TripleDES Classe

Definição

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

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.InteropServices.ComVisible(true)>]
type TripleDES = class
    inherit SymmetricAlgorithm

Public MustInherit Class TripleDES
Inherits SymmetricAlgorithm

Herança

Object

SymmetricAlgorithm

TripleDES

Derivado

System.Security.Cryptography.TripleDESCng

System.Security.Cryptography.TripleDESCryptoServiceProvider

Atributos

ComVisibleAttribute

Exemplos

O exemplo de código seguinte mostra como criar e usar um TripleDES objeto para encriptar e desencriptar dados num ficheiro.

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

O exemplo de código seguinte mostra como criar e usar um TripleDES objeto para encriptar e desencriptar dados na memória.

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

Observações

TripleDES utiliza três iterações sucessivas do DES algoritmo. Pode usar duas ou três chaves de 56 bits.

Este algoritmo suporta comprimentos de chave de 128 a 192 bits em incrementos de 64 bits.

Ver também

• Aes
• Serviços de criptografia