncryptTextToMemory(original, key, iv);

            // Decrypt the buffer back to a string.
            string decrypted = DecryptTextFromMemory(encrypted, key, iv);

            // Display the decrypted string to the console.
            Console.WriteLine(decrypted);
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
    }

    public static byte[] EncryptTextToMemory(string text, byte[] key, byte[] iv)
    {
        try
        {
            // Create a MemoryStream.
            using (MemoryStream mStream = new MemoryStream())
            {
                // Create a new TripleDES object.
                using (TripleDES tripleDes = TripleDES.Create())
                // Create a TripleDES encryptor from the key and IV
                using (ICryptoTransform encryptor = tripleDes.CreateEncryptor(key, iv))
                // Create a CryptoStream using the MemoryStream and encryptor
                using (var cStream = new CryptoStream(mStream, encryptor, CryptoStreamMode.Write))
                {
                    // Convert the provided string to a byte array.
                    byte[] toEncrypt = Encoding.UTF8.GetBytes(text);

                    // Write the byte array to the crypto stream and flush it.
                    cStream.Write(toEncrypt, 0, toEncrypt.Length);

                    // Ending the using statement for the CryptoStream completes the encryption.
                }

                // Get an array of bytes from the MemoryStream that holds the encrypted data.
                byte[] ret = mStream.ToArray();

                // Return the encrypted buffer.
                return ret;
            }
        }
        catch (CryptographicException e)
        {
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message);
            throw;
        }
    }

    public static string DecryptTextFromMemory(byte[] encrypted, byte[] key, byte[] iv)
    {
        try
        {
            // Create a buffer to hold the decrypted data.
            // TripleDES-encrypted data will always be slightly bigger than the decrypted data.
            byte[] decrypted = new byte[encrypted.Length];
            int offset = 0;

            // Create a new MemoryStream using the provided array of encrypted data.
            using (MemoryStream mStream = new MemoryStream(encrypted))
            {
                // Create a new TripleDES object.
                using (TripleDES tripleDes = TripleDES.Create())
                // Create a TripleDES decryptor from the key and IV
                using (ICryptoTransform decryptor = tripleDes.CreateDecryptor(key, iv))
                // Create a CryptoStream using the MemoryStream and decryptor
                using (var cStream = new CryptoStream(mStream, decryptor, CryptoStreamMode.Read))
                {
                    // Keep reading from the CryptoStream until it finishes (returns 0).
                    int read = 1;

                    while (read > 0)
                    {
                        read = cStream.Read(decrypted, offset, decrypted.Length - offset);
                        offset += read;
                    }
                }
            }

            // Convert the buffer into a string and return it.
            return Encoding.UTF8.GetString(decrypted, 0, offset);
        }
        catch (CryptographicException e)
        {
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message);
            throw;
        }
    }
}

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

Module MemorySample

    Sub Main()
        Try
            Dim key As Byte()
            Dim iv As Byte()

            ' Create a new TripleDES object to generate a key
            ' and initialization vector (IV).
            Using tripleDes As TripleDES = TripleDES.Create
                key = tripleDes.Key
                iv = tripleDes.IV
            End Using

            ' Create a string to encrypt.
            Dim original As String = "Here is some data to encrypt."

            ' Encrypt the string to an in-memory buffer.
            Dim encrypted As Byte() = EncryptTextToMemory(original, key, iv)

            ' Decrypt the buffer back to a string.
            Dim decrypted As String = DecryptTextFromMemory(encrypted, key, iv)

            ' Display the decrypted string to the console.
            Console.WriteLine(decrypted)
        Catch e As Exception
            Console.WriteLine(e.Message)
        End Try
    End Sub


    Function EncryptTextToMemory(text As String, key As Byte(), iv As Byte()) As Byte()
        Try
            ' Create a MemoryStream.
            Using mStream As New MemoryStream
                ' Create a new TripleDES object,
                ' Create a TripleDES encryptor from the key and IV,
                ' Create a CryptoStream using the MemoryStream And encryptor
                Using tripleDes As TripleDES = TripleDES.Create,
                    encryptor As ICryptoTransform = tripleDes.CreateEncryptor(key, iv),
                    cStream = New CryptoStream(mStream, encryptor, CryptoStreamMode.Write)

                    ' Convert the passed string to a byte array.
                    Dim toEncrypt As Byte() = Encoding.UTF8.GetBytes(text)

                    ' Write the byte array to the crypto stream and flush it.
                    cStream.Write(toEncrypt, 0, toEncrypt.Length)

                    ' Ending the using block for the CryptoStream completes the encryption.
                End Using

                ' Get an array of bytes from the MemoryStream that holds the encrypted data.
                Dim ret As Byte() = mStream.ToArray()

                ' Return the encrypted buffer.
                Return ret
            End Using
        Catch e As CryptographicException
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message)
            Throw
        End Try
    End Function


    Function DecryptTextFromMemory(encrypted As Byte(), key As Byte(), iv As Byte()) As String
        Try
            ' Create a buffer to hold the decrypted data.
            ' TripleDES-encrypted data will always be slightly bigger than the decrypted data.
            Dim decrypted(encrypted.Length - 1) As Byte
            Dim offset As Integer = 0

            ' Create a new MemoryStream using the provided array of encrypted data.
            ' Create a new TripleDES object.
            ' Create a TripleDES decryptor from the key and IV
            ' Create a CryptoStream using the MemoryStream and decryptor
            Using mStream As New MemoryStream(encrypted),
                tripleDes As TripleDES = TripleDES.Create,
                decryptor As ICryptoTransform = tripleDes.CreateDecryptor(key, iv),
                cStream = New CryptoStream(mStream, decryptor, CryptoStreamMode.Read)

                ' Keep reading from the CryptoStream until it finishes (returns 0).
                Dim read As Integer = 1

                While (read > 0)
                    read = cStream.Read(decrypted, offset, decrypted.Length - offset)
                    offset += read
                End While
            End Using

            ' Convert the buffer into a string and return it.
            Return New ASCIIEncoding().GetString(decrypted, 0, offset)
        Catch e As CryptographicException
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message)
            Return Nothing
        End Try
    End Function
End Module

注釈

TripleDES では、 DES アルゴリズムの 3 つの反復が使用されます。 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 ビットまでのキー長を 64 ビットずつサポートします。

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