DES Class

Represents the base class for the Data Encryption Standard (DES) algorithm from which all DES implementations must derive.

Namespace:  System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

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

The DES type exposes the following members.

  NameDescription
Protected methodDESInitializes a new instance of the DES class.
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  NameDescription
Public propertyBlockSizeGets or sets the block size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm.)
Public propertyFeedbackSizeGets or sets the feedback size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm.)
Public propertyIVGets or sets the initialization vector (IV) for the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Public propertyKeyGets or sets the secret key for the Data Encryption Standard (DES) algorithm. (Overrides SymmetricAlgorithm.Key.)
Public propertyKeySizeGets or sets the size, in bits, of the secret key used by the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Public propertyLegalBlockSizesGets the block sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Public propertyLegalKeySizesGets the key sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Public propertyModeGets or sets the mode for operation of the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Public propertyPaddingGets or sets the padding mode used in the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
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  NameDescription
Public methodClearReleases all resources used by the SymmetricAlgorithm class. (Inherited from SymmetricAlgorithm.)
Public methodStatic memberCreate()Creates an instance of a cryptographic object to perform the Data Encryption Standard (DES) algorithm.
Public methodStatic memberCreate(String)Creates an instance of a cryptographic object to perform the specified implementation of the Data Encryption Standard (DES) algorithm.
Public methodCreateDecryptor()Creates a symmetric decryptor object with the current Key property and initialization vector (IV). (Inherited from SymmetricAlgorithm.)
Public methodCreateDecryptor(Byte[], Byte[])When overridden in a derived class, creates a symmetric decryptor object with the specified Key property and initialization vector (IV). (Inherited from SymmetricAlgorithm.)
Public methodCreateEncryptor()Creates a symmetric encryptor object with the current Key property and initialization vector (IV). (Inherited from SymmetricAlgorithm.)
Public methodCreateEncryptor(Byte[], Byte[])When overridden in a derived class, creates a symmetric encryptor object with the specified Key property and initialization vector (IV). (Inherited from SymmetricAlgorithm.)
Public methodDispose()Releases all resources used by the current instance of the SymmetricAlgorithm class. (Inherited from SymmetricAlgorithm.)
Protected methodDispose(Boolean)Releases the unmanaged resources used by the SymmetricAlgorithm and optionally releases the managed resources. (Inherited from SymmetricAlgorithm.)
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGenerateIVWhen overridden in a derived class, generates a random initialization vector (IV) to use for the algorithm. (Inherited from SymmetricAlgorithm.)
Public methodGenerateKeyWhen overridden in a derived class, generates a random key (Key) to use for the algorithm. (Inherited from SymmetricAlgorithm.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodStatic memberIsSemiWeakKeyDetermines whether the specified key is semi-weak.
Public methodStatic memberIsWeakKeyDetermines whether the specified key is weak.
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodValidKeySizeDetermines whether the specified key size is valid for the current algorithm. (Inherited from SymmetricAlgorithm.)
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  NameDescription
Protected fieldBlockSizeValueRepresents the block size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm.)
Protected fieldFeedbackSizeValueRepresents the feedback size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm.)
Protected fieldIVValueRepresents the initialization vector (IV) for the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Protected fieldKeySizeValueRepresents the size, in bits, of the secret key used by the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Protected fieldKeyValueRepresents the secret key for the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Protected fieldLegalBlockSizesValueSpecifies the block sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Protected fieldLegalKeySizesValueSpecifies the key sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Protected fieldModeValueRepresents the cipher mode used in the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Protected fieldPaddingValueRepresents the padding mode used in the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
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This algorithm supports a key length of 64 bits.

NoteNote

A newer asymmetric encryption algorithm, Advanced Encryption Standard (AES), is available. Consider using the Aes class instead of the DES class. Use DES only for compatibility with legacy applications and data.

The following code example uses DESCryptoServiceProvider (an implementation of DES) to encrypt a string to an in-memory buffer. It then decrypts and displays the round-tripped string.

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

namespace TripleDESCryptoServiceProvider_Example
{
    class TripleDESManagedExample
    {
        public static void Main()
        {
            try
            {

                string original = "Here is some data to encrypt!";

                // Create a new instance of the TripleDESCryptoServiceProvider 
                // class.  This generates a new key and initialization  
                // vector (IV). 
                using (TripleDESCryptoServiceProvider myTripleDES = new TripleDESCryptoServiceProvider())
                {
                    // Encrypt the string to an array of bytes. 
                    byte[] encrypted = EncryptStringToBytes(original, myTripleDES.Key, myTripleDES.IV);

                    // Decrypt the bytes to a string. 
                    string roundtrip = DecryptStringFromBytes(encrypted, myTripleDES.Key, myTripleDES.IV);

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

            }
            catch (Exception e)
            {
                Console.WriteLine("Error: {0}", e.Message);
            }
        }
        static byte[] EncryptStringToBytes(string plainText, byte[] Key, byte[] IV)
        {
            // Check arguments. 
            if (plainText == null || plainText.Length <= 0)
                throw new ArgumentNullException("plainText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("Key");
            byte[] encrypted;
            // Create an TripleDESCryptoServiceProvider object 
            // with the specified key and IV. 
            using (TripleDESCryptoServiceProvider tdsAlg = new TripleDESCryptoServiceProvider())
            {
                tdsAlg.Key = Key;
                tdsAlg.IV = IV;

                // Create a decrytor to perform the stream transform.
                ICryptoTransform encryptor = tdsAlg.CreateEncryptor(tdsAlg.Key, tdsAlg.IV);

                // Create the streams used for encryption. 
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {

                            //Write all data to the stream.
                            swEncrypt.Write(plainText);
                        }
                        encrypted = msEncrypt.ToArray();
                    }
                }
            }


            // Return the encrypted bytes from the memory stream. 
            return encrypted;

        }

        static string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV)
        {
            // Check arguments. 
            if (cipherText == null || cipherText.Length <= 0)
                throw new ArgumentNullException("cipherText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("Key");

            // Declare the string used to hold 
            // the decrypted text. 
            string plaintext = null;

            // Create an TripleDESCryptoServiceProvider object 
            // with the specified key and IV. 
            using (TripleDESCryptoServiceProvider tdsAlg = new TripleDESCryptoServiceProvider())
            {
                tdsAlg.Key = Key;
                tdsAlg.IV = IV;

                // Create a decrytor to perform the stream transform.
                ICryptoTransform decryptor = tdsAlg.CreateDecryptor(tdsAlg.Key, tdsAlg.IV);

                // Create the streams used for decryption. 
                using (MemoryStream msDecrypt = new MemoryStream(cipherText))
                {
                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                        {

                            // Read the decrypted bytes from the decrypting stream 
                            // and place them in a string.
                            plaintext = srDecrypt.ReadToEnd();
                        }
                    }
                }

            }

            return plaintext;

        }
    }
}

Decryption can be handled in the same way; use CreateDecryptor instead of CreateEncryptor. The same key (Key) and initialization vector (IV) used to encrypt the file must be used to decrypt it.

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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